As filed with the U.S. Securities and Exchange Commission on March 31, 2026.

Registration No. 333-291359​

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Amendment No. 3
to

FORM S-4

REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

Beacon Topco, Inc.*

(Exact name of Registrant as specified in its charter)

Beacon Topco, Inc.
20400 Century Boulevard, Suite 210
Germantown, MD 20874
(443) 917-0966

(Address, including zip code, and telephone number, including area code, of Registrant’s principal executive offices)

William Enright
Chief Executive Officer
20400 Century Boulevard, Suite 210
Germantown, MD 20874
(443) 917-0966

(Name, address, including zip code, and telephone number, including area code, of agent for service)

with copies to:

Approximate date of commencement of proposed sale of the securities to the public:   As soon as practicable after this registration statement becomes effective and upon completion of the transactions described in this registration statement.

If the securities being registered on this Form are being offered in connection with the formation of a holding company, and there is compliance with General Instruction G, check the following box.  ☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.  ☐

If applicable, place an X in the box to designate the appropriate rule provision relied upon in conducting this transaction:

Exchange Act Rule 13e-4(i) (Cross-Border Issuer Tender Offer)  ☐

Exchange Act Rule 14d-1(d) (Cross-Border Third-Party Tender Offer)  ☐

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act, or until the registration statement shall become effective on such date as the Securities and Exchange Commission, pursuant to said Section 8(a), may determine.

*

The registrant is currently named Beacon Topco, Inc. The registrant plans to change its name to “Clywedog Therapeutics Holdings, Inc.” following the effective date of this registration statement and completion of the transactions described in the enclosed proxy statement/​prospectus.

​

Information contained in this proxy statement/prospectus is subject to completion or amendment. A registration statement relating to the securities being offered by this proxy statement/prospectus has been filed with the U.S. Securities and Exchange Commission. These securities may not be sold nor may offers to buy these securities be accepted prior to the time the registration statement becomes effective. This document shall not constitute an offer to sell or the solicitation of any offer to buy nor shall there be any sale of such securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction.​

PRELIMINARY — SUBJECT TO COMPLETION, DATED MARCH 31, 2026

BUSINESS COMBINATIONS PROPOSED — YOUR VOTE IS VERY IMPORTANT

[•], 2026​

On September 29, 2025, Barinthus Biotherapeutics plc, a public limited company organized under the laws of England and Wales (“Barinthus Bio”), entered into an Agreement and Plan of Merger (as amended or otherwise modified prior to February 22, 2026, the “Original Merger Agreement”), as amended by that certain Amendment to the Agreement and Plan of Merger, dated as of February 22, 2026 (such amendment, the “Merger Agreement Amendment” and, together with the Original Merger Agreement, as it may be further amended or modified from time to time, the “Merger Agreement”) with Beacon Topco, Inc. (“Topco”), a Delaware corporation and a direct wholly owned subsidiary of Barinthus Bio, Cdog Merger Sub, Inc. (“Merger Sub”), a Delaware corporation and a direct wholly owned subsidiary of Topco, and Clywedog Therapeutics, Inc., a Delaware corporation (“Clywedog”), which provides for, amongst other things, the acquisition of Barinthus Bio and Clywedog by Topco (together, the “Combinations”). The combined company will advance a novel portfolio of clinical-stage candidates targeting metabolic and autoimmune diseases. You are receiving this proxy statement/prospectus to ask you to vote in favor of these transactions and other related matters.

Pursuant to the Merger Agreement, the Combinations are expected to be implemented as follows: (i) Topco will acquire the entire issued and to be issued share capital of Barinthus Bio pursuant to (i) a scheme of arrangement (subject to any modification, addition or condition which (a) Barinthus Bio, Topco and Clywedog mutually agree and which (if required) is approved by the High Court of Justice of England and Wales (the “Court”) or (b) is otherwise imposed by the Court and mutually acceptable to Barinthus Bio, Topco and Clywedog, each acting reasonably and in good faith, in each case in accordance with Part 26 of the United Kingdom Companies Act 2006 (the “UK Companies Act”) pursuant to which the entire issued and to be issued ordinary share capital of Barinthus Bio will be acquired (the “Scheme of Arrangement”), (ii) a share purchase agreement pursuant to which the deferred A shares in the capital of Barinthus Bio will be acquired by Topco subject to and upon effectiveness of the Scheme of Arrangement, and (iii) the Merger Agreement (such transaction, together with the Scheme of Arrangement, the “Scheme Transaction”), resulting in Barinthus Bio becoming a direct wholly owned subsidiary of Topco, and (ii) Merger Sub will merge with and into Clywedog, with Clywedog continuing as the surviving corporation and a direct wholly owned subsidiary of Topco in accordance with the General Corporation Law of the State of Delaware (the “Merger”). The Scheme Transaction will be consummated prior to the Merger.

At the effective time of the Scheme Transaction (the “Scheme Effective Time”), upon the terms and subject to the conditions set forth in the Merger Agreement, Topco will acquire each outstanding ordinary share of Barinthus Bio, with a par value £0.000025 per share (the “Barinthus Ordinary Shares,” and each such acquired Barinthus Ordinary Share, a “Scheme Share”), which, for the avoidance of doubt, will include Barinthus Ordinary Shares held by The Bank of New York Mellon (the “Depositary”) (and represented by American Depositary Shares (the “Barinthus ADSs”), each representing one (1) Barinthus Ordinary Share, dated as of April 29, 2021, among Barinthus Bio, the Depositary, and all holders from time to time of the Barinthus ADS, as may be amended from time to time), from the holders of Scheme Shares whose names appear in the register of members of Barinthus Bio at the Scheme Effective Time) in accordance with the provisions of the Scheme of Arrangement, and each Scheme Share will be converted into the right to receive (i) between 0.1 and 0.166667, as finally determined by the Board of Directors of Barinthus Bio (or a duly appointed committee thereof) in its sole discretion prior to the Scheme Effective Time, shares of common stock, $0.0001 par value per share, of Topco (the “Topco Common Stock”), rounded down to the nearest whole share, plus (ii) cash in lieu of any fraction of a real share, each subject to and strictly in accordance with the terms of the Scheme of Arrangement. Following the Scheme Effective Time, Topco may in its discretion elect to commence a self-tender offer (the “Self-Tender Offer” and together with the Combinations and the other transactions contemplated by the Merger Agreement, including without limitation, the Scheme of Arrangement and Stock Issuance, the “Transactions”) to purchase up to $27,000,000 in shares of Topco Common Stock then issued and outstanding, which Self-Tender Offer, if elected, will be consummated prior to the Merger. Barinthus Bio may elect to commence the Self-Tender Offer for an aggregate amount less than $27,000,000 based on the cash balance of Barinthus Bio as well as the trading price of Barinthus Bio shares and aggregate market capitalization as of immediately prior to the Scheme Effective Time.

At the effective time of the Merger (the “Merger Effective Time”), subject to adjustment in accordance with the terms of the Merger Agreement, each share of common stock, $0.0001 par value per share, of Clywedog (the “Clywedog

Common Stock”) and each share of Series Seed Preferred Stock, $0.0001 par value per share, of Clywedog (the “Clywedog Preferred Stock,” and together with the Clywedog Common Stock, the “Clywedog Shares”), other than Clywedog Shares held as treasury stock or owned by Topco or Merger Sub immediately prior to the Merger Effective Time, will be converted solely into the right to receive (i) between 0.000305 and 0.000508, as finally determined by Clywedog and Barinthus Bio, of shares of Topco Common Stock (the “Merger Exchange Ratio”), rounded down to the nearest whole share, plus (ii) cash in lieu of any fraction of a share. Pursuant to the terms of the Merger Agreement, the Merger Exchange Ratio will be adjusted proportionately to reflect the number of outstanding shares of Topco Common Stock held by former Beacon shareholders as of immediately prior to the Merger (giving effect to the Self-Tender Offer, if elected).

The aggregate number of shares of Topco Common Stock that Topco expects to issue to Barinthus Bio shareholders and Clywedog securityholders at the closing of the Transactions is 20,678,394.00 shares, assuming the Scheme Transactions had occurred and the consummation of the Self-Tender Offer for the purchase price of $20.25 million, representing 75% of the full purchase price of $27 million, at an offer price of $0.60, the closing price of Barinthus ADSs on March 12, 2026. The market value of the shares of Topco Common Stock that will be issued to Barinthus Bio shareholders and Clywedog stockholders in the Combinations could vary significantly due to, among other things, changes in the market value of Barinthus ADSs as of the date the Original Merger Agreement was entered into, the date of this proxy statement/prospectus, the date of the Barinthus General Meeting or the date that Clywedog stockholder approval is received.

The parties intend to list the shares of Topco Common Stock on the Nasdaq Stock Market (“Nasdaq”) under the ticker symbol “CLYD.” As a result of the Combinations, Barinthus ADSs will no longer trade on the Nasdaq Global Market.

Upon closing of the Combinations, Topco will be renamed “Clywedog Therapeutics Holdings, Inc.”

Under the terms of the Merger Agreement, which was unanimously approved by the board of directors of each of Barinthus Bio and Clywedog, Barinthus Bio and Clywedog are entering into a business combination with Topco, a new holding company to be controlled by Clywedog stockholders. If the Transactions are completed, Barinthus Bio’s shareholders are expected to own approximately 34% of Topco and Clywedog’s stockholders are expected to own approximately 66% of Topco on a fully diluted basis, based on the respective capitalizations of Barinthus Bio and Clywedog as of the date the parties entered into the Original Merger Agreement. In the event Barinthus Bio elects to commence the Self-Tender Offer, the Merger Exchange Ratio will be adjusted proportionately to reflect the number of outstanding shares of Topco Common Stock held by former Beacon shareholders as of immediately prior to the Merger (giving effect to the Self-Tender Offer) such that upon the Closing, Barinthus Bio’s shareholders will own approximately 34% of Topco and Clywedog’s stockholders will own approximately 66% of Topco.

This document, which forms part of a registration statement on Form S-4 (the “Registration Statement”) filed with the U.S. Securities and Exchange Commission (the “SEC”) by Topco, is a proxy statement/prospectus for Barinthus Bio to solicit proxies for the Barinthus shareholder meetings to approve the Scheme Transaction, amend the articles of association of Barinthus Bio and authorize the directors of Barinthus Bio to take all such action as they may consider necessary or appropriate for carrying the Scheme Transaction into effect. The Registration Statement includes the scheme circular with respect to the Scheme Transaction (as required by the UK Companies Act) and registers the shares of Topco Common Stock to be issued in the Combinations.

Your vote is very important.   The parties cannot complete these transactions unless Barinthus Bio’s shareholders vote to approve the Scheme Transaction and certain matters related thereto. The Scheme Transaction also requires the sanction of the Court. IT IS IMPORTANT THAT AS MANY HOLDERS OF BARINTHUS ORDINARY SHARES AS POSSIBLE VOTE AND/OR PROVIDE VOTING INSTRUCTIONS ON THE SCHEME TRANSACTION SO THAT THE COURT MAY BE SATISFIED THAT THERE IS A FAIR AND REASONABLE REPRESENTATION OF THE OPINION OF HOLDERS OF INTERESTS IN BARINTHUS SHARES.

Please carefully read this entire document, including the section entitled “Risk Factors,” beginning on page 29 of this proxy statement/prospectus for a discussion of the risks relating to the Combinations and Topco following the Combinations. None of the SEC, any state securities regulatory authority or the UK Financial Conduct Authority (the “UK FCA”) has approved or disapproved of the Combinations or the securities to be issued in the Combinations or has passed upon the adequacy or accuracy of the disclosure in this proxy statement/prospectus. Any representation to the contrary is a criminal offense.

For the avoidance of doubt, this proxy statement/prospectus is not intended to be, and is not, a prospectus for the purposes of the Prospectus Rules made under Part 6 of the UK Financial Services and Markets Act 2000 (as set out in the UK FCA’s Handbook).

 

The accompanying proxy statement/prospectus is dated [•], 2026, and is first being mailed to Barinthus Shareholders on or about [•], 2026.

BARINTHUS BIOTHERAPEUTICS PLC

(Incorporated and registered in England and
Wales with registered number 13084624)

NOTICE OF COURT MEETING
TO BE HELD ON [•], 2026

IN THE HIGH COURT OF JUSTICE
BUSINESS AND PROPERTY COURTS OF ENGLAND AND WALES
COMPANIES COURT (ChD)

CR-2026-[•]​

IN THE MATTER OF BARINTHUS BIOTHERAPEUTICS PLC
and
IN THE MATTER OF THE UK COMPANIES ACT 2006

NOTICE IS HEREBY GIVEN that, by an order dated [•], 2026 made in the above matters, the High Court of Justice in England and Wales (the “Court”) has given permission for a meeting (the “Barinthus Court Meeting”) to be convened of the holders of Scheme Shares (as defined in the Scheme of Arrangement (as defined below)) at the Barinthus Ordinary Share Voting Record Time (as defined below) for the purpose of considering and, if thought fit, approving (with or without modification) a scheme of arrangement proposed to be made pursuant to Part 26 of the United Kingdom Companies Act 2006 (the “UK Companies Act”) between Barinthus Biotherapeutics plc (“Barinthus Bio”) and the holders of Scheme Shares (the “Scheme of Arrangement”), and that the Barinthus Court Meeting will be held at the offices of Goodwin Procter (UK) LLP at Sancroft, 10-15 Newgate Street, London, EC1A 7AZ at [•] [a.m./p.m.] (London Time) on [•], 2026, at which time all holders of Scheme Shares are able to attend in person or by proxy.

A copy of the Scheme of Arrangement and a copy of the explanatory statement required to be published pursuant to section 897 of the UK Companies Act are incorporated in the proxy statement/​prospectus of which this Notice of Barinthus Court Meeting forms a part.

Unless the context requires otherwise, any capitalized term used but not defined in this Notice of Barinthus Court Meeting shall have the meaning given to such term in the proxy statement/prospectus of which this Notice of Barinthus Court Meeting forms a part.

Voting on the resolution to approve the Scheme of Arrangement will be by poll, which shall be conducted as the Chair of the Barinthus Court Meeting (the “Court Meeting Chair”) may determine.

It is important that, for the Barinthus Court Meeting, as many votes as possible are cast so that the Court may be satisfied that there is a fair representation of the opinions of holders of Scheme Shares. At the Barinthus Court Meeting, the Scheme of Arrangement must be approved by a simple majority in number of holders of Scheme Shares present and voting, in person or by proxy, representing at least 75% in value of the Scheme Shares in respect of which a vote has been cast. Holders of Scheme Shares are strongly encouraged to submit proxy appointments and instructions for the Barinthus Court Meeting as soon as possible, using any of the methods set out below, to ensure your vote is recorded.

 

 

Holders of Barinthus Ordinary Shares

Right to vote and appoint a proxy

Holders of ordinary shares of Barinthus Bio, with a par value £0.000025 per share (the “Barinthus Ordinary Shares”) entitled to attend and vote at the Barinthus Court Meeting may attend such meeting in person or they may appoint another person or persons, whether a member of Barinthus Bio or not, as their proxy or proxies, to exercise all or any of their rights to attend, submit written questions and vote at the Barinthus Court Meeting, provided that, where more than one proxy is appointed, each proxy is appointed to exercise the rights attached to a different share or shares.

The completion and return of the BLUE Form of Proxy by post (or transmission of a proxy appointment or voting instruction electronically, online, through CREST or by any other procedure described below) will not prevent you from attending and voting at the Barinthus Court Meeting if you are entitled to and wish to do so.

Any holders of Barinthus Ordinary Share who hold their Barinthus Ordinary Shares indirectly through a broker, bank, trust company or other nominee must rely on the procedures of such broker, bank, trust company or other nominee in order to assert the rights of a holder of Barinthus Ordinary Shares to vote at the Barinthus Court Meeting. If this applies to you, Barinthus Bio encourages you to consult your broker, bank, trust company or other nominee as soon as possible to obtain the necessary documentation in order to provide voting instructions in relation to the Barinthus Court Meeting in the manner and by the cut off time stipulated by such broker, bank, trust company or other nominee. In addition, you are encouraged to provide voting instructions to your broker, bank, trust company or other nominee so that they may submit a proxy. Such holders of Barinthus Ordinary Shares who hold their Barinthus Ordinary Shares indirectly and who wish to attend, speak and vote on an individual basis (in particular, for the purpose of approval of the Scheme of Arrangement by a majority in number of the holders of Scheme Shares present and voting at the Barinthus Court Meeting), or to send a proxy or corporate representative to represent them at the Barinthus Court Meeting, may need first to arrange with their broker, bank, trust company or other nominee for the transfer of their Barinthus Ordinary Shares into their own name.

As an alternative to appointing a proxy, any holder of Barinthus Ordinary Shares which is a corporation may appoint one or more corporate representatives who may exercise on its behalf all its powers as a member (see section below for further information).

By post

A BLUE Form of Proxy, for use at the Barinthus Court Meeting, has been provided with this Notice of Barinthus Court Meeting. Instructions for its use are set out on the form. It is requested that the BLUE Form of Proxy (together with any power of attorney or other authority, if any, under which it is signed, or a duly certified copy thereof) be returned in the pre-paid envelope provided to Barinthus Bio’s Registrar, Computershare Trust Company, N.A. (“Computershare”), by post to Computershare, The Pavilions, Bridgwater Road, Bristol BS99 6ZY, United Kingdom, so as to be received as soon as possible and not later than [1:00] p.m. (London Time) on [•], 2026 (or, in the case of an adjournment or postponement of the Barinthus Court Meeting, 48 hours (excluding any part of such 48 hour period falling on a non-working day) before the time appointed for the adjourned or postponed meeting).

If the BLUE Form of Proxy for the Barinthus Court Meeting is not lodged by the relevant time, it may be presented in person to the Court Meeting Chair or Computershare representative who will be present at the Barinthus Court Meeting, at any time prior to the commencement of the Barinthus Court Meeting (or any adjournment or postponement thereof).

If you require additional proxy forms, please contact Computershare by telephone at +44 0370 730 0369 (for international callers) or by post to Computershare, The Pavilions, Bridgwater Road, Bristol BS99 6ZY, United Kingdom. Calls are charged at the standard geographic rate and will vary by provider. Calls from outside the United Kingdom will be charged at the applicable international rate. The helpline is open between 8:30 a.m. and 5:30 p.m., Monday to Friday, excluding public holidays in England and Wales. Please

 

 

note that Computershare cannot provide any financial, legal or tax advice and calls may be recorded and monitored for security and training purposes.

By CREST

If you hold Barinthus Ordinary Shares in uncertificated form through CREST and wish to appoint a proxy or proxies for the Barinthus Court Meeting (or any adjournment or postponement thereof) using the CREST electronic proxy appointment service, you may do so by using the procedures described in the CREST Manual. CREST personal members or other CREST sponsored members, and those CREST members who have appointed any voting service provider(s), should refer to their CREST sponsor or voting service provider(s), who will be able to take the appropriate action on their behalf.

In order for a proxy appointment or instruction made using the CREST service to be valid, the appropriate CREST message (a “CREST Proxy Instruction”) must be properly authenticated in accordance with the specifications of Euroclear and must contain the information required for such instructions as described in the CREST Manual. The message (regardless of whether it constitutes the appointment of a proxy or an amendment to the instructions given to a previously appointed proxy) must, in order to be valid, be transmitted so as to be received by Computershare (ID number 3RA50), not later than 48 hours (excluding any part of such 48-hour period falling on a non-working day) before the time fixed for the Barinthus Court Meeting or any adjournment or postponement thereof. For this purpose, the time of receipt will be taken to be the time (as determined by the timestamp applied to the message by the CREST Applications Host) from which Computershare is able to retrieve the message by enquiry to CREST in the manner prescribed by CREST.

If the CREST proxy appointment or instruction is not received by this time, the BLUE Form of Proxy may be presented in person to the Court Meeting Chair or Computershare representative who will be present at the Barinthus Court Meeting, at any time prior to the commencement of the Barinthus Court Meeting (or any adjournment or postponement thereof).

CREST members and, where applicable, their CREST sponsors or voting service providers should note that Euroclear does not make available special procedures in CREST for any particular messages. Normal system timings and limitations will therefore apply in relation to the input of CREST Proxy Instructions. It is the responsibility of the CREST member concerned to take (or, if the CREST member is a CREST personal member or sponsored member or has appointed any voting service provider(s), to procure that his/​her CREST sponsor or voting service provider(s) take(s)) such action as shall be necessary to ensure that a message is transmitted by means of the CREST system by any particular time. For further information on the logistics of submitting messages in CREST, CREST members and, where applicable, their CREST sponsors or voting service providers are referred, in particular, to those sections of the CREST Manual concerning practical limitations of the CREST system and timings.

Barinthus Bio may treat as invalid a CREST Proxy Instruction in the circumstances set out in Regulation 35(5)(a) of the CREST Regulations.

Barinthus Ordinary Share Voting Record Time

Entitlement to attend and vote at (in person or by proxy) the Barinthus Court Meeting or any adjournment or postponement thereof and the number of votes which may be cast at the Barinthus Court Meeting will be determined by reference to the register of members of Barinthus Bio at 6:00 p.m. (London Time) on [•], 2026 or, if the Barinthus Court Meeting is adjourned, 6:30p.m. (London Time) on the day which is two Business Days before the date of such adjourned or postponed meeting (the “Barinthus Ordinary Share Voting Record Time”). Changes to the register of members after the relevant time shall be disregarded in determining the rights of any person to attend and vote at (in person or by proxy) the Barinthus Court Meeting.

Joint holders

In the case of joint holders of Barinthus Ordinary Shares, the vote of the senior who tenders a vote, whether in person or by proxy, will be accepted to the exclusion of the vote(s) of the other joint holder(s).

 

 

For this purpose, seniority will be determined by the order in which the names stand in the register of members of Barinthus Bio in respect of the joint holding (the first being the most senior).

Corporate representatives

As an alternative to appointing a proxy, any holder of Barinthus Ordinary Shares which is a corporation may appoint one or more corporate representatives who may exercise on its behalf all its powers as a member, provided that, if two or more corporate representatives purport to vote in respect of the same shares, if they purport to exercise the power in the same way as each other, the power is treated as exercised in that way, and in other cases the power is treated as not exercised.

