The information in this preliminary proxy statement/prospectus is not complete and may be changed. These securities may not be sold until the registration statement filed with the Securities and Exchange Commission is effective. This preliminary proxy statement/prospectus is not an offer to sell and it is not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED JULY 15, 2026

PROPOSED MERGER

YOUR VOTE IS VERY IMPORTANT

To the Stockholders of Rallybio Corporation,

Rallybio Corporation, a Delaware corporation (“Rallybio”), and Avenzo Therapeutics, Inc., a Delaware corporation (“Avenzo”) have entered into an Agreement and Plan of Merger and Reorganization, dated May 31, 2026 (the “Merger Agreement”), pursuant to which, among other matters, Farmington Merger Sub, Inc., a Delaware corporation and wholly owned subsidiary of Rallybio (“Merger Sub”), will merge with and into Avenzo, with Avenzo surviving as a wholly owned subsidiary of Rallybio (such transaction, the “Merger”). In connection with the Merger, Rallybio will change its name to Avenzo Therapeutics, Inc. (together with its subsidiaries following the Merger, the “combined company”).

The Merger will become effective at the time the Certificate of Merger has been duly filed with the Secretary of State of the State of Delaware or such other date and time as is agreed upon by Rallybio and Avenzo and specified in the Certificate of Merger in accordance with the General Corporation Law of the State of Delaware (“DGCL”) (such date, the “Closing Date,” and such time, the “Effective Time”). At the Effective Time, (a) each outstanding share of Avenzo Class A common stock, par value $0.0001 per share (“Avenzo Common Stock”), and each share of Avenzo preferred stock, par value $0.0001 per share (“Avenzo Preferred Stock” and, together with the Avenzo Common Stock, “Avenzo Capital Stock”) (excluding shares held by Avenzo stockholders who have exercised and perfected appraisal rights, shares of Avenzo Capital Stock held as treasury stock by Avenzo or held or owned by Rallybio, Merger Sub or any subsidiary of Rallybio or Avenzo, and any shares described in the following clause (b)) will be converted into the right to receive approximately 0.5020 shares of common stock of Rallybio, par value $0.0001 per share (“Rallybio Common Stock”), based on an assumed exchange ratio of 0.5020 (the “Exchange Ratio”) (which is further subject to certain adjustments as described below), and (b) each share of Avenzo Common Stock issued in the Concurrent Financing (as defined and described in more detail below) will be converted into the right to receive a number of shares of Rallybio Common Stock calculated in accordance with the exchange ratio formula set forth in the Merger Agreement (the “Concurrent Financing Exchange Ratio”), which is assumed to be 0.5020 and is subject to the same assumptions as the Exchange Ratio described above and below. Rallybio will assume outstanding and unexercised options to purchase shares of Avenzo Common Stock, and in connection with the Merger such options will be converted into options to purchase shares of Rallybio Common Stock based on the Exchange Ratio.

The Exchange Ratio described above does not give effect to the proposed reverse stock split of Rallybio Common Stock and is subject to adjustment based on Rallybio’s final Rallybio Net Cash (as defined below) at the closing of the Merger (the “Closing”) and the final number of shares of Rallybio Common Stock outstanding immediately prior to the Closing, as described in more detail in the section titled “The Merger Agreement—Merger Consideration and Exchange Ratio” of the accompanying proxy statement/prospectus.

Each share of Rallybio Common Stock issued and outstanding at the time of the Merger will remain issued and outstanding, and, subject to the proposed reverse stock split, will be unaffected by the Merger. In addition, on May 31, 2026, Avenzo entered into a subscription agreement (the “Subscription Agreement”) with certain investors, pursuant to which Avenzo has agreed to sell, and such investors have agreed to purchase, shares of Avenzo Common Stock for an aggregate purchase price of $215.0 million, immediately prior to the Effective Time of the Merger (such transaction, the “Concurrent Financing”). The closing of the Concurrent Financing is conditioned upon the satisfaction or waiver of each of the conditions to the Closing as well as certain other conditions. The Concurrent Financing is more fully described in the section titled “The Merger Agreement—Subscription Agreement.”

Under the Exchange Ratio and Concurrent Financing Exchange Ratio formulas in the Merger Agreement, immediately after the Closing, on a pro forma basis and based upon the number of shares of Rallybio Common Stock expected to be issued in connection with the Merger, pre-Merger equityholders of Avenzo (other than investors in the Concurrent Financing) are expected to own approximately 56.6% of the combined company, pre-Merger equityholders of Rallybio are expected to own approximately 2.8% of the combined company and the investors in the Concurrent Financing are expected to own approximately 40.6% of the combined company (assuming proceeds from the Concurrent Financing of $215.0 million), in each case, calculated on a fully diluted basis, using the treasury stock method, and subject to certain assumptions, including (i) a valuation for Rallybio of $15.0 million (calculated after giving effect to the expected payment of Parent Distributions (as defined below)), (ii) a fixed valuation for Avenzo of $300.0 million, and (iii) the relative capitalization of Rallybio and Avenzo. The percentage of the combined company that each party’s

Shares of Rallybio Common Stock are currently listed on The Nasdaq Capital Market (“Nasdaq”) under the symbol “RLYB.” Avenzo will file an initial listing application for the combined company with Nasdaq. After completion of the Merger, Rallybio will be renamed “Avenzo Therapeutics, Inc.”, and it is expected that the common stock of the combined company will trade on Nasdaq under the symbol “AVZO.” On     , 2026, the last trading day before the date of the accompanying proxy statement/prospectus, the closing sale price of Rallybio Common Stock was $      per share.

Rallybio stockholders are cordially invited to attend the 2026 annual meeting of Rallybio stockholders (the “Rallybio annual meeting”). The Rallybio annual meeting is being held on      , unless postponed or adjourned to a later date, in order to obtain the stockholder approvals necessary to complete the Merger, the Concurrent Financing and related matters. The Rallybio annual meeting will be held entirely online. Rallybio stockholders will be able to attend and participate in the Rallybio annual meeting by registering at www.virtualshareholdermeeting.com/RLYB2026 where they will be able to listen to the meeting live, submit questions and vote. At the Rallybio annual meeting, Rallybio will ask its stockholders to:

As described in the accompanying proxy statement/prospectus, certain Rallybio stockholders who in the aggregate owned approximately 24.3% of the outstanding shares of Rallybio Common Stock as of May 31, 2026, and certain Avenzo stockholders who in the aggregate owned approximately 78% of the outstanding shares of Avenzo Capital Stock as of May 31, 2026, are parties to support agreements with Rallybio and Avenzo, respectively, whereby such stockholders have agreed to vote (i) in the case of Rallybio stockholders, in favor of the Merger and the other transactions and actions contemplated by the Merger Agreement (collectively, the “Contemplated Transactions”), including (a) the Nasdaq Stock Issuance Proposal, (b) the Reverse Stock Split Proposal, (c) the Name Change Proposal, (d) the Authorized Share Proposal, and (e) and the other transactions and actions contemplated by the Merger Agreement, including the Concurrent Financing and the Asset Dispositions (in each case, as defined in the Merger Agreement), and (ii) in the case of Avenzo stockholders, in favor of adopting the Merger Agreement and approving the Merger and the other Contemplated Transactions, in each case, subject to the terms of the support agreements. Within three (3) business days following the effectiveness of the registration statement on Form S-4 of which the accompanying proxy statement/prospectus is a part, and pursuant to the Merger Agreement, Avenzo will seek to obtain approval for the Merger Agreement and the Contemplated Transactions from stockholders holding a sufficient number of shares of Avenzo Capital Stock to adopt and approve such matters.

After careful consideration, each of Rallybio’s board of directors (the “Rallybio Board”) and Avenzo’s board of directors (the “Avenzo Board”) have approved the Merger Agreement and the Contemplated Transactions and have determined that it is advisable to consummate the Merger. The Rallybio Board has approved the proposals described in the accompanying proxy statement/prospectus and unanimously recommends that its stockholders vote “FOR” the proposals described in the accompanying proxy statement/prospectus.

More information about Rallybio, Avenzo, the Merger Agreement and Contemplated Transactions, and the foregoing proposals is contained in the accompanying proxy statement/prospectus. Rallybio urges you to read the accompanying proxy statement/prospectus carefully and in its entirety. IN PARTICULAR, YOU SHOULD CAREFULLY CONSIDER THE MATTERS DISCUSSED UNDER “RISK FACTORS” BEGINNING ON PAGE 29 OF THE ACCOMPANYING PROXY STATEMENT/PROSPECTUS.

Rallybio is excited about the opportunities the Merger brings to Rallybio’s stockholders and thanks you for your consideration and continued support.

Stephen Uden, M.D.

President and Chief Executive Officer

Rallybio Corporation

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of the accompanying proxy statement/prospectus. Any representation to the contrary is a criminal offense.

The accompanying proxy statement/prospectus is dated     , 2026, and is first being mailed to Rallybio’s stockholders on or about      , 2026.

RALLYBIO CORPORATION

PO Box no. 325

East Berlin, CT 06023

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

To the stockholders of Rallybio Corporation:

On behalf of the Rallybio Board, we are pleased to deliver this proxy statement/prospectus for the proposed Merger between Rallybio and Avenzo pursuant to which, among other matters, Merger Sub will merge with and into Avenzo, with Avenzo surviving as a wholly owned subsidiary of Rallybio.

The Rallybio annual meeting will be held on      , unless postponed or adjourned to a later date. The Rallybio annual meeting will be held entirely online. You will be able to attend and participate in the Rallybio annual meeting by registering at www.virtualshareholdermeeting.com/RLYB2026. Upon entry of your control number and other required information, you will receive further instructions via email that provide you access to the Rallybio annual meeting and to vote and submit questions during the Rallybio annual meeting. The Rallybio annual meeting will be held for the following purposes, which are collectively referred to as the “Proposals”:

The Rallybio Board has fixed      , 2026 as the record date for the determination of stockholders entitled to notice of, and to vote at, the Rallybio annual meeting and any adjournment or postponement thereof. Only holders of record of shares of Rallybio Common Stock at the close of business on the record date are entitled to notice of, and to vote at, the Rallybio annual meeting. At the close of business on the record date, Rallybio had       shares of Rallybio Common Stock outstanding and entitled to vote.

Your vote is important. The affirmative vote of a majority of the total votes cast by the holders of Rallybio Common Stock entitled to vote at the Rallybio annual meeting, assuming a quorum is present, is required for the approval of Proposal Nos. 1, 2, 3, 6, 7 and 8. The affirmative vote of the holders of at least seventy-five percent of the outstanding shares of Rallybio Common Stock entitled to vote at the Rallybio annual meeting is required for the approval of Proposal No. 4. The votes cast for a nominee for director by holders of Rallybio Common Stock entitled to vote at the Rallybio annual meeting must exceed the votes cast against by such holders for the election of directors pursuant to Proposal No. 5, assuming a quorum is present. The affirmative vote of the holders of a majority of the shares of Rallybio Common Stock present in person (by virtual attendance) or represented by proxy at the Rallybio annual meeting and entitled to vote on the matter is required for the approval of Proposal 9. Each of Proposal Nos. 1, 2 and 3 is a condition to completion of the Merger. The closing of the Concurrent Financing is conditioned upon the satisfaction or waiver of each of the conditions to the Closing as well as certain other conditions. Therefore, the Merger and the Concurrent Financing cannot be consummated without the approval of Proposal Nos. 1, 2 and 3. The issuance of Rallybio Common Stock in connection with the Merger and the change of control of Rallybio resulting from the Merger will not take place unless Proposal Nos. 1, 2 and 3 are approved by Rallybio stockholders, Rallybio’s name is changed to “Avenzo Therapeutics, Inc.” and the Merger is consummated. Proposal Nos. 4, 7 and 8 are each conditioned on the consummation of the Merger. Therefore, if Proposal Nos. 1, 2 and 3 are not approved and the Merger is not consummated, Proposal Nos. 4, 7 and 8 will each have no effect, even if one or more are approved by Rallybio stockholders.

Even if you plan to virtually attend the Rallybio annual meeting, Rallybio requests that you sign and return the enclosed proxy or vote by mail, by phone or online to ensure that your shares will be represented at the Rallybio annual meeting if you are unable to virtually attend. You may change or revoke your proxy at any time before it is voted at the Rallybio annual meeting.

THE RALLYBIO BOARD HAS UNANIMOUSLY DETERMINED AND BELIEVES THAT EACH OF THE PROPOSALS OUTLINED ABOVE IS FAIR TO, ADVISABLE AND IN THE BEST INTERESTS OF RALLYBIO AND ITS STOCKHOLDERS AND HAS APPROVED EACH SUCH PROPOSAL. THE RALLYBIO BOARD UNANIMOUSLY RECOMMENDS THAT RALLYBIO STOCKHOLDERS VOTE “FOR” EACH SUCH PROPOSAL.

The proxy statement/prospectus and annual report to stockholders are available at

By Order of the Rallybio Board of Directors,

Stephen Uden, M.D.

President and Chief Executive Officer

    , 2026

REFERENCES TO ADDITIONAL INFORMATION

This proxy statement/prospectus incorporates certain information about Rallybio that is not included in or delivered with this document. You may obtain this information without charge through the Securities and Exchange Commission (“SEC”) website (www.sec.gov) or upon your oral or written request by sending a written request to: Rallybio Corporation, PO Box no. 325, East Berlin, CT 06023, Attention: Secretary.

To ensure timely delivery of these documents, any request should be made no later than      , 2026, which is five business days prior to the date of the Rallybio annual meeting, in order to receive them before the Rallybio annual meeting.

For additional details about where you can find information about Rallybio, please see the section titled “Where You Can Find More Information” beginning on page 448 of this proxy statement/prospectus.

TABLE OF CONTENTS

QUESTIONS AND ANSWERS

Except where specifically noted, the following information and all other information contained in this proxy statement/prospectus does not give effect to the proposed reverse stock split described in Proposal No. 2 of this proxy statement/prospectus.

The following section provides answers to frequently asked questions about the Merger. This section, however, provides only summary information. For a more complete response to these questions and for additional information, please refer to the cross-referenced sections.

The Merger will become effective at the time the Certificate of Merger has been duly filed with the Secretary of State of the State of Delaware or such other date and time as is agreed upon by Rallybio and Avenzo and specified in the Certificate of Merger in accordance with the DGCL. At the Effective Time, (a) each outstanding share of Avenzo Common Stock and each share of Avenzo Preferred Stock (excluding shares held by Avenzo stockholders who have exercised and perfected appraisal rights as more fully described in the section titled “The Merger—Appraisal Rights” of this proxy statement/prospectus, shares of Avenzo Capital Stock held as treasury stock by Avenzo or held or owned by Rallybio, Merger Sub or any subsidiary of Rallybio or Avenzo, and any shares described in the following clause (b)) will be automatically converted solely into the right to receive a number of shares of Rallybio Common Stock equal to the Exchange Ratio, and (b) each share of Avenzo Common Stock issued in the Concurrent Financing, as more fully described in the section titled “Agreements Related to the Merger—Subscription Agreement” of this proxy statement/prospectus, will be automatically converted solely into the right to receive a number of shares of Rallybio Common Stock equal to the Concurrent Financing Exchange Ratio. Rallybio will assume outstanding and unexercised options to purchase shares of Avenzo Common Stock, and in connection with the Merger they will be converted into options to purchase shares of Rallybio Common Stock based on the Exchange Ratio.