Holders of Barinthus ADSs

Right to vote and appoint a proxy

Holders of American Depositary Shares representing Barinthus Ordinary Shares (“Barinthus ADSs”) are not entitled to attend or vote, in person or by proxy, at the Barinthus Court Meeting. If you or your broker, bank, trust company or other nominee are a registered holder of Barinthus ADSs as of the Barinthus ADS Voting Record Time (as defined below), Barinthus Bio’s depositary, The Bank of New York Mellon (the “Depositary”), will send a Barinthus ADS voting instruction card to you. You will be able to instruct the Depositary to vote the Scheme Shares represented by your Barinthus ADSs on your behalf by completing and returning a Barinthus ADS voting instruction card to the Depositary no later than the time and date specified in the Barinthus ADS voting instruction card. Holders of Barinthus ADSs are encouraged to timely submit voting instructions to the Depositary for the Barinthus Court Meeting as soon as possible. A Barinthus ADS voting instruction card with your voting instructions must be received by the Depositary by [12:00] p.m. (Eastern Time) on [•], 2026 in the manner and at the address specified in the Barinthus ADS voting instruction card.

Holders of Barinthus ADSs who hold their Barinthus ADSs indirectly through a broker, bank, trust company or other nominee must rely on the procedures of such broker, bank, trust company or other nominee in order to assert the rights of a Barinthus ADS holder to issue voting instructions to the Depositary. You should receive voting instructions from your broker, bank, trust company or nominee. If you do not, Barinthus Bio encourages you to consult your bank, broker or nominee as soon as possible to obtain the necessary documentation. You must provide voting instructions in the manner and prior to the cut-off date and time stipulated by such broker, bank, trust company, or other nominee.

By post

If you are a registered holder of Barinthus ADSs, you may vote by mail by completing, signing and dating the enclosed Barinthus ADS voting instruction card and returning it in the enclosed postage-paid envelope. Votes submitted through the mail must be received by no later than [12:00] p.m. (Eastern Time) on [•], 2026.

If you are a registered holder of Barinthus ADSs, you can submit a new Barinthus ADS voting instruction card at any time during the Barinthus ADS voting period. If you wish to amend the Barinthus ADS voting instruction card, you must do so in writing and sign your new Barinthus ADS voting instruction card. The Barinthus ADS voting instruction card last received by the Depositary prior to the expiration of the Barinthus ADS voting period will be the one that is followed.

By internet

If you are a registered holder of Barinthus ADSs, you may vote at www.proxypush.com/BRNS, 24 hours a day, seven days a week, by following the instructions at that site for submitting your vote electronically. You will need the 12-digit control number included on your Barinthus ADS voting instruction card. Votes submitted through the Internet must be received by no later than [12:00] p.m. (Eastern Time) on [•], 2026.

 

 

By telephone

If you are a registered holder of Barinthus ADSs, you may vote using a touch-tone telephone by calling 1-855-782-8499 (toll-free from the U.S., U.S. territories and Canada), 24 hours a day, seven days a week. You will need the 12-digit control number included on your Barinthus ADS voting instruction card. Votes submitted by telephone must be received by no later than [12:00] p.m. (Eastern Time) on [•], 2026.

Barinthus ADS Voting Record Time

In order to exercise your vote as a holder of Barinthus ADSs, you must either (i) have been a registered holder of Barinthus ADSs in the Barinthus ADS register maintained by the Depositary or (ii) Barinthus ADSs must be credited to your securities account maintained with a broker or other securities intermediary that is a direct or indirect participant in The Depository Trust Company (“DTC”), in either case by [6:00] p.m., (Eastern Time) on [•], 2026 (the “Barinthus ADS Voting Record Time”).

For registered holders of Barinthus ADSs, whose Barinthus ADSs are registered under their own name, and who have any queries about the Barinthus Court Meeting, should contact Barinthus Bio at Barinthus Biotherapeutics plc, 20400 Century Boulevard, Suite 210, Germantown, MD 20874, Attention: Corporate Secretary, or MacKenzie Partners, Barinthus Bio’s proxy solicitor, by e-mailing proxy@mackenziepartners.com or calling toll-free at +1 (800) 322-2885, between 9:00 a.m. and 5:30 p.m. (London Time). For beneficial holders, if you have queries on how you can deliver voting instructions about the Barinthus Court Meeting, please contact your brokerage firm or bank who is holding the Barinthus ADSs.

Votes to be taken by a poll and results

At the Barinthus Court Meeting, voting to approve and give effect to the Scheme of Arrangement (the “Barinthus Scheme Proposal”) will be by poll. The results of the poll will be announced by the filing of a Current Report on Form 8-K with the U.S. Securities and Exchange Commission (the “SEC”) and published on Barinthus Bio’s website at www.barinthusbio.com as soon as reasonably practicable following the conclusion of the Barinthus Court Meeting.

Website providing information regarding the Barinthus Court Meeting

Information regarding the Barinthus Court Meeting and a copy of this Notice of Barinthus Court Meeting may be found on Barinthus Bio’s website at www.barinthusbio.com. The information contained on Barinthus Bio’s website is not incorporated into, and does not form a part of, this proxy statement/prospectus or any other report or document on file with or furnished to the SEC.

By the said order, the Court has appointed [•] or, failing that, any other members of Barinthus Bio’s Board of Directors to act as Court Meeting Chair and has directed the Court Meeting Chair to report the result thereof to the Court.

The Scheme of Arrangement will be subject to the subsequent sanction of the Court.

Dated [•], 2026
GOODWIN PROCTER (UK) LLP
Sancroft, 10-15 Newgate Street, London EC1A 7AZ
Solicitors for Barinthus Biotherapeutics plc​

 

 

BARINTHUS BIOTHERAPEUTICS PLC

NOTICE OF GENERAL MEETING OF
BARINTHUS BIOTHERAPEUTICS PLC
TO BE HELD ON [•], 2026

NOTICE is hereby given that a general meeting (the “Barinthus General Meeting” and, together with Barinthus Court Meeting, the “Barinthus Shareholder Meetings”) of Barinthus Biotherapeutics plc (“Barinthus Bio”) will be held at the offices of Goodwin Procter (UK) LLP at Sancroft, 10-15 Newgate Street, London, EC1A 7AZ at [•] [a.m./p.m.] (London Time) on [•], 2026 (or as soon thereafter as the Barinthus Court Meeting concludes or is adjourned or postponed) for the purpose of considering and, if thought fit, passing the following resolutions, which will be proposed as special resolutions (together, the “Scheme Implementation Proposal”):

SPECIAL RESOLUTIONS

1.

RESOLVED THAT, for the purpose of giving effect to the Scheme of Arrangement dated [•], 2025 between Barinthus Bio and the holders of Scheme Shares (as defined in such Scheme of Arrangement), a print of which has been produced to this meeting and for the purposes of identification signed by the Chair of this meeting, in its original form or with or subject to any modification, addition, or condition as may be agreed from time to time (including, for the avoidance of doubt, after the date of this resolution) between Barinthus Bio and Beacon Topco, Inc., a Delaware corporation (“Topco”), which (if required) is approved by the High Court of Justice of England and Wales (the “Court”), or which is otherwise imposed by the Court and is mutually acceptable to Barinthus Bio and Topco, each acting reasonably and in good faith (the “Scheme”), the directors of Barinthus Bio (or a duly authorized committee of the directors) be and are hereby:

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a.

authorized and directed to take all such action as they may consider necessary or appropriate for carrying the Scheme into effect;

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b.

directed that they shall procure the delivery of the order of the Court sanctioning the Scheme of Arrangement on behalf of Barinthus Bio to the Registrar of Companies in England and Wales provided that no injunction or other order by any court or other tribunal of competent jurisdiction shall have been entered and shall continue to be in effect and no law shall have been adopted that remains in effect or effective, in each case that prevents, enjoins, prohibits or makes illegal the Scheme becoming effective by such delivery; and

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c.

directed that if, in accordance with the Agreement and Plan of Merger by and among Barinthus Bio, Topco, Cdog Merger Sub, Inc., a Delaware corporation and a direct wholly owned subsidiary of Topco (“Merger Sub”), and Clywedog Therapeutics, Inc., a Delaware corporation (“Clywedog”), dated September 29, 2025 (as amended or otherwise modified prior to February 22, 2026, the “Original Merger Agreement”), as amended by that certain Amendment to the Agreement and Plan of Merger, dated as of February 22, 2026 (such amendment, the “Merger Agreement Amendment” and, together with the Original Merger Agreement, as it may be further amended or modified from time to time, the “Merger Agreement”), a print of which has been produced to this meeting and for the purposes of identification signed by the Chair of this meeting, in its original form or with or subject to any modification, addition, or condition as may be agreed from time to time (including, for the avoidance of doubt, after the date of this resolution) between Barinthus Bio, Topco, Merger Sub and Clywedog, a Superior Offer is made, they shall not (unless permitted to do so under the Merger Agreement) undertake a Beacon Board Adverse Recommendation Change in connection with a Superior Offer or cause Barinthus Bio to terminate the Merger Agreement

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in order to enter into a definitive agreement relating to a Superior Offer following the time at which the Required Beacon Shareholder Vote is obtained (capitalized terms in this resolution having the meanings set forth in the Merger Agreement);

2.

RESOLVED THAT, with effect from the passing of this resolution, the articles of association of Barinthus Bio be and are hereby amended by the adoption and inclusion of the following new article 145:

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“145.

Scheme of Arrangement

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[145.1

In this Article 145, references to the “Scheme of Arrangement” are to the scheme of arrangement dated [•], 2025 between the Company and the holders of Scheme Shares (as defined in the Scheme of Arrangement) under Part 26 of the Act in its original form or with or subject to any modification, addition or condition agreed between the Company and Topco (the “Acquiror”) which (if required) is approved or imposed by the Court and (save as defined in this Article 145) terms defined in the Scheme of Arrangement shall have the same meanings in this Article 145.

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145.2

Notwithstanding any other provision of these articles or the terms of any resolution, whether ordinary or special, passed by the Company in general meeting, if the Company issues or transfers out of treasury any shares on or after the date of the adoption of this Article 145 and prior to the Scheme Record Time, such shares shall be issued or transferred in the name of the relevant person subject to the terms of the Scheme of Arrangement (and shall be Scheme Shares for the purposes thereof) and the original or any subsequent holder or holders of such shares shall be bound by the Scheme of Arrangement accordingly.

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145.3

Notwithstanding any other provision of these articles, if any shares in the Company are issued or transferred out of treasury to any person or such person’s nominee (a “New Member”) at or after the Scheme Record Time (each a “Post-Scheme Share”) such shares will, provided that the Scheme of Arrangement has become effective, be issued or transferred on terms that they shall (on the Effective Date) or, if later, on issue or transfer (but subject to the terms of this Article 145.3 and Article 145.6) be immediately transferred to the Acquiror (or such persons as the Acquiror may direct) (the “Purchaser”), who shall be obliged to acquire each Post-Scheme Share in consideration of and conditional upon the Acquiror procuring delivery to the New Member of such number of shares of Topco Common Stock as is equal to the number of shares payable to a holder of the Scheme Shares under the Scheme of Arrangement (“Exchange Shares”) (the “Share Deliverable” and the ratio that an Exchange Share bears to each Scheme Share being the “Exchange Ratio”) for each Post-Scheme Share as would have been payable to a holder of the Scheme Shares under the Scheme of Arrangement, subject to Article 145.5.

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145.4

The Exchange Shares allotted and issued or transferred to a New Member (or nominee) pursuant to Article 145.3 shall be credited as fully paid and shall rank equally in all respects with all other fully paid Topco Common Stock in issue at that time (other than as regards any dividend or other distribution payable by reference to a record date preceding the date of allotment or transfer) and shall be subject to the constitution of the Acquiror from time to time.

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145.5

No fraction of an Exchange Share shall be allotted, issued or transferred to a New Member (or nominee) pursuant to this Article. Any fraction of an Exchange Share to which a New Member would otherwise have become entitled shall be aggregated with the fractional entitlements of any other New Members whose shares are being transferred under this article on the same date and the maximum whole number of Exchange Shares resulting therefrom shall be allotted and issued to a person appointed by the Company. Such Exchange Shares will then (at the discretion of the Acquiror, acting in the interests of the relevant New Members and in accordance with Applicable Law) as soon as reasonably practicable after (i) the Exchange Shares

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become freely tradeable on a recognised investment exchange, or (ii) a liquid market develops for the Exchange Shares, be sold and the net proceeds of the sale (after the deduction of the expenses of the sale (including any tax and amounts in respect of irrecoverable value added tax payable thereon), without interest and subject to any required tax withholding) be paid to the persons entitled thereto in due proportion to the fractional Exchange Shares to which they would otherwise have been entitled (rounded down to the nearest penny).

145.6

On any reorganisation of, or material alteration to, the share capital of the Company or Acquiror (including, without limitation, any subdivision and/or consolidation of shares) carried out after the Effective Date, or if a stock or scrip dividend is declared with a record date after the Effective Date, or any similar event shall have occurred (or if the number of Beacon Ordinary Shares represented by each Beacon ADS shall have been changed pursuant to the Deposit Agreement (as defined in the Transaction Agreement)), or the number or class of Beacon Ordinary Shares or Topco Common Stock shall have been changed or exchanged for a different number or class of Beacon Ordinary Shares or Topco Common Stock, then the Exchange Ratio and the Share Deliverable shall be appropriately adjusted by the directors in such manner as the auditors of the Company or an independent investment bank selected by the Company (whichever in their absolute discretion the directors may elect) may determine to be appropriate to reflect such reorganisation or alteration and to provide to Acquiror, Scheme Shareholders and New Members the same economic effect as contemplated under Article 145.3. References in this Article 145 to such shares shall, following such adjustment, be construed accordingly.

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145.7

To give effect to any transfer of Post-Scheme Shares required by this Article 145, the Purchaser may appoint any person as attorney and/or agent for the New Member to transfer the Post-Scheme Shares to the Purchaser and execute and deliver as transferor a form or forms of transfer or other instrument or instruction of transfer (whether as a deed or otherwise) on behalf of the New Member (or any subsequent holder or any nominee of such New Member or any such subsequent holder) in favour of the Purchaser and do all such other things and execute and deliver all such documents (whether as a deed or otherwise) as may in the opinion of the attorney and/or agent be necessary or desirable to vest the Post-Scheme Shares in the Purchaser and, pending such vesting, to exercise all such rights and privileges attaching to the Post-Scheme Shares as the Purchaser may direct. If an attorney and/or agent is so appointed, the New Member shall not thereafter (except to the extent that the attorney and/or agent fails to act in accordance with the directions of the Purchaser) be entitled to exercise any rights or privileges attaching to the Post-Scheme Shares unless so agreed by the Purchaser. The Company may give good receipt for the delivery of the Share Deliverable for each Post-Scheme Share and may register the Purchaser as holder thereof and issue to it certificates for the same. The Company shall not be obliged to issue a certificate to the New Member for any Post-Scheme Shares. The Purchaser shall, subject to Applicable Law, settle the consideration due to the New Member pursuant to Article 145.3 above by the delivery of the Share Deliverable for each Post-Scheme Share as soon as reasonably practicable following the issue of the Post-Scheme Shares to the New Member. Acquiror shall allot and issue or transfer the Exchange Shares to the New Member and make payment of any amounts payable under Article 145.5 as soon as reasonably practicable and in accordance with the provisions of Article 145.5, unless:

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(a)

the Company, in its sole discretion, determines in accordance with Article 145.8 in respect of any New Member with a registered address in a jurisdiction outside the United Kingdom or whom the Company reasonably believes to be a citizen, resident or national of a jurisdiction outside the United Kingdom that such Exchange Shares shall be sold in which case the Exchange Shares shall be

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sold and the net proceeds of sale distributed to the persons so entitled in accordance with Article 145.8; or

(b)

the Company, in its sole discretion, determines in accordance with Article 145.8 in respect of any New Member with a registered address in a jurisdiction outside the United Kingdom or whom the Company reasonably believes to be a citizen, resident or national of a jurisdiction outside the United Kingdom that a cash amount equal to the value of the Exchange Shares shall be paid to the New Member, in which case Acquiror shall send a cheque in sterling drawn on a UK clearing bank in favour of the New Member for the consideration for such Post-Scheme Shares and in respect of any fractional entitlements no later than 14 days after the date of the issue or transfer of the Post-Scheme Shares to the New Member.

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145.8

If, in respect of any New Member with a registered address in a jurisdiction outside the United Kingdom or whom the Company reasonably believes to be a citizen, resident or national of a jurisdiction outside the United Kingdom, the Company is advised that the allotment and/or issue or transfer of Exchange Shares pursuant to this Article would or may infringe the laws of such jurisdiction or would or may require the Company and/or the Acquiror to comply with any governmental or other consent or any registration, filing or other formality with which the Company and/or Acquiror is unable to comply or compliance with which the Company and/or the Acquiror regards as unduly onerous, the Company may, in its sole discretion, determine that such Exchange Shares shall be sold for a cash amount equal to the value of the Exchange Shares shall be paid to the New Member. In the event that the Exchange Shares are to be sold, the Company shall appoint a person to act as attorney or agent for the New Member (including to execute and deliver as transferor a form of transfer or other instrument or instruction of transfer on behalf of the New Member (whether as a deed or otherwise)) pursuant to this Article and such person shall be authorised on behalf of such New Member to procure that any shares in respect of which the Company has made such determination shall, as soon as practicable following the allotment, issue or transfer of such shares and after (i) the Exchange Shares become freely tradeable on a recognised investment exchange, or (ii) a liquid market develops for the Exchange Shares, be sold and the net proceeds of the sale (after the deduction of the expenses of the sale (including any tax and amounts in respect of irrecoverable value added tax payable thereon), without interest and subject to any required tax withholding) be paid to the persons entitled thereto in due proportion to the Exchange Shares to which they would otherwise have been entitled.

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145.9

Notwithstanding any other provision of these Articles, both the Company and the directors of the Company shall refuse to register the transfer of any shares between the Scheme Record Time and the Effective Date, other than to the Purchaser pursuant to the Scheme of Arrangement.

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145.10

If the Scheme of Arrangement shall not have become effective by the date referred to in (or otherwise set in accordance with) clause 11 of the Scheme of Arrangement, this Article 145 shall cease to be of any effect.”; and

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3.

RESOLVED THAT, subject to receipt of Court approval, the amount standing to the credit of Barinthus Bio’s share premium account be reduced to nil.

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Such resolutions will be proposed as special resolutions and under English law, assuming that a quorum is present, a special resolution is passed on a show of hands if it is approved by at least 75% of the votes cast by shareholders present (in person or by proxy) at the meeting and entitled to vote. If a poll is demanded, a special resolution is passed if it is approved by holders representing at least 75% of the total voting rights of shareholders present (in person or by proxy) who (being entitled to vote) vote on the resolution.

Barinthus Bio’s Board of Directors (the “Barinthus Board”) values the opinions of its shareholders as expressed through such votes and will carefully consider the outcome of the votes on all proposed resolutions.

 

 

The results of any polls taken on the resolutions at the Barinthus General Meeting and any other information required by the United Kingdom Companies Act 2006 (the “UK Companies Act”) will be made available on Barinthus Bio’s website (www.barinthusbio.com) as soon as reasonably practicable following the Barinthus General Meeting and for the required period thereafter.

Unless the context requires otherwise, any capitalized term used but not defined in this Notice of Barinthus General Meeting shall have the meaning given to such term in the proxy statement/prospectus of which this Notice of Barinthus General Meeting forms a part.

[•], 2026
By order of the Barinthus Board
William Enright
Chief Executive Officer​

Barinthus Biotherapeutics plc

Registered Office: 3rd Floor, 1 Ashley Road, Altrincham, Cheshire, WA14 2DT, United Kingdom.

Registered in England and Wales, company number 13282620.

Notes for holders of Barinthus Ordinary Shares:

The following notes explain your general rights as a holder of ordinary shares of Barinthus Bio, with a par value £0.000025 per share (“Barinthus Ordinary Shares”), and your right to attend and vote at the Barinthus General Meeting or to appoint someone else to vote on your behalf.

a)

Only those holders of Barinthus Ordinary Shares registered in the register of members of Barinthus Bio at [•] p.m. (London Time) on [•], 2026 will be entitled to attend and vote at the Barinthus General Meeting in respect of the number of Barinthus Ordinary Shares registered in their name at the time. Changes to entries on the relevant register after that deadline will be disregarded in determining the rights of any person to attend and vote at the Barinthus General Meeting. Should the Barinthus General Meeting be adjourned to a time not more than 48 hours after the deadline, the same deadline will also apply for the purpose of determining the entitlement of members to attend and vote (and for the purpose of determining the number of votes they may cast) at the adjourned Barinthus General Meeting. Should the Barinthus General Meeting be adjourned for a longer period, then to be so entitled, members must be entered on the register of members of Barinthus Bio at the time which is 48 hours before the time fixed for the adjourned Barinthus General Meeting or, if Barinthus Bio gives notice of the adjourned Barinthus General Meeting, at the time specified in the notice.

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b)

Any member may appoint a proxy to attend, speak and vote on his/her behalf. A member may appoint more than one proxy in relation to the Barinthus General Meeting provided that each proxy is appointed to exercise the rights attached to a different share or shares of the member. A proxy need not be a member but must attend the meeting in person. The YELLOW Form of Proxy should be lodged with Barinthus Bio’s Registrar, Computershare Trust Company, N.A. (“Computershare”), not later than [•] p.m. (London Time) on [•], 2026. Completion and return of the YELLOW Form of Proxy does not prevent a member from attending and voting in person if he/she is entitled to do so and so wishes. The attached proxy statement/prospectus explains proxy voting and the matters to be voted on in more detail. Please read the proxy statement/prospectus carefully. For specific information regarding the voting of your Barinthus Ordinary Shares, please refer to the section entitled “Questions and Answers About the Combinations and the Barinthus Shareholder Meetings.”

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c)

Any corporation which is a member can appoint one or more corporate representatives who may exercise on its behalf all of its powers as a member provided that they do not do so in relation to the same shares.

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d)

In the case of joint holders, the vote of the senior holder who tenders the vote whether in person or by proxy will be accepted to the exclusion of the votes of any other joint holders. For these

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purposes, seniority shall be determined by the order in which the names stand in Barinthus Bio’s relevant register of members for the certificated or uncertificated shares of Barinthus Bio (as the case may be) in respect of the joint holding.

e)

As of [•], 2026 (being the latest practicable date prior to the publication of this Notice of Barinthus General Meeting), Barinthus Bio’s issued ordinary share capital consisted of [•] Barinthus Ordinary Shares (including Barinthus Ordinary Shares represented by Barinthus ADSs), carrying one vote each.

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f)

Except as set out in the notes to this notice, any communication with Barinthus Bio in relation to the Barinthus General Meeting, including in relation to proxies, should be sent to Computershare, The Pavilions, Bridgwater Road, Bristol BS99 6ZY, United Kingdom. No other means of communication will be accepted. In particular, you may not use any electronic address provided either in this Notice or in any related documents to communicate with Barinthus Bio for any purpose other than those expressly stated.

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g)

Copies of the Scheme of Arrangement will be available for inspection at the registered office of Barinthus Bio during normal business hours on any weekday (public holidays excepted) and at the place of the Barinthus General Meeting for one hour before the Barinthus General Meeting and at the Barinthus General Meeting itself.

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h)

Under section 319A of the UK Companies Act, any holder of Barinthus Ordinary Shares attending the Barinthus General Meeting has the right to ask questions. Holders of Barinthus Ordinary Shares, if attending in person, will be permitted to ask questions at the Barinthus General Meeting. Barinthus Bio must cause to be answered any such question relating to the business being dealt with at the Barinthus General Meeting but no such answer need be given if: (i) to do so would interfere unduly with the preparation for the Barinthus General Meeting or involve the disclosure of confidential information; (ii) the answer has already been given on a website in the form of an answer to a question; or (iii) it is undesirable in the interests of Barinthus Bio or the good order of the Barinthus General Meeting that the question be answered.

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i)

If your Barinthus Ordinary Shares are held in an account at a broker, bank, trust company or other nominee and you are the beneficial owner of shares as of [•], 2026, these proxy materials should be forwarded to you by that organization. The organization holding your account is considered the shareholder of record for purposes of voting at the Barinthus General Meeting. You should follow directions provided by your broker, bank, trust company or other nominee. You are encouraged to provide voting instructions to your broker, bank, trust company or other nominee so that they may submit a proxy.

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j)

Holders of Barinthus Ordinary Shares who have any queries about the Barinthus General Meeting, or are in any doubt as to how to complete the YELLOW Forms of Proxy or to submit proxies electronically or online, should contact Computershare by telephone at +44 370 703 0369 (for international callers) or by post to Computershare, The Pavilions, Bridgwater Road, Bristol BS99 6ZY, United Kingdom. Calls are charged at the standard geographic rate and will vary by provider. Calls from outside the United Kingdom will be charged at the applicable international rate. The helpline is open between 8:30 a.m. and 5:30 p.m., Monday to Friday, excluding public holidays in England and Wales. Please note that Computershare cannot provide any financial, legal or tax advice and calls may be recorded and monitored for security and training purposes.

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Notes for holders of Barinthus ADSs:

The following notes explain your general rights as a holder of American Depositary Shares representing Barinthus Ordinary Shares (“Barinthus ADSs”) and your right to give voting instructions with respect to those Barinthus Ordinary Shares at the Barinthus General Meeting.

a)

Barinthus ADS holders are not entitled to attend or vote, in person or by proxy, at the Barinthus General Meeting. In order to exercise your vote as a holder of Barinthus ADSs, (i) you must have been registered as a holder of Barinthus ADSs in the Barinthus ADS register maintained by

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Barinthus Bio’s depositary, The Bank of New York Mellon (the “Depositary”), or (ii) Barinthus ADSs must be credited to your securities account maintained with a broker or other securities intermediary that is a direct or indirect participant in The Depository Trust Company (“DTC”), in either case by 5:00 p.m. Eastern Time on [•], 2026 (the “Barinthus ADS Voting Record Time”).

b)

Beneficial holders of Barinthus ADSs who hold their Barinthus ADSs indirectly through a broker, bank, trust company or other nominee must rely on the procedures of such broker, bank, trust company or other nominee in order to assert the rights of a Barinthus ADS holder to issue voting instructions to the Depositary. If this applies to you, Barinthus Bio encourages you to consult your broker, bank, trust company or other nominee as soon as possible to obtain the necessary documentation in order to provide voting instructions in relation to the Barinthus General Meeting in the manner and by the cut-off time stipulated by such broker, bank, trust company or other nominee. If you have queries on how you can deliver voting instructions about the Barinthus General Meeting, please contact your broker, bank, trust company or other nominee.

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c)

If you are a registered holder of Barinthus ADSs on the Depositary’s ADS register as of the Barinthus ADS Voting Record Time, you will be able to instruct the Depositary to vote the Barinthus Ordinary Shares represented by your Barinthus ADSs on your behalf by completing and returning a Barinthus ADS voting instruction card to the Depositary, to be received no later than the time and date specified in the Barinthus ADS voting instruction card. The Depositary will send a Barinthus ADS voting instruction card to registered holders of Barinthus ADSs as of the Barinthus ADS Voting Record Time. Holders of Barinthus ADSs are encouraged to timely submit voting instructions to the Depositary for the Barinthus General Meeting as soon as possible. A Barinthus ADS voting instruction card with your voting instructions must be received by the Depositary by 10:00 a.m. (Eastern Time) on [•], 2026 in the manner and at the address specified in the Barinthus ADS voting instruction card.

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d)

As of [•], 2026 (the record date for Barinthus ADS holders), Barinthus Bio’s issued ordinary share capital consisted of [•] Barinthus Ordinary Shares, carrying one vote each.

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e)

Holders of Barinthus ADSs who have any queries about the Barinthus General Meeting should contact Barinthus Bio at Barinthus Biotherapeutics plc, 20400 Century Boulevard, Suite 210, Germantown, MD 20874, Attention: Corporate Secretary, or MacKenzie Partners, Barinthus Bio’s proxy solicitor, by e-mailing proxy@mackenziepartners.com or calling toll-free at +1 (800) 322-2885, between 9:00 a.m. and 5:30 p.m. (London Time).

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Information regarding the Barinthus General Meeting, including information required by section 311A of the UK Companies Act and a copy of this Notice of Barinthus General Meeting may be found on Barinthus Bio’s website at www.barinthusbio.com. The information contained on Barinthus Bio’s website is not incorporated into, and does not form a part of, this proxy statement/prospectus or any other report or document on file with or furnished to the U.S. Securities and Exchange Commission.

Holders of Barinthus Ordinary Shares may not use any electronic address provided in this Notice of Barinthus General Meeting or in any related documents to communicate with Barinthus Bio for any purpose other than those expressly stated. Any electronic communications, including the lodgment of any electronic proxy form or voting instruction card, received by Barinthus Bio, or its agents, that is found to contain any virus will not be accepted.

 

 

REFERENCES TO ADDITIONAL INFORMATION

You can obtain the documents free of charge by visiting the SEC’s website at www.sec.gov, from Barinthus Bio by visiting www.barinthusbio.com or by requesting them in writing or by telephone from Barinthus Bio at Barinthus Biotherapeutics plc, 20400 Century Boulevard, Suite 210, Germantown, MD 20874, Attention: Corporate Secretary, or (443) 917-0966. The information contained on Barinthus Bio’s website is not incorporated into, and does not form a part of, the accompanying proxy statement/​prospectus or any other report or document on file with or furnished to the SEC.

If you are a holder of Barinthus Ordinary Shares or Barinthus ADSs (a “Barinthus Shareholder”), you may also request copies of this proxy statement/prospectus and documents or other information concerning Barinthus Bio, without charge, by written or telephonic request directed to MacKenzie Partners, Inc. (“MacKenzie Partners”), Barinthus Bio’s proxy solicitor, by e-mailing proxy@mackenziepartners.com or calling toll-free at +1 (800) 322-2885, between 9:00 a.m. and 5:30 p.m. (London Time). If you would like to request any documents, please do so by [•], 2026 in order to receive them before the Barinthus Shareholder Meetings (as defined below).

 

 

ABOUT THIS PROXY STATEMENT/PROSPECTUS

This document, which forms part of a registration statement on Form S-4 filed with the SEC by Topco (File No. 333-291359), constitutes a prospectus of Topco under the U.S. Securities Act of 1933, as amended (the “Securities Act”), with respect to the shares of Topco Common Stock to be issued pursuant to the Merger Agreement.

This document also constitutes a proxy statement of Barinthus Bio under Section 14(a) of the U.S. Securities Exchange Act of 1934, as amended (the “Exchange Act”), with respect to the Barinthus General Meeting. It also constitutes a notice of meeting with respect to the Barinthus Court Meeting and the Barinthus General Meeting and contains an explanatory statement in respect of the Scheme Transaction as required by Section 897 of the UK Companies Act.

You should rely only on the information contained in or incorporated by reference into this proxy statement/prospectus. No person has been authorized to provide you with information that is different from what is contained in, or incorporated by reference into, this proxy statement/prospectus, and, if given or made by any person, such information must not be relied upon as having been authorized. You should not assume that the information contained in this proxy statement/prospectus is accurate as of any date other than its date as specified on the cover unless otherwise specifically provided herein. Further, you should not assume that the information contained in or incorporated by reference into this proxy statement/​prospectus is accurate as of any date other than the date of the incorporated document. Neither the mailing of this proxy statement/prospectus to Barinthus Shareholders nor the issuance by Topco of shares of Topco Common Stock pursuant to the Merger Agreement will create any implication to the contrary.

None of the SEC, the UK FCA, nor any securities commission of any jurisdiction has approved or disapproved any of the transactions described in this proxy statement/prospectus or the securities to be issued under this proxy statement/prospectus or passed upon the adequacy or accuracy of this proxy statement/​prospectus. Any representation to the contrary is a criminal offense. This proxy statement/prospectus does not constitute an offer to buy or sell, or a solicitation of an offer to buy or sell, any securities, or a solicitation of a proxy, in any jurisdiction to or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction. The distribution or possession of this proxy statement/prospectus in or from certain jurisdictions may be restricted by law. For the avoidance of doubt, this proxy statement/prospectus does not constitute an offer to buy or sell securities or a solicitation of an offer to buy or sell any securities in the United Kingdom or any state in the European Economic Area or a solicitation of a proxy under the laws of England and Wales, and it is not intended to be, and is not, a prospectus or an offer document for the purposes of the UK FCA’s Prospectus Rules. You should inform yourself about and observe any such restrictions, and none of Barinthus Bio, Topco or Clywedog accepts any liability in relation to any such restrictions.

The information concerning Barinthus Bio, Topco and Merger Sub contained in this proxy statement/​prospectus has been provided by Barinthus Bio and the information concerning Clywedog contained in this proxy statement/prospectus has been provided by Clywedog. As used in this proxy statement/prospectus, except where otherwise stated or indicated by the context, all references to Barinthus Bio are to Barinthus Biotherapeutics plc and its consolidated subsidiaries and all references to Clywedog are to Clywedog Therapeutics, Inc. and its consolidated subsidiaries, in each case, prior to the consummation of the Transactions.

In this proxy statement/prospectus, unless the context otherwise requires:

“ACA” means the federal Physician Payments Sunshine Act, enacted as part of the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act of 2010.

“Acquisition Proposal” means with respect to a party to the Merger Agreement, any offer or proposal, whether written or oral (other than an offer or proposal made or submitted by or on behalf of Clywedog or any of its affiliates, on the one hand, or by or on behalf of Barinthus Bio or any of its affiliates, on the other hand, to the other party) contemplating or otherwise relating to any Acquisition Transaction with such party.

 

 

“Acquisition Inquiry” means, with respect to a party, an inquiry, indication of interest or request for information (other than an inquiry, indication of interest or request for information made or submitted by Clywedog, on the one hand, or Barinthus Bio, on the other hand, to the other party) that could reasonably be expected to lead to an Acquisition Proposal.

“Acquisition Transaction” means any transaction or series of related transactions involving (other than the Self-Tender Offer):

(a)   any merger, consolidation, amalgamation, share exchange, business combination, issuance of securities, acquisition of securities, reorganization, recapitalization, tender offer, exchange offer or other transaction: (i) in which a party to the Merger Agreement is a constituent entity, (ii) in which a person or “group” ​(as defined in the Exchange Act and the rules promulgated thereunder) of persons directly or indirectly acquires beneficial or record ownership of securities representing more than 20% of the outstanding securities of any class of voting securities of a party or any of its subsidiaries or (iii) in which a party or any of its subsidiaries issues securities representing more than 20% of the outstanding securities of any class of voting securities of such party or any of its subsidiaries; or

(b)   any sale, lease, exchange, transfer, license, acquisition or disposition of any business or businesses or assets that constitute or account for 20% or more of the consolidated book value or the fair market value of the assets of a party and its subsidiaries, taken as a whole, other than the sale, divestiture and/or winding down of the Barinthus Legacy Business or the sale, license or other disposition of any or all of the Barinthus Legacy Assets by Barinthus Bio.

“Aggregate Tender Offer Consideration” means the consideration payable by Topco in the Self-Tender Offer.

“Ancillary Agreements” means the Barinthus Voting Deeds, the Clywedog Voting Agreements and the Lock-Up Agreements.

“Barinthus Bio” means Barinthus Biotherapeutics plc, a public limited company organized under the Laws of England and Wales.

“Barinthus ADSs” means the American Depositary Shares of Barinthus Bio, each representing one Barinthus Ordinary Share.

“Barinthus Board” means the board of directors of Barinthus Bio.

“Barinthus Court Meeting” means, in the matters of Barinthus Biotherapeutics plc and the UK Companies Act, the meeting for which the Court has given permission by the order dated [•], 2026.

“Barinthus Deferred A Shares” means the deferred A shares in the capital of Barinthus Bio in issue, each with a nominal value £1.00 per share.

“Barinthus EMI Option” means each option to acquire Barinthus Ordinary Shares granted under the Barinthus EMI Share Option Scheme.

“Barinthus EMI Share Option Scheme” means the Barinthus EMI Share Option Scheme approved by the Barinthus Board on February 5, 2018, as amended from time to time.

“Barinthus ESPP” means Barinthus Bio’s 2021 Employee Stock Purchase Plan.

“Barinthus Equity Plans” means the Barinthus EMI Share Option Scheme, the Barinthus Share Award Plan 2021 or other plan under which Barinthus Bio or any of its subsidiaries has granted any equity or equity-based compensation (other than the Barinthus ESPP), in each case, as amended.

“Barinthus General Meeting” means such meeting(s) (and any adjournment, postponement or reconvention thereof) convened with the permission of the Court pursuant to section 896 of the UK Companies Act for the purpose of considering and, if thought fit, approving (with or without modification) the Scheme of Arrangement.

 

 

“Barinthus Legacy Assets” means all assets, technology and intellectual property of Barinthus Bio as they existed at any time prior to the date of the Original Merger Agreement that are primarily used in or primarily related to (i) VTP-300, (ii) VTP-500 and corresponding non-dilutive CEPI funding contract and (iii) VTP-850.

“Barinthus Legacy Business” means the business of Barinthus Bio as conducted immediately prior to the date of the Original Merger Agreement.

“Barinthus Legacy Transaction” means the sale, license or other disposition of any or all of the assets, technology and intellectual property of Barinthus Bio as they existed at any time prior to the date of the Original Merger Agreement that are primarily used in or primarily related to the Barinthus Legacy Assets by Barinthus Bio.

“Barinthus Material Adverse Effect” means any Effect that, considered together with all other Effects that have occurred prior to the date of determination of the occurrence of the Barinthus Material Adverse Effect, has or would reasonably be expected to have a material adverse effect on the business, financial condition, assets, liabilities or results of operations of Barinthus Bio; provided, however, that Effects arising or resulting from the following shall not be taken into account in determining whether there has been a Barinthus Material Adverse Effect: (a) the announcement of the Merger Agreement or the pendency of the Transactions; provided, that this clause (a) shall not apply to any representation or warranty (or condition to the consummation of the Combinations relating to such representation or warranty) the purpose of which is to address the consequences resulting from the execution and delivery of the Merger Agreement or the consummation of the Transactions, (b) any change in the stock price or trading volume of Barinthus ADSs (it being understood, however, that any Effect causing or contributing to any change in stock price or trading volume of Barinthus ADSs may be taken into account in determining whether a Barinthus Material Adverse Effect has occurred, unless such Effects are otherwise excepted from this definition), (c) the taking of any action by Barinthus Bio that is required to comply with the terms of the Merger Agreement, (d) the sale, license or other disposition of the Barinthus Legacy Assets, (e) any natural disaster or any act or threat of terrorism or war anywhere in the world, any armed hostilities or terrorist activities anywhere in the world, any threat or escalation or armed hostilities or terrorist activities anywhere in the world or any governmental or other response or reaction to any of the foregoing, (f) any epidemic or pandemic in the United States or any other country or region in the world, or any escalation of the foregoing, (g) any change in U.S. GAAP or applicable Law or the interpretation thereof following the date hereof, (h) general economic or general business conditions generally affecting the industries in which Barinthus Bio operates or; except, in each case with respect to clauses (e), (f), (g) and (h), to the extent disproportionately affecting Barinthus Bio relative to other similarly situated companies in the industries in which Barinthus Bio operates.

“Barinthus Minimum Cash” means the amounts of Barinthus Net Cash that Barinthus is required to have, subject to the Beacon Collar (as defined in the Merger Agreement), assuming the Closing occurs by such dates as set forth in the Merger Agreement.

“Barinthus Net Cash” means as of the Determination Time and, as applicable, determined in a manner consistent with the manner in which such items were historically determined (and in any event consistent with U.S. GAAP) and in accordance with the applicable parties’ audited financial statements and unaudited interim balance sheet (without duplication), (i) cash, minus (ii) all unpaid Barinthus Transaction Costs, minus (iii) the amount of the Aggregate Tender Offer Consideration to be paid in the Self-Tender Offer less any amounts that have already been paid whether to a tendering shareholder or to a third party paying agent for purposes of distribution to tendering shareholders, minus (iv) fifty percent (50%) of the aggregate costs for obtaining the D&O tail insurance policy, plus (v) the amount of proceeds received prior to the Merger Effective Time from a Barinthus Legacy Transaction (less, in each case, any applicable Tax thereon).

“Barinthus Option” means each option to acquire Barinthus Ordinary Shares or Barinthus ADSs granted under a Barinthus Equity Plan.

“Barinthus Ordinary Shares” means the ordinary shares in the capital of Barinthus Bio, each with a par value £0.000025 per share (which, for the avoidance of doubt, shall include ordinary shares in the capital of Barinthus Bio held by the Depositary (or the extent that the Depositary is not itself the registered

 

 

holder of the such shares that underly the Barinthus ADSs, whichever nominee, custodian or other entity is the registered holder under the terms of the Deposit Agreement)).

“Barinthus RSU” means each outstanding restricted share unit granted under Barinthus Bio’s Equity Plans.

“Barinthus Scheme Proposal” means the proposal to vote and approve the Scheme of Arrangement at the Barinthus Court Meeting to give effect to the Scheme of Arrangement.

“Barinthus Share Award Plan” means Barinthus Bio’s Share Award Plan 2021 approved by the Barinthus Board on April 8, 2021, as amended from time to time.

“Barinthus Shareholders” means the holders of Barinthus ADSs and Barinthus Ordinary Shares.

“Barinthus Shareholder Meetings” mean the Barinthus Court Meeting and the Barinthus General Meeting.

“Barinthus Transaction Costs” means with respect to Barinthus Bio, without duplication, the sum of (a) the cash cost of any change of control payments, transaction bonus payments or severance payments that are or become due to any current or former employee, director or officer of Barinthus Bio and its subsidiaries that are unpaid as of the Closing, (b) the cash cost of any retention payments that are or become due to any employee or consultant of Barinthus Bio and its subsidiaries at or prior to the Merger Effective Time or as a result of the Merger or the Transactions, (c) the cash cost of any payments (whether absolute, contingent or otherwise) that are or may be due to any former employee of Barinthus Bio pursuant to a consulting agreement with Barinthus Bio that are unpaid as of Closing, (d) any costs, fees and expenses incurred by Barinthus Bio and its subsidiaries, and for which Barinthus Bio and its subsidiaries is liable, solely in connection with the negotiation, preparation and execution of this Agreement and the consummation of the Transactions and that are unpaid as of the Closing, including the amount of brokerage fees and commissions, finders’ fees and financial advisory fees, and any fees and expenses of counsel or accountants payable by Barinthus Bio and its subsidiaries, (e) fifty percent (50%) of the fees paid to the SEC in connection with filing the Registration Statement, this proxy statement/prospectus and any amendments and supplements thereto, and any expenses in connection with the printing, mailing and distribution of the Registration Statement, this proxy statement/prospectus and any amendments and supplements thereto, (f) the employer portion of any payroll, employment or similar Taxes incurred in connection with the payments described in the foregoing clauses (a) through (d) and the Barinthus Bio transaction payroll taxes, (g) all applicable stamp duty payable in connection with the Combinations, (h) any costs, fees and expenses incurred by Barinthus Bio and its subsidiaries, and for which Barinthus Bio and its subsidiaries is liable, in connection with the Barinthus Legacy Transactions, and (i) any costs, fees and expenses incurred by Barinthus Bio and its subsidiaries, and for which Barinthus Bio and its subsidiaries is liable, in connection with the undertaking of any action or activity listed in the Merger Agreement.

“Barinthus Triggering Event” shall be deemed to have occurred: (a) upon any Barinthus Board Adverse Recommendation Change or if the Barinthus Board approved, endorsed or recommended any Acquisition Proposal or (b) if Barinthus Bio shall have entered into any contract relating to any Acquisition Proposal (other than an Acceptable Confidentiality Agreement permitted pursuant to Section 5.4 of the Merger Agreement).

“Barinthus Voting Deed” means those voting and support deeds entered into by certain shareholders of Barinthus Bio with Clywedog on September 29, 2025, pursuant to which such individuals agreed to vote all of their shares of capital stock of Barinthus Bio (a) in favor of all resolutions to approve and give effect to the Scheme Transaction and certain related matters and any matter necessary to implement the Transactions and (b) against certain proposals or actions that would reasonably be expected to prevent the consummation of the Transactions.

“Bribery Act” means the UK Bribery Act of 2010.

“Chancery Court” means the Court of Chancery of the State of Delaware.

“CHIP” means the Children’s Health Insurance Program.

 

 

“Clywedog” means Clywedog Therapeutics, Inc., a Delaware corporation.

“Clywedog Board” means the board of directors of Clywedog.

“Clywedog Common Stock” means the common stock, $0.0001 par value per share, of Clywedog.

“Clywedog Material Adverse Effect” means any Effect that, considered together with all other Effects that have occurred prior to the date of determination of the occurrence of a Clywedog Material Adverse Effect, has or would reasonably be expected to have a material adverse effect on the business, financial condition, assets, liabilities or results of operations of Clywedog or its subsidiaries, taken as a whole; provided, however, that Effects arising or resulting from the following shall not be taken into account in determining whether there has been a Clywedog Material Adverse Effect: (a) the announcement of the Merger Agreement or the pendency of the Transactions; provided, that this clause (a) shall not apply to any representation or warranty (or condition to the consummation of the Combinations relating to such representation or warranty) the purpose of which is to address the consequences resulting from the execution and delivery of the Merger Agreement or the consummation of the Transactions, (b) the taking of any action, or the failure to take any action, by Clywedog that is required to comply with the terms of the Merger Agreement, (c) any natural disaster or any act or threat of terrorism or war anywhere in the world, any armed hostilities or terrorist activities anywhere in the world, any threat or escalation or armed hostilities or terrorist activities anywhere in the world or any governmental or other response or reaction to any of the foregoing, (d) any epidemic or pandemic in the United States or any other country or region in the world, or any escalation of the foregoing, (e) any change in U.S. GAAP or applicable Law or the interpretation thereof following the date hereof or (f) general economic or general business conditions generally affecting the industries in which Clywedog and its subsidiaries operate; except in each case with respect to clauses (c), (d), (e) and (f), to the extent disproportionately affecting Clywedog and its subsidiaries, taken as a whole, relative to other similarly situated companies in the industries in which Clywedog and its subsidiaries operate.