Under the Exchange Ratio and Concurrent Financing Exchange Ratio formulas in the Merger Agreement, upon the Closing, on a pro forma basis and based upon the number of shares of Rallybio Common Stock expected to be issued in connection with the Merger, pre-Merger equityholders of Avenzo (other than investors in the Concurrent Financing) are expected to own approximately 56.6% of the combined company, pre-Merger equityholders of Rallybio are expected to own approximately 2.8% of the combined company and the investors in the Concurrent Financing are expected to own approximately 40.6% (assuming proceeds from the Concurrent Financing of $215.0 million), in each case, calculated on a fully diluted basis, using the treasury stock method, and subject to certain assumptions, including (i) a valuation for Rallybio of $15.0 million (calculated after giving effect to expected payment of Parent Distributions (as defined below)), (ii) a fixed valuation for Avenzo of $300.0 million, and (iii) the relative capitalization of Rallybio and Avenzo. The percentage of the combined company that each party’s equityholders will own following the Closing is subject to certain adjustments (as described in more detail in the section titled “The Merger Agreement—Merger Consideration and Exchange Ratio”), including the amount of the final Rallybio Net Cash at the Closing. Rallybio Net Cash as calculated under the Merger Agreement makes certain adjustments to the value of Rallybio’s Cash and Cash Equivalents (as defined in the Merger Agreement), and was equal to approximately $87.7 million as of March 31, 2026. The adjustments are described in the section titled “The Merger Agreement—Calculation of Rallybio Net Cash.” Based on its Cash and Cash Equivalents and other balance sheet line items as of March 31, 2026 and current estimates of the other elements of Rallybio Net Cash (including projected adjustments to Rallybio’s Cash and Cash Equivalents), Rallybio calculates that it had Rallybio Net Cash of approximately $83.2 million as of June 30, 2026. Rallybio expects to continue to incur losses in future periods primarily related to the proposed Merger and, as a result, available Cash and Cash Equivalents will continue to decrease and Rallybio intends to distribute substantially all of the Rallybio Net Cash to its pre-Closing stockholders in connection with the

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Merger, which may be payable after the Closing Date, up to an aggregate amount equal to the aggregate of the amount by which Rallybio Net Cash will equal or exceed $0 (excluding any proceeds from any asset disposition, to the extent contingent or to be received following the date for payment of such distribution). For a description of the calculation of Rallybio Net Cash as set forth in the Merger Agreement, please see the section titled “The Merger Agreement—Calculation of Rallybio Net Cash.”

Each share of Rallybio Common Stock issued and outstanding at the time of the Merger will remain issued and outstanding, and, subject to the proposed reverse stock split, will be unaffected by the Merger. In addition, on May 31, 2026, Avenzo entered into the Subscription Agreement with certain investors, pursuant to which Avenzo has agreed to sell, and such investors have agreed to purchase, shares of Avenzo Common Stock for an aggregate purchase price of $215.0 million immediately prior to the Effective Time. The closing of the Concurrent Financing is conditioned upon the satisfaction or waiver of each of the conditions to the Closing as well as certain other conditions. The Concurrent Financing is more fully described in the section titled “Agreements Related to the Merger—Subscription Agreement” of this proxy statement/prospectus.

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Each of Proposal Nos. 1, 2 and 3 is a condition to the completion of the Merger. The closing of the Concurrent Financing is conditioned upon the satisfaction or waiver of each of the conditions to the Closing as well as certain other conditions. The issuance of Rallybio Common Stock in connection with the Merger and the change of control of Rallybio resulting from the Merger will not take place unless Proposal Nos. 1, 2 and 3 are approved by the required Rallybio stockholders, Rallybio’s name is changed to “Avenzo Therapeutics, Inc.” and the Merger is consummated.

In addition to the requirement of obtaining the approval of Proposal Nos. 1, 2 and 3 by the required Rallybio stockholders, the Closing is subject to the satisfaction or waiver of each of the other closing conditions set forth in the Merger Agreement. In the event of a waiver of a condition, the Rallybio Board will evaluate the materiality of any such waiver to determine whether amendment of this proxy statement/prospectus and re-solicitation of stockholder approval is necessary. For a more complete description of the closing conditions under the Merger Agreement, please see the section titled “The Merger Agreement—Conditions to the Completion of the Merger” of this proxy statement/prospectus.

The presence of the holders of a majority of the shares of Rallybio Common Stock entitled to vote, present in person or represented by proxy, at the Rallybio annual meeting is necessary to constitute a quorum at the meeting for the Proposals.

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The approval of Proposals No. 4, 5, 6, 7, 8 and 9 are not conditions to the Merger. Proposal Nos. 4, 7 and 8 are each conditioned on the consummation of the Merger. Rallybio does not expect that any matter other than the Proposals will be brought before the Rallybio annual meeting.

The presence of the holders of a majority of the shares of Rallybio Common Stock entitled to vote, present in person or represented by proxy, at the Rallybio annual meeting is necessary to constitute a quorum at the meeting for the purpose of approving the Proposals.

As of the date of this proxy statement/prospectus, the Rallybio Board does not know of any business to be presented at the Rallybio annual meeting other than as set forth in the notice accompanying this proxy statement/prospectus. If any other matters should properly come before the Rallybio annual meeting, it is intended that the shares represented by proxies will be voted with respect to such matters in accordance with the judgment of the persons voting the proxies.

Votes will be counted by the inspector of election appointed for the meeting, who will separately count “FOR” and “AGAINST” votes, abstentions and broker non-votes. Abstentions and broker non-votes will be treated as shares present for the purpose of determining the presence of a quorum for the transaction of business at the Rallybio annual meeting, but will not be counted as votes cast and will have no effect on the outcome of the vote for each of Proposals No. 1, 2, 3, 5, 6, 7, 8 and 9. We do not expect broker non-votes in connection with Proposal No. 6. Abstentions and broker non-votes will have the same effect as votes “AGAINST” Proposal No. 4.

As of      , 2026, the directors and executive officers of Rallybio owned or controlled       outstanding shares of Rallybio Common Stock entitled to vote at the Rallybio annual meeting. As of May 31, 2026, the Rallybio stockholders that are party to a support agreement, including the directors and executive officers of Rallybio, owned an aggregate number of shares of Rallybio Common Stock representing approximately 24.3% of the outstanding shares of Rallybio Common Stock. Each stockholder that entered into a Rallybio support agreement has agreed to vote all shares of Rallybio Common Stock owned by him, her or it as of the

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record date (i) in favor of approving the Merger and the other transactions and actions contemplated by the Merger Agreement, including the Nasdaq Stock Issuance Proposal, Reverse Stock Split Proposal, Name Change Proposal, the Authorized Share Proposal, the Concurrent Financing and the Asset Dispositions (collectively, the “Contemplated Transactions”), (ii) against any proposal made in opposition to, or in competition with, the Merger Agreement or the Merger and (iii) against any acquisition proposal involving a third party.

Pursuant to the Rallybio CVR Agreement, during the period beginning on the Closing Date (following the Closing) and ending on December 31, 2031 (the “CVR Term”), each Rallybio CVR holder will be entitled to receive on a pro rata basis all of the net proceeds received, if any, by Rallybio as a result of payment of (i) any upfront, milestone, royalty and other payments received under any disposition agreement related to the Legacy Assets (as defined in the section titled “Agreements Related to the Merger—Rallybio Contingent Value Rights Agreement”), and (ii) any cash proceeds received from Recursion Pharmaceuticals, Inc. (“Recursion”) pursuant to Section 1.1(c) of the membership interest purchase agreement, dated as of July 8, 2025, entered into between Rallybio and Recursion

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and the other parties thereto. For a period of four months after the Closing, the combined company will use commercially reasonable efforts to effect the disposition of the Legacy Assets to a third party that Rallybio provided Avenzo with written notice of the potential buyer and proposed terms prior to the Closing Date and the applicable disposition agreement does not contain post-closing obligations or indemnity. Rallybio CVR Payments (as defined in the section titled “Agreements Related to the Merger—Rallybio Contingent Value Rights Agreement”) of less than $1,000,000 in any given CVR payment period are not distributed at that time, as they are rolled forward and aggregated with subsequent periods until either the aggregate reaches $1,000,000 or the final CVR payment period.

The Rallybio CVR Payments, if any, will become payable to the designated rights agent for subsequent distribution to the Rallybio CVR holders. In the event that no such proceeds are received during the CVR Term (as defined in the Rallybio CVR Agreement), holders of the Rallybio CVRs will not receive any payment pursuant to the Rallybio CVR Agreement. There can be no assurance that any Rallybio CVR holders will receive any Rallybio CVR Payments.

The right to the contingent payments contemplated by the Rallybio CVR Agreement is a contractual right only and is not transferable, except in the limited circumstances specified in the Rallybio CVR Agreement. The Rallybio CVRs are not evidenced by a certificate or any other instrument and are not registered with SEC. The Rallybio CVRs do not have any voting or dividend rights and do not represent any equity or ownership interest in Rallybio or any of its respective affiliates. No interest will accrue on any amounts payable in respect of the Rallybio CVRs.

Further, holders of Rallybio Common Stock, pre-funded warrants, restricted stock units and in the money stock options of record as of the close of business on the last business day prior to the day on which the Effective Time occurs will receive one Rallybio CVR for each outstanding share of Rallybio Common Stock, pre-funded warrant, restricted stock unit and in the money stock option held by such holder on such date, as described in more detail in the section titled “Agreements Related to the Merger—Rallybio Contingent Value Rights Agreement.”

In addition, prior to the Closing, the Rallybio Board will declare one or more cash distributions (each, a “Parent Distribution”) to holders of Rallybio Common Stock and, if applicable, securities convertible into or exchangeable or exercisable for shares of Rallybio Common Stock as of each record date set by the Rallybio Board (each, a “Parent Distribution Record Date”), up to an aggregate amount equal to the amount by which Rallybio Net Cash will equal or exceed $0 (excluding any proceeds from any Asset Disposition, to the extent contingent or to be received following the date for payment of such distributions). Only one Parent Distribution may be declared prior to the Rallybio Stockholders’ Meeting and no more than $50,000,000 in the aggregate may be declared as a Parent Distribution prior to the Rallybio stockholders’ meeting. For a more complete description, please see the section titled “The Merger Agreement —Parent Distributions.”

For a more complete description of the treatment of Rallybio securities (as defined below) in the Merger, please see the sections titled “The Merger Agreement—Merger Consideration and Exchange Ratio” and “Market Price and Dividend Information” of this proxy statement/prospectus.

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For a more complete description of the treatment of Avenzo Common Stock and Avenzo stock options in the Merger, please see the sections titled “The Merger Agreement—Merger Consideration and Exchange Ratio” of this proxy statement/prospectus. For a description of the effect of the Concurrent Financing on Avenzo’s current securityholders, please see the sections titled “Agreements Related to the Merger—Subscription Agreement” and “Agreements Related to the Merger—Registration Rights Agreement” of this proxy statement/prospectus.

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If you are a Rallybio stockholder of record, as of the record date, you may provide your proxy instructions in one of four different ways:

We provide internet proxy voting to allow you to vote your shares online, with procedures designed to ensure the authenticity and correctness of your proxy vote instructions. However, please be aware that you must bear any costs associated with your internet access, such as usage charges from internet access providers and telephone companies.

If you hold your shares in “street name” (as described below), you may provide your proxy instructions by following the instructions on your vote instruction form provided by your broker, bank or other agent. Please provide your proxy instructions only once, unless you are revoking a previously delivered proxy instruction, and as soon as possible so that your shares can be voted at the Rallybio annual meeting.

If you are a beneficial owner of shares registered in the name of your broker, bank or other agent, you should have received a voting instruction card and voting instructions with these proxy materials from that organization rather than from Rallybio. Simply complete and mail the voting instruction card to ensure that your vote is counted. To vote at the Rallybio annual meeting, you may visit www.virtualshareholdermeeting.com/RLYB2026, press the “Attend Meeting” button and follow the instructions. You may be instructed to obtain a legal proxy from your broker, bank, or other nominee and submit a copy in advance of the meeting. Further instructions will be provided to you via email.

Whether or not you plan to attend the Rallybio annual meeting, Rallybio encourages you to vote by proxy to ensure your vote is counted. Even if you have submitted a proxy before the Rallybio annual meeting, you may still attend the Rallybio annual meeting and vote. In such case, your previously submitted proxy will be disregarded.

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Rallybio expects that Proposal Nos. 1, 2, 3, 4, 5, 7, 8 and 9 will be considered to be “non-routine” matters, and thus a Rallybio stockholder’s broker, bank or other agent may not vote shares on those Proposals in the absence of such holders’ voting instructions. If a Rallybio stockholder does not instruct their broker how to vote with respect to these Proposals, those votes will be counted as broker “non-votes,” and will have no effect on the outcome of each Proposal other than Proposal No. 4, which will have the same effect as a vote “AGAINST” such Proposal. Rallybio expects that Proposal No. 6 is considered to be a “routine” matter, and thus if a Rallybio stockholder does not return voting instructions to their broker, such holder’s shares may be voted by his or her broker in its discretion. To make sure that your vote is counted, you should instruct your broker or other agent to vote your shares, following the procedures provided by your broker.

Broker non-votes will be treated as shares present for the purpose of determining the presence of a quorum for the transaction of business at the Rallybio annual meeting, but will not be counted as votes cast and will have no effect on the outcome of the vote for each of Proposals No. 1, 2, 3, 5, 6, 7, 8 and 9. We do not expect broker non-votes in connection with Proposal No. 6. Broker non-votes will have the same effect as votes “AGAINST” Proposal No. 4.

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All properly executed proxies that are not revoked will be voted at the Rallybio annual meeting and at any adjournments or postponements of the Rallybio annual meeting in accordance with the instructions contained in the proxy. If a holder of Rallybio Common Stock executes and returns a proxy and does not specify otherwise, the shares represented by that proxy will be voted “FOR” all of the Proposals in accordance with the recommendations of the Rallybio Board.

If a Rallybio stockholder who owns shares of Rallybio Common Stock in “street name” has instructed a broker to vote its shares of Rallybio Common Stock, the stockholder must follow directions received from its broker to change those instructions.

51 West 52^nd Street, 6^th Floor

New York NY 10019

Call Toll Free: (866) 539-7406

Email: rallybio@georgeson.com

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RISK FACTORS

The combined company will be faced with a market environment that cannot be predicted and that involves significant risks, many of which will be beyond its control. In addition to the other information contained or incorporated by reference in this proxy statement/prospectus, you should carefully consider the material risks described below before deciding how to vote your shares of Rallybio Common Stock. You should also read and consider the other information in this proxy statement/prospectus. Please see the section titled “Where You Can Find More Information” beginning on page 448 of this proxy statement/prospectus for further information.

Risks Related to the Merger

The Exchange Ratio will not be adjusted based on the market price of Rallybio Common Stock, so the consideration at the Closing may have a greater or lesser value than at the time the Merger Agreement was signed.