“Clywedog Minimum Cash” means the amounts of Clywedog Net Cash that Clywedog is required to have, subject to the Clywedog Collar (as defined in the Merger Agreement), assuming the Closing occurs by such dates as set forth in the Merger Agreement.

“Clywedog Net Cash” means as of the Determination Time and, as applicable, determined in a manner consistent with the manner in which such items were historically determined (and in any event consistent with U.S. GAAP) and in accordance with the applicable parties’ audited financial statements and unaudited interim balance sheet (without duplication), (i) cash, cash equivalents and marketable securities, plus (ii) accounts, interest and other receivables and deposits (including any Tax refund claims pending as of the date of the Original Merger Agreement) minus (iii) all unpaid Clywedog Transaction Costs, plus (iv) all prepaid Clywedog expenses, minus (v) fifty percent (50%) of the aggregate costs for obtaining the D&O tail insurance policy.

“Clywedog Options” means options or other rights to purchase shares of Clywedog Common Stock issued by Clywedog.

“Clywedog Plan” means Clywedog’s 2020 Stock Plan, as amended.

“Clywedog Preferred Stock” means the Series Seed Preferred Stock, $0.0001 par value per share, of Clywedog.

“Clywedog Shares” means Clywedog Common Stock and Clywedog Preferred Stock.

“Clywedog Transaction Costs” means with respect to Clywedog, without duplication, the sum of (a) the cash cost of any change of control payments, transaction bonus payments or severance payments that are or become due to any employee, director or officer of Clywedog and its subsidiaries that are unpaid as of the Closing, (b) the cash cost of any retention payments that are or become due to any employee of Clywedog and its subsidiaries at or prior to the Merger Effective Time or as a result of the Merger or the Transactions, (c) the cash cost of any payments (whether absolute, contingent or otherwise) that are or may be due to any former employee of Clywedog pursuant to a consulting agreement with Clywedog that are unpaid as of Closing, (d) any costs, fees and expenses incurred by Barinthus Bio and its subsidiaries, and for which Clywedog and its subsidiaries is liable, solely in connection with the negotiation, preparation and

 

 

execution of the Merger Agreement and the consummation of the Transactions and that are unpaid as of the Closing, including the amount of brokerage fees and commissions, finders’ fees and financial advisory fees, and any fees and expenses of counsel or accountants payable by Clywedog and its subsidiaries, (e) fifty percent (50%) of the fees paid to the SEC in connection with filing the Registration Statement, this proxy statement/prospectus and any amendments and supplements thereto, and any expenses in connection with the printing, mailing and distribution of the Registration Statement, this proxy statement/prospectus and any amendments and supplements thereto, and (f) the employer portion of any payroll, employment or similar Taxes incurred in connection with the payments described in the foregoing clauses (a) through (d).

“Clywedog Triggering Event” shall be deemed to have occurred: (a) upon any Clywedog Board Adverse Recommendation Change (as defined below) or if the Clywedog Board approved, endorsed or recommended any Acquisition Proposal or (b) if Clywedog shall have entered into any contract relating to any Acquisition Proposal (other than an Acceptable Confidentiality Agreement permitted pursuant to Section 5.4).

“Clywedog Voting Agreement” means those voting and support agreements entered into by the officers, directors and certain stockholders of Clywedog on September 29, 2025, pursuant to which such individuals agreed to vote all of their shares of capital stock of Clywedog (a) in favor of adopting and approving the Merger Agreement, the Merger and the Transactions and certain related matters and (b) against certain proposals or actions that would reasonably be expected to prevent the consummation of the Transactions.

“Code” means the Internal Revenue Code of 1986, as amended.

“Combinations” means the Merger and the Scheme, together.

“Court” means the High Court of Justice of England and Wales.

“Combined Business” means the business of Topco after closing of the Combinations.

“Deposit Agreement” means the Deposit Agreement, dated as of April 29, 2021, among Barinthus Bio, The Bank of New York Mellon, as depositary, and all holders from time to time of Barinthus ADSs, as may be amended from time to time.

“Depositary” means The Bank of New York Mellon, or such other entity as may from time to time act as the “Depositary” ​(as such term is defined in the Deposit Agreement).

“Deposited Shares” means those Scheme Shares that are deposited under the Deposit Agreement and represented by Barinthus ADSs.

“Determination Time” means the close of business on the last business day prior to the anticipated closing date of the Merger.

“DGCL” means the General Corporation Law of the State of Delaware.

“Effect” means any effect, change, event, circumstance, or development.

“EMA” means the European Medicines Agency and any successor entity.

“Exchange Act” means the Securities Exchange Act of 1934, as amended.

“Exchange Agent” or “Computershare” means Computershare Trust Company, N.A.

“Exchange Shares” means the Topco Common Stock to be delivered to the Scheme Shareholders in exchange for the Scheme Shares in accordance with this Agreement and the Scheme of Arrangement.

“FCPA” means the U.S. Foreign Corrupt Practices Act of 1977.

“FDA” means the U.S. Food and Drug Administration.

“FDCA” means the Federal Food, Drug, and Cosmetic Act.

“FTC” means the Federal Trade Commission.

“GCPs” means good clinical practices.

 

 

“GDPR” means the General Data Protection Regulation 2016/679.

“HHS” means the U.S. Department of Health and Human Services.

“HIPAA” means Health Insurance Portability and Accountability Act of 1996.

“IRB” means institutional review board.

“IRS” means the United States Internal Revenue Service.

“IND” means an investigational new drug application filed with the FDA pursuant to 21 C.F.R. Part 312, including all amendments, supplements, and other related submissions thereto, which is required to commence administering an investigational drug or biological product to humans in the United States in connection with a clinical study.

“Lock-Up Agreements” means those lock-up agreements entered into by and between Topco and certain officers, directors and shareholders of Barinthus Bio and Clywedog on September 29, 2025.

“Merger” means the merger of Merger Sub with and into Clywedog, with Clywedog continuing as the surviving corporation and a direct wholly owned subsidiary of Topco in accordance with the DGCL.

“Merger Agreement” means the Original Merger Agreement, as amended by the Merger Agreement Amendment and as it may be further amended or modified from time to time.

“Merger Agreement Amendment” means the Amendment to the Agreement and Plan of Merger entered into by and among Barinthus Bio, Topco, Merger Sub and Clywedog on February 22, 2026.

“Merger Effective Time” means the effective time of the Merger.

“Merger Exchange Ratio” means a number between 0.000305 and 0.000508, as finally determined by Clywedog and Barinthus Bio in accordance with Section 2.6(a) of the Merger Agreement.

“Merger Sub” means Cdog Merger Sub, Inc., a Delaware corporation and a direct wholly owned subsidiary of Topco.

“Nasdaq” means the Nasdaq Stock Market.

“NSIA” means the United Kingdom National Security and Investment Act 2021.

“OFAC” means the Office of Foreign Assets Control.

“Oppenheimer” means Oppenheimer & Co. Inc.

“Original Merger Agreement” means the merger agreement entered into by and among Barinthus Bio, Topco, Merger Sub and Clywedog on September 29, 2025.

“PwC” means PricewaterhouseCoopers LLP.

“Rule 144” means Rule 144 of the Securities Act.

“SAFE Agreements” means collectively, (i) that Simple Agreement for Future Equity by and between Clywedog and TPAV, LLC dated as of October 11, 2024, (ii) that Simple Agreement for Future Equity by and between Clywedog and OrbiMed dated as of October 11, 2024, (iii) that Simple Agreement for Future Equity by and between Clywedog and TPAV, LLC dated as of December 26, 2024, (iv) Simple Agreement for Future Equity by and between Clywedog and OrbiMed dated as of December 26, 2024, and (v) any similar agreements entered into following the date hereof between Clywedog and TPAV, LLC or OrbiMed, as applicable.

“Sarbanes-Oxley Act” means the Sarbanes-Oxley Act of 2002 and the related rules and regulations promulgated under such act.

“Scheme Exchange Ratio” means a number between 0.1 and 0.166667, as finally determined by the Barinthus Board in accordance with the Scheme of Arrangement (or a duly appointed committee thereof) in its sole discretion prior to the Scheme Effective Time.

 

 

“Scheme of Arrangement” means the arrangement pursuant to which, as more particularly described in the Merger Agreement, Topco will acquire the entire issued and to be issued share capital of Barinthus Bio pursuant to a scheme of arrangement (subject to any modification, addition or condition which (a) Barinthus Bio, Topco and Clywedog mutually agree and which (if required) is approved by the Court or (b) is otherwise imposed by the Court and mutually acceptable to Barinthus Bio, Topco and Clywedog, each acting reasonably and in good faith, in each case in accordance with Part 26 of the UK Companies Act and the Merger Agreement).

“Scheme Effective Time” means the effective time of the Scheme Transaction.

“Scheme Record Date” means the record date for determining the holders of Scheme Shares entitled to vote at the Scheme Meeting.

“Scheme Shares” means the Barinthus Ordinary Shares acquired in the Scheme Transaction.

“Scheme Shareholder” means a holder of Scheme Shares whose name appears in the register of Members of Barinthus Bio at the Scheme Record Date.

“Scheme Transaction” means the transaction effected by the Scheme of Arrangement (which, for the avoidance of doubt, shall include Barinthus Ordinary Shares represented by Barinthus ADSs).

“SEC” means the United States Securities and Exchange Commission.

“Securities Act” means the Securities Act of 1933, as amended.

“Self-Tender Offer” means that self-tender offer to purchase up to $27,000,000 in shares of Topco Common Stock that may be commenced by Topco following the Scheme Effective Time and prior to the Merger.

“Stock Issuance” means the issuance of the Exchange Shares in connection with the Scheme Transaction.

“Superior Offer” means an unsolicited bona fide written Acquisition Proposal (with all references to twenty percent (20%) in the definition of Acquisition Transaction being treated as references to fifty percent (50%) for these purposes) that: (a) was not obtained or made as a direct or indirect result of a breach of (or in violation of) the Agreement and (b) is on terms and conditions that the Barinthus Board or the Clywedog Board, as applicable, determines in good faith, based on such matters that it deems relevant (including the likelihood of consummation thereof and the financing terms thereof), as well as any written offer by the other party to the agreement to amend the terms of the agreement, and following consultation with its outside legal counsel and financial advisors, if any, are more favorable, from a financial point of view, to Barinthus Bio’s shareholders or Clywedog’s stockholders, as applicable, than the terms of the Transactions.

“Termination Date” means September 30, 2026, subject to extension as provided in the Merger Agreement.

“Topco” means Beacon Topco, Inc., a Delaware corporation and a direct wholly owned subsidiary of Barinthus Bio.

“Topco A&R Charter” means the Amended and Restated Certificate of Incorporation of Topco to be in effect as of the Scheme Effective Time.

“Topco A&R Bylaws” means the Amended and Restated Bylaws of Topco to be in effect as of the Scheme Effective Time.

“Topco Board” means the Board of Directors of Topco.

“Topco Common Stock” means the common stock, $0.0001 par value per share, of Topco.

“Transactions” means the Combinations and the other transactions contemplated by the Merger Agreement, including, without limitation, the Scheme of Arrangement, Stock Issuance and the Self-Tender Offer.

 

 

“Treasury Regulations” means the United States Treasury regulations promulgated under the Code.

“UK Companies Act” means the United Kingdom Companies Act of 2006 and any statutory instruments made under it, and every statutory modification or re-enactment thereof for the time being in force.

“UK FCA” means the UK Financial Conduct Authority.

“U.S. GAAP” means U.S. generally accepted accounting principles.

“USPTO” means the United States Patent and Trademark Office.

“WSB” means WithumSmith+Brown, PC.

EXPECTED TIMETABLE OF PRINCIPAL EVENTS

All dates and times relating to the Scheme of Arrangement are based on Barinthus Bio and Clywedog’s current expectations and are subject to change. If any of the dates or times in this expected timetable change materially, the revised dates and/or times will be published by public announcement in the United States and by making such announcement available on Barinthus Bio’s website at www.barinthusbio.com.

The following dates and times associated with the Scheme of Arrangement are presented for illustrative purposes only, are subject to change and will depend on, among other things, the date on which the conditions to the Scheme of Arrangement are satisfied or, if capable of waiver, waived, the date on which the Court sanctions the Scheme of Arrangement and the date on which the Court Order is delivered to the Registrar of Companies in England and Wales. Barinthus Bio will give adequate notice of all of these dates and times, when known, by public announcement in the United States and by making the announcement available of Barinthus Bio’s website at www.barinthusbio.com. Further updates and changes to these times will be notified in the same way. See also note(1).

 

 

(1)

The dates and times given are indicative only and are based on current expectations and are subject to change.

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(2)

It is requested that BLUE Forms of Proxy for the Barinthus Court Meeting be lodged not later than [•] [a.m./p.m.] (London Time) on [•], 2026 or, if the Barinthus Court Meeting is adjourned or postponed, 48 hours (excluding any part of such 48-hour period falling on a non-working day) prior to the time fixed for any adjourned or postponed Barinthus Court Meeting. If the BLUE Form of Proxy for the Barinthus Court Meeting is not lodged by [•] [a.m./p.m.] (London Time) on [•], 2026, it may be presented in person to the Chair of the Court Meeting or Computershare representative who will be present at the Barinthus Court Meeting, at any time prior to the commencement of the Barinthus Court Meeting (or any adjournment or postponement thereof).

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(3)

In order to be valid, the YELLOW Forms of Proxy for the Barinthus General Meeting must be lodged not later than [•] [a.m./p.m.] (London Time) on [•], 2026 or, if the Barinthus General Meeting is adjourned or postponed, 48 hours (excluding any part of such 48-hour period falling on a non-working day) prior to the time fixed for the adjourned or postponed Barinthus General Meeting.

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(4)

If either the Barinthus Court Meeting or the Barinthus General Meeting is adjourned or postponed, the Barinthus Ordinary Share Voting Record Time for the relevant adjourned or postponed meeting will be 48 hours (excluding any part of such 48-hour period falling on a non-working day) before the time appointed for the adjourned or postponed meeting.

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(5)

To commence at [•] [a.m./p.m.] (London Time) or as soon thereafter as the Barinthus Court Meeting concludes or is adjourned or postponed.

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(6)

This is the latest date by which the Merger may become effective. However, the Closing Date may be extended to such later date as may be agreed by Barinthus Bio and Clywedog.

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CAUTIONARY STATEMENT REGARDING FORWARD LOOKING STATEMENTS

This proxy statement/prospectus contains forward-looking statements within the meaning of federal securities laws concerning Barinthus Bio, Topco, Clywedog, the Combinations and other matters that involve material risks, assumptions and uncertainties. These statements may discuss goals, intentions and expectations as to future plans, trends, events, results of operations or financial condition, or other matters, based on the current beliefs of the management of Barinthus Bio and Clywedog as well as assumptions made by, and information currently available to, the management of both companies. Forward-looking statements may be accompanied by words such as “aim,” “anticipate,” “believe,” “plan,” “could,” “would,” “should,” “estimate,” “expect,” “forecast,” “future,” “guidance,” “intend,” “may,” “will,” “possible,” “potential,” “likely,” “predict,” “project” or similar words, phrases or expressions, although some forward-looking statements are expressed differently. These forward-looking statements generally include statements regarding the expected timeline for completing the Combinations; the ability to complete the Combinations; the Self-Tender Offer, including the value of shares, if any, that may be purchased by Topco; expected cost and revenue synergies, impacts and benefits of the Combinations; projected financial information; future opportunities; and other statements regarding Barinthus Bio’s, Topco’s and Clywedog’s future expectations, beliefs, plans, objectives, results of operations, financial condition and cash flows, or future events or performance. These statements are subject to various risks and uncertainties, many of which are outside the parties’ control, which may cause actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by these statements. Consequences of material differences in results as compared with those anticipated in the forward-looking statements could include, among other things, business disruption, operational problems, financial loss, legal liability to third parties and similar risks, any of which could have a material adverse effect on Barinthus Bio’s, Topco’s and Clywedog’s respective businesses, financial conditions, and results of operations.

Factors that could cause actual results to differ materially from those discussed in these forward-looking statements include, but are not limited to, risks and uncertainties detailed in the section entitled “Risk Factors” beginning on page 29 of this proxy statement/prospectus, and the following factors:

•

the occurrence of any change, effect, event, occurrence, development, matter, state of facts, series of events or circumstances that could give rise to the termination of the Merger Agreement;

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•

failure to obtain applicable regulatory or stockholder and shareholder approvals in a timely manner or otherwise, or being required to accept conditions that could reduce the anticipated benefits of the Combinations as a condition to obtaining regulatory approvals;

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•

failure to satisfy other closing conditions to the Combinations;

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•

risks associated with tax liabilities, or changes in U.S., UK or other tax laws or interpretations to which the companies are subject;

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•

the unaudited prospective financial information for Barinthus Bio and Clywedog included in this proxy statement/prospectus reflects management estimates and may not prove to be reflective of actual future financial results;

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•

risks associated with assumptions the parties make in connection with critical accounting estimates and legal proceedings;

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•

the inability of Barinthus Bio and Clywedog to meet expectations regarding the timing, completion, accounting and tax treatments with respect to the Combinations;

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•

limitations placed on the ability of Barinthus Bio and Clywedog to operate their respective businesses by the Merger Agreement pending consummation of the Combinations;

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•

the potential impact of the announcement or consummation of the Combinations on relationships with third parties, including customers, employees and competitors;

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•

risks that the executive officers, directors and affiliates of Barinthus Bio and Clywedog may have interests in the Combinations that are different from, or in addition to, the rights of the Barinthus Shareholders or the Clywedog stockholders;

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•

risks that the newly combined businesses will not be integrated successfully or that the cost, time and effort required to integrate the newly combined businesses may be greater than anticipated;

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•

failure to effectively manage the newly combined businesses, or that Topco will not realize any or all of the anticipated benefits, synergies and growth expected from the Combinations, or that the foregoing may take longer to realize than expected, which could adversely affect its business, financial condition and operating results;

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•

diversion of the attention of Barinthus Bio’s and Clywedog’s management from ongoing business concerns;

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•

the outcome of any legal proceedings that may be instituted against Clywedog, Barinthus Bio and/or others relating to the Combinations;

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•

operating costs or business disruption (including, without limitation, difficulties in maintaining relationships with employees, distributors or suppliers) being greater than expected in anticipation of, or, if consummated, following, the Combinations;

​

•

the market price for Topco Common Stock potentially being affected following the Combinations by factors that historically have not affected the market price for Barinthus Bio’s securities when Barinthus Bio was a standalone company;

​

•

the ability of Barinthus Bio and Clywedog to hire and retain personnel;

​

•

legislation, regulatory and economic development affecting the companies, including, without limitation, impacts of the U.S. federal government shutdown that commenced on October 1, 2025;

​

•

international, national or local economic, social or political conditions that could adversely affect Barinthus Bio, Clywedog or their respective businesses;

​

•

unanticipated changes relating to competitive factors in the industries in which the companies operate; and

​

•

the parties’ international operations, which are subject, among other factors, to the risks of currency fluctuations and foreign exchange controls.

​

The foregoing list of factors is not exhaustive. Unlisted factors may present significant additional obstacles to the realization of forward-looking statements. You should carefully consider the foregoing factors and the other risks and uncertainties that affect the parties’ businesses, including those described in this proxy statement/prospectus.

Except as otherwise required by applicable securities laws, Barinthus Bio, Topco and Clywedog are under no obligation, and each expressly disclaims any obligation, to update, alter or otherwise revise any forward-looking statements, whether written or oral, that may be made from time to time, whether as a result of new information, future events or otherwise. Persons reading this proxy statement/prospectus are cautioned not to place undue reliance on these forward-looking statements, which only speak as of the date hereof.

 

 

TABLE OF CONTENTS

 

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ii

 

 

iii

 

 

iv

 

 

v

 

QUESTIONS AND ANSWERS ABOUT THE COMBINATIONS AND THE BARINTHUS SHAREHOLDER MEETINGS

The following questions and answers are intended to briefly address some commonly asked questions regarding the Combinations (including the Scheme of Arrangement), the Merger Agreement, and the Barinthus Shareholder Meetings. These questions and answers may not address all questions that may be important to you. Please refer to the section entitled “Summary” beginning on page 12 of this proxy statement/prospectus and the more detailed information contained elsewhere in this proxy statement/prospectus, the annexes to this proxy statement/prospectus and the documents referred to in this proxy statement/prospectus, which you should read carefully and in their entirety.

Q:

What is this document?

​

A:

This document, which is referred to as the “proxy statement/prospectus,” serves as:

​

•

the proxy statement through which Barinthus Bio will (a) solicit proxies to seek to obtain the necessary Barinthus Bio shareholder approvals for the Combinations, and (b) inform holders of Scheme Shares of the upcoming Barinthus Shareholder Meetings at which Barinthus Shareholders will vote on the Combinations, authorize the directors of Barinthus Bio (or a duly authorized committee of the directors) to take all such action as they may consider necessary or appropriate for carrying the Scheme of Arrangement into effect and amend the articles of association of Barinthus Bio; and

​

•

the prospectus by which Topco will (a) issue Topco Common Stock to Barinthus Shareholders and Clywedog stockholders in connection with the Combinations, (b) provide details of the Merger Agreement and the consideration Barinthus Shareholders and Clywedog stockholders will receive upon completion of the Combinations, and (c) provide Barinthus Shareholders and Clywedog stockholders with important details about Topco and their rights as potential stockholders of Topco.

​

Q:

What is the proposed transaction I am being asked to vote on, and how will it be implemented?