The Exchange Ratio will not change based on changes in the trading price of Rallybio Common Stock. Therefore, if before the completion of the Merger, the market price of Rallybio Common Stock increases from the market price on the date of the Merger Agreement, Avenzo stockholders could then receive merger consideration with substantially higher value for their shares of Avenzo Common Stock than the parties had negotiated when they established the Exchange Ratio. The Merger Agreement does not include a price-based termination right. Under the Exchange Ratio and Concurrent Financing Exchange Ratio formulas in the Merger Agreement, immediately after the Closing, on a pro forma basis and based upon the number of shares of Rallybio Common Stock expected to be issued in connection with the Merger, pre-Merger equityholders of Avenzo (other than investors in the Concurrent Financing) are expected to own approximately 56.6% of the combined company, pre-Merger equityholders of Rallybio are expected to own approximately 2.8% of the combined company and the investors in the Concurrent Financing are expected to own approximately 40.6% (assuming proceeds from the Concurrent Financing of $215.0 million), in each case, calculated on a fully diluted basis, using the treasury stock method, and subject to certain assumptions, including (i) a valuation for Rallybio of $15.0 million (calculated after giving effect to expected payment of Parent Distributions), (ii) a fixed valuation for Avenzo of $300.0 million, and (iii) the relative capitalization of Rallybio and Avenzo. The percentage of the combined company that each party’s equityholders will own following the Closing is subject to certain adjustments (as described in more detail in the section titled “The Merger Agreement—Merger Consideration and Exchange Ratio”), including the amount of the final Rallybio Net Cash at the Closing. Rallybio Net Cash as calculated under the Merger Agreement makes certain adjustments to the value of Rallybio’s Cash and Cash Equivalents (as defined in the Merger Agreement). The adjustments are described in the section titled “The Merger Agreement—Calculation of Rallybio Net Cash.” Based on its Cash and Cash Equivalents and other balance sheet line items as of March 31, 2026 and current estimates of the other elements of Rallybio Net Cash (including projected adjustments to Rallybio’s Cash and Cash Equivalents), Rallybio calculates that it had Rallybio Net Cash of approximately $83.2 million as of June 30, 2026. Rallybio expects to continue to incur losses in future periods primarily related to the proposed Merger and, as a result, available Cash and Cash Equivalents will continue to decrease and Rallybio intends to distribute substantially all of the Rallybio Net Cash to its pre-Closing stockholders in connection with the Merger, which may be payable after the Closing Date. For a description of the calculation of Rallybio Net Cash as set forth in the Merger Agreement, please see the section titled “The Merger Agreement—Calculation of Rallybio Net Cash.”

If the conditions to the Closing are not met, the Merger may not occur.

Even if Proposal Nos. 1, 2 and 3 are approved by the stockholders of Rallybio, specified conditions must be satisfied or, to the extent permitted by applicable law, waived to complete the Merger. These conditions are set forth in the Merger Agreement and each material condition to the completion of the Merger is described in the section titled “The Merger Agreement—Conditions to the Completion of the Merger.” Rallybio and Avenzo cannot assure you that all of the conditions will be satisfied or waived. If the conditions are not satisfied or waived, the Merger may not occur or will be delayed, and Rallybio and Avenzo each may lose some or all the intended benefits of the Merger.

The Merger may be completed even though a material adverse effect may result from the announcement of the Merger, industry-wide changes and/or other causes.

In general, either Rallybio or Avenzo can refuse to complete the Merger if there is a Rallybio Material Adverse Effect (as defined in the Merger Agreement) or a Company Material Adverse Effect (as defined in the Merger Agreement), as applicable, between May 31, 2026, the date of the Merger Agreement, and the Closing. However, certain types of

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changes do not permit either party to refuse to complete the Merger, even if such change could be said to have a material adverse effect on Rallybio or Avenzo, including:

If a material adverse change occurs with respect to either party or both parties and Rallybio and Avenzo still complete the Merger, the stock price of the combined company following the Closing may suffer and may reduce the value of the Merger to the stockholders of Rallybio, Avenzo or both.

Some executive officers and directors of Rallybio have interests in the Merger that are different from the stockholders of Rallybio and that may influence them to support or approve the Merger without regard to the interests of the stockholders of Rallybio.

Certain executive officers and directors of Rallybio are parties to arrangements that provide them with interests in the Merger that are different from the stockholders of Rallybio, including severance benefits, the acceleration of equity award vesting and continued indemnification.

The Rallybio Board was aware of and considered these interests, among other matters, in reaching its determination (i) that the terms of the Merger Agreement and the Merger and the other Contemplated Transactions are fair to, advisable and in the best interest of Rallybio and its stockholders, (ii) to approve and declare advisable the Merger Agreement and the Contemplated Transactions, including the Merger and the issuance of shares of Rallybio Common Stock to the stockholders of Avenzo pursuant to the Merger Agreement and (iii) to recommend, upon the terms and subject to the terms and conditions set forth in the Merger Agreement, that the stockholders of Rallybio vote to approve Proposal Nos. 1, 2 and 3. These interests, among other factors, may have influenced the directors and executive officers of Rallybio to support or approve the Merger.

For more information regarding the interests of Rallybio executive officers and directors in the Merger, see the section titled “The Merger—Interests of Rallybio’s Directors and Executive Officers in the Merger.”

Rallybio stockholders may not realize a benefit from the Merger commensurate with the ownership dilution they will experience in connection with the Merger.

If the combined company is unable to realize the full strategic and financial benefits currently anticipated from the Merger, Rallybio stockholders will have experienced substantial dilution of their ownership interests without receiving any commensurate benefit, or only receiving part of the commensurate benefit to the extent the combined company is able to realize only part of the strategic and financial benefits currently anticipated from the Merger.

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If the Merger is not completed, Rallybio’s stock price may decline significantly.

The market price of Rallybio Common Stock is subject to significant fluctuations. During the 12-month period ended May 31, 2026, the closing per share sales price of Rallybio Common Stock on Nasdaq ranged from a high of $16.00 on May 22, 2026 to a low of $2.16 (after giving effect to Rallybio’s 1-for-8 reverse stock split approved by Rallybio’s stockholders on January 26, 2026 at a Special Meeting of Stockholders and effective as of 12:01 Eastern Time on February 6, 2026) on June 4, 2025. Market prices for securities of pharmaceutical, biotechnology and other life science companies have historically been particularly volatile. In addition, the market price of Rallybio Common Stock will likely be volatile based on whether stockholders and other investors believe that Rallybio can complete the Merger or otherwise raise additional capital to support Rallybio’s operations if the Merger is not consummated and another strategic transaction cannot be identified, negotiated and consummated in a timely manner, if at all. The volatility of the market price of Rallybio Common Stock is exacerbated by low trading volume.

Additional factors that may cause the market price of Rallybio Common Stock to fluctuate include:

Moreover, the stock markets in general have experienced substantial volatility that has often been unrelated to the operating performance of individual companies. These broad market fluctuations may also adversely affect the trading price of Rallybio Common Stock. In the past, following periods of volatility in the market price of a company’s securities, stockholders have often instituted class action securities litigation against such companies.

Rallybio and Avenzo equityholders will have a reduced ownership and voting interest in, and will exercise less influence over the management of, the combined company following the completion of the Merger as compared to their current ownership and voting interests in the respective companies.

After the completion of the Merger, the current stockholders of Rallybio and Avenzo will own a smaller percentage of the combined company than their ownership of their respective companies prior to the Merger. Under the Exchange Ratio and Concurrent Financing Exchange Ratio formulas in the Merger Agreement, immediately after the Closing, on a pro forma basis and based upon the number of shares of Rallybio Common Stock expected to be issued in connection with the Merger, pre-Merger equityholders of Avenzo (other than investors in the Concurrent Financing) are expected to own approximately 56.6% of the combined company, pre-Merger equityholders of Rallybio are expected to own approximately 2.8% of the combined company and the investors in the Concurrent Financing are expected to own approximately 40.6% (assuming proceeds from the Concurrent Financing of $215.0 million), in each case, calculated on a fully diluted basis, using the treasury stock method, and subject to certain assumptions, including (i) a valuation for Rallybio of $15.0 million (calculated after giving effect to expected payment of Parent Distributions), (ii) a fixed valuation for Avenzo of $300.0 million, and (iii) the relative capitalization of Rallybio and Avenzo. The percentage of the combined company that each party’s equityholders will own following the Closing is subject to certain adjustments (as described in more detail in the section titled “The Merger Agreement—Merger Consideration and Exchange Ratio”), including the amount of the final Rallybio Net Cash at the Closing. Rallybio Net Cash as calculated under the Merger Agreement makes certain adjustments to the value of Rallybio’s Cash and Cash Equivalents (as defined in the Merger Agreement). The adjustments are described in the section titled “The Merger Agreement—Calculation of Rallybio Net Cash.” Based on its Cash and Cash Equivalents and other balance sheet line items as of March 31, 2026 and current estimates of the other elements of Rallybio Net Cash (including projected adjustments to Rallybio’s Cash and Cash Equivalents), Rallybio calculates that it had Rallybio Net Cash of approximately $83.2 million as of June 30, 2026. Rallybio expects to continue to incur losses in future periods primarily related to the proposed Merger and, as a result, available Cash and Cash Equivalents will continue to decrease and Rallybio intends to distribute substantially all of the Rallybio Net Cash to its pre-Closing stockholders

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in connection with the Merger. For a description of the calculation of Rallybio Net Cash as set forth in the Merger Agreement, please see the section titled “The Merger Agreement—Calculation of Rallybio Net Cash.”

The amount of the Parent Distributions payable to Rallybio stockholders is uncertain and may be less than currently anticipated, or the Parent Distributions may not be made at all.

In connection with the Merger, the Rallybio Board will declare one or more Parent Distributions payable to holders of Rallybio Common Stock and, if applicable, securities convertible into or exchangeable or exercisable for shares of Rallybio Common Stock, in an aggregate amount not to exceed the amount by which Rallybio Net Cash equals or exceeds $0 (excluding any proceeds from Asset Dispositions that are contingent or to be received following the date for payment of such distributions). The amount of Rallybio Net Cash available for the Parent Distributions is subject to numerous factors, many of which are outside of Rallybio’s control, including the amount of Rallybio’s transaction expenses, the costs of any tail policy associated with Rallybio’s directors’ and officers’ insurance, lease termination costs, payments required to terminate existing agreements, expenses associated with the wind-down of Rallybio’s prior research and development activities, payroll taxes associated with the Parent Distributions, severance or change-in-control payments, and other accrued or contingent liabilities. Rallybio expects to continue to incur losses in future periods primarily related to the proposed Merger and, as a result, available Cash and Cash Equivalents will continue to decrease prior to the Closing. If these expenses and liabilities are greater than currently estimated, or if unforeseen liabilities arise, the amount available for the Parent Distributions will be reduced accordingly. In addition, the Parent Distributions are subject to Avenzo’s prior review and approval (not to be unreasonably withheld, conditioned or delayed), and the final determination of Rallybio Net Cash may involve resolution by an independent auditor if Rallybio and Avenzo cannot agree. There can be no assurance that the aggregate amount of the Parent Distributions will equal the amount that Rallybio stockholders currently expect to receive, or that any Parent Distribution will be made at all. Rallybio stockholders should not rely on any estimate of the amount of the Parent Distributions, as the actual amount paid may be materially less than the estimated amount set forth in this proxy statement/prospectus.

The Merger may not be completed on the terms or timeline currently contemplated, or at all.

The consummation of the Merger is subject to numerous conditions, including (1) the effectiveness of the registration statement of which this proxy statement/prospectus forms a part, (2) the approval by Rallybio’s stockholders of the Rallybio Stockholder Matters, (3) the approval by Avenzo’s stockholders of the Avenzo Stockholder Matters, and (4) other customary closing conditions and there can be no assurance that the Merger will be consummated. See the section titled “The Merger Agreement—Conditions to the Completion of the Merger.”

If the Merger is not completed for any reason, the price of Rallybio Common Stock may decline to the extent that the market price of Rallybio Common Stock reflects or previously reflected positive market assumptions that the Merger would be completed and the related benefits would be realized. In addition, Rallybio and Avenzo have expended and will continue to expend significant management time and resources and have incurred and will continue to incur significant expenses due to legal, advisory, printing and financial services fees related to the Merger. These expenses must be paid regardless of whether the Merger is consummated.

Lawsuits may be filed against Rallybio and the members of the Rallybio Board arising out of the proposed Merger, which may delay or prevent the proposed Merger.

Putative stockholder complaints, including stockholder class action complaints, and other complaints may be filed against Rallybio, the Rallybio Board, Avenzo, the Avenzo Board and others in connection with the transactions contemplated by the Merger Agreement. The outcome of litigation is uncertain, and Rallybio may not be successful in defending against any such future claims. Lawsuits that may be filed against Rallybio, the Rallybio Board, Avenzo, or the Avenzo Board could delay or prevent the Merger, divert the attention of Rallybio’s management and employees from Rallybio’s day-to-day business and otherwise adversely affect Rallybio’s financial condition.

During the pendency of the Merger Agreement, Rallybio and Avenzo may not be able to enter into a business combination with another party at a favorable price because of restrictions in the Merger Agreement, which could adversely affect their respective businesses.

Covenants in the Merger Agreement impede the ability of Rallybio and Avenzo to make acquisitions, subject to specified exceptions relating to fiduciary duties, or complete other mergers, sales of assets or other business combinations pending completion of the Merger. As a result, if the Merger is not completed, the parties may be at a disadvantage to their competitors during that period. In addition, while the Merger Agreement is in effect, each party

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is generally prohibited from soliciting, initiating, knowingly encouraging or entering into specified extraordinary transactions, such as a merger, sale of assets or other business combination, with any third party, subject to specified exceptions, even if any such transaction could be favorable to such party’s stockholders or stockholders, as applicable. For a more complete description of the restrictions on pursuing alternative transactions please see the section titled “The Merger Agreement.”

Certain provisions of the Merger Agreement may discourage third parties from submitting competing proposals, including proposals that may be superior to the arrangements contemplated by the Merger Agreement.

The terms of the Merger Agreement prohibit each of Rallybio and Avenzo from soliciting competing proposals or cooperating with persons making unsolicited takeover proposals, except in certain limited circumstances. The Rallybio Board and Avenzo Board may respond to an unsolicited competing proposal if it determines in good faith, after consultation with its outside financial advisor and outside legal counsel, that the unsolicited competing proposal constitutes, or is reasonably likely to result in, a superior competing proposal and, after consultation with its outside legal counsel, that failure to take such action would be inconsistent with the fiduciary duties of the Rallybio Board or Avenzo Board, as applicable.

In certain circumstances, and subject to compliance with the Merger Agreement, the Rallybio Board or the Avenzo Board may change its recommendation to its respective stockholders if it determines such recommendation change is required to avoid a breach of its fiduciary duties. Additionally, subject to compliance with the procedures set forth in the Merger Agreement, including paying the applicable termination fee, Avenzo may terminate the Merger Agreement in order to enter into an agreement with respect to a Superior Offer.

Upon termination of the Merger Agreement in certain circumstances, Avenzo may be required to pay to Rallybio a termination fee of (x) $20.0 million, including (i) where the Avenzo Board changes or withdraws its recommendation in favor of the Merger or recommends to enter into an alternative transaction, (ii) in certain circumstances where Avenzo enters into a Permitted Alternative Agreement (as defined in the Merger Agreement); or (iii) if (a) the Merger Agreement is terminated because Avenzo (1) fails to obtain the requisite stockholder approval of the Merger Agreement and the transactions contemplated thereby or (2) breaches the Merger Agreement, (b) an alternative acquisition proposal was announced or disclosed prior to obtaining Avenzo’s stockholder approval, and (c) within 12 months of the termination of the Merger Agreement, Avenzo enters into a definitive agreement with respect to an alternative transaction; or (y) $8.0 million, if (i) the Merger Agreement is terminated because the Merger has not been consummated by the End Date (as defined in the Merger Agreement), (ii) an alternative acquisition proposal was announced or disclosed prior to obtaining Avenzo’s stockholder approval, and (iii) within 12 months of the termination of the Merger Agreement, Avenzo enters into a definitive agreement with respect to an alternative transaction.