​

A:

On September 29, 2025, Barinthus Bio and Topco entered into a definitive agreement for Topco to acquire the entire issued and to be issued ordinary share capital of Barinthus Bio in exchange for the Scheme Consideration (as defined below) by way of a court-sanctioned scheme of arrangement under Part 26 of the UK Companies Act. The Combinations are to be implemented by means of (i) a scheme of arrangement whereby Topco will acquire the entire issued and to be issued ordinary share capital of Barinthus Bio (the “Scheme of Arrangement”) and (ii) a merger by and between Merger Sub and Clywedog, whereby Merger Sub will merge with and into Clywedog, with Clywedog continuing as the surviving corporation and a direct wholly owned subsidiary of Topco in accordance with the DGCL (the “Merger” and, together with the Scheme of Arrangement, the “Combinations”). In addition, pursuant to the Merger Agreement, following the Scheme Effective Time, Topco may in its discretion elect to commence a self-tender offer (“Self-Tender Offer” and, together with the Combinations and the other transactions contemplated by the Merger Agreement, the “Transactions”) to purchase up to $27,000,000 in shares of Topco Common Stock then issued and outstanding, which Self-Tender Offer, if elected, will be consummated prior to the Merger. Barinthus Bio may elect to commence the Self-Tender Offer for an aggregate amount less than $27,000,000 based on the cash balance of Barinthus Bio as well as the trading price of Barinthus Bio shares and aggregate market capitalization as of immediately prior to the Scheme Effective Time.

​

Barinthus Shareholders are being asked to vote upon the Barinthus Scheme Proposal at the Barinthus Court Meeting, and the Scheme Implementation Proposal at the Barinthus General Meeting, in each case to approve and give effect to the Scheme of Arrangement. For more information about the Scheme of Arrangement, see the section entitled “Barinthus Scheme Proposal and the Barinthus Court Meeting and the Barinthus General Meeting — Explanatory Statement” of this proxy statement/​prospectus.

Q:

Why did the parties amend the original merger agreement?

​

A:

A company seeking to list its securities on Nasdaq is required to, among other things, have a minimum

​

 

1

 

bid price requirement of $4.00 per share pursuant to Nasdaq Listing Rule 5404(a)(1) (the “Minimum Price Requirement”). Nasdaq will determine Topco’s ability to satisfy the Minimum Price Requirement based on the most recent trading price of Barinthus ADSs. Based on the current trading price of Barinthus ADSs, which was $0.60 as of March 12, 2026, Barinthus Bio would likely be required to effectuate a reverse stock split or use alternative means to allow Topco to satisfy the Minimum Price Requirement. Given the complexities of effectuating a reverse stock split, the parties agreed that the Scheme Exchange Ratio could be adjusted such that, subject to approval of the Scheme of Arrangement by Barinthus Shareholders at the Court Meeting and the passing of the Scheme Implementation Proposal by Barinthus Shareholders at the Barinthus General Meeting, the price per share of Topco Common Stock to be issued in exchange for the Scheme Shares would be sufficient to satisfy the Minimum Price Requirement. Therefore, the Merger Agreement Amendment provides that the Scheme Exchange Ratio will be between 0.1 and 0.166667 (the “ Scheme Exchange Ratio Range”), as determined by the Barinthus Board (or a duly appointed committee thereof) in its discretion prior to the Scheme Effective Time.

Pursuant to the Merger Agreement Amendment, the form of Scheme Document to be approved by the Barinthus Shareholders will provide that the Barinthus Board (or a duly appointed committee thereof) will determine the final Scheme Exchange Ratio within the Scheme Exchange Ratio Range prior to the Scheme Effective Time in order to ensure that the price per share of Topco Common Stock to be issued for the Scheme Shares would be sufficient to satisfy the Minimum Price Requirement based on the then-current trading price of Barinthus ADSs. The Merger Exchange Ratio was also adjusted in the Merger Agreement Amendment to be a number between 0.000305 and 0.000508, as determined by Clywedog and Barinthus Bio in accordance with the Merger Agreement, correspondingly based on the change to the Scheme Exchange Ratio, in order to maintain the agreed ownership split of Topco following closing of the Combinations.

The Merger Agreement Amendment also expands the definitions of Beacon Minimum Cash and Clywedog Minimum Cash to include the required minimum cash amounts based on an assumed closing date of May 31, 2026 and June 30, 2026 in light of the unexpected delay in the overall transaction timeline due to the U.S. federal government shutdowns. See the section entitled “The Transactions — Background of the Transactions.”

Q:

Why are Barinthus Bio and Clywedog proposing this transaction?

​

A:

The Barinthus Board and the Clywedog Board believe that the Combinations will benefit Barinthus Shareholders and Clywedog stockholders, respectively, by creating a combined company that will bring together innovative and highly complementary therapeutic portfolios with world-class technologies and platforms that enhance the health and well-being of patients across the globe.

​

For more details on the reasons for the Combinations, see the section entitled “The Transactions — Barinthus Bio’s Reasons for the Combinations and Recommendation of the Barinthus Board” of this proxy statement/prospectus.

Q:

Why did I receive this proxy statement/prospectus and proxy card?

​

A:

You are receiving this proxy statement/prospectus because (i) you were a shareholder of record of Barinthus Bio on the record date for the Barinthus Shareholder Meetings, and are accordingly entitled to vote at the Barinthus Shareholder Meetings or (ii) you were a holder Barinthus ADSs as of the ADS Voting Record Date, and are accordingly entitled to give instructions with respect to voting of the Barinthus Ordinary Shares represented by your Barinthus ADSs at the Barinthus Shareholder Meetings. This document serves (i) as a proxy statement of Barinthus Bio used to solicit proxies to obtain the necessary shareholder approval for the Barinthus Scheme Proposal at the Barinthus Court Meeting and for the Scheme Implementation Proposal at the Barinthus General Meeting, and (ii) as a prospectus of Topco used to offer Topco Common Stock in exchange for Barinthus Ordinary Shares and Clywedog Shares (as defined below) pursuant to the terms of the Merger Agreement. The enclosed voting materials allow Barinthus Shareholders to vote their shares by proxy without attending the Barinthus Shareholder Meetings in person.

​

 

2

 

Q:

What will Barinthus Shareholders receive in the Combinations?

​

A:

If the Combinations are approved, at the effective time of the Scheme (the “Scheme Effective Time”), Topco will acquire each outstanding ordinary share of Barinthus Bio, with a par value £0.000025 per share (the “Barinthus Ordinary Shares,” and each such acquired Barinthus Ordinary Share, a “Scheme Share”), which, for the avoidance of doubt, will include Barinthus Ordinary Shares held the Depositary (or by its custodian or nominee) and represented by American Depositary Shares (the “Barinthus ADSs”), each representing one (1) Barinthus Ordinary Share,, from the holders of Scheme Shares whose names appear in the register of members of Barinthus Bio at the Scheme Effective Time, in accordance with the provisions of the Scheme of Arrangement, and each Scheme Share will be converted into the right to receive (i) one share of Topco Common Stock, rounded down to the nearest whole share (the “Per Share Scheme Consideration”), plus (ii) cash in lieu of any fractional shares (the “Fractional Scheme Share Consideration” and together with the Per Share Scheme Consideration, the “Scheme Consideration”). Following the Scheme Effective Time, Topco may, in its discretion, elect to commence the Self-Tender Offer to purchase up to $27,000,000 in shares of Topco Common Stock then issued and outstanding, which Self-Tender Offer, if elected, will be consummated prior to the Merger. The parties intend to list the Topco Common Stock to be issued in the Combinations on Nasdaq”. Barinthus Bio may elect to commence the Self-Tender Offer for an aggregate amount less than $27,000,000 based on the cash balance of Barinthus Bio as well as the trading price of Barinthus Bio shares and aggregate market capitalization as of immediately prior to the Scheme Effective Time.

​

Q:

What percentage will former Barinthus Shareholders hold in Topco following completion of the Combinations?

​

A:

It is anticipated that, immediately following completion of the Combinations, former Clywedog stockholders will own approximately 66% of Topco on a fully diluted basis and former Barinthus Shareholders will own approximately 34% of Topco on a fully diluted basis, based on the respective capitalizations of Clywedog and Barinthus Bio as of the date the parties entered into the Original Merger Agreement. The exact equity stakes that former Clywedog stockholders and former Barinthus Shareholders will hold in Topco immediately following the Combinations will depend on the number of Clywedog Shares and Barinthus Ordinary Shares issued and outstanding on a fully diluted basis immediately prior to the Scheme Effective Time and the effective time of the Merger (the “Merger Effective Time” and, together with Scheme Effective Time, the “Effective Times”).

​

Q:

If the Combinations are completed, will the Topco Common Stock be listed for trading?

​

A:

Yes. The Topco Common Stock you will receive in the Combinations are expected to be listed on Nasdaq following the completion of the Combinations, which will occur following the Merger Effective Time. As such, it is intended that, between the Scheme Effective Time and the Merger Effective Time, the Topco Common Stock will not be listed on any securities exchange.

​

Completion of the Combinations is subject to, among other conditions, the Topco Common Stock being approved for listing on Nasdaq, subject to official notice of issuance. Shares of Topco Common Stock received in the Combinations are expected to be freely transferable under applicable securities laws (subject to any applicable minimum holding period in respect of Topco Common Stock received in exchange for Clywedog Shares and Barinthus Ordinary Shares delivered upon vesting of certain equity awards), except for any shares of Topco Common Stock subject to the lock-up agreements entered into by certain executive officers, directors and stockholders of Barinthus Bio and Clywedog.

Q:

When do you expect the Combinations to be completed?

​

A:

The Combinations are expected to close in the first half of 2026, subject to the approvals of Clywedog stockholders and Barinthus Shareholders, receipt of regulatory approvals and consents and satisfaction or waiver of other closing conditions. For more details, see the section entitled “Questions and Answers About the Combinations and the Barinthus Shareholder Meetings — What other conditions must be satisfied to complete the Combinations?” of this proxy statement/prospectus.

​

 

3

 

Q:

What happens if the Combinations are not completed?

​

A:

If Clywedog stockholders do not approve the Combinations, if the Barinthus Shareholders do not approve the Combinations, or if the Combinations are not completed for any other reason, Clywedog and Barinthus Bio will remain independent companies. In the event of a termination, Barinthus ADSs will continue to be listed and traded individually on Nasdaq and Barinthus Bio will continue to be registered under the Exchange Act and file periodic reports with the SEC.

​

The Merger Agreement may be terminated by mutual written consent of Barinthus Bio and Clywedog. The Merger Agreement also contains certain termination rights for either of Barinthus Bio or Clywedog, including, among others, if (i) the Closing Date will not have occurred by September 30, 2026, subject to up to a 60 day extension if the SEC has not declared effective the Registration Statement by July 31, 2026; (ii) a governmental authority of competent jurisdiction has issued a final, non-appealable order prohibiting the Combinations; (iii) the required Barinthus Bio shareholder approvals or Clywedog stockholder approval is not obtained in accordance with the Merger Agreement; (iv) the Scheme of Arrangement is not sanctioned by the Court; (v) either the Barinthus Net Cash or the Clywedog Net Cash is less than the Barinthus Minimum Cash or Clywedog Minimum Cash, respectively, as of the Determination Time, provided that neither Barinthus Bio nor Clywedog shall have the right to terminate the Merger Agreement if the amount of the shortfall is less than 2% of the Clywedog Minimum Cash (the “Barinthus Collar”) or the less than 2% of the Barinthus Minimum Cash (the “Clywedog Collar”), respectively; or (vi) another party breaches or fails to perform in any material respect any of its covenants or any of the other party’s representations or warranties are inaccurate and such breach, failure to perform or inaccuracy would result in certain of the closing conditions not being satisfied, subject to a cure period.

In addition, either Barinthus Bio or Clywedog may terminate the Merger Agreement in certain additional limited circumstances, including if prior to obtaining the relevant shareholder approvals, the other party’s board of directors changes its recommendation of the Combinations to its shareholders or the other party’s board of directors authorizes such party to enter into an agreement providing for an alternative acquisition that constitutes a Superior Offer, subject to the additional terms and conditions set forth in the Merger Agreement.

Q:

What other conditions must be satisfied to complete the Combinations?

​

A:

The closing of the Combinations is subject to the satisfaction or waiver of certain conditions, including, among other things: (i) the effectiveness of a registration statement to register the shares of Topco Common Stock to be issued in connection with the Combinations (the “Registration Statement”); (ii) the absence of any law or order that enjoins, prevents, prohibits, or makes illegal the consummation of the Combinations; (iii) approval by Barinthus Shareholders of the Scheme of Arrangement and certain related matters, and sanction by the Court of the Scheme; (iv) approval by Clywedog’s stockholders of the Merger Agreement, the Merger and the Combinations; (v) the approval for listing by Nasdaq of the shares of Topco Common Stock issuable in the Combinations, subject to official notice of issuance; (vi) certain consents, clearances and expirations or terminations of waiting periods under applicable antitrust laws; (vii) the absence of a material adverse effect with respect to either party; (viii) the completion of the Self-Tender Offer to the extent that Topco elects to commence the Self-Tender Offer; (ix) minimum net cash requirements for each of Barinthus Bio and Clywedog as of the Determination Time; and (xi) subject to certain materiality and material adverse effect qualifiers, the accuracy of the representatives and warranties of the parties contained in the Merger Agreement and the compliance by each party with the covenants contained in the Merger Agreement.

​

Q:

What are the U.S. federal income tax considerations to Barinthus Shareholders of the Combinations?

​

A:

The exchange of Barinthus Ordinary Shares for shares of Topco Common Stock pursuant to the Scheme Transaction, taken together with the Merger, will qualify as a transaction described in Section 351 of the Internal Revenue Code of 1986, as amended (the “Code”). As a result, subject to the limitations and qualifications described in the section entitled “Material U.S. Federal Income Tax Considerations” of this proxy statement/prospectus, no gain or loss is expected to be recognized on the exchange of

​

 

4

 

Barinthus Ordinary Shares for shares of Topco Common Stock pursuant to the Scheme Transaction. However, there is uncertainty as to whether Section 1291(f) of the Code may apply to prohibit such nonrecognition treatment due to the status of Barinthus as a PFIC, as discussed and defined in the section entitled “Material U.S. Federal Income Tax Considerations” of this proxy statement/prospectus. The treatment of the cash received in lieu of fractional shares of Topco Common Stock is discussed separately in the section entitled “Material U.S. Federal Income Tax Considerations” of this proxy statement/prospectus.

Please carefully review the information set forth in the section entitled “Material U.S. Federal Income Tax Considerations” of this proxy statement/prospectus for a general discussion of material U.S. federal income tax considerations relating to the Combinations. You are strongly urged to consult your tax advisors as to the specific tax consequences to you.

Q:

What are the UK tax considerations to shareholders of the Combinations?

​

A:

See the section entitled “Material UK Tax Considerations” of this proxy statement/prospectus.

​

Q:

As Barinthus Bio is a UK public limited company, do the UK rules on takeovers apply to the proposed Combinations?

​

A:

The UK Panel on Takeovers and Mergers has confirmed that the City Code on Takeovers and Mergers (the “City Code”) will not apply to any transaction involving Barinthus Bio (including the Combinations) because the place of central management and control of Barinthus Bio for purposes of the City Code is outside of the UK, the Isle of Man and the Channel Islands.

​

Q:

Are Barinthus Shareholders entitled to exercise dissenters’, appraisal, cash exit, or similar rights?

​

A:

No. Barinthus Shareholders are not entitled to appraisal or dissenters’ rights in connection with the Transactions.

​

Q:

What impact will the Scheme have on Barinthus Bio mandates relating to the payment of dividends?

​

A:

Any mandates relating to the payment of dividends on any Scheme Shares and other instructions (including communications preferences) given to Barinthus Bio by Barinthus Shareholders in force at the Scheme Record Date relating to Scheme Shares will, as from the time the Scheme becomes effective (the “Scheme Effective Time”), cease to be valid.

​

Q:

What are shareholders being asked to consider and approve at the Barinthus Shareholder Meetings?

​

A:

Barinthus Shareholders being asked to consider and approve the following resolutions at the Barinthus Shareholder Meetings:

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5

 

​

Q:

How do I vote my Barinthus Ordinary Shares and/or Barinthus ADSs at Barinthus Shareholder Meetings?

​

A:

The Barinthus Ordinary Share voting record time for the Barinthus Court Meeting is [6:30] p.m. (London Time) on [•], 2026 (the “Barinthus Ordinary Share Voting Record Time”). The Barinthus ADS voting record time for the Barinthus General Meeting is 6:00 p.m. (Eastern Time) on [•], 2026 (the “Barinthus ADS Voting Record Time”). Only those shareholders registered on the register of members of Barinthus Bio as of such time are entitled to vote at the Barinthus Shareholder Meetings. Each such holder will receive a BLUE Form of Proxy for use in respect of the Barinthus Court Meeting and a YELLOW Form of Proxy for use in respect of the Barinthus General Meeting, and is entitled to cast one vote on each matter properly brought before the Barinthus Court Meeting and one vote on each matter properly brought before the Barinthus General Meeting for each Barinthus Ordinary Share that such holder owned of record as of the applicable record time. Each Barinthus Shareholder may cast their vote for, against, or abstain from voting on the proposals described above.

​

The Depositary will collate all votes properly submitted by the Barinthus ADS holders and, provided they are received in time and in compliance with the Barinthus ADS voting instructions, endeavor, insofar as practicable, to vote or cause to be voted the Barinthus Ordinary Shares underlying the Barinthus ADSs as instructed by the Barinthus ADS holders.

Even if you plan to attend the Barinthus Court Meeting or the Barinthus General Meeting, after carefully reading and considering the information contained in this proxy statement/prospectus, please submit your proxy promptly to ensure that your shares are represented at the respective meeting(s). If you decide to attend the meeting(s) and vote virtually, your vote by ballot will revoke any proxy previously submitted. Your attendance at a meeting will not automatically revoke your proxy.

If you are a beneficial owner (i.e., hold Barinthus Ordinary Shares in “street name”), please refer to the instructions provided by your broker, bank, trust company or other nominee to see which of the above choices are available to you. Please note that if you are a beneficial owner and wish to vote virtually at your respective meeting(s), you must obtain a legal proxy from your broker, bank, trust company or other nominee. If you hold Barinthus ADSs in a securities account with a broker, bank, trust company or nominee and wish to give voting instructions, you must follow the instructions received from your broker, bank, trust company or nominee before the cutoff date and time establish by your broker, bank, trust company or nominee.

Q:

Do I need to do anything with my Barinthus Ordinary Shares or Barinthus ADSs other than voting for the proposals at the Barinthus Shareholder Meetings?

​

A:

No. You do not need to take any action at this time with respect to your shares. Please do not send your stock certificates, if any, with your proxy card or ADS voting instruction card.

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6

 

Q:

What happens if I sell my Barinthus Ordinary Shares or Barinthus ADSs before the Barinthus Shareholder Meetings?

​

A:

The Barinthus Ordinary Share Voting Record Time and Barinthus ADS Voting Record Time for the Barinthus Shareholder Meetings are earlier than the date of each such meeting and the date that the Combinations are expected to be completed. If you transfer your shares after the Barinthus Ordinary Share Voting Record Time and Barinthus ADS Voting Record Time, as applicable, but before the Barinthus Court Meeting or the Barinthus General Meeting, as applicable, you will, unless the transferee receives a proxy from you, retain your right to vote at the respective meeting(s), but you will have transferred the right to receive the consideration in connection with the Combinations. In order to receive the consideration, you must hold your Barinthus Ordinary Shares through the Scheme Effective Time or your Barinthus ADSs through the Scheme Effective Time.

​

Q:

What are the voting recommendations of the Barinthus Board regarding the proposals?

​

The Barinthus Board has unanimously (i) approved and declared advisable the Merger Agreement (as amended or modified) and consummation of the Transactions, including the Scheme Transaction and the Scheme of Arrangement, (ii) determined that the terms of the Merger Agreement and the Scheme of Arrangement, the Scheme Transaction and the Transactions are in the best interests of Barinthus Bio and would promote the success of Barinthus Bio for the benefit of Barinthus Shareholders as a whole, and (iii) resolved to recommend that the Barinthus Shareholders approve the Barinthus Scheme Proposal at the Barinthus Court Meeting and the Scheme Implementation Proposal at the Barinthus General Meeting. The Barinthus Board unanimously recommends that Barinthus Shareholders vote “FOR” the Barinthus Scheme Proposal at the Barinthus Court Meeting and “FOR” the Scheme Implementation Proposal at the Barinthus General Meeting.

For more details, see the section entitled “The Transactions — Barinthus Bio’s Reasons for the Combinations and Recommendation of the Barinthus Board” of this proxy statement/prospectus.

Q:

What constitutes a quorum?

​

A:

Consistent with the Nasdaq rules applicable to Barinthus Bio as a U.S. domestic registrant and in accordance with Barinthus Bio’s articles of association, Barinthus Bio requires qualified persons present at a meeting and between them holding (or being the proxy or corporate representative of the holders of) at least 331∕3 percent in number of the issued shares (excluding any shares held as treasury shares) entitled to vote on the business to be transacted at the Barinthus General Meeting.

​

Barinthus ADS holders are the beneficial owners of the Barinthus Ordinary Shares underlying their respective Barinthus ADSs and therefore the Depositary shall attend the Barinthus General Meeting (either in person or by proxy) in order to vote the underlying Barinthus Ordinary Shares on behalf of the Barinthus ADS holders in accordance with the voting instructions cards received from Barinthus ADS holders. The Depositary will not vote Deposited Shares to the extent it does not receive voting instructions from Barinthus ADS holders and those uninstructed Deposited Shares also will not be counted toward the quorum.

If you are a holder of record of Barinthus Ordinary Shares, your Barinthus Ordinary Shares will be counted towards the quorum only if you are present in person or represented by proxy at the Barinthus General Meeting. A member represented by a proxy at the Barinthus General Meeting will be counted towards the quorum requirement even where the proxy abstains from voting. If a form of proxy does not instruct the proxy how to vote, the proxy may vote as he or she sees fit or abstain in relation to any business of the Barinthus General Meeting, but the member represented by that proxy at the Barinthus General Meeting will be counted towards the quorum requirement.

If there is no quorum, the Barinthus General Meeting will stand adjourned to such time, date and place as may be fixed by the Chair of the General Meeting Chair (the “General Meeting Chair”) (being not less than 10 clear days after the date of the original meeting). Barinthus Bio requires a quorum of at least 331∕3 percent in number of the issued shares (excluding any shares held as treasury shares) entitled to vote on the business to be transacted if the Barinthus General Meeting is reconvened, consistent

 

7

 

with the Nasdaq rules applicable to Barinthus Bio as a U.S. domestic registrant and Barinthus Bio’s articles of association. If such quorum is not present at the adjourned meeting within 15 minutes (or such longer interval as the General Meeting Chair in their absolute discretion thinks fit) from the time appointed for holding the meeting, or if a quorum ceases to be present during a meeting, the meeting shall be dissolved if convened on the requisition of members and in all other cases shall stand adjourned to another time, date and place as may be fixed by the General Meeting Chair (being not less than 10 clear days after the date of the original meeting).

Q:

What are the effects of abstentions and broker non-votes at the Barinthus Court Meeting and the Barinthus General Meeting?

​

A:

In connection with the Barinthus Shareholder Meetings, abstentions and broker non-votes will be considered in determining the presence of a quorum. However, abstentions and broker non-votes are not considered votes cast under the UK Companies Act. An abstention occurs when a Barinthus Shareholder abstains from voting (either in person or by proxy) on one or more of the proposals. Broker non-votes occur when a broker, bank, trust or other nominee returns a proxy but does not have authority to vote on a particular proposal. As a result, for purposes of determining whether each of the resolutions set out in the Notice of Barinthus Court Meeting and Notice of Barinthus General Meeting has been approved in accordance with the UK Companies Act, abstentions and broker non-votes will not have any effect on the outcome of the vote.

​

Q:

What happens if I am a Barinthus Shareholder located outside of the United States?

​

A:

The availability of the Scheme of Arrangement and the transaction deliverables to overseas Barinthus Shareholders (i.e., those outside the United States) may be affected by the laws of the relevant jurisdictions. Overseas Barinthus Shareholders should inform themselves about, and should observe, any applicable legal requirements. It is the responsibility of all overseas Barinthus Shareholders to satisfy themselves as to their full compliance with the laws of the relevant jurisdiction, including obtaining any governmental, exchange control or other consents which may be required and their compliance with any other necessary formalities which are required to be observed and the payment of any issue, transfer or other taxes due in such jurisdiction. If you are in any doubt regarding such matters, you should consult an independent professional adviser in the relevant jurisdiction without delay. Overseas Barinthus Shareholders should consult their own legal and tax advisers with respect to the legal and tax consequences of the Combinations in their particular circumstances.

​

Q:

Will the Scheme Shareholders vote as one class at the Barinthus Court Meeting?

​

A:

It is expected that the Court will confirm at a directions hearing on November 17, 2025 that the Scheme Shareholders should be treated as a single class of shareholders for the purpose of voting at the Barinthus Court Meeting, in which case, there will be no separate class votes in respect of the Barinthus Scheme Proposal.

​

Q:

How will the Barinthus Ordinary Shares represented by my Barinthus ADSs be voted if I do not specify how they should be voted?

​

A:

For Barinthus ADS holders, if you have not returned your Barinthus ADS voting instruction card in compliance with the Barinthus ADS voting instructions or if you have failed to indicate how you would like your Barinthus ADSs to be voted, the Depositary shall not vote or attempt to exercise the right to vote attaching to your deposited ordinary shares. The Depositary may only vote or attempt to exercise the right to vote attaching to your deposited shares in accordance with the Barinthus ADS voting instructions submitted by you.

​

For holders of record of Barinthus Ordinary Shares of record, if you sign and send your form of proxy but do not indicate how you want your shares to be voted, your shares may be voted by the person that you appoint as your proxy as he or she sees fit or such person may abstain in relation to any business of the Barinthus Shareholder Meetings.

 

8

 

Q:

Can I change my vote or revoke a proxy?

​

A:

A registered holder of Barinthus Ordinary Shares can revoke his or her proxy before the time of voting at either of the Barinthus Shareholder Meetings in several ways by:

​

1.

mailing a revised form of proxy dated later than the prior form of proxy; or

​

2.

notifying Barinthus Bio at Barinthus Biotherapeutics plc, 20400 Century Boulevard, Suite 210, Germantown, MD 20874, Attention: Corporate Secretary in writing that you are revoking your proxy. Your revocation must be received at Barinthus Bio’s registered office before the applicable Barinthus Shareholder Meeting to be effective.

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A shareholder would also be able to revoke his or her proxy by voting in person at the applicable Barinthus Shareholder Meeting.

If your Barinthus Ordinary Shares are held in an account at a broker, bank, trust company or other nominee, you may change or revoke your voting instructions by contacting the broker, bank, trust company or other nominee holding the shares or by your broker, bank, trust company or other nominee validly appointing you as proxy to attend the applicable Barinthus Shareholder Meetings.

Q:

Who counts the votes?

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A:

Computershare has been engaged as Barinthus Bio’s independent agent to tabulate shareholder votes. If you are a holder of record of Barinthus Ordinary Shares, you can return your executed form of proxy to Computershare for tabulation (see instructions on the applicable form of proxy). If you hold your Barinthus Ordinary Shares through a broker, bank, trust company or other nominee, such nominee will return the applicable form of proxy to Computershare for tabulation.

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If you are a registered holder of record of Barinthus ADSs on the Depositary register, you can vote by returning your executed Barinthus ADS voting instruction card, if one is requested, to the Depositary for tabulation. If you hold your Barinthus ADSs through a broker, bank, trust company or other nominee, that nominee can return the voting instruction to the Depositary following your instruction. The Depositary will submit your votes to Computershare for tabulation.

Q:

How are votes counted?

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A:

Votes will be counted by Computershare, who will separately count “for” and “against” votes, and “votes withheld” or abstentions. A “vote withheld” or abstention will not be counted in the calculation of the votes “for” and “against” a resolution.

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Q:

How many votes do I have?

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A:

On a show of hands, holder of record of Barinthus Ordinary Shares present in person, and each duly authorized representative present in person of a shareholder that is a corporation, has one vote. On a show of hands, each proxy present in person who has been duly appointed by one or more shareholders has one vote, but a proxy has one vote for and one vote against a resolution if, in certain circumstances, the proxy is instructed by more than one shareholder to vote in different ways on a resolution. On a poll, each shareholder present in person or by proxy or, in the case of a corporation, by a duly authorized representative has one vote for each share held by the shareholder.

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The holders of record of Barinthus ADSs are entitled to give voting instructions with respect to all matters that are subject to shareholder vote. If you are a Barinthus ADS holder and have submitted your Barinthus ADS voting instruction card in time and in compliance with the instructions on the voting card, the Depositary will attend the Barinthus Shareholder Meetings (either in person or by appointing a proxy) and endeavor vote or cause to be voted the Barinthus Ordinary Shares underlying your Barinthus ADSs as directed by you.

Q:

How do you solicit proxies?

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A:

Barinthus Bio has retained MacKenzie Partners to assist it in soliciting proxies. Barinthus Bio will pay the fees of MacKenzie Partners, which Barinthus Bio expects to be approximately $15,000, plus

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reimbursement of reasonable and customary out-of-pocket expenses. The initial solicitation of proxies may be supplemented by additional mail communications and by telephone, fax, e-mail, internet and personal solicitation by Barinthus Bio’s directors, officers or other employees. No additional compensation for soliciting proxies will be paid to Barinthus Bio’s directors, officers or other employees for their proxy solicitation efforts. Barinthus Bio will also reimburse the Depositary for their expenses in sending materials, including Barinthus ADS voting instruction cards, to Barinthus ADS holders of record.

Q:

What do I do if I receive more than one notice or form of proxy?

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A:

If you hold your Barinthus Ordinary Shares or your Barinthus ADSs in more than one account, you will receive a form of proxy or a Barinthus ADS voting instruction card (as applicable) for each account. In addition, as described above, each holder of record of Barinthus Ordinary Shares will receive a BLUE Form of Proxy for use in respect of the Barinthus Court Meeting and a YELLOW Form of Proxy for use in respect of the Barinthus General Meeting, whereas each holder of record of Barinthus ADSs will receive a single ADS voting instruction card for use in respect of both of the Barinthus Shareholder Meetings, in each case for each account. To ensure that all of your Barinthus Ordinary Shares or Barinthus ADSs are voted, please sign, date and return all proxy forms or Barinthus ADS voting instruction cards (as applicable). Please be sure to vote all of your Barinthus Ordinary Shares or Barinthus ADSs.

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Q:

Are there risks associated with the Combinations that I should consider in deciding how to vote?

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A:

Yes. You should carefully read the detailed description of the risks associated with the Combinations and Topco’s operations following the Combinations described in the section entitled “Risk Factors” of this proxy statement/prospectus. You also should read and carefully consider the risk factors associated with the businesses of both Clywedog and Barinthus Bio that are included in this proxy statement/​prospectus because these risks will relate to the business of Topco following the completion of the Combinations.

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Q:

How can I find out the results of the voting at the Barinthus Shareholder Meetings?

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A:

Voting results will be announced by the filing of current reports on Form 8-K by Barinthus Bio with the SEC within four business days after the Barinthus Court Meeting and Barinthus General Meeting. If final voting results are unavailable at that time, Barinthus Bio will file an amended current report on Form 8-K within four business days of the day the final results are available.

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Q:

Who can answer my questions?

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A:

The information provided above in the question-and-answer format is for your convenience only and is merely a summary of some of the information contained in this proxy statement/prospectus. You should read carefully the entire proxy statement/prospectus, including the information in the annexes. See the section entitled “Where You Can Find More Information” of this proxy statement/prospectus. If you would like additional copies of this proxy statement/prospectus or the enclosed proxy card, without charge, or if you have questions about the Combinations, including the procedures for voting your shares, you should contact Barinthus Bio at Barinthus Biotherapeutics plc, 20400 Century Boulevard, Suite 210, Germantown, MD 20874, Attention: Corporate Secretary, or MacKenzie Partners, Barinthus Bio’s proxy solicitor, by e-mailing proxy@mackenziepartners.com or calling toll-free at +1 (800) 322-2885, between 9:00 a.m. and 5:30 p.m. (London Time).

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Beneficial holders of Barinthus ADSs, whose Barinthus ADSs are registered under a nominee name, and who have any queries about how to deliver voting instructions for the Barinthus Shareholder Meetings, should contact their broker, bank, trust company or other nominee who is holding the Barinthus ADSs.

No other methods of communication from stockholders will be accepted. You may not use any electronic address provided in this proxy statement/prospectus or any related documents to communicate with Barinthus Bio for any purposes other than those expressly stated.

 

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NOTE ON PRESENTATION

Barinthus Bio Financial Information

Historical financial information of Barinthus Bio included in this proxy statement/prospectus has been derived from the audited consolidated financial statements of Barinthus Bio as of and for each of the fiscal years ended December 31, 2025 and 2024, each of which are included in this proxy statement/​prospectus. See the section entitled “Index to Barinthus Bio’s Financial Statements” beginning on page F-1 of this proxy statement/prospectus for more information regarding the audited consolidated financial statements of Barinthus Bio for the covered periods.

The consolidated financial statements of Barinthus Bio are reported pursuant to U.S. GAAP and are presented in U.S. dollars.

Clywedog Financial Information

Historical financial information of Clywedog included in this proxy statement/prospectus has been derived from the audited consolidated financial statements of Clywedog as of and for each of the fiscal years ended December 31, 2025 and 2024, each of which are included in this proxy statement/prospectus. See the section entitled “Index to Clywedog’s Financial Statements” beginning on page F-35 of this proxy statement/​prospectus for more information regarding the audited consolidated financial statements of Clywedog for the covered periods.

The consolidated financial statements of Clywedog are reported pursuant to U.S. GAAP and are presented in U.S. dollars.

 

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RISK FACTORS

Investing in Topco Common Stock involves risks, some of which are related to the Combinations. You should carefully consider the risks described below, as well as the other information included in this proxy statement/prospectus, including the matters addressed in the section entitled “Cautionary Statement Regarding Forward Looking Statements” of this proxy statement/prospectus. These risk factors are not exhaustive, and investors are encouraged to perform their own investigation with respect to each of the businesses of Barinthus Bio and Clywedog because these risks will relate to the Combined Business of Topco following the completion of the Combinations. The occurrence of one or more of the events or circumstances described in these risk factors, alone or in combination with other events or circumstances, may adversely affect the ability to complete or realize the anticipated benefits of the Combinations, and may have a material adverse effect on the Combined Business of Topco, as well as the respective businesses of Barinthus Bio and Clywedog, as well as their respective financial condition or results of operations. The risks discussed below may not prove to be exhaustive and are based on certain assumptions made by Topco, Barinthus Bio, and Clywedog which later may prove to be incorrect or incomplete. Topco, Barinthus Bio, and Clywedog may face additional risks and uncertainties that are not presently known to such entities, or that are currently deemed immaterial, which may also impair their business or financial condition.

Risks Relating to the Transactions

Completion of the Combinations is subject to certain conditions, some of which are outside of the parties’ control, and if these conditions are not satisfied or waived, the Combinations will not be completed.

The closing of the Combinations is subject to certain conditions, including, amongst other things, (i) the effectiveness of this Registration Statement for the issuance of the shares of Topco Common Stock in connection with the Combinations; (ii) the absence of any order issued by a court or other governmental authority preventing or prohibiting the Transactions; (iii) the absence of any applicable law prohibiting or making illegal completion of the Transactions; (iv) approval of the Scheme of Arrangement by Barinthus Shareholders at the Barinthus Court Meeting and the passing of the Scheme Implementation Proposal by Barinthus Shareholders at the Barinthus General Meeting; (v) the sanctioning of the Scheme of Arrangement (including the Capital Reduction) by the Court; (vi) receipt of Clywedog stockholder approval of the Merger and related matters; (vii) receipt of Nasdaq listing approval for shares of Topco Common Stock, subject to official notice of issuance; (viii) receipt of evidence that the Cabinet Office has notified each of Topco, OrbiMed and TPAV, pursuant to section 14(8)(b)(ii) of the NSIA, that no further action will be taken in relation to the Transactions; (ix) Barinthus Bio and Clywedog having not less than the Barinthus Minimum Cash and the Clywedog Minimum Cash, respectively, as of the Closing Date, in each case subject to the Barinthus Collar and the Clywedog Collar; and (x) subject to certain materiality exceptions, the accuracy of each of Barinthus Bio’s and Clywedog’s representations and warranties in the Merger Agreement and performance by each of Barinthus Bio and Clywedog of its obligations under the Merger Agreement. For a more complete summary of the conditions that must be satisfied or waived prior to completion of the Transactions, see the section entitled “The Merger Agreement — Conditions to the Completion of the Combinations” beginning on page 310 of this proxy statement/prospectus.

The requirement to satisfy each of the foregoing conditions could delay completion of the Combinations for a significant period of time or prevent them from occurring at all. Any delay in completing the Combinations could cause Topco not to realize some or all of the benefits that the parties expect Topco to achieve if the Combinations are successfully completed within the expected timeframe. Further, as a condition to approving the Combinations, governmental authorities may impose conditions, terms, obligations or restrictions on the conduct of the parties’ business after the completion of the Combinations. If the parties were to become subject to any conditions, terms, obligations or restrictions, it is possible that such conditions, terms, obligations or restrictions will delay completion of the Combinations or otherwise adversely affect the parties’ business, financial condition, or operations. Furthermore, governmental authorities may require that the parties divest assets or businesses as a condition to the closing of the Combinations. If the parties are required to divest assets or businesses, there can be no assurance that Barinthus Bio or Clywedog will be able to negotiate such divestitures expeditiously or on favorable terms or that the governmental authorities will approve the terms of such divestitures. There can be no assurance that the conditions to the closing of the Combinations will be satisfied or, where applicable, waived or that the Combinations will be completed.

 

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In addition, if the Closing Date shall not have occurred by September 30, 2026 (subject to certain extension rights), either Barinthus Bio or Clywedog may choose not to proceed with the Combinations. Barinthus Bio and Clywedog may also terminate the Merger Agreement under certain other circumstances. See the sections titled “The Merger Agreement — Termination” beginning on page 328 of this proxy statement/prospectus.

Some of the conditions to the Combinations and termination rights may be waived by Barinthus Bio or Clywedog without resoliciting Barinthus Shareholder or Clywedog stockholder approval.

Some of the conditions to completing the Combinations and termination rights set forth in the Merger Agreement may be waived by Barinthus Bio or Clywedog, subject to certain limitations, without resoliciting Barinthus Shareholder approval or Clywedog stockholder approval. If any conditions or termination rights are waived, Barinthus Bio and Clywedog will evaluate whether the amendment of this proxy statement/​prospectus and resolicitation of proxies would be warranted. Subject to applicable law, if Barinthus Bio and Clywedog determine that resolicitation of Barinthus Shareholders or Clywedog stockholders is not warranted, the parties will have the discretion to complete the Combinations without seeking such additional Barinthus Shareholder approval or Clywedog stockholder approval, as applicable. No action by the Barinthus Board or Clywedog Board with respect to the Merger Agreement may adversely affect the Barinthus Shareholders or stockholders of Clywedog, respectively, or affect the consideration to be received by the Barinthus Shareholders or the stockholders of Clywedog in the Combinations, unless their shareholders or stockholders, as applicable, approve such action.

Failure to complete the Combinations could negatively impact the price of the Barinthus ADSs and the future business and financial results of Barinthus Bio and Clywedog, respectively.

If the Combinations are not completed for any reason, including as a result of Barinthus Shareholders failing to approve the Scheme Transaction or Clywedog stockholders failing to approve the Merger and related matters, the ongoing businesses of Clywedog and Barinthus Bio may be adversely affected and, without realizing any of the benefits of having completed the Combinations, Barinthus Bio and Clywedog would be subject to a number of risks, including the following:

•

Barinthus Bio and Clywedog are subject to certain restrictions on the conduct of their businesses prior to completing the Combinations, which may adversely affect their respective abilities to execute certain of their respective business strategies going forward if the Combinations are not completed;

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Barinthus Bio and Clywedog have incurred and will continue to incur significant costs and fees associated with the proposed Combinations, such as legal, accounting, financial advisor and printing fees, regardless of whether the Combinations are completed;

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Barinthus Bio may experience negative reactions from the financial markets, including negative impacts on the price of the Barinthus ADSs;

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•

Barinthus Bio and Clywedog may experience negative reactions from their partners, third-party providers, regulators and employees; and

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matters relating to the Combinations (including integration planning) will require substantial commitments of time and resources by Barinthus Bio’s and Clywedog’s management, which would otherwise have been devoted to day-to-day operations and other opportunities that may have been beneficial to Barinthus Bio and Clywedog as independent companies.

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In addition, Barinthus Bio and Clywedog could be subject to litigation related to the Combinations that may prevent the Combinations from being completed in the time frame expected or at all. Legal actions related to the Combinations may also result from a failure to complete the Combinations or any enforcement proceeding commenced against Barinthus Bio, Clywedog or Topco to perform its obligations under the Merger Agreement and, if such actions occur, it may result in significant costs of defense, indemnification and liability and draw the attention of Barinthus Bio and Clywedog’s management teams away from the Combinations. If the Combinations are not completed, these risks may materialize and may adversely affect Barinthus Bio’s or Clywedog’s respective businesses, financial conditions, financial results and the price of the Barinthus ADSs.

 

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The number of shares of Topco Common Stock that Barinthus Shareholders will receive in the Scheme Transaction and Clywedog stockholders will receive in the Merger is based on fixed exchange ratios that will not be adjusted to reflect changes in the market value of Barinthus ADSs. Further, when Barinthus Shareholders and Clywedog stockholders vote on the transactions contemplated in the Merger Agreement, they will not know the exact value of the shares of Topco Common Stock that will be issued in connection with the Combinations. The value of the shares of Topco Common Stock that Barinthus Shareholders and Clywedog stockholders receive upon completion of the Combinations could vary based on changes in the market value of Barinthus ADSs from the time that the Barinthus Shareholders and Clywedog stockholders vote to approve the Scheme Transaction or approve the Merger Agreement and related matters, as applicable.

At the Scheme Effective Time, Barinthus Shareholders will be entitled to receive between 0.1 and 0.166667, as finally determined by the Barinthus Board (or a duly appointed committee thereof) in its sole discretion prior to the Scheme Effective Time, shares of Topco Common Stock for each Scheme Share that they own. Upon completion of the Merger, Clywedog stockholders will be entitled to receive between 0.000305 and 0.000508, as finally determined by Clywedog and Barinthus Bio, shares of Topco Common Stock for each Clywedog Share that they own. Immediately following consummation of the Combinations, it is expected that former Barinthus Shareholders will own approximately 34% of Topco and former Clywedog stockholders will own approximately 66% of Topco, on a fully diluted basis, based on the respective capitalizations of Barinthus Bio and Clywedog as of the date the parties entered into the Original Merger Agreement. The market value of the shares of Topco Common Stock that Barinthus shareholders will be entitled to receive when the Scheme Transaction is completed and that Clywedog stockholders will be entitled to receive when the Merger is completed could vary significantly due to a change in the market value of Barinthus ADSs from the date the Original Merger Agreement was entered into, the date of this proxy statement/prospectus, the date of the Barinthus General Meeting or the date that Clywedog stockholder approval is received. Because the applicable exchange ratios will not be adjusted to reflect any changes in the market value of Barinthus ADSs, such market price fluctuations may affect the relative value that Barinthus Shareholders will receive at the Scheme Effective Time or that Clywedog stockholders will receive at the Merger Effective Time. Share price changes may result from a variety of factors, including changes in the business, operations or prospects of Barinthus Bio or Clywedog, market assessments of the likelihood that the Combinations will be completed, market assessments of the value of Topco, the timing of the Combinations, regulatory considerations, governmental actions, general market and economic conditions, legal proceedings and other factors, each of which may be beyond the control of Topco, Barinthus Bio or Clywedog. Prior to making any investment decision, stockholders are urged to obtain updated market quotations for Barinthus ADSs.

The trading of shares of Topco Common Stock after completion of the Combinations may cause the market price of shares of Topco Common Stock to fall.

Following completion of the Combinations, shares of Topco Common Stock are expected to be publicly traded on Nasdaq, enabling former Barinthus Shareholders and Clywedog stockholders to sell the shares of Topco Common Stock that they receive in the Combinations, subject to applicable lock-up restrictions. Sales of certain of such shares of Topco Common Stock may take place promptly following the Combinations and could have the effect of decreasing the market price for the shares of Topco Common Stock owned by former Barinthus Shareholders and Clywedog stockholders below the market price or valuations of the Scheme Shares or Clywedog Shares owned by such former Barinthus Shareholders and Clywedog stockholders, respectively, prior to completion of the Combinations.

The Combinations may be completed even though material adverse changes subsequent to the announcement of the Combinations, such as industry-wide changes or other events, may occur.

In general, Barinthus Bio or Clywedog can, on the terms and conditions set forth in the Merger Agreement, refuse to complete the Combinations if a Clywedog Material Adverse Effect or a Barinthus Material Adverse Effect, respectively, has occurred since execution of the Original Merger Agreement. However, some types of changes do not permit either Clywedog or Barinthus Bio to refuse to complete the Combinations, even if such changes would have a material adverse effect on either of the parties. For example, a worsening of Barinthus Bio’s or Clywedog’s financial condition or results of operations due to either party taking an action that is required by the Merger Agreement; the sale, license or other disposition by

 

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Barinthus Bio of the Barinthus Legacy Assets; a change in the market price or trading volume of Barinthus ADSs; or any natural disaster, act of war or hostility around the world, epidemic or pandemic or decrease in general economic conditions, except to the extent affecting Barinthus Bio or Clywedog, as applicable, in a disproportionate manner relative to other businesses operating in the industries in which they operate, would not give the other party the right to refuse to complete the Combinations. If adverse changes occur that affect either party, but the parties are still required to complete the Combinations, the price of shares of Topco Common Stock and the business and financial results of Topco may suffer.