Upon termination of the Merger Agreement in certain circumstances, a termination fee of $600,000 may be payable by Rallybio to Avenzo if (i)(a) the Merger Agreement is terminated because the Merger has not been consummated by the End Date (as defined in the Merger Agreement) or Rallybio (1) fails to obtain the requisite stockholder approval of the Rallybio Stockholder Matters or (2) breaches the Merger Agreement, (b) an alternative acquisition proposal was announced or disclosed prior to such termination, and (c) within 12 months of the termination of the Merger Agreement, Rallybio enters into a definitive agreement with respect to an alternative transaction, (ii) Rallybio fails to include its board recommendation in this proxy statement/prospectus, or (iii) the Rallybio Board of directors changes or withdraws its recommendation in favor of the Merger or approves an alternative transaction, or willfully and intentionally breaches its non-solicitation or certain other obligations under the Merger Agreement.

Avenzo and Rallybio have also each agreed to reimburse the other party for up to $750,000 for third-party expenses, as applicable, if the Merger Agreement is terminated in certain circumstances.

These termination fees and expense reimbursement provisions may discourage third parties from submitting competing proposals to Rallybio or Avenzo or their respective stockholders and may cause the Rallybio Board or the Avenzo Board, as the case may be, to be less inclined to recommend a competing proposal. For more information regarding the potential termination fees, see the section titled “The Merger Agreement-Termination and Termination Fees.”

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Because the lack of a public market for the shares of Avenzo Capital Stock makes it difficult to evaluate the fairness of the Merger, the stockholders of Avenzo may receive consideration in the Merger that is less than the fair market value of the shares of Avenzo Capital Stock or Rallybio may pay more than the fair market value of the Avenzo Capital Stock.

The outstanding shares of Avenzo Capital Stock are privately held and are not traded in any public market. The lack of a public market makes it extremely difficult to determine the fair market value of the shares of Avenzo Capital Stock. Because the percentage of Rallybio equity to be issued to Avenzo stockholders was determined based on negotiations between the parties, it is possible that the value of the Rallybio Common Stock to be received by Avenzo stockholders will be less than the fair market value of the shares of Avenzo Capital Stock, or Rallybio may pay more than the aggregate fair market value for the shares of Avenzo Capital Stock.

The opinion delivered by Citizens to the Rallybio Board prior to the entry into the Merger Agreement does not reflect changes in circumstances that may occur after the date thereof.

The Rallybio Board has not obtained an updated opinion either as of the date of this proxy statement/prospectus or as of any other date subsequent to the date of the opinion of Citizens, Rallybio’s financial advisor. Changes in circumstances, including without limitation the operations and prospects of Rallybio or Avenzo, stock prices, general market and economic conditions and other factors, some or all of which may be beyond the control of Rallybio and Avenzo, are not reflected in the opinion of Citizens. The opinion of Citizens does not speak as of any date other than the date thereof.

Rallybio or Avenzo may waive one or more of the conditions to the Merger without recirculation of this proxy statement/prospectus or resoliciting stockholder approval.

Conditions to Rallybio’s or Avenzo’s obligations to complete the Merger may be waived, in whole or in part, to the extent permitted by law, in certain circumstances unilaterally or by agreement of Rallybio and Avenzo. In the event of a waiver of a condition, the Rallybio Board will evaluate the materiality of any such waiver to determine whether amendment of this proxy statement/prospectus and re-solicitation of stockholder approval is necessary.

In the event that the Rallybio Board, in its own reasonable discretion, determines any such waiver is not significant enough to require recirculation of this proxy statement/prospectus and re-solicitation of its stockholders, it will have the discretion to complete the Merger without seeking further stockholder approval, which decision may have a material adverse effect on the Rallybio stockholders. For example, if Rallybio and Avenzo agree to waive the requirement that the shares of Rallybio Common Stock to be issued in the Merger have been approved for listing (subject to official notice of issuance) on Nasdaq as of the Closing, and their respective boards of directors elect to proceed with the Closing, Nasdaq may notify the combined company of its determination to delist the combined company’s securities based upon the failure to satisfy the initial inclusion criteria in the Nasdaq application. The combined company may appeal the determination to a hearings panel but such appeal will not stay the suspension and delisting action and Nasdaq may notify the combined company that its common stock will be immediately suspended from trading and delisted.

In addition, in order to meet the initial listing requirements of Nasdaq or as otherwise determined in the discretion of the combined company board pursuant to the terms of the Lock-Up Agreements, the Rallybio Board or combined company board may release stockholders from their Lock-Up Agreements and waive the requirement that such Lock-Up Agreements be in full force and effect immediately following the Effective Time. Such release would increase the number of shares that may be sold in the public market immediately after the Merger and any such sales could cause the combined company’s stock price to decline.

Transfers of the combined company’s securities utilizing Rule 144 may be limited.

Certain of the combined company’s securities will be restricted from immediate resale. Holders should be aware that transfers of Rallybio’s securities pursuant to Rule 144 may be limited as Rule 144 is not available, subject to certain exceptions, for the resale of securities initially issued by shell companies (other than business combination related shell companies) or issuers that have previously been a shell company. Rallybio’s winddown of its general and administrative operations that will not be needed after Closing and the proposed Merger (including the issuance of the Rallybio CVRs in connection therewith) will make Rallybio subject to the SEC requirements applicable to reporting shell company business combinations. Rallybio anticipates that following the consummation of the Merger, the combined company will no longer be a shell company. As a result, Rallybio anticipates that holders of restricted

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securities of the combined company, including affiliates of the combined company, will not be able to sell such securities pursuant to Rule 144 without registration until one year after the combined company files Form 10 information with the SEC. For more information, see the section titled “Securities Act Restrictions on Resale of Combined Company Common Stock.”

Rallybio’s winddown of its historical operations, the sale of assets, the suspension of development activities and the proposed Merger, resulting in the conversion of Avenzo into a public company, will make Rallybio subject to the SEC requirements applicable to reporting shell company business combinations. As a result, the combined company will be subject to more stringent reporting requirements, offering limitations and resale restrictions.

According to SEC guidance, the requirements applicable to reporting shell company business combinations apply to any company that sells or otherwise disposes of its historical assets or operations in connection with or as part of a plan to combine with a non-shell private company in order to convert the private company into a public one. Rallybio has taken steps to winddown its general and administrative operations that will not be needed after Closing and expects to issue the Rallybio CVRs in connection with the Closing and, as such, Rallybio’s plan to merge with Avenzo, resulting in the conversion of Avenzo into a public company, will be subject to the SEC requirements applicable to reporting shell company business combinations, which are as follows:

The foregoing SEC requirements will increase the combined company’s time and cost of raising capital, offering stock under equity plans, and complying with securities laws. Furthermore, such requirements will add burdensome restrictions on the resale of the combined company common stock by affiliates of Avenzo and any holders of “restricted” or “control” securities of the combined company.

For more information about the conditions to the completion of the Merger, see the section titled “The Merger Agreement-Conditions to the Completion of the Merger.”

Rallybio equityholders may not receive any payment on the Rallybio CVRs and the Rallybio CVRs may otherwise expire valueless.

The right of Rallybio equityholders to receive any future payment for or derive any value from the Rallybio CVRs will be contingent solely upon (i) Rallybio’s and Avenzo’s (or the combined company’s) ability to monetize all or any part of the Legacy Assets pursuant to one or more disposition agreements entered into within the time period specified in the Rallybio CVR Agreement, and the timing and amount of the consideration received thereunder and (ii) the receipt of cash proceeds from Recursion under the Membership Interest Purchase Agreement, dated July 8, 2025, by and among Recursion Pharmaceuticals, Inc., Exscientia Ventures I, Inc., Rallybio and Rallybio IPB, LLC (the “Membership Interest Purchase Agreement”). If Rallybio and/or Avenzo or the combined company (x) are not successful in entering into disposition agreements related to the Legacy Assets (as defined below) or

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receiving payments thereunder, or if such payments are not sufficient to result in the payment of any Rallybio CVR Payments as a result of permitted deductions thereto and (y) do not receive cash proceeds from Recursion pursuant to the Membership Interest Purchase Agreement, in each case within the time period specified in the Rallybio CVR Agreement, no payments will be made in respect of the Rallybio CVRs, and the Rallybio CVRs will expire valueless.

Following the effective time, the combined company will have sole authority over whether and how to monetize the Legacy Assets (if at all), and the combined company’s only obligations will be to carry out the obligations set forth in the Rallybio CVR Agreement.

Furthermore, the Rallybio CVRs will be unsecured obligations of the combined company and all payments under the Rallybio CVRs and all other obligations under the Rallybio CVR Agreement and the Rallybio CVRs and any rights or claims relating thereto will be subordinated in right of payment to the prior payment in full of all current or future senior obligations of the combined company.

The tax treatment of the CVRs is uncertain.

Rallybio intends to treat a holder’s receipt of the Rallybio CVRs after the Closing Date as a distribution of property with respect to the holder’s existing shares of Rallybio Common Stock for U.S. federal income tax purposes, which could be taxable to Rallybio stockholders without the corresponding receipt of cash. However, the U.S. federal income tax treatment of the Rallybio CVRs is uncertain. There is no legal authority directly addressing the U.S. federal income tax treatment of the receipt of, and payments under, the Rallybio CVRs, and there can be no assurance that the Internal Revenue Service (“IRS”) would not assert, or that a court would not sustain, a position that could result in adverse U.S. federal income tax consequences to holders of the Rallybio CVRs. For more information regarding the U.S. federal income tax consequences of the CVRs, see the section titled “Agreements Related to the Merger—Material U.S. Federal Income Tax Consequences of the Rallybio CVRs to holders of Rallybio Common Stock.”

Risks Related to Rallybio

Unless otherwise indicated or the context otherwise requires, references in this section to “Rallybio,” the “Company,” “we,” “us,” “our” and other similar terms refer to Rallybio and its subsidiaries.

Risks Related to Our Financial Position and Need for Additional Capital

We have incurred significant losses since our inception and anticipate that, if we continue to progress the development of our product candidates, we will continue to incur losses in the foreseeable future. We have not commercialized any products and have never generated revenue from the commercialization of any product. We are not currently profitable, and we may never achieve or sustain profitability.

We are a clinical-stage biotechnology company with a limited operating history. As a result, we are not profitable and we have incurred significant operating losses since inception, including net losses of $8.3 million and $9.4 million for the three months ended March 31, 2026 and 2025, respectively. As of March 31, 2026, we had an accumulated deficit of $310.3 million. 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 gain regulatory approval and become commercially viable. Since inception, we have devoted substantially all of our resources to raising capital, conducting discovery and research activities, acquiring product candidates, establishing and protecting our intellectual property, preparing for and conducting clinical trials, and establishing arrangements with third parties for the manufacture of our product candidates. We do not have any product candidates approved for sale and have not generated any revenue from product sales.

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If we continue to progress the development of our product candidates, we expect to incur significant additional operating losses in the foreseeable future as we advance our programs and operate our business. The costs of advancing product candidates through each clinical phase tend to increase substantially over the duration of the clinical development process. The total costs to advance a single product candidate to marketing approval in even a single jurisdiction are substantial. Because of the numerous risks and uncertainties associated with pharmaceutical product development, we are unable to accurately predict the timing or amount of increased expenses or when, or if, we will be able to generate revenue from the commercialization of any product candidates or achieve or maintain profitability. Our expenses will increase substantially if and as we:

We do not know when or whether we will become profitable. Our ability to generate revenue and become profitable depends upon our ability to successfully complete the development of our product candidates and to obtain the necessary regulatory approvals for their commercialization, which is subject to substantial additional risks and uncertainties, as described under “—Risks Related to Discovery, Development, Clinical Testing, Manufacturing, and Regulatory Approval.”

Each of our product candidates will require additional preclinical and/or clinical development, regulatory approval in multiple jurisdictions, the securing of clinical and commercial manufacturing supply, the building of a commercial organization, and substantial investment before we generate any revenue from product sales. As a result, if we continue to progress the development of our product candidates, we expect to continue to incur net losses and negative cash flows in the foreseeable future. These net losses and negative cash flows have had, and will continue to have, an adverse effect on our stockholders’ equity and working capital. The amount of our future net losses will depend, in part, on the rate of future growth of our expenses and our ability to generate revenues. If we are unable to develop and commercialize one or more product candidates, either alone or through current or future collaborations, or if revenues from any product that receives marketing approval are insufficient, we will not achieve profitability. Even if we successfully commercialize RLYB116 or any of our other product candidates, we may continue to incur substantial research and development and other expenses to develop other current or future product candidates. Even if we do achieve profitability, we may not be able to sustain or increase profitability on a quarterly or annual basis or meet outside expectations for our profitability. Our failure to become and remain profitable would decrease the value of the Company and could impair our ability to raise capital, maintain our research and development efforts, expand our business, execute our business plan or continue our operations.

If we continue to progress the development of our product candidates, we will require significant additional capital to fund our operations. If we continue to progress the development of our product candidates and fail to obtain necessary financing, we may not be able to complete the development or commercialization of RLYB116 or any other product candidate. Given our limited resources and access to capital, we may decide to prioritize development of certain product candidates, the choice of which may prove to be wrong and adversely affect our business.

If we continue to progress the development of our product candidates, we expect to spend significant amounts of capital to complete the development of, and if approved, commercialize, one or more product candidates, including RLYB116. We are obligated to make certain payments under our agreements with Affibody, Sobi, and Kymab Limited (“Sanofi”), including milestone and royalty payments in connection with achievement of certain development and commercial milestones as well as the sale of resulting products under such agreements. We may

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also spend significant capital to develop laboratory tests to identify patients for inclusion in our clinical trials or who are likely to respond to our product candidates.

If we continue to progress the development of our product candidates, we believe that our existing cash, cash equivalents and marketable securities as of March 31, 2026, will be sufficient to fund our operating expenses and capital expenditure requirements for at least 12 months beyond the date of the filing of this proxy statement/prospectus. This estimate and our expectation to advance the preclinical and clinical development of RLYB116 and any other product candidates are based on assumptions that may prove to be wrong, or we may be subject to changing circumstances. We could exhaust our available capital resources sooner than we expect. Our business is subject to numerous risks and uncertainties, and we may be unable to accurately estimate the actual amount of funds we will require for development and commercialization of our product candidates. Our future capital requirements, both near and long-term, will depend on many factors, including, but not limited to:

If we continue to progress the development of our product candidates, we will require significant additional capital, which we may raise through equity offerings, debt financings, marketing and distribution arrangements, strategic alliances and licensing arrangements or other sources. Depending on our business performance, the economic climate and market conditions, we may be unable to raise additional funds when needed on favorable terms, or at all. Furthermore, pursuant to Instruction I.B.6, a company with a public float of less than $75 million measured at certain time periods may not issue securities under Registration Statements on Form S-3 in excess of one-third of its public float in a 12-month period. For purposes of the prior sentence, “public float” means the aggregate market value of a company’s shares held by non-affiliates. We are subject to the limitations of Instruction I.B.6 which may limit the amount of funds we can raise using Registration Statements on Form S-3. Moreover, uncertain geopolitical events, such as the war in Ukraine and conflict in Israel, and uncertain global economic conditions, including as a result of changes in tariffs and other trade restrictions, have impacted the global economy, and a severe or prolonged economic downturn could result in a variety of challenges for our business, including disruptions in the financial markets, which could adversely impact our ability to raise additional capital when needed or on favorable terms, if at all. If we do not succeed in raising additional funds on acceptable terms, we may need to significantly delay, scale back or discontinue the development of one or more of our product candidates or the commercialization of any product that may be approved for marketing, or we could be forced to discontinue operations. In addition,

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attempting to secure additional financing may divert the time and attention of our management from day-to-day activities and harm our product candidate development efforts.

Because we have limited financial resources, we have focused and may continue to focus on a limited set of research programs and product candidates and for a limited set of indications. We may forego or delay pursuit of opportunities with certain other product candidates or for other indications that could have greater commercial potential or a greater likelihood of success. Our capital allocation decisions may cause us to fail to realize value from, or advance, viable commercial products or profitable market opportunities.

Raising additional capital may cause dilution to our stockholders, restrict our operations or require us to relinquish rights to our intellectual property or product candidates.

If we continue to progress the development of our product candidates, until such time, if ever, as we generate significant revenue from product sales, we expect to finance our operations through the sale of equity, debt financings, collaborations, strategic alliances and licensing arrangements or other sources. We do not currently have any committed external source of funds. In addition, we may seek additional capital due to favorable market conditions or strategic considerations, even if we believe that we have sufficient funds for our current or future operating plans.

To the extent that we raise additional capital through the future sale of equity or convertible debt securities, including sales of our common stock pursuant to the Sales Agreement with TD Securities (USA) LLC, each equityholder’s ownership interest will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect their rights as a common stockholder. In addition, debt financing and preferred equity financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. If we raise additional funds through debt financing, we may be subject to covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends, and we may need to dedicate a substantial additional portion of any operating cash flows to the payment of principal and interest on such indebtedness. Any future indebtedness, combined with our other financial obligations, could increase our vulnerability to adverse changes in general economic, industry and market conditions, limit our flexibility in planning for, or reacting to, changes in our business and the industry and impose a competitive disadvantage compared to our competitors that have less debt or better debt servicing options. If we raise additional funds through collaborations, strategic alliances or licensing arrangements with third parties, we may be required to relinquish valuable rights to our intellectual property, future revenue streams or product candidates or grant licenses on terms that may not be favorable to us. If we are unable to raise additional funds when needed, we may be required to delay, limit, reduce or terminate development or future commercialization efforts for one or more of our product candidates.

We have a limited operating history and no history of commercializing pharmaceutical products, which may make it difficult to evaluate the prospects for our future viability.

Rallybio was founded in January 2018 and our operations to date have been limited primarily to research and development activities, and raising capital. We have not yet demonstrated the ability to successfully complete a large-scale, pivotal clinical trial, obtain marketing approval, manufacture a commercial-scale product, or arrange for a third-party to do so on our behalf, or conduct sales and marketing activities necessary for successful commercialization. Consequently, predictions about our future success or viability may not be as accurate as they could be if we had a longer operating history or a history of successfully developing and commercializing pharmaceutical products.

As a business with a limited operating history, we may encounter unforeseen expenses, difficulties, complications, delays and other known and unknown challenges. If we continue to progress the development of our product candidates, we will eventually need to transition from a company with a research and development focus to a company capable of supporting commercial activities. We may not be successful in such a transition and, as a result, our business may be adversely affected.

Our quarterly and annual financial results may fluctuate, which makes our results difficult to predict and may cause our results to fall short of expectations.

Our financial condition and operating results have varied in the past and will continue to fluctuate from quarter-to-quarter and year-to-year in the future due to a variety of factors, many of which are beyond our control.

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Factors relating to our business that may contribute to these fluctuations include the following, as well as other factors described elsewhere in this proxy statement/prospectus:

Due to these and other factors, the results of any of our prior quarterly or annual periods should not be relied upon as indications of our future operating performance, and a period-to-period comparison of our results of operations may not be a meaningful indication of our future performance. In any particular quarter or quarters, our operating results could be below the expectations of securities analysts or investors, which could cause our stock price to decline.

Our ability to use our net operating loss and income tax credit carryforwards to offset future income tax liabilities may be subject to certain limitations.

We have incurred substantial NOLs during our history. To the extent that we continue to generate taxable losses, unused losses will carry forward and can be used to offset future taxable income, if any, until such unused losses expire, if at all. NOLs generated in taxable years beginning after December 31, 2017 are not subject to expiration. Federal NOLs generated in taxable years beginning after December 31, 2017 generally may not be carried back to prior taxable years. The deduction for NOLs arising in taxable years beginning after December 31, 2017 is generally limited to 80% of current year taxable income. We also have substantial federal and state research and development and other tax credit carryforwards. These tax credit carryforwards could expire unused and be unavailable to offset future income tax liabilities. In addition, in general, under Sections 382 and 383 of the Code, a corporation that undergoes an “ownership change” is subject to limitations on its ability to use its pre-change NOLs and tax credit carryforwards to offset future taxable income. Some of our historical NOLs may be subject to annual limitations on our ability to use them due to prior ownership changes.

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Additionally, the Merger may result in such an ownership change, and we may experience such ownership changes in the future as a result of future transactions in our stock, some of which may be outside our control. If we undergo an ownership change, our ability to use our NOLs and income tax credit carryforwards could be further limited. For these reasons, we may not be able to use a material portion of our NOLs or tax credit carryforwards, even if we attain profitability.

Risks Related to Discovery, Development, Clinical Testing, Manufacturing, Marketing Approval and Commercialization

We are heavily dependent on the success of RLYB116, which is in early-stage clinical development. If we continue to progress the development of our product candidates, and are not able to develop, obtain marketing approval for, or successfully commercialize our product candidates, or if we experience significant delays in doing so, our business will be materially harmed.

Our lead program, RLYB116, is in early-stage clinical development and we do not currently have any products that generate revenues or any other sources of revenue. To date, we have invested a significant portion of our efforts and financial resources in the development of RLYB212 and RLYB116. If we continue to progress the development of our product candidates, our future success is substantially dependent on our ability to successfully complete preclinical and clinical development for, obtain marketing approval for, and successfully commercialize, RLYB116 and our other product candidates, which may never occur. None of our product candidates are approved for commercial sale and we may never be able to develop a marketable product.

Before obtaining marketing approvals for the commercial sale of our product candidates, we must demonstrate the safety and efficacy of our product candidates for use in each target indication through lengthy, complex and expensive preclinical studies and clinical trials. Failure can occur at any time during the preclinical study and clinical trial processes. Because our product candidates are in an early stage of development, there is a high risk of failure, and we may never succeed in developing marketable products. If we continue to progress the development of our product candidates, our ability to generate product revenue will depend heavily on the successful development and eventual commercialization of our product candidates, which may never occur. Ongoing and future preclinical studies and clinical trials of our product candidates may not show sufficient safety or efficacy or be of sufficient quality to obtain or maintain marketing approvals. For example, PK data from the Phase 2 clinical trial for RLYB212 demonstrated an inability of the RLYB212 dose regimen to achieve predicted target concentrations, as well as the minimum target concentration required for efficacy. There can be no assurance that any of our product candidates, even if approved, will prove to be commercially viable therapeutics.

RLYB116 is designed for SC self-administration. The formulation or physical properties of RLYB116 may ultimately be determined to be inadequate to support this route of administration. If SC administration is not feasible, then we may need to identify additional formulations or routes of administration, which could delay initiation of our future clinical trials or commercialization and result in significant additional costs. Further, alternative formulations and routes of administration may be required to differentiate our product candidates from competitors and/or secure access to support successful commercialization.

If we continue to progress the development of our product candidates, the success of our product candidates will depend on several factors, including the following:

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If we do not successfully address one or more of these factors in a timely manner or at all, we could experience significant delays or an inability to commercialize our product candidates, which would materially harm our business. Due to the uncertain and time-consuming clinical development and marketing approval process, we may not successfully develop any of our product candidates and may choose to discontinue the development of any of our product candidates prior to receiving marketing approval. If we discontinue development of a product candidate, we will not receive anticipated revenues from that product candidate and we may not receive any return on our investment in that product candidate. We may discontinue a product candidate for clinical reasons if it does not prove to be safe and effective for its targeted indications, or if such product candidates do not achieve the necessary efficacy at tolerated doses required for patient benefit. For example, we discontinued RLYB212 development based on PK data from the Phase 2 clinical trial that demonstrated an inability of the RLYB212 dose regimen to achieve predicted target concentrations, as well as the minimum target concentration required for efficacy. In addition, there may be important facts about the safety, efficacy and risk versus benefit of our product candidates that are not known to us at this time. Any unexpected safety events or our failure to generate sufficient data in our clinical trials to demonstrate efficacy may cause a product candidate to fail clinical development. Furthermore, even if that product candidate meets its safety and efficacy endpoints, we may discontinue its development for various reasons, such as changes in the competitive environment or the standard of care and the prioritization of our resources.

The U.S. Supreme Court’s June 2024 decision in Loper Bright Enterprises v. Raimondo overturned the longstanding Chevron doctrine, under which courts were required to give deference to regulatory agencies’ reasonable interpretations of ambiguous federal statutes. The Loper decision could result in additional legal challenges to regulations and guidance issued by federal agencies, including the FDA, on which we rely. Any such legal challenges, if successful, could have a material impact on our business. Additionally, the Loper decision may result in increased regulatory uncertainty, inconsistent judicial interpretations, and other impacts to the agency rulemaking process, any of which could adversely impact our business and operations. We cannot predict the likelihood, nature or extent of government regulation that may arise from future legislation or administrative action or as a result of legal challenges, either in the United States or abroad. If we are slow or unable to adapt to changes in existing requirements or the adoption of new requirements or policies, or if we are not able to maintain regulatory compliance, our business could be materially harmed.

Preclinical studies and clinical trials are expensive, time consuming and difficult to design and implement, and involve uncertain outcomes. If we continue to progress the development of our product candidates, we may incur additional costs or experience delays in completing, or ultimately be unable to complete, the development of our product candidates.

Before obtaining marketing approval from the FDA, EMA or other comparable regulatory authorities for the sale of our product candidates, we must complete preclinical studies and extensive clinical trials to demonstrate the safety and efficacy of our product candidates. To initiate clinical trials for any future product candidates, we must submit the results of preclinical studies to the FDA, EMA or other comparable foreign regulatory authorities, along with other

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information, including information about CMC and our proposed clinical trial protocol, as part of an IND or similar regulatory filing that must be accepted by the FDA, EMA or other applicable regulatory authorities before we may proceed with clinical development. In the event that regulators require us to complete additional preclinical studies or we are required to satisfy other regulator requests, such as obtaining alignment on the device regulatory pathway for our FNAIT prevention program, the start of our clinical trials may be delayed or prevented. Even after we receive and incorporate guidance from these regulatory authorities, the FDA, EMA or other regulatory authorities could (i) disagree that we have satisfied their requirements to commence our clinical trial, (ii) change their position on the acceptability of our data, trial design or the clinical endpoints selected, which may require us to complete additional preclinical studies or clinical trials or (iii) impose stricter requirements for approval than we currently expect.

If we continue to progress the development of our product candidates, we may experience events that could delay or prevent our ability to complete current clinical trials or initiate and complete new trials, any of which may impact our product development timelines, result in increased costs, affect our ability to obtain marketing approval according to our plans, and delay commercialization of our product candidates. These events include, but are not limited to:

In addition, we could encounter delays if a clinical trial is suspended or terminated by us, the IRBs or IECs of the institutions in which such trials are being conducted, the FDA, EMA or other regulatory authorities, or recommended for termination by a Data and Safety Monitoring Board (“DSMB”) for such trial. Such authorities may impose a suspension or termination or recommend an alteration to clinical trials due to several factors, including failure to conduct the clinical trial in accordance with regulatory requirements or our clinical protocols, the identification of

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safety issues or adverse side effects, failure to demonstrate a benefit from using a drug, changes in governmental regulations or administrative actions.

Furthermore, we rely and will rely on CROs and clinical trial sites to ensure the proper and timely conduct of our clinical trials and, while we have agreements governing their committed activities, we have limited influence over their actual performance, as described in the section titled “—Risks Related to Our Dependence on Third Parties.”

Principal investigators for our clinical trials could serve as scientific advisors or consultants to us from time to time and receive compensation in connection with such services. Under certain circumstances, we may be required to report some of these relationships to the FDA. The FDA may conclude that a financial relationship between us and a principal investigator has created a conflict of interest or otherwise affected interpretation of a clinical trial. The FDA may therefore question the integrity of the data generated at the applicable clinical trial site, and the utility of the clinical trial itself may be jeopardized. This could result in a delay in approval, or rejection, of our marketing applications by the FDA and may ultimately lead to the denial of marketing approval of our product candidates.

Any delays in completing our clinical trials will increase our costs, slow down our product candidate development and approval process and jeopardize our ability to commence product sales and generate revenues. In addition, many of the factors that cause, or lead to, termination or suspension of, or a delay in the commencement or completion of, clinical trials may also ultimately lead to the denial of regulatory approval of our product candidates. Any delays to our clinical trials could shorten any period during which we may have the exclusive right to commercialize our product candidates and our competitors may be able to bring products to market before we do, and the commercial viability of our product candidates could be significantly reduced. Any of these occurrences may harm our business, financial condition and prospects significantly.

If we continue to progress the development of our product candidates, results of preclinical studies, clinical trials or analyses that we may announce or publish from time to time, may not be indicative of results obtained in later trials, and any interim results we may publish could be different than final results.

The results of preclinical studies, clinical trials or analyses of the results from such trials, may not be predictive of the results of later clinical trials. Product candidates in later clinical trials may fail to show the desired safety and efficacy traits despite having progressed through preclinical studies and prior clinical trials or having shown promising results based on analyses of data from earlier trials. Late-stage clinical trials may include a larger number of patients and could differ in other significant ways from early-stage clinical trials, including changes to inclusion and exclusion criteria, patient population, efficacy endpoints, dosing regimen and statistical design. A number of companies in the biopharmaceutical industry have suffered significant setbacks in later-stage clinical trials due to lack of efficacy or adverse safety profiles, notwithstanding earlier promising results. In addition, conclusions based on promising data from analyses of clinical results, such as the prospective and post hoc analysis of results may be shown to be incorrect in subsequent clinical trials that have pre-specified end points or may not be considered adequate by regulatory authorities. We have completed Phase 1 clinical studies for RLYB116, however, even if we complete later clinical trials as planned, we cannot be certain that their results will support the safety and efficacy requirements sufficient to obtain regulatory approval, and, as a result, our clinical development plans may be materially harmed.

Similarly, interim, “top-line” and preliminary data from our clinical trials that we announce or publish may change as more patient data become available or as additional analyses are conducted. The data obtained in such clinical trials are subject to additional audit and verification procedures and following such procedures, such interim data could be materially different from the final data.

Enrollment and retention of patients in rare disease clinical trials is an expensive and time-consuming process and could be made more difficult or rendered impossible by multiple factors outside our control.

If we continue to progress the development of our product candidates, identifying and qualifying patients to participate in clinical trials of our product candidates is critical to our success. We currently are conducting, and plan to conduct, clinical trials with our product candidates in rare disease indications, which can make completion of such trial more difficult. The timely completion of clinical trials in accordance with their protocols depends, among other things, on the speed at which we can recruit eligible patients to participate in testing our product candidates and our ability to enroll a sufficient number of patients who remain in the study until its conclusion.

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Clinical trial recruitment delays often result in increased costs, delays in advancing product development, delays in testing the effectiveness of technologies, delays in obtaining marketing approval or termination of clinical trials.