The Merger Agreement contains provisions that restrict Barinthus Bio’s and Clywedog’s ability to pursue alternatives to the Combinations.

Under the Merger Agreement, each of Barinthus Bio, Clywedog and Topco is restricted, subject to certain exceptions, from soliciting, initiating, knowingly encouraging or facilitating, discussing or negotiating, or furnishing non-public information with regard to, any inquiry, proposal or offer for a competing Acquisition Proposal from any person or entity. If any party receives a competing Acquisition Proposal and such party’s board of directors determines (after consultation with such party’s financial advisors and outside legal counsel) that such proposal constitutes a Superior Offer and the board of directors makes a change in recommendation in response to such proposal to the shareholders or stockholders of such company, Barinthus Bio, on the one hand, or Clywedog, on the other hand, would be entitled, upon complying with certain requirements, to terminate the Merger Agreement, subject to the terms of the Merger Agreement. These provisions could discourage a third party that may have an interest in acquiring all or a significant part of either company from considering or proposing such an acquisition, even if such third party was prepared to enter into a transaction that would be more favorable to one of the companies and its respective shareholders or stockholders than the Combinations. See the sections entitled “The Merger Agreement — Acquisition Proposals” and “The Merger Agreement — Termination” of this proxy statement/prospectus.

Until the completion of the Combinations or the termination of the Merger Agreement pursuant to its terms, Barinthus Bio and Clywedog are each prohibited from entering into certain transactions and taking certain actions that might otherwise be beneficial to Barinthus Bio and its shareholders and/or Clywedog and its stockholders, respectively.

From and after the date of the Original Merger Agreement and prior to the completion of the Combinations or the termination of the Merger Agreement pursuant to its terms, the Merger Agreement restricts Barinthus Bio and Clywedog from taking specified actions without the consent of the other party and requires that their respective businesses be conducted in the ordinary course. These restrictions may prevent Barinthus Bio or Clywedog, as applicable, from taking actions during the pendency of the Combinations that would have been beneficial, other than Barinthus Legacy Transactions. Adverse effects arising from these restrictions during the pendency of the Combinations could be exacerbated by any delays in the completion of the Combinations or termination of the Merger Agreement. See the section entitled “The Merger Agreement — Covenants; Conduct of Business Pending the Combinations” of this proxy statement/prospectus.

Barinthus Bio and Clywedog will incur significant transaction and merger-related costs in connection with the Combinations, whether or not the Combinations are consummated.

Barinthus Bio and Clywedog have incurred and expect to incur a number of non-recurring direct and indirect costs associated with the Combinations. These costs and expenses include fees paid to financial, legal and accounting advisors, severance and other potential employment-related costs, including payments that may be made to certain Barinthus Bio and Clywedog executives, UK stamp duties, filing fees, printing expenses and other related charges. Some of these costs are payable by Barinthus Bio and Clywedog regardless of whether the Combinations are completed. There are also processes, policies, procedures, operations, technologies and systems that must be integrated in connection with the Combinations and the integration of the two companies’ businesses. While both Barinthus Bio and Clywedog have assumed that a certain level of expenses would be incurred in connection with the Combinations and the other Transactions and continue to assess the magnitude of these costs, there are many factors beyond their control that could affect the total amount or the timing of the integration and implementation expenses.

 

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There may also be additional unanticipated significant costs in connection with the Combinations that Barinthus Bio and Clywedog may not recoup, including as a result of litigation related to the Combinations. These costs and expenses could reduce the realization of efficiencies and strategic benefits Barinthus Bio and Clywedog expect Topco to achieve from the Combinations. Although Barinthus Bio and Clywedog expect that these benefits will offset the transaction expenses and implementation costs over time, this net benefit may not be achieved in the near term or at all.

In connection with the Combinations, Barinthus Bio, Clywedog and/or Topco may be required to take write-downs or write-offs, restructuring and impairment or other charges that could negatively affect the business, assets, liabilities, prospects, outlook, financial condition and results of operations of Barinthus Bio, Clywedog and/or Topco.

Although Barinthus Bio and Clywedog have conducted extensive due diligence in connection with the Combinations and related transactions, they cannot assure you that this diligence revealed all material issues that may be present, that it would be possible to uncover all material issues through a customary amount of due diligence or that factors outside of Barinthus Bio’s and Clywedog’s control will not later arise. Even if Barinthus Bio’s and Clywedog’s due diligence successfully identifies certain risks, unexpected risks may arise and previously known risks may materialize in a manner not consistent with Barinthus Bio’s and Clywedog’s preliminary risk analysis. Further, as a result of the Combinations, purchase accounting and the proposed operation of Topco going forward, Barinthus Bio, Clywedog and/or Topco may be required to take write-offs or write-downs, restructuring and impairment or other charges. As a result, Barinthus Bio, Clywedog and/or Topco may be forced to write-down or write-off assets, restructure its operations or incur impairment or other charges that could negatively affect the business, assets, liabilities, prospects, outlook, financial condition and results of operations of Barinthus Bio, Clywedog and/or Topco.

After the Combinations, Barinthus Shareholders and Clywedog stockholders will have a reduced ownership and voting interest in Topco than they currently have in Barinthus Bio and Clywedog, respectively, and will exercise less influence over Topco’s management.

Immediately following consummation of the Combinations, it is expected that former Barinthus Shareholders will own approximately 34% of Topco and former Clywedog stockholders will own approximately 66% of Topco, on a fully diluted basis, based on the respective capitalizations of Barinthus Bio and Clywedog as of the date the parties entered into the Original Merger Agreement. Consequently, former Barinthus Shareholders will have a reduced ownership of Topco than they currently have of Barinthus Bio and will exercise less influence over the management and policies of Topco than they currently have over the management and policies of Barinthus Bio. Additionally, former Clywedog stockholders will have a reduced ownership of Topco than they currently have of Clywedog and will exercise less influence over the management and policies of Topco than they currently have over the management and policies of Clywedog.

In addition, following the closing of the Combinations, it is expected that the Topco Board will initially be comprised of five (5) directors, consisting of four existing directors of Barinthus Bio, expected to consist of William Eright, Robin Wright, Anne M. Phillips and Karen T. Dawes, at least three (3) of whom will qualify as an “independent director” under the applicable rules of Nasdaq, and one individual designated by Clywedog, expected to be Dr. Iain Dukes.

It is currently expected that following the closing of the Combinations, (i) William Enright, the current Chief Executive Officer of Barinthus Bio, will serve as Chief Executive Officer of Topco; (ii) Dr. Iain Dukes, the current President of Clywedog, will serve as Executive Chairman of Topco; (iii) Leon Hooftman, current Chief Medical Officer of Barinthus Bio, will serve as Chief Medical Officer of Topco; and (iv) Gemma Jones, current Chief Financial Officer of Barinthus Bio, will serve as Interim Chief Financial Officer of Topco.

Barinthus Bio and Clywedog may have difficulty attracting, motivating and retaining executives and other key employees due to uncertainty associated with the Combinations.

Topco’s success after completion of the Combinations will depend in part upon the ability of Topco to retain key employees of Barinthus Bio and Clywedog. Competition for qualified personnel can be intense. Current and prospective employees of Barinthus Bio or Clywedog may experience uncertainty about the

 

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effect of the Combinations, which may impair Barinthus Bio’s and Clywedog’s ability to attract, retain and motivate key management, scientific, research, technical and other personnel prior to and following the Combinations. Employee retention may be particularly challenging during the pendency of the Combinations, as employees of Barinthus Bio and Clywedog may experience uncertainty about their future roles with Topco.

In addition, pursuant to change in control and/or severance provisions in Barinthus Bio’s severance schemes and executive employment agreements, certain key employees of Barinthus Bio are entitled to receive severance payments upon certain qualifying terminations of their employment. Certain key Barinthus Bio employees potentially could terminate their employment following specified circumstances set forth in the applicable executive severance scheme or employment agreement, including certain changes in such key employees’ title, status, authority, duties, responsibilities or compensation, and be entitled to receive severance. Such circumstances could occur in connection with the Combinations as a result of changes in roles and responsibilities.

While Barinthus Bio and Clywedog may employ the use of certain retention programs, there can be no guarantee that they will prove to be successful. If key employees of Barinthus Bio or Clywedog depart, the integration of the companies may be more difficult and Topco’s business following the Combinations may be harmed. Furthermore, Topco may be required to incur significant costs in identifying, hiring, training and retaining replacements for departing employees and may lose significant expertise and talent relating to the businesses of Barinthus Bio or Clywedog, which may adversely affect Topco’s ability to realize the anticipated benefits of the Combinations. In addition, there could be disruptions to or distractions for the workforce and management associated with activities of labor unions or works councils or integrating employees into Topco. Accordingly, no assurance can be given that Topco will be able to attract or retain key employees of Barinthus Bio and Clywedog to the same extent that those companies have been able to attract or retain their own employees in the past.

Barinthus Bio’s and Clywedog’s business relationships may be subject to disruption due to uncertainty associated with the Combinations.

Companies with which Barinthus Bio or Clywedog do business may experience uncertainty associated with the Combinations, including with respect to current or future business relationships with Barinthus Bio, Clywedog or Topco. Barinthus Bio’s and Clywedog’s business relationships may be subject to disruption as suppliers, vendors and others may attempt to negotiate changes in existing business relationships or consider entering into business relationships with parties other than Barinthus Bio, Clywedog or Topco. These disruptions could have an adverse effect on the businesses, financial condition, results of operations or prospects of Topco, including an adverse effect on Topco’s ability to realize the anticipated benefits of the Combinations. The risk and adverse effect of such disruptions could be exacerbated by a delay in completion of the Combinations.

Barinthus Bio’s executive officers and directors have interests in the Combinations that may be different from the interests of Barinthus Shareholders, generally.

When considering the recommendation of the Barinthus Board that Barinthus Shareholders approve the Scheme Transaction, Barinthus Shareholders should be aware that directors and executive officers of Barinthus Bio have certain interests in the Combinations that may be different from or in addition to the interests of Barinthus Shareholders generally. These interests include, but are not limited to, the treatment of Barinthus equity awards in the Scheme Transaction, severance protection provided for in compensation arrangements of certain executives, and potential changes to their roles and responsibilities with Topco following the completion of the Combinations. The Barinthus Board was aware of these interests and considered them, among other things, in evaluating and negotiating the Merger Agreement and the Combinations and in recommending that the Barinthus Shareholders approve the Scheme Transaction.

See the sections entitled “The Transactions — Background of the Transactions,” “Interests of Certain Persons in the Transactions (Barinthus Bio)” and “The Merger Agreement — Indemnification and Insurance” of this proxy statement/prospectus.

 

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Completion of the Combinations may trigger change-in-control or other provisions in certain agreements that Barinthus Bio or Clywedog is party to.

The completion of the Combinations may trigger change-in-control or other provisions in certain agreements that Barinthus Bio or Clywedog is party to. If Barinthus Bio or Clywedog, as applicable, is unable to negotiate waivers of those provisions, the respective counterparties may exercise their rights and remedies under the applicable agreements, including in some instances potentially terminating the agreements or seeking monetary damages or other remedies. Even if Barinthus Bio or Clywedog, as applicable, is able to negotiate waivers, the respective counterparties may require a fee for such waivers or seek to renegotiate the agreements on terms less favorable to the combined business.

If the Scheme Transaction does not qualify as part of an exchange described under Section 351 of the Code, U.S. shareholders of Barinthus Bio may be required to pay substantial U.S. federal income taxes. Likewise, if the Merger does not qualify as part of an exchange described under Section 351 of the Code or a “reorganization” within the meaning of Section 368(a) of the Code, U.S. stockholders of Clywedog may be required to pay substantial U.S. federal income taxes.

For U.S. federal income tax purposes, the Combinations, taken together as a single integrated transaction, are intended to qualify as an exchange described under Section 351 of the Code and the payment of cash pursuant to the Combinations is intended to be treated as a payment pursuant to Section 351(b) of the Code (the “Intended Tax Treatment”). The Merger may also qualify as a “reorganization” within the meaning of Section 368(a) of the Code. All parties intend to report the Combinations consistent with the Intended Tax Treatment. However, neither Barinthus Bio nor Clywedog intends to obtain a ruling from the IRS with respect to the tax consequences of the Combinations. If the IRS or a court determines that the Scheme Transaction does not qualify as part of an exchange under Section 351 of the Code, a U.S. shareholder of Barinthus Bio would generally recognize taxable gain or loss upon the exchange of its Scheme Shares for shares of Topco Common Stock and cash pursuant to the Combinations (whereas if the Scheme Transaction qualifies as part of an exchange under Section 351 of the Code, the U.S. shareholder of Barinthus Bio would only recognize taxable gain on the exchange with respect to the cash portion of the consideration). If the IRS or a court determines that the Merger does not qualify as part of an exchange under Section 351 of the Code and does not qualify as a “reorganization” under Section 368(a) of the Code, a U.S. stockholder of Clywedog would generally recognize taxable gain or loss upon the exchange of Clywedog Shares and cash for shares of Topco Common Stock pursuant to the Combinations. See the section entitled “Material U.S. Federal Income Tax Considerations.”

If the Scheme Transaction does not qualify for UK taxation purposes as a scheme of reconstruction pursuant to Section 137 of the UK Taxation of Chargeable Gains Act 1992 (the “TCGA”), UK Barinthus Shareholders may be required to pay substantial UK taxes.

The receipt of shares of Topco Common Stock by a Barinthus Shareholder in respect of, and in proportion to, such shareholder’s Barinthus Ordinary Shares (or, in respect of a holder of Barinthus ADSs, their beneficial interest in such Barinthus Ordinary Shares) pursuant to the Combinations may potentially be treated as a scheme of reconstruction for the purposes of CGT. On that basis, a Barinthus Shareholder would not be treated as making a disposal of their Barinthus Ordinary Shares (or, in respect of a holder of Barinthus ADSs, their beneficial interest in such Barinthus Ordinary Shares) and, therefore, no liability to CGT would arise in respect of the receipt of shares of Topco Common Stock (or, in respect of a holder of Barinthus ADSs, their beneficial interest in such Topco Common Stock) by a Barinthus Shareholder pursuant to the Combinations. However, if the “rollover” treatment described above is not available (and no assurance is or can be given that such treatment will be available), a Barinthus Shareholder would be treated as having made a full disposal of their Barinthus Ordinary Shares (or, in respect of a holder of Barinthus ADSs, their beneficial interest in such Barinthus Ordinary Shares) and may, depending on such shareholder’s personal circumstances, be liable to pay CGT.

Risks Relating to Topco Following the Completion of the Combinations

In addition to the risks described below, you should carefully consider the risks discussed under “— Risks Relating to Clywedog” and “— Risks Relating to Barinthus Bio,” as these risks will also be applicable to the business of Topco following the completion of the Combinations.

 

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The failure to successfully integrate the businesses of Barinthus Bio and Clywedog in the expected timeframe would adversely affect Topco’s future business and financial performance following the Combinations.

The combination of two independent companies is a complex, costly and time-consuming process. As a result, the combined company will be required to devote significant management attention and resources to integrate the business practices and operations of Barinthus Bio and Clywedog. The integration process may disrupt the business of either or both of the companies and, if implemented ineffectively, could preclude realization of the full benefits expected by Barinthus Bio and Clywedog from the Combinations. The failure of Topco to meet the challenges involved in successfully integrating the operations of Barinthus Bio and Clywedog or otherwise to realize the anticipated benefits of the Combinations could cause an interruption of the activities of Topco and could seriously harm its results of operations. In addition, the overall integration of the two companies may result in material unanticipated problems, expenses, liabilities, competitive responses, loss of customer relationships and diversion of management’s attention, and may cause Topco’s stock price to decline. The difficulties of combining the operations of Clywedog and Barinthus Bio include, among others:

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managing a significantly larger company;

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coordinating geographically separate organizations, including extensive international operations;

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the potential diversion of management’s focus and resources from other strategic opportunities and from operational matters;

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performance shortfalls at one or both of the companies as a result of the diversion of management’s attention caused by completing the Combinations and integrating the companies’ operations;

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aligning and executing the strategy of Topco;

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retaining existing business relationships and executing new strategic or commercial relationships;

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maintaining employee morale and retaining key management and other employees;

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the disruption of, or the loss of momentum in, each company’s ongoing business or inconsistencies in standards, controls, systems, procedures and policies;

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integrating two unique business cultures, which may prove to be incompatible;

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the possibility of faulty assumptions underlying expectations regarding the integration process;

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consolidating corporate and administrative infrastructures and eliminating duplicative operations;

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integrating IT, communications and other systems;

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changes in applicable laws and regulations;

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managing tax costs or inefficiencies associated with integrating the operations of Barinthus Bio and Clywedog;

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unforeseen expenses or delays associated with the Combinations; and

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taking actions that may be required in connection with obtaining regulatory approvals.

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Many of these factors will be outside of Topco’s control and any one of them could result in increased costs and diversion of management’s time and energy, which could materially impact the combined company’s business, financial condition and results of operations. In addition, even if the operations of Barinthus Bio and Clywedog are integrated successfully, Topco may not realize the full benefits of the Combinations, including the synergies, cost savings or growth opportunities that Barinthus Bio and Clywedog expect. These benefits may not be achieved within the anticipated timeframe, or at all. As a result, Barinthus Bio and Clywedog cannot assure their respective shareholders and stockholders that the combination of Barinthus Bio and Clywedog will result in the realization of the full benefits anticipated from the Combinations.

The synergies attributable to the Combinations may vary from expectations.

Topco may fail to realize the anticipated benefits and synergies expected from the Combinations, which could adversely affect its business, financial condition and operating results. The success of the Combinations

 

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will depend, in significant part, on Topco’s ability to successfully integrate the businesses of Barinthus Bio and Clywedog and realize the anticipated strategic benefits and synergies from the Combinations. Barinthus Bio and Clywedog believe that the combination of the two businesses will complement each party’s strategy by providing a balanced and diversified product portfolio, operational efficiencies, complementary geographic footprints and research and development synergies. However, achieving these goals requires, among other things, realization of the targeted cost synergies expected from the Combinations. The anticipated benefits of the Combinations and actual operating, technological, strategic and scientific opportunities may not be realized fully or at all, or may take longer to realize than expected. If Topco is not able to achieve these objectives and realize the anticipated benefits and synergies expected from the Combinations within the anticipated timeframe or at all, Topco’s business, financial condition and operating results may be adversely affected.

The future results of Topco will suffer if Topco does not effectively manage its expanded operations following the Combinations.

Following the Combinations, the size of the business of Topco will increase beyond the current size of either Barinthus Bio’s or Clywedog’s business. Topco’s future results depend, in part, upon its ability to manage this expanded business, which will pose substantial challenges for management, including challenges related to the management and monitoring of new operations and associated increased costs and complexity. There can be no assurance that Topco will be successful or that it will realize the expected operating efficiencies, cost savings and other benefits currently anticipated from the Combinations. If Topco is unable to raise capital when needed, or on acceptable terms, it may be forced to delay, reduce and/or eliminate one or more of its research and product development programs or future commercialization efforts.

Business issues currently faced by Barinthus Bio or Clywedog may be imputed to the operations of the other.

To the extent either Barinthus Bio or Clywedog currently has, or is perceived by the market to have, operational challenges, such as service performance, safety issues or workforce issues, those challenges may raise concerns by existing vendors or suppliers of the other company following the Combinations, which may limit or impede Topco’s future ability to conduct business with those parties.

No trading market currently exists or will exist for the Topco Common Stock prior to Merger Effective Time, and an active trading market may never develop.

Prior to the completion of the Combinations, there has been no trading market for the Topco Common Stock. The shares of Topco Common Stock to be issued in the Combinations are expected to be listed on Nasdaq following the completion of the Combinations, which will occur following the Merger Effective Time. As such, between the Scheme Effective Time and the Merger Effective Time, no trading market will exist for the Topco Common Stock. However, there can be no assurance that an active trading market for shares of Topco Common Stock will develop after the closing of the Combinations, or if it develops, that such market will be sustained. In the absence of an active trading market for the shares of Topco Common Stock, investors may not be able to sell their shares of Topco Common Stock at the time that they would like to sell.

The market price of shares of Topco Common Stock may be volatile.

The market price of shares of Topco Common Stock may be volatile. Broad general economic, political, market and industry factors may adversely affect the market price of shares of Topco Common Stock, regardless of Topco’s actual operating performance and the success of the integration of Barinthus Bio and Clywedog. Factors that could cause fluctuations in the price of shares of Topco Common Stock include, amongst others:

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actual or anticipated variations in quarterly operating results and the results of competitors;

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changes in financial projections by Topco, if any, or by any securities analysts that may cover Topco Common Stock;

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conditions or trends in the industry, including regulatory changes or changes in the securities marketplace;

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•

announcements by Topco or its competitors of significant acquisitions, strategic partnerships or other transactions;

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announcements of investigations or regulatory scrutiny of Topco’s operations or lawsuits filed against it;

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additions or departures of key personnel; and

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issuances or sales of shares of Topco Common Stock, including sales of shares by Topco’s directors and officers or its key investors.

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Future sales of shares of Topco Common Stock by Topco or its stockholders in the public market, or the perception that such sales may occur, could reduce the price of shares of Topco Common Stock, and any additional capital raised by Topco through the sale of equity or convertible securities may dilute ownership in Topco.

The sale of shares of Topco Common Stock in the public market, or the perception that such sales could occur, could harm the prevailing market price of shares of Topco Common Stock. These sales, or the possibility that these sales may occur, also might make it more difficult for Topco to sell equity securities in the future at a time and at a price that Topco deems appropriate.

After the completion of the Combinations, including the Self-Tender Offer, Topco is expected to have approximately [•] million outstanding shares of Topco Common Stock. Following the completion of the Combinations, it is expected that former Barinthus Shareholders will own approximately 34% of Topco and former Clywedog stockholders will own approximately 66% of Topco, on a fully diluted basis, based on the respective capitalizations of Barinthus Bio and Clywedog as of the date the parties entered into the Original Merger Agreement.