Patient enrollment and retention in clinical trials depends on many factors, including:

Additionally, we may have difficulty identifying and enrolling patients for any planned clinical trials because the conditions for which we plan to evaluate our current product candidates are rare diseases and we anticipate that there will be limited patient pools from which to draw for clinical trials. Further, because screening for many of these diseases is not widely adopted, and because it can be difficult to diagnose these diseases in the absence of screening, we may have difficulty finding patients who are eligible to participate in our studies or trials. Our clinical trials for RLYB116 may compete with other clinical trials for product candidates that are being tested for the same indications. This competition will reduce the number and types of patients available to us because some patients who might have opted to enroll in our trials may instead opt to enroll in a trial being conducted by one of our competitors. Furthermore, any negative results we may report in clinical trials of any of our product candidates may make it difficult or impossible to recruit and retain patients in other clinical trials of that same or a similar product candidate.

Outside of the United States, our ability to initiate, enroll and complete a clinical trial successfully is subject to numerous additional risks, including:

We may not be able to initiate or continue clinical trials required by the FDA, EMA or other regulatory authorities if we cannot enroll a sufficient number of eligible patients to participate in the clinical trials. If we have difficulty enrolling a sufficient number of patients to conduct our clinical trials as planned, we may need to delay, limit or terminate ongoing or planned clinical trials. Delays or failures in planned patient enrollment or retention may result in increased costs or program delays, which could have a harmful effect on our ability to develop our product candidates or could render further development impossible.

If we continue to progress the development of our product candidates, any product candidates that we develop or the administration thereof, may cause serious adverse events or undesirable side effects, which may halt their clinical development, delay or prevent marketing approval, or, if approved, require them to be taken off the market, include safety warnings, or otherwise limit their sales.

Adverse events or undesirable side effects caused by any product candidates we develop could cause us or regulatory authorities or IRBs, IECs or DSMBs, where applicable, to interrupt, delay, or halt clinical trials and, if we seek

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approval of any such product candidate, could result in a more restrictive label, imposition of a Risk Evaluation and Mitigation Strategy (“REMS”) program by the FDA or the delay or denial of regulatory approval by the FDA, EMA or other comparable foreign regulatory authorities. Additionally, the administration process or related procedures associated with our product candidates also may cause adverse side effects. Even if we determine that serious adverse events are unrelated to study treatment, such occurrences could affect patient recruitment or the ability of enrolled patients to complete the trial. Results of any clinical trial we conduct could reveal a high and unacceptable severity and prevalence of side effects. For example, complement inhibitors have, by design, immunosuppressive effects and, in some cases, may be administered to patients with significantly compromised health. As a result, administration of RLYB116 could make patients more susceptible to infection. The chronic dosing of patients with RLYB116 could lead to an immune response that causes adverse reactions or impairs the activity and/or efficacy of RLYB116. Patients may develop an allergic reaction to the drug and/or develop antibodies directed at RLYB116, or may require immunization with a meningococcal vaccine and prophylactic antibiotics. An immune response that causes adverse reactions or impairs the activity of RLYB116 could cause a delay in or termination of our development plans.

Some potential therapeutics that initially showed therapeutic promise in early-stage trials have later been found to cause side effects that prevented their further development. In addition, side effects could affect patient recruitment or the ability of enrolled patients to complete a trial or result in potential clinical trial or product liability claims. Inadequate training or failures by clinical trial personnel in recognizing or managing the potential side effects of our product candidates could result in patient injury or death. Furthermore, clinical trials by their nature utilize a sample of the potential patient population. With a limited number of subjects and limited duration of exposure, rare and severe side effects of our product candidates or those of our competitors may only be uncovered when a significantly larger number of patients have been exposed to the drug.

If we or others later identify undesirable side effects caused by any product candidate that we develop after the product is approved, several negative consequences could result, which could materially harm our business, including:

We cannot predict whether our product candidates will cause toxicities in humans that would preclude or lead to the revocation of marketing approval based on preclinical studies or early-stage clinical trials. Even if the side effects do not preclude the drug from obtaining or maintaining marketing approval, undesirable side effects may inhibit market acceptance of the approved product due to its tolerability versus other therapies. Any of these events could prevent us from achieving or maintaining market acceptance of a product candidate, if approved, and could significantly harm our business, results of operations, and prospects.

The marketing approval processes of the FDA, EMA and comparable foreign regulatory authorities, including the MHRA, are lengthy, time-consuming and inherently unpredictable, and if we continue to progress the development of our product candidates, and we are ultimately unable to obtain marketing approval for RLYB116 or any of our other product candidates, our business will be substantially harmed.

In the United States, we are not permitted to market a product candidate until we receive approval of a Biologics License Application (“BLA”) or a New Drug Application (“NDA”) from the FDA. The process of obtaining BLA and NDA approval is expensive, often takes many years and can vary substantially based upon the type, complexity and novelty of the products involved. Approval policies or regulations may change, and the FDA and other regulatory authorities have substantial discretion in the approval process, including the ability to delay, limit or deny approval of a product candidate for many reasons. In addition, the FDA may require post-approval clinical trials or studies as a condition of approval, which also may be costly. The FDA approval for a limited indication or approval with

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required warning language, such as a boxed warning, could significantly impact our ability to successfully market our product candidates. The FDA also may require adoption of a REMS requiring prescriber training, post-market registries, or otherwise restricting the marketing and dissemination of these products. Certain of our product candidates will rely on delivery systems, such as PFSs, pen-injectors and/or autoinjectors, and may ultimately be regulated as a drug/device combination product. Although the FDA and similar foreign regulatory agencies have systems in place for the review and approval of combination products, we may experience delays in the development and commercialization of our product candidates due to regulatory timing constraints and uncertainties in the product development and approval process. Despite the time and expense invested in the clinical development of product candidates, regulatory approval is never guaranteed for our product candidates. Assuming successful clinical development, we intend to seek product approvals in countries outside the United States, including in Europe. As a result, we would be subject to regulation by the EMA, as well as the other regulatory agencies in these countries.

Of the large number of drugs in development, only a small percentage successfully complete the marketing approval processes and are commercialized. This lengthy approval process, as well as the unpredictability of future clinical trial results, may result in our failing to obtain marketing approval to market our product candidates and we may be forced to abandon our development efforts for our product candidate, which would significantly harm our business, results of operations, and prospects.

The time required to obtain approval by the FDA, EMA and other comparable foreign regulatory authorities is unpredictable but typically takes many years following the commencement of clinical trials and depends upon numerous factors. In addition, approval policies, regulations, or the type and amount of clinical data necessary to gain approval may change during a product candidate’s clinical development and may vary among jurisdictions. We have not obtained marketing approval for any product candidate and it is possible that we will never obtain marketing approval for any product candidate.

Prior to obtaining approval to commercialize a product candidate in the United States or abroad, we must demonstrate to the satisfaction of the FDA, EMA or other comparable foreign regulatory authority, that such product candidates are safe and effective for their intended uses. Data obtained from preclinical studies and clinical trials are susceptible to varying interpretations, and regulatory authorities may not interpret our data as favorably as we do, which may further delay, limit, or prevent development efforts, clinical trials, or marketing approval. Even if we believe the preclinical or clinical data for our product candidates are sufficient to support approval, such data may not be considered sufficient to support approval by the FDA, EMA and other comparable regulatory authorities.

If we continue to progress the development of our product candidates, the FDA, EMA or other comparable foreign regulatory authority can delay, limit, or deny approval of RLYB116 or any of our other product candidates that we develop or require us to conduct additional preclinical or clinical testing or abandon a program for many reasons, including, but not limited to:

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We have never obtained marketing approval for a product candidate. If we continue to progress the development of our product candidates, any delay in obtaining, or an inability to obtain, marketing approvals would prevent us from commercializing our product candidates, generating revenues, and achieving and sustaining profitability.

Our product candidates target rare diseases and conditions, and if we continue to progress the development of our product candidates, the market opportunities for RLYB116 or any of our other product candidates, if approved, may be smaller than we anticipate. We must be able to successfully identify patients and capture a significant market share to achieve profitability and growth.

Our product candidates target rare diseases and conditions. With respect to RLYB116, we estimate that there are approximately 8,000 patients with immune PTR and up to 10,000 patients with refractory APS in the United States. Our projections of the number of eligible patients are based on our beliefs and estimates. These estimates have been derived from a variety of sources, including scientific literature, population statistics and market research, and may prove to be incorrect. Further, new sources may reveal a change in the estimated number of eligible patients, and the number of patients may turn out to be lower than expected. Additionally, the potentially addressable patient population for our current programs or future product candidates may be limited or may not be amenable to treatment with our product candidates, and new patients may become increasingly difficult to identify or gain access to. For example, even if we obtain FDA approval for RLYB116, the drug may be approved for a target population that is more limited than what we currently anticipate. Furthermore, even if we obtain significant market share for any product candidate, if approved, the potential target populations for our product candidates are for rare diseases, and we may never achieve profitability.

Further, in many cases there are either limited screening or diagnostic tests for the indications our product candidates are being developed to potentially treat. The lack of screening and diagnostic tests, coupled with the fact that there is frequently limited awareness among certain health care providers concerning the rare diseases we may seek to treat, often means that a proper diagnosis can, and frequently does, take years to identify (or an appropriate diagnosis may never be made for certain patients). As a result, even if one of our product candidates is approved for commercial sale, we may not be able to grow our revenues due to difficulty in identifying eligible patients. There can be no guarantee that any of our programs will be effective at identifying patients that will benefit from our product candidates, and even if we can identify patients that our product candidates can help, the number of patients that our product candidates may ultimately treat may turn out to be lower than we expect, they may not be otherwise amenable to treatment with our product candidates, or new patients may become increasingly difficult to identify, all of which may adversely affect our ability to grow and generate revenue and adversely affect our results of operations and our business. In addition, even in instances where we are able to expand the number of patients being treated, the number may be offset by the number of patients that discontinue use of the applicable product in a given period resulting in a net loss of patients and potentially decreased revenue.

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We face significant competition from biotechnology and pharmaceutical companies, and if we continue to progress the development of our product candidates, our operating results will suffer if we fail to compete effectively.

The biotechnology and pharmaceutical industries are highly competitive and subject to significant and rapid technological change. Our success is highly dependent on our ability to acquire, develop, and obtain marketing approval for new products on a cost-effective basis and to market them successfully. If a product candidate we develop is approved, we will face intense competition. There are many public and private biopharmaceutical companies, universities, government agencies and other research organizations actively engaged in the research and development of products that may be like our product candidates or address similar markets. Mergers and acquisitions in the pharmaceutical, biotechnology and diagnostic industries may result in even more resources being concentrated among a smaller number of our competitors. These competitors also compete with us in establishing clinical trial sites and patient registration for clinical trials, as well as in acquiring technologies complementary to, or necessary for, our programs. Smaller or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies. In addition, the number of companies seeking to develop and commercialize products and therapies competing with our product candidates is likely to increase. However, we seek to build our portfolio with key differentiating attributes to provide a competitive advantage in the markets we target. If we successfully develop and, if approved, commercialize RLYB116, this therapy may compete with anticoagulants such as Warfarin, or potentially be used in conjunction, with currently marketed treatments and any new therapies that may become available in the future.

If we continue to progress the development of our product candidates, competition could render any product candidate we develop obsolete, less competitive, or uneconomical. In addition, product candidates developed by our competitors may prove to be more safe or more effective than our product candidates. Our competitors may, among other things:

If we are not able to effectively compete for any of the foregoing reasons, our business will be materially harmed.

Disruptions in the FDA and other government agencies caused by funding shortages or global health concerns could hinder their ability to hire and retain key leadership and other personnel, or otherwise prevent new products and services from being developed or commercialized in a timely manner, which, if we continue to progress the development of our product candidates, could negatively impact our business.

The ability of the FDA to review and approve new products can be affected by a variety of factors, including government budget and funding levels, ability to hire and retain key personnel and accept the payment of user fees, and statutory, regulatory, and policy changes and other events that may otherwise affect the FDA’s ability to perform routine functions. Average review times at the agency have fluctuated in recent years as a result. In addition, government funding of other government agencies that fund research and development activities is subject to the political process, which is inherently fluid and unpredictable.

Disruptions at the FDA and other agencies may also slow the time necessary for new drugs to be reviewed or approved by necessary government agencies, which would adversely affect our business. For example, in recent years, including for 43 days beginning on October 1, 2025 and for 35 days beginning on December 22, 2018, the U.S. government has shut down several times and certain regulatory agencies, such as the FDA, have had to furlough

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critical employees and stop critical activities. The Trump Administration has reduced the number of employees serving in government agencies, including the FDA. If a prolonged government shutdown occurs, or if the U.S. government takes other personnel actions, it could significantly impact the ability of the FDA to timely review and process our regulatory submissions, which could have a material adverse effect on our business.

Even if we obtain marketing approval for a product candidate in the United States, we or our current or future collaborators may never obtain approval for or commercialize the product candidate in any other jurisdiction, which would limit our ability to realize its full market potential.

In order to market any product in a particular jurisdiction, we or our current or future collaborators must establish and comply with numerous and varying regulatory requirements regarding safety and efficacy on a country-by-country basis. Approval by the FDA in the United States does not ensure approval by comparable regulatory authorities in other countries or jurisdictions. However, the failure to obtain approval in one jurisdiction may negatively impact our or our collaborators’ ability to obtain approval elsewhere. In addition, clinical trials conducted in one country may not be accepted by regulatory authorities in other countries, and regulatory approval in one country does not guarantee regulatory approval in any other country.

Approval processes vary among countries and can involve additional product testing and validation and additional administrative review periods. Seeking foreign regulatory approval could result in difficulties and increased costs for us and require additional preclinical studies or clinical trials which could be costly and time- consuming. Regulatory requirements can vary widely from country to country and could delay or prevent the introduction of our products in those countries. We do not have any product candidates approved for sale in any jurisdiction, including in international markets, and we do not have experience in obtaining regulatory approval in international markets. If we or our collaborators fail to comply with regulatory requirements in international markets or to obtain and maintain required approvals, or if regulatory approvals in international markets are delayed, our target market will be reduced and we will be unable to realize the full market potential of any product we develop.

Even if we obtain marketing approval for any of our product candidates, we will still face extensive and ongoing regulatory requirements and obligations and continued regulatory review, which may result in significant additional expense. We may be subject to penalties if we fail to comply with regulatory requirements or experience unanticipated problems with any product candidates.

Any product candidate for which we obtain marketing approval will be subject to extensive and ongoing requirements of the FDA and other regulatory authorities. These requirements include submissions of safety and other post-marketing information and reports, establishment registration and drug listing requirements, continued compliance with the FDA’s current cGMP requirements regarding the distribution of samples to physicians and recordkeeping and Good Laboratory Practice (“GLP”) and GCP requirements for non-clinical studies and any clinical trials that we conduct post-approval.

The FDA may also require costly post-marketing studies or clinical trials and surveillance to monitor the safety or efficacy of a product. Additionally, the FDA closely regulates the post-approval marketing and promotion of drugs to ensure drugs are marketed only for the approved indications and in a manner that is consistent with the provisions of the approved labeling. If we market our products for uses beyond their approved indications or otherwise inconsistent with the FDA-approved labeling, we may be subject to enforcement action for off-label marketing by the FDA and other federal and state enforcement agencies, including the DOJ. Violation of the FDCA and other statutes, including the False Claims Act, and equivalent legislation in other countries relating to the promotion and advertising of prescription products may also lead to investigations or allegations of violations of federal and state and other countries’ health care fraud and abuse laws and state consumer protection laws. Even if it is later determined we were not in violation of these laws, we may be faced with negative publicity, incur significant expenses defending our actions and have to divert significant management resources from other matters.

In addition, later discovery of previously unknown adverse events or other problems with our products, manufacturers, or manufacturing processes or failure to comply with regulatory requirements, may yield various results, including, but not limited to:

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If we obtain FDA approval for RLYB116, safety risks not identified in our prior clinical trials may first appear after we obtain approval and commercialize RLYB116. Any new post-marketing adverse events may significantly impact our ability to market the drugs and may require that we recall and discontinue commercialization of RLYB116. Furthermore, if any confirmatory post-marketing trial fails to confirm the clinical profile or clinical benefits of RLYB116, the FDA may withdraw its approval, which would materially harm our business.

We also cannot predict the likelihood, nature, or extent of government regulation that may arise from future legislation or administrative or executive action, either in the United States or abroad. Further, the FDA’s, EMA’s and other comparable regulatory authorities’ policies may change, and additional government regulations may be enacted that could prevent, limit, or delay regulatory approval of a product candidate or increase the costs and regulatory burden of commercialization. If we are slow or unable to adapt to changes in existing requirements or the adoption of new requirements or policies, or if we are not able to maintain regulatory compliance, we may lose any marketing approval that we may have obtained, and we may not achieve or sustain profitability, which would adversely affect our business, prospects, financial condition, and results of operations. Furthermore, non-compliance by us or any collaborator with regulatory requirements, including safety monitoring or pharmacovigilance, may also result in significant financial penalties, which would adversely affect our business.

If we continue to progress the development of our product candidates, we may seek Fast Track designation, Breakthrough Therapy designation, or Priority Medicines (“PRIME”) program designation for our product candidates, but we might not receive any such designation, and even if we do, such designation may not actually lead to a faster development or regulatory review or approval process.

If a drug is intended for the treatment of a serious or life-threatening condition, and non-clinical or clinical data demonstrate the potential to address an unmet medical need for this condition, the product candidate may qualify for FDA Fast Track designation, for which sponsors must apply. Sponsors of fast-track products may have more frequent interactions with the FDA, and, in some circumstances, the FDA may initiate review of sections of a fast track product’s application before the application is complete. We may submit an application for Fast Track designation for RLYB116. The FDA has broad discretion whether to grant this designation, and we may not receive it. Moreover, even if we receive Fast Track designation, Fast Track designation does not ensure that we will receive marketing approval and we may not experience a faster development or regulatory review or approval process with Fast Track designation compared to conventional FDA procedures. In addition, the FDA may withdraw Fast Track designation if it believes that the designation is no longer supported by data from our clinical development program. Fast Track designation alone does not guarantee qualification for the FDA’s priority review procedures.

If we continue to progress the development of our product candidates, we also may seek a Breakthrough Therapy designation for some of our product candidates if future results support such designation. A Breakthrough Therapy is defined as a drug (including biologic) that is intended, alone or in combination with one or more other drugs, to treat a serious condition, and preliminary clinical evidence indicates that the drug may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. Sponsors of products that have been designated as breakthrough therapies are eligible to receive more intensive FDA guidance on establishing an efficient drug development program,

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an organization commitment involving senior managers, and may be eligible for rolling review. Drugs designated as breakthrough therapies by the FDA may also be eligible for other expedited review programs, including accelerated approval and priority review, if supported by clinical data at the time the BLA or NDA is submitted to the FDA.

Designation as a Breakthrough Therapy is within the discretion of the FDA. Accordingly, even if we believe that a product candidate meets the criteria for designation as a Breakthrough Therapy, the FDA may disagree and instead determine not to make such designation. Even if we receive Breakthrough Therapy designation, the receipt of such designation may not result in a faster development or regulatory review or approval process compared to drugs considered for approval under conventional FDA procedures and does not assure ultimate approval by the FDA. In addition, even if a product candidate qualifies as a Breakthrough Therapy, the FDA may later decide that such product candidate no longer meets the conditions for qualification or decide that the time period for FDA review or approval will not be shortened.

In the European Union (“EU”) we may seek PRIME designation for some of our product candidates in the future. PRIME is a voluntary program aimed at enhancing the EMA’s role to reinforce scientific and regulatory support in order to optimize development and enable accelerated assessment of new medicines that are of major public health interest with the potential to address unmet medical needs. The program focuses on medicines that target conditions for which there exists no satisfactory method of treatment in the EU or even if such a method exists, it may offer a major therapeutic advantage over existing treatments. PRIME is limited to medicines under development and not authorized in the EU and the applicant intends to apply for an initial MA application through the centralized procedure. To be accepted for PRIME, a product candidate must meet the eligibility criteria in respect of its major public health interest and therapeutic innovation based on information that can substantiate the claims. The benefits of a PRIME designation include the appointment of a Committee for Medicinal Products for Human Use (“CHMP”) rapporteur to provide continued support and help to build knowledge ahead of a MA application, early dialogue and scientific advice at key development milestones, and the potential to qualify products for accelerated review, meaning reduction in the review time for an opinion on approvability to be issued earlier in the application process. PRIME enables an applicant to request parallel EMA scientific advice and Health Technology Assessment (“HTA”) advice to facilitate timely market access. Even if we receive PRIME designation for any of our product candidates, the designation may not result in a materially faster development process, review or approval compared to conventional EMA procedures. Further, obtaining PRIME designation does not assure or increase the likelihood of EMA’s grant of a marketing authorization.

If we continue to progress the development of our product candidates, we may be unsuccessful in obtaining or may be unable to maintain the benefits associated with orphan drug designation, including the potential for market exclusivity. If our competitors are able to obtain orphan drug exclusivity for products that constitute the same drug and treat the same indications as RLYB116 or any of our other product candidates, we may not be able to have competing products approved by the applicable regulatory authority for a significant period of time.

Regulatory authorities in some jurisdictions, including the United States and the EU may designate drugs for relatively small patient populations as orphan drugs. Under the U.S. Orphan Drug Act, the FDA may designate a drug as an orphan drug if it is a drug intended to treat a rare disease or condition, which is generally defined as a patient population of fewer than 200,000 individuals annually in the United States, or a patient population of more than 200,000 in the United States where there is no reasonable expectation that the cost of developing the drug will be recovered from sales in the United States. In the EU, the EMA’s Committee for Orphan Medicinal Products evaluates, and the EC grants, an orphan drug designation principally to promote the development of products that are intended for the diagnosis, prevention or treatment of a life-threatening or chronically debilitating condition affecting not more than five in 10,000 persons in the EU. In addition, the product under consideration is indicated for a condition where there exists no satisfactory method of diagnosis, prevention or treatment authorized in the EU or, if such method exists, that the medicinal product will be of significant benefit to those affected by that condition. We may seek orphan drug designation in the United States and the EU for certain of our product candidates but may be unsuccessful in doing so. There can be no assurance that the FDA or the EMA’s Committee for Orphan Medicinal Products will consider orphan designation for any indication for which we apply or re-apply, or that we will be able to maintain such designation. In the United States, orphan drug designation entitles a party to financial incentives such as opportunities for grant funding towards clinical trial costs, tax advantages and user-fee waivers. Orphan drug designation neither shortens the development time or regulatory review time of a drug nor gives the drug any advantage in the regulatory review or approval process.

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If a product candidate with an orphan drug designation subsequently receives the first marketing approval for the indication for which it has such designation, the product is entitled to a period of marketing exclusivity, which precludes the EMA or the FDA from approving another marketing application for the same drug or biologic for the same orphan designation for that time period, except in limited circumstances, such as a showing of clinical superiority to the product with orphan drug exclusivity or where the manufacturer is unable to assure sufficient product quantity. In the United States, the exclusivity period is seven years. The applicable exclusivity period is ten years in Europe, but such exclusivity period can be reduced to six years in Europe if a product no longer meets the criteria for orphan designation or if the product is sufficiently profitable so that market exclusivity is no longer justified. Moreover, orphan drug exclusive marketing rights in the United States may be lost if the FDA later determines that the request for designation was materially defective or if the manufacturer is unable to assure sufficient quantity of the drug to meet the needs of patients with the rare disease or condition. Similarly, in the EU, the market exclusivity can be broken if the holder of the MA for the original orphan medicinal product is unable to supply sufficient quantities of the medicinal product. In addition, in both the United States and EU, if a different drug is subsequently approved for marketing for the same or a similar indication as any of our product candidates that receive marketing approval, we may face increased competition and lose market share regardless of orphan drug exclusivity, which only protects against approval of the “same” drug for the same indication.

If we continue to progress the development of our product candidates, we may seek accelerated approval by the FDA for one or more of our product candidates. Accelerated approval by the FDA, even if granted for any of our product candidates, may not lead to a faster development or regulatory review or approval process and it does not increase the likelihood that our product candidates will receive marketing approval.

We may in the future seek an accelerated approval for our one or more of our product candidates. Under the accelerated approval program, the FDA may grant accelerated approval to a product candidate designed to treat a serious or life-threatening condition that provides meaningful therapeutic benefit over available therapies upon a determination that the product candidate has an effect on a surrogate endpoint or intermediate clinical endpoint that is reasonably likely to predict clinical benefit. As a condition of approval, the FDA requires that a sponsor of a product receiving accelerated approval perform a post-marketing confirmatory clinical trial or trials. In addition, the FDA currently requires as a condition for accelerated approval the pre-submission of promotional materials to FDA for review.

Prior to seeking accelerated approval for any of our product candidates, we intend to seek feedback from the FDA and will otherwise evaluate our ability to seek and receive accelerated approval. There can be no assurance that after our evaluation of the feedback and other factors we will decide to pursue or submit a BLA for accelerated approval or any other form of expedited development, review or approval. Furthermore, if we decide to submit an application for accelerated approval there can be no assurance that such submission or application will be accepted or that the FDA will determine that the product candidate is eligible for or grant accelerated approval. A failure to obtain any planned accelerated approval for our product candidates would result in a longer time period to commercialization of our product candidates, if approved, could increase the cost of development of our product candidates and could harm our competitive position in the marketplace. If we receive accelerated approval for any of our product candidates, the FDA may withdraw accelerated approval if, among other things, a confirmatory trial required to verify the predicted clinical benefit of the product fails to verify such benefit or if such trial is not conducted with due diligence. Withdrawal of any accelerated approval could substantially harm our business.

If we continue to progress the development of our product candidates, the successful commercialization of any product candidate we develop will depend in part on the extent to which regulatory authorities and private health insurers establish coverage and reimbursement. Failure to obtain or maintain coverage and reimbursement for our product candidates, if approved, could limit our ability to market those products and decrease our or our ability to generate revenue.

If any product candidate is approved for marketing, coverage and reimbursement for such product by governmental healthcare programs, such as Medicare and Medicaid, private health insurers, and other third-party payors would be essential for most patients to be able to afford the prescription medication. Our ability to achieve acceptable levels of coverage and reimbursement for products or procedures using our products will therefore have an effect on our ability to successfully commercialize any product candidates we develop. We cannot be sure that coverage and reimbursement will be available for our product candidates, if and when such candidates obtain marketing approval, and any reimbursement that may become available may not be adequate and may be decreased or eliminated in the future.

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Moreover, increasing efforts by governmental and third-party payors in the United States to cap or reduce healthcare costs may cause third-party payors to limit both coverage and the level of reimbursement for newly approved products and, as a result, such payors may not cover or provide adequate payment for any product we commercialize. We expect to experience pricing pressures in connection with the sale of our product candidates due to the trend toward managed health care and additional legislative, administrative, or regulatory changes. The downward pressure on healthcare costs in general, particularly prescription drugs and biologics and related administration procedures, has become intense and new products face increasing challenges in entering the market successfully. Third-party payors are increasingly challenging the price and examining the cost-effectiveness of new products in addition to their safety and efficacy. To obtain or maintain coverage and reimbursement for any product, we may need to conduct expensive pharmacoeconomic studies to demonstrate the medical necessity and cost-effectiveness of our product.

We may also need to provide discounts to purchasers to encourage purchasing of any approved product and rebates to third party payors to increase the possibility of favorable coverage and adequate cost sharing thresholds for patients. We may be required to provide discounts or rebates on any approved product under government healthcare programs or to certain government and private purchasers in order to obtain coverage under federal health care programs such as Medicaid. Participation in such programs would require us to track and report certain drug prices. We may be subject to fines and other penalties if we fail to report such prices accurately.

No uniform policy for coverage and reimbursement for products exists among third-party payors in the United States. Therefore, coverage and reimbursement for products can differ significantly from payor to payor, and one third-party payor’s decision to cover a particular product does not ensure that other payors will also provide similar coverage. Additionally, the process for determining whether a third-party payor will provide coverage for a product is typically separate from the process for setting the price of such product or establishing the reimbursement rate that the payor will pay for the product once coverage is approved. As a result, the coverage determination process is often a time-consuming and costly process that will require us to provide scientific and clinical support for the use of our product candidates to each payor separately, with no assurance that coverage and reimbursement will be obtained or will be consistent across payors. And, even if products are covered, third party payors may implement various mechanisms to control utilization (e.g., requiring prior approval for coverage for each patient). Additionally, coverage and reimbursement for screening and diagnostic tests associated with any products would be assessed and determined separately. Furthermore, rules and regulations regarding reimbursement change frequently, in some cases at short notice, and we believe that changes in these rules and regulations are likely. If coverage or reimbursement is not available or is available only at limited levels, we may not be able to successfully commercialize our product candidates and may not be able to obtain a satisfactory financial return on our product candidates.

We may also be subject to extensive governmental price controls and other market regulations outside of the United States, and we believe the increasing emphasis on cost-containment initiatives in other countries have and will continue to put pressure on the pricing and usage of medical products. In many countries, the prices of medical products are subject to varying price control mechanisms as part of national health systems. Other countries allow companies to fix their own prices for medical products but monitor and control company profits. Additional foreign price controls or other changes in pricing regulation could restrict the amount that we are able to charge for our products. Accordingly, in markets outside of the United States, the reimbursement for products we commercialize may be reduced compared with the United States and may be insufficient to generate commercially reasonable revenue and profits.

If we continue to progress the development of our product candidates, even if a product candidate we develop receives marketing approval, it may fail to achieve market acceptance by physicians, patients, third-party payors or others in the medical community necessary for commercial success.

Even if our product candidates receive regulatory approval, they may not gain market acceptance among physicians, patients, healthcare payors and the medical community. Various factors will influence whether our product candidates are accepted in the market if approved for commercial sale, including, but not limited to:

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Market acceptance of our product candidates is heavily dependent on patients’ and physicians’ perceptions that our product candidates are safe and effective treatments for their targeted indications and willingness to use screening and/or diagnostic tests to identify at-risk target populations for our therapeutics. The perceptions of any product are also influenced by perceptions of competitors’ products that are in the same class or that have a similar mechanism of action. Because we expect sales of our product candidates, if approved, to generate substantially all our revenues in the foreseeable future, the failure of our product candidates to find market acceptance would harm our business and could require us to seek additional financing.

If approved, our product candidates that are regulated as biologics may face competition from biosimilars approved through an abbreviated regulatory pathway.

The Biologics Price Competition and Innovation Act of 2009 (“BPCIA”) was enacted as part of the Affordable Care Act (“ACA”) to establish an abbreviated pathway for the approval of biosimilar and interchangeable biological products. The regulatory pathway establishes legal authority for the FDA to review and approve biosimilar biologics, including the possible designation of a biosimilar as “interchangeable” based on its similarity to an approved biologic. Under the BPCIA, a reference biological product is granted 12 years of data exclusivity from the time of first licensure of the product, and the FDA will not accept an application for a biosimilar or interchangeable product based on the reference biological product until four years after the date of first licensure of the reference product. In addition, the approval of a biosimilar product may not be made effective by the FDA until 12 years from the date on which the reference product was first licensed. During this 12-year period of exclusivity, another company may still develop and receive approval of a competing biologic, so long as their BLA does not rely on the reference product, sponsor’s data or submit the application as a biosimilar application. Any new policies or processes adopted by the FDA could have a material adverse effect on the future commercial prospects for our biological products.