All shares of Topco Common Stock that will be issued in connection with the Combinations are expected to be freely tradable without restriction or further registration under the Securities Act, except for those shares subject to transfer restrictions pursuant to the Lock-Up Agreements and any shares of Topco Common Stock held by Topco’s affiliates, as that term is defined under Rule 144, including certain of Topco’s directors, executive officers and other affiliates, which shares may be sold in the public market only if they are registered under the Securities Act or are sold pursuant to an exemption from registration such as Rule 144. Following the completion of the Combinations, the shares of Topco Common Stock covered by registration rights are expected to represent 100% of the outstanding shares of Topco Common Stock. The market price of the Topco Common Stock could drop significantly if the holders of these shares of Topco Common Stock sell them or are perceived by the market as intending to sell them. These factors could also make it more difficult for Topco to raise additional funds through future offerings of shares of Topco Common Stock or other securities.

In addition, Topco intends to file a registration statement with the SEC on Form S-8 providing for the registration of approximately [•] shares of Topco Common Stock issued or reserved for issuance under the Topco Equity Incentive Plan and Topco ESPP that will be adopted by Topco prior to the Scheme Effective Time. Subject to the satisfaction of vesting conditions, shares registered under the registration statement on Form S-8 may be made available for resale immediately in the public market without restriction.

In the future, Topco may also issue its securities in connection with investments or acquisitions, or otherwise. Topco cannot predict the size of future issuances of shares of Topco Common Stock or securities convertible into shares of Topco Common Stock or the effect, if any, that future issuances and sales of shares of Topco Common Stock will have on the market price of the Topco Common Stock. Sales of substantial amounts of shares of Topco Common Stock (including shares issued in connection with an acquisition), or the perception that such sales could occur, may adversely affect prevailing market prices of the Topco Common Stock.

If securities or industry analysts do not publish research or reports about Topco, the trading price of the Topco Common Stock could decline.

The trading market for shares of Topco Common Stock will be influenced by any research and reports that industry or securities analysts publish about Topco or its business. If one or more of these analysts cease

 

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coverage of Topco or fail to publish reports on Topco regularly, Topco could lose visibility in the financial markets, which in turn could cause Topco’s stock price or trading volume to decline. Moreover, if one or more of the analysts who cover Topco downgrade the Topco Common Stock or if Topco’s operating results do not meet their expectations, the trading price of the Topco Common Stock could decline.

The shares of Topco Common Stock to be received by Barinthus Shareholders and Clywedog stockholders as a result of the Combinations will have rights different from the Barinthus Ordinary Shares and Clywedog Shares that they hold prior to the Effective Times.

Upon completion of the Combinations, the rights of former Barinthus Shareholders and Clywedog stockholders who become stockholders of Topco will be governed by the Topco A&R Charter and the Topco A&R Bylaws and by the DGCL. The rights associated with Barinthus Ordinary Shares and Clywedog Shares are different from the rights associated with shares of Topco Common Stock. See the section entitled “Comparison of Rights of Stockholders of Clywedog, Barinthus Bio and Topco” of this proxy statement/​prospectus.

The Topco A&R Bylaws will designate the Chancery Court as the sole and exclusive forum for certain types of actions and proceedings that may be initiated by Topco’s stockholders, which could limit Topco’s stockholders’ ability to obtain a favorable judicial forum for disputes with Topco or its directors, officers, employees or agents.

The Topco A&R Bylaws after the Scheme Effective Time will provide that, unless Topco consents in writing to the selection of an alternative forum, (i) the Chancery Court (or, if the Chancery Court does not have, or declines to accept, jurisdiction, another state court or a federal court located within the State of Delaware) will, to the fullest extent permitted by applicable law, be the sole and exclusive forum for any claims (other than any cause of action arising under the Securities Act), including claims in the right of Topco that are based upon a violation of duty by a current or former director, officer, employee or stockholder in such capacity, or as to which the DGCL confers jurisdiction upon the Chancery Court, and (ii) the federal district courts of the United States of America will, to the fullest extent permitted by applicable law, be the sole and exclusive forum for any cause of action arising under the Securities Act, but that the forum selection provision will not apply to claims brought to enforce a duty or liability created by the Exchange Act. Any person or entity purchasing or otherwise acquiring any interest in shares of Topco’s capital stock will be deemed to have notice of, and to have consented to, the provisions of the Topco A&R Bylaws described in the preceding sentence. This forum selection provision may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes with Topco or its directors, officers, employees or agents, which may discourage such lawsuits against Topco and such persons and result in increased costs for a stockholder to bring a claim. There is uncertainty as to whether a court would enforce such provisions and stockholders cannot waive compliance with the federal securities laws and the rules and regulations thereunder. If a court were to find these provisions of the Topco A&R Bylaws inapplicable to, or unenforceable in respect of, one or more of the specified types of actions or proceedings, Topco may incur additional costs associated with resolving such matters in other jurisdictions, which could adversely affect Topco’s business, financial condition or results of operations.

If Topco fails to develop or maintain an effective system of internal controls, it may not be able to accurately report its financial results or prevent fraud. As a result, stockholders could lose confidence in Topco’s financial reporting, which would harm its business and the trading price of Topco Common Stock.

Effective internal controls are necessary for Topco to provide reliable financial reports, prevent fraud and operate successfully as a public company. If Topco cannot provide reliable financial reports or prevent fraud, its reputation and operating results would be harmed. Topco cannot be certain that its efforts to develop and maintain an effective system of internal controls will be successful, that it will be able to maintain adequate controls over its financial processes and reporting in the future, or that it will be able to comply with its obligations under Section 404 of the Sarbanes-Oxley Act of 2002. Any failure to develop or maintain effective internal controls, or difficulties encountered in implementing or improving internal controls, could harm Topco’s operating results or cause Topco to fail to meet its reporting obligations. Ineffective internal controls could also cause investors to lose confidence in Topco’s reported financial information, which would likely have a negative effect on the trading price of the Topco Common Stock.

 

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Topco’s IT systems may be vulnerable to hacker intrusion, malicious viruses and other cybercrime attacks, which may harm its business and expose it to liability.

Topco’s operations will depend to a great extent on the reliability and security of its IT systems, software and network, which are subject to damage and interruption caused by human error, problems relating to telecommunications networks, software failure, natural disasters, sabotage, viruses and similar events. Any interruption in Topco’s IT systems could have a negative effect on the quality of research and development conducted and, as a result, on the development pipeline of its product candidates.

Topco will be exposed to significant risks in relation to compliance with anti-corruption laws and regulations and economic sanctions programs.

Doing business on a worldwide basis will require the combined company to comply with the laws and regulations of various jurisdictions, and Topco’s failure to successfully comply with these rules and regulations may expose it to liabilities. These laws and regulations apply to companies, individual directors, officers, employees and agents, and may restrict the combined company’s operations, trade practices, investment decisions and partnering activities. In particular, Topco’s international operations are subject to anti-corruption and anti-bribery laws and regulations, such as the FCPA and the Bribery Act, among others, and economic and trade sanctions, including those administered by the United Nations, the European Union, the OFAC and the U.S. Department of State. The FCPA prohibits providing anything of value to foreign officials for the purposes of obtaining or retaining business or securing any improper business advantage. Topco may deal with state-owned business enterprises, the employees and representatives of which may be considered foreign officials for purposes of the FCPA. Topco will be subject to the jurisdiction of various governments and regulatory agencies outside of the United States, which may bring Topco’s personnel into contact with foreign officials responsible for issuing or renewing permits, licenses or approvals or for enforcing other governmental regulations. The provisions of the Bribery Act extend beyond bribery of foreign public officials and are more onerous than the FCPA in a number of other respects, including jurisdiction, non-exemption of facilitation payments and penalties. Economic and trade sanctions restrict Topco’s transactions or dealings with certain sanctioned countries, territories and designated persons, absent authorizations or exemptions under applicable law, such as OFAC’s licenses permitting certain humanitarian trade.

As a result of doing business in foreign countries, including through partners, distributors, agents and other third parties acting on Topco’s behalf, Topco will be exposed to a risk of violating anti-corruption and anti-bribery laws and sanctions regulations. Some of the international locations in which Topco will operate have developing legal systems and may have higher levels of corruption than more developed nations. Violations of anti-corruption and anti-bribery laws and economic and trade sanctions are punishable by civil penalties, including fines, denial of export privileges, injunctions, asset seizures, debarment from government contracts (and termination of existing contracts) and revocations or restrictions of licenses, as well as criminal fines and imprisonment. In addition, any major violations could have a significant impact on Topco’s reputation and consequently on its ability to win future business.

While Barinthus Bio and Clywedog believe that Topco will have a strong culture of compliance and an adequate system of internal controls, including procedures to minimize and detect fraud in a timely manner, as well as processes for complying with OFAC authorizations or exemptions, Barinthus Bio and Clywedog will seek to continuously improve Topco’s system of internal controls and to remedy any weaknesses identified. There can be no assurance, however, that Topco’s policies and procedures will be followed at all times or will effectively detect and prevent violations of the applicable laws by one or more of its employees, consultants, agents or partners and, as a result, Topco could be subject to penalties and material adverse consequences on its business, financial condition or results of operations.

Topco’s ability to utilize the U.S. net operating loss carryforwards may be limited.

The ability of Topco and its affiliates, including Barinthus Bio and Clywedog, to utilize any U.S. federal net operating loss carryforwards (“NOLs”) and other tax attributes existing at the time of the Combinations to reduce future taxable income following the consummation of the Combinations is subject to limitations under U.S. federal income tax laws and depends on many factors, including its future income, which cannot be assured. In addition, Section 382 of the Code (“Section 382”) generally imposes

 

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an annual limitation on the amount of NOLs that may be used to offset taxable income when a corporation has undergone an “ownership change” ​(as determined under Section 382), as is expected to be the case for Barinthus Bio following the Combinations. An ownership change generally occurs if one or more stockholders (or groups of stockholders) who are each deemed to own at least 5% of such corporation’s stock increase their ownership by more than 50 percentage points over their lowest ownership percentage within a rolling three-year period. Section 382 may apply as a result of the Combinations and limit the use of any NOLs prior to their expiration.

Topco and its subsidiaries will be subject to U.S. and foreign tax laws, and changes to such tax laws or differing interpretation of those laws by the relevant governmental authorities could adversely affect Topco.

The U.S. Congress, the Organization for Economic Co-operation and Development and other government agencies in jurisdictions where Topco and its affiliates do business have had an extended focus on issues related to the taxation of multinational corporations. One example is in the area of “base erosion and profit shifting,” where payments are made between affiliates from a jurisdiction with high tax rates to a jurisdiction with lower tax rates. Additionally, changes proposed by the current U.S. administration, including significant tax reform, could significantly change the U.S. federal income tax rules and regulations applicable to Topco and its affiliates, although the prospect of tax reform, and the nature of any such reform, remains highly uncertain. Thus, the tax laws in the United States, the United Kingdom and other countries in which Topco and its affiliates do business could change on a prospective or retroactive basis, and any such changes could adversely affect Topco.

In addition, the tax laws and regulations in the United States, the United Kingdom and the various other jurisdictions in which Topco and its subsidiaries operate or may in the future operate are inherently complex, and Topco and its subsidiaries will be obligated to make judgments and interpretations about the application of these laws and regulations to Topco and its subsidiaries and their operations and businesses. The interpretation and application of these laws and regulations could be challenged by the relevant governmental authorities, which could result in material administrative or judicial procedures, actions or sanctions.

The unaudited prospective financial information for Barinthus Bio and Clywedog included in this proxy statement/​prospectus reflects management estimates and may not prove to be reflective of actual future financial results.

In connection with the Combinations, Barinthus Bio and Clywedog prepared and considered, among other things, certain internal, unaudited prospective financial information for Barinthus Bio and Clywedog. This unaudited prospective financial information included assumptions regarding future market conditions, operating cash flows, expenditures and growth of Barinthus Bio and Clywedog, as applicable. This internal, unaudited prospective financial information speaks only as of the date made and, except as required by applicable securities laws, will not be updated. This unaudited prospective financial information is subject to significant economic, competitive, industry and other uncertainties, which may cause the unaudited prospective financial information or the underlying assumptions to be inaccurate. As a result of these contingencies, there can be no assurance that the unaudited prospective financial information of Barinthus Bio and Clywedog will be achieved in full, at all or within projected timeframes. In light of these uncertainties, the inclusion of the unaudited prospective financial information of Barinthus Bio and Clywedog in this proxy statement/prospectus should not be regarded as an indication that the Barinthus Board, the Clywedog Board, Barinthus Bio, Clywedog, Oppenheimer or any other recipient of this information considered, or now considers, it to be an assurance of the achievement of future financial results.

Topco’s actual financial position and results of operations may differ materially from the unaudited pro forma financial information included in this proxy statement/prospectus.

Topco has been recently incorporated and has no operating history and no revenues. While the unaudited pro forma financial information contained in this proxy statement/prospectus represents the best estimates of Barinthus Bio’s and Clywedog’s management, it is presented for illustrative purposes only and may not be an accurate indication of Topco’s financial position or results of operations if the Combinations and associated financing transactions are completed on the dates indicated. The unaudited pro forma financial information has been derived from the audited and unaudited historical financial

 

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statements of Barinthus Bio and Clywedog and certain adjustments and assumptions have been made regarding Topco after giving effect to the Combinations. The unaudited pro forma combined financial information has been prepared in accordance with Article 11 of Regulation S-X, as amended. The process for estimating the fair value of acquired assets and assumed liabilities requires the use of judgment in determining the appropriate assumptions and estimates. These estimates may be revised as additional information becomes available and as additional analyses are performed. Differences between preliminary estimates in the unaudited pro forma financial information and the final acquisition accounting will occur and could have a material impact on the unaudited pro forma financial information and Topco’s financial position and future results of operations.

In addition, the assumptions used in preparing the unaudited pro forma financial information may not prove to be accurate, and other factors may affect Topco’s financial condition or results of operations following the closing of the Combinations. Any potential decline in Topco’s financial condition or results of operations may cause significant fluctuations in the price of shares of Topco Common Stock. See the section entitled “Unaudited Pro Forma Combined Financial Information” of this proxy statement/prospectus.

Topco will be exposed to foreign currency exchange risk.

Upon completion of the Combinations, Topco will transact business in various countries around the world and expects that a significant portion of its business will continue to take place in international markets. Topco will conduct its business and prepare its consolidated financial statements in its functional currency, while the financial statements of each of its subsidiaries will be prepared in the functional currency of that entity and the business of that entity will be conducted in the functional currency of that entity. Accordingly, fluctuations in the exchange rate of the functional currencies of Topco’s foreign currency entities against the functional currency of Topco will impact its results of operations and financial condition. Accordingly, it is expected that Topco’s financial performance will be exposed to the risks that may arise from fluctuations in foreign currency exchange rates, which could have a material adverse effect on Topco’s business, results of operations or financial condition.

Risks Relating to Barinthus Bio

Risks Related to Barinthus Bio’s Financial Position and Capital Needs

Barinthus Bio is a clinical-stage biopharmaceutical company with a limited operating history. Barinthus Bio has incurred significant losses since inception. Barinthus Bio expects to incur losses for at least the next several years and may never achieve or maintain profitability.

Barinthus Bio is a clinical-stage biopharmaceutical company with a limited operating history, and it is in the early stages of its product development efforts. Investment in biopharmaceutical product development is highly speculative because it entails substantial upfront capital expenditures and significant risk that any potential product candidate will fail to demonstrate adequate efficacy or an acceptable safety profile, obtain marketing authorization and become commercially viable. Currently, Barinthus Bio has no products approved for commercial sale and is not generating any revenue from product sales. To date, Barinthus Bio has devoted substantially all of its resources to organizing and staffing the company, business planning, raising capital, undertaking preclinical studies and clinical trials of its product candidates, securing related intellectual property rights and conducting discovery, research and development activities for its programs. Barinthus Bio has incurred net losses each year since inception through to December 31, 2021. For the year ended December 31, 2022, Barinthus Bio generated net income of $5.3 million, primarily as a result of revenues (royalties/milestone payments) arising from AstraZeneca sales of Vaxzevria and Barinthus Bio’s license agreement with Oxford University Innovation (“OUI”), as amended (the “OUI License Agreement”). In December 2025, Barinthus Bio delivered written notice to OUI to terminate the OUI License Agreement. The OUI License Agreement will remain in effect during the three-month notice period and terminated on March 2, 2026 in accordance with its terms. For the years ending December 31, 2025 and 2024, Barinthus Bio incurred net losses of $66.5 million and $61.2 million, respectively. As of December 31, 2025 and 2024, Barinthus Bio had an accumulated deficit of $304.1 million and $237.7 million, respectively, and it does not currently expect profits or positive cash flows from operations in the foreseeable future. Barinthus Bio anticipates that its expenses will increase substantially if, and as it:

 

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pursues the clinical and preclinical development of its current product candidates;

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uses its technologies to advance additional product candidates into preclinical and clinical development;

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seeks marketing authorizations for product candidates that successfully complete clinical trials, if any;

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attracts, hires and retains additional clinical, regulatory, quality control and other personnel;

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conducts preclinical studies and clinical trials for its current and future product candidates based on its proprietary synthetic platform, SNAP-TI and its other technologies;

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expands its operational, financial and management systems and increase personnel, including personnel to support its clinical development, manufacturing and commercialization efforts and its operations as a public company;

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establishes its manufacturing capabilities through third parties or by itself and scale-up manufacturing to provide adequate supply for clinical trials and commercialization;

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expands, maintains, protects and enforces its intellectual property portfolio;

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establishes a sales, marketing, medical affairs and distribution infrastructure to commercialize any products for which Barinthus Bio may obtain marketing approval and intend to commercialize on its own or through a selected partner;

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acquires or in-licenses other product candidates and technologies for development and commercialization; and

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incurs additional legal, accounting and other expenses in operating its business, including the additional costs associated with operating as a public company.

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Even if Barinthus Bio succeeds in commercializing one or more of its product candidates, it will continue to incur substantial research and development costs and other expenditures to develop and market additional product candidates and it may never generate revenue that is significant or large enough to achieve profitability. Barinthus Bio may also encounter unforeseen expenses, difficulties, complications, delays and other unknown factors that may adversely affect its business. The size of Barinthus Bio’s future net losses will depend, in part, on the rate of future growth of its expenses and its ability to generate revenue. Barinthus Bio’s prior losses and expected future losses have had and will continue to have an adverse effect on its stockholders’ equity and working capital unless and until such losses are eliminated by revenue.

If Barinthus Bio does achieve profitability, it may not be able to sustain or increase profitability on a quarterly or annual basis. Accordingly, Barinthus Bio’s failure to become and remain profitable would decrease the value of it and could impair its ability to raise capital, maintain its research and development efforts, expand its business or continue its operations. A decline in the value of Barinthus Bio also could cause you to lose all or part of your investment.

Barinthus Bio has not yet generated any material revenue from its current product candidates.

Barinthus Bio’s ability to become profitable depends upon its ability to generate revenue. Barinthus Bio does not expect to generate significant revenue from its current or future product candidates unless or until it successfully completes clinical development and obtain marketing authorization for, and then successfully commercialize, at least one of its product candidates.

Certain of Barinthus Bio’s product candidates are in the preclinical stages of development and will require additional preclinical studies, and all of its product candidates will require additional clinical development, regulatory review and approval, substantial investment, access to sufficient commercial manufacturing capacity and significant marketing efforts before it can generate any revenue from product sales. Barinthus Bio has not yet administered certain of its product candidates to humans and, as such, Barinthus Bio faces significant translational risk as its product candidates advance into and through the clinical stage, as promising results in preclinical studies may not be replicated in subsequent clinical trials, and testing on animals may not accurately predict human experience. Barinthus Bio’s ability to generate revenue depends on a number of factors, including, but not limited to:

 

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timely completion of Barinthus Bio’s manufacturing, preclinical studies and clinical trials, which may be significantly slower or cost more than Barinthus Bio currently anticipates and will depend substantially upon the performance of third-party contractors;

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delays out of Barinthus Bio’s control, such as participant willingness to enroll in Barinthus Bio’s clinical trials;

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Barinthus Bio’s ability to complete INDs, enabling trials and successfully submit INDs or comparable applications, for Barinthus Bio’s product candidates;

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whether Barinthus Bio is required by the FDA, the EMA, or the MHRA or similar foreign regulatory authorities, to conduct additional clinical trials or other studies beyond those planned to support the approval and commercialization of Barinthus Bio’s product candidates or any future product candidates;

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Barinthus Bio’s ability to demonstrate to the satisfaction of the FDA and similar foreign regulatory authorities the safety, potency, purity, efficacy and acceptable risk to benefit profile of Barinthus Bio’s product candidates or any future product candidates and such regulatory authorities’ acceptance of Barinthus Bio’s development strategy;

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the prevalence, duration and severity of potential side effects or other safety issues experienced with Barinthus Bio’s product candidates or future product candidates, if any;

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the timely receipt of necessary marketing approvals from the FDA and similar foreign regulatory authorities;

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the willingness of physicians, operators of clinics and patients to utilize or adopt any of Barinthus Bio’s product candidates or future product candidates over alternative or more conventional approaches, including immune modulators, monoclonal antibodies, CRISPR editing, or other small molecules, RNA, DNA, nanoparticle, peptide, protein, or other technologies;

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the actual and perceived availability, cost, risk profile and side effects and efficacy of Barinthus Bio’s product candidates, if approved, relative to existing and future alternative immunotherapies, and competitive product candidates and technologies; Barinthus Bio’s ability and the ability of third parties with whom Barinthus Bio contracts to manufacture adequate clinical and commercial supplies of Barinthus Bio’s product candidates or any future product candidates, remain in good standing with regulatory authorities and develop, validate and maintain commercially viable manufacturing processes that are compliant with cGMP;

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Barinthus Bio’s ability to successfully develop a commercial strategy and thereafter commercialize Barinthus Bio’s product candidates or any future product candidates in the United States and internationally, if approved for marketing, reimbursement, sale and distribution in such countries and territories, whether alone or in collaboration with others;

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patient demand for Barinthus Bio’s product candidates and any future product candidates, if approved;

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Barinthus Bio’s ability to establish, maintain, protect and enforce intellectual property rights in and to Barinthus Bio’s product candidates or any future product candidates;

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the ability of Barinthus Bio’s licensees and collaborators to develop and commercialize Barinthus Bio’s products effectively;

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the possibility that immune tolerance with Barinthus Bio’s SNAP-TI platform may not translate into clinical benefit; and

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the increased costs and complexities associated with manufacturing.

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Many of the factors listed above are beyond Barinthus Bio’s control and could cause Barinthus Bio to experience significant delays or prevent it from obtaining marketing authorizations for, or commercializing, its product candidates. Even if Barinthus Bio is able to commercialize its product candidates, it may not achieve profitability soon after generating product sales, if ever. If Barinthus Bio is unable to generate sufficient revenue through the sale of its product candidates or any future product candidates, Barinthus Bio may be unable to continue operations without continued funding.

 

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