We believe that any of the product candidates we develop that is approved in the United States as a biological product under a BLA should qualify for the 12-year period of exclusivity. However, there is a risk that this exclusivity could be shortened due to congressional action or otherwise, or that the FDA will not consider the subject product candidates to be reference products for competing products, potentially creating the opportunity for biosimilar competition sooner than anticipated. Moreover, the extent to which a biosimilar, once approved, will be substituted for any one of the reference products in a way that is similar to traditional generic substitution for non-biological products is not yet clear, and will depend on a number of marketplace and regulatory factors that are still developing. The approval of a biosimilar of our product candidates could have a material adverse impact on our business due to increased competition and pricing pressure.

If we continue to progress the development of our product candidates, and are unable to establish sales, marketing and distribution capabilities either on our own or in collaboration with third parties, we may not be successful in commercializing any product candidates we develop, if approved.

In order to market and successfully commercialize any product candidates we develop, if approved, we must build our sales and marketing capabilities or enter into collaborations with third parties for these services. We currently

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have no sales, marketing or distribution capabilities and as a company have no experience in marketing products. If we commercialize any of our product candidates that may be approved ourselves, we will need to develop an in-house marketing organization and sales force across rare disease therapeutic areas, which will require significant expenditures, management resources, and time. There are significant expenses and risks involved with establishing our own sales and marketing capabilities, including our ability to hire, train, retain, and appropriately incentivize a sufficient number of qualified individuals, generate sufficient sales leads and provide our sales and marketing team with adequate access to physicians who may prescribe our products, effectively manage a geographically dispersed sales and marketing team, and other unforeseen costs and expenses. We will have to compete with other pharmaceutical and biotechnology companies to recruit, hire, train, and retain marketing and sales personnel. Any failure or delay in the development of a product candidate that affects the expected timing of commercialization of the product candidate or results in the failure of the product candidate to be commercialized could result in us having prematurely or unnecessarily incurred costly commercialization expenses. Our investment would be lost if we are unable to retain or reposition our sales and marketing personnel.

We may also enter into collaborations for the sales and marketing of our product candidates, if approved. To the extent that we depend on collaborators for sales and marketing activities, any revenues we receive will depend upon the success of those collaborators’ sales and marketing teams and the collaborators’ prioritization of our products and compliance with applicable regulatory requirements, and there can be no assurance that the collaborators’ efforts will be successful. If we are unable to build our own sales and marketing team or enter into a collaboration for the commercialization of product candidates we develop, if approved, we may be forced to delay the commercialization of our product candidates or reduce the scope of our sales or marketing activities, which would have an adverse effect on our business, operating results and prospects.

Under the current presidential administration, we face uncertainty regarding potential regulatory developments that may adversely affect our business if we continue to progress the development of our product candidates.

There have been significant and wide-ranging changes in law, regulation and policy under the current Trump administration. Current and future legislation, regulation, or policy could adversely affect our business or create a more challenging and costly environment to pursue the development and commercialization of our current or future product candidates. For example, the federal government, including the FDA, may implement legislative, regulatory, or policy changes regarding the standards for approving biologic products that we may be unable to satisfy or regarding the marketing of approved biologics that may limit or prohibit the advertising and promotion of our current or future product candidates, if approved. Additionally, the Trump administration has undertaken significant efforts to reduce the size and spending of the federal government, including at the FDA. A significant reduction in the FDA’s workforce or the FDA’s budget or other disruptions at the FDA could impact the FDA’s ability to engage in routine regulatory and oversight activities and result in delays or limitations on our ability to proceed with clinical development programs and obtain regulatory approvals. It is difficult to predict how executive actions that may be taken under the current Trump administration may affect the FDA’s ability to exercise its regulatory authority. If such executive actions impose constraints on the FDA’s ability to engage in routine oversight and product review activities in the normal course, our business may be negatively impacted.

Risks Related to Our Dependence on Third Parties

If we continue to progress the development of our product candidates, we may pursue business development transactions and collaborate with third parties for the development and commercialization of our product candidates. We may not succeed in identifying and acquiring businesses or assets, in-licensing or out-licensing intellectual property rights or establishing and maintaining collaborations, which may significantly limit our ability to successfully develop and commercialize our product candidates, if at all, and these transactions could disrupt our business, cause dilution to our stockholders or reduce our financial resources.

We acquired all rights to RLYB116 and RLYB114 from Sobi in 2019. We also obtained worldwide exclusive rights to RLYB332 from Sanofi in 2022. If we continue to progress the development of our product candidates, we may acquire or in-license rights to product candidates, products or technologies, acquire other businesses or enter into collaborations with third parties. We may not be able to enter into such transactions on favorable terms, or at all. Any such acquisitions, in-licenses or collaborations may not strengthen our competitive position, and these transactions may be viewed negatively by analysts, investors, customers, or other third parties with whom we have relationships. We may decide to incur debt in connection with an acquisition, or in-license or issue our common stock or other

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equity securities as consideration for the acquisition, which would reduce the percentage ownership of our existing stockholders.

We could incur losses resulting from undiscovered liabilities of the acquired business that are not covered by the indemnification we may obtain from the sellers of the acquired business. In addition, we may not be able to successfully integrate the acquired personnel, technologies, and operations into our existing business in an effective, timely, and non-disruptive manner. Such transactions may also divert management attention from day-to-day responsibilities, increase our expenses, and reduce our cash available for operations and other uses. We cannot predict the number, timing or size of future acquisitions or in-licenses or the effect that any such transactions might have on our operating results.

We may not realize the anticipated benefits of any current or future collaboration, each of which involves or will involve numerous risks, including:

If any collaborator fails to fulfill its responsibilities in a timely manner, or at all, our research, clinical development, manufacturing, or commercialization efforts related to that collaboration could be delayed or terminated, or it may be necessary for us to assume responsibility for expenses or activities that would otherwise have been the responsibility of our collaborator. If we are unable to establish and maintain collaborations on acceptable terms or to successfully transition away from terminated collaborations, we may have to delay or discontinue further development of one or more of our product candidates, undertake development and commercialization activities at our own expense, or find alternative sources of capital, which would have a material adverse impact on our clinical development plans and business. If we fail to establish and maintain collaborations related to our product candidates, we could bear all of the risk and costs related to the development of any such product candidate, and we may need to seek additional financing, hire additional employees and otherwise develop expertise for which we have not budgeted. This could negatively affect the development and commercialization of our product candidates.

We may face significant competition in identifying and acquiring businesses or assets, in-licensing intellectual property rights and seeking appropriate collaboration partners for our product candidates, and the negotiation process may be time-consuming and complex. In order for us to successfully partner our product candidates,

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potential collaborators must view these product candidates as economically valuable in markets they determine to be attractive in light of the terms that we are seeking and other products or product candidates available for licensing from or in connection with collaborations with other companies. Our success in acquiring business or assets or in partnering with collaborators may depend on our history or perceived capability of successful product development. Even if we are successful in our efforts to acquire businesses or assets, in-license intellectual property rights or establish collaborations, we may not be successful in developing such product candidates or technologies or able to maintain such collaborations if, for example, development or approval of a product candidate is delayed or sales of an approved product are disappointing.

Our reliance on a central team consisting of a limited number of employees and third parties who provide various administrative, research and development, and other services across our organization presents operational challenges that may adversely affect our business.

As of June 30, 2026, we had 7 full-time employees, upon whom we rely for various administrative, research and development, business development and other support services shared among our subsidiaries. The size of our centralized team may limit our ability to devote adequate personnel, time, and resources to support the operations of all of our subsidiaries, including their research and development activities, the management of financial, accounting, and reporting matters, and the oversight of our third-party vendors and partners. If our centralized team or our third-party vendors and partners performing such functions fail to provide adequate administrative, research and development, or other services across our entire organization, our business, financial condition, and results of operations could be harmed.

Our employees and independent contractors, including principal investigators, CROs, consultants and vendors, may engage in misconduct or other improper activities, including noncompliance with regulatory standards and requirements, which could have a material adverse effect on our business.

Misconduct by our employees and independent contractors, including principal investigators, CROs, consultants, vendors and any third parties we may engage in connection with research, development, regulatory, manufacturing, quality assurance and other pharmaceutical functions and commercialization, could include intentional, reckless or negligent conduct or unauthorized activities that violate various laws, including: (i) the laws and regulations of the FDA, and other similar regulatory authorities, including those laws that require the reporting of true, complete and accurate information to such authorities; (ii) manufacturing standards; (iii) data privacy, security, fraud and abuse and other healthcare laws and regulations; or (iv) laws that require the reporting of true, complete and accurate financial information and data. Sales, marketing and business arrangements in the healthcare industry are subject to extensive laws and regulations intended to prevent fraud, misconduct, kickbacks, self-dealing and other abusive practices. These laws and regulations may restrict or prohibit a wide range of pricing, discounting, marketing and promotion, sales commission, customer incentive programs, and other business arrangements. Activities such as the improper use or misrepresentation of information obtained in the course of clinical trials, creation of fraudulent data in preclinical studies or clinical trials, or illegal misappropriation of drug product, could also result in regulatory sanctions and cause serious harm to our reputation. It is not always possible to identify and deter misconduct by employees and other third parties, and the precautions we take to detect and prevent this activity may not be effective in controlling unknown or unmanaged risks or losses or in protecting us from governmental investigations or other actions or lawsuits stemming from a failure to comply with such laws or regulations. Additionally, we are subject to the risk that a person or government agency could allege such fraud or other misconduct, even if none occurred. If any such actions are instituted against us or them and we are not successful in defending ourselves or asserting our rights, those actions could have a significant impact on our business and results of operations, including the imposition of significant civil, criminal, and administrative penalties, damages, monetary fines, possible exclusion from participation in Medicare, Medicaid, other U.S. federal healthcare programs or healthcare programs in other jurisdictions, individual imprisonment, other sanctions, contractual damages, reputational harm, diminished profits and future earnings, and curtailment of our operations.

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We currently rely and will rely on third parties for the manufacture of drug substance and drug product for our preclinical studies and clinical trials and, if we continue to progress the development of our product candidates, expect to continue to do so for commercialization of any product candidates that we may develop that are approved for marketing. Our reliance on third parties may increase the risk that we will not have sufficient quantities of such drug substance, product candidates, or any products that we may develop and commercialize, or that such supply will not be available to us at an acceptable cost, which could delay, prevent, or impair our development or commercialization efforts.

We have limited personnel with experience in manufacturing, and we do not own facilities for manufacturing RLYB116 or any other product candidate. Instead, we rely on and expect to continue to rely on contract manufacturers for the supply of cGMP-drug substance and drug product of RLYB116 and any other product candidates we develop and, in the future, for commercial supply. Reliance on third parties may expose us to more risk than if we were to manufacture our product candidates ourselves.

We may be unable to establish necessary supply agreements with third-party manufacturers or to do so on acceptable terms. Even if we are able to establish agreements with third-party manufacturers, reliance on third-party manufacturers entails additional risks, including:

Third-party manufacturers may fail to comply with cGMP regulations or similar regulatory requirements outside the United States. Any failure to follow cGMP or other regulatory requirements or delay, interruption or other issues that arise in the manufacture, fill-finish, packaging, or storage of our product candidates as a result of a failure of our facilities or the facilities or operations of third parties to comply with regulatory requirements or pass any regulatory authority inspection could significantly impair our ability to develop and commercialize our product candidates, including leading to significant delays in the availability of our product candidates for our clinical trials or the termination of or suspension of a clinical trial, or the delay or prevention of a filing or approval of marketing applications for our product candidates. Moreover, our failure, or the failure of our third-party manufacturers, to comply with applicable regulations could result in sanctions being imposed on us, including fines, injunctions, civil penalties, delays, suspension or withdrawal of approvals, license revocations, seizures or recalls of product candidates or medicines, operating restrictions, and criminal prosecutions, any of which could significantly and adversely affect supplies of our medicines and harm our business, financial condition, results of operations, and prospects.

While we provide oversight of manufacturing activities, we have limited ability to control the execution of manufacturing activities by, and are or will be dependent on, our CMOs for compliance with cGMP requirements for the manufacture of our product candidates by our CMOs. As a result, we are subject to the risk that our product candidates may have manufacturing defects or fail to comply with regulatory requirements, which we have limited ability to prevent. CMOs may also have competing obligations that prevent them from manufacturing our product candidates in a timely manner. If a CMO cannot successfully manufacture drug substance that conforms to our specifications and the regulatory requirements, we will not be able to secure or maintain regulatory approval for the use of our product candidates in clinical trials, or for commercial distribution of our product candidates, if approved. In addition, we have limited control over the ability of our CMOs to maintain adequate quality control, quality assurance, and qualified personnel, and we were not involved in developing our CMOs’ policies and procedures.

The facilities and processes used to manufacture our product candidates are subject to inspection by the FDA, EMA and other comparable foreign authorities. If the FDA, EMA or other comparable foreign regulatory authority finds deficiencies with or does not approve these facilities for the manufacture of our product candidates or if it withdraws any such approval or finds deficiencies in the future, we may need to find alternative manufacturing facilities or conduct additional studies, which would delay our development program and significantly impact our ability to

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develop, obtain regulatory approval for, or commercialize our product candidates, if approved. Furthermore, CMOs may breach existing agreements they have with us because of factors beyond our control. They may also terminate or refuse to renew their agreement at a time that is costly or otherwise inconvenient for us. Finding new CMOs or third-party suppliers involves additional cost and requires our management’s time and focus. In addition, there is typically a transition period when a new CMO commences work.

Any significant delay in the supply of our product candidates or the raw materials needed to produce our product candidates, could considerably delay conducting our clinical trials and potential regulatory approval of our product candidates. If we were unable to find an adequate CMO or another acceptable solution in time, our clinical trials could be delayed, or our commercial activities could be harmed.

We rely on and will continue to rely on CMOs to purchase from third-party suppliers the raw materials necessary to produce our product candidates. We have limited ability to control the process or timing of the acquisition of these raw materials by our CMOs. Moreover, we currently do not have any agreements for the production of these raw materials. Supplies of raw materials could be interrupted from time to time and we cannot be certain that alternative supplies could be obtained within a reasonable time frame, at an acceptable cost, or at all. In addition, a disruption in the supply of raw materials could delay the commercial launch of our product candidates, if approved, or result in a shortage in supply, which would impair our ability to generate revenues from the sale of our product candidates. Growth in the costs and expenses of raw materials may also impair our ability to cost effectively manufacture our product candidates. There are a limited number of suppliers for the raw materials that we may use to manufacture our product candidates and we may need to assess alternative suppliers to prevent a possible disruption of the manufacture of our product candidates. Moreover, our product candidates utilize drug substances that are produced on a small scale, which could limit our ability to reach agreements with alternative suppliers.

As part of their manufacture of our product candidates, our CMOs and third-party suppliers are expected to comply with and respect the intellectual property and proprietary rights of others. If a CMO or third-party supplier fails to acquire the proper licenses or otherwise infringes, misappropriates or otherwise violates the intellectual property or the proprietary rights of others in the course of providing services to us, we may have to find alternative CMOs or third-party suppliers or defend against claims of infringement, either of which would significantly impact our ability to develop, obtain regulatory approval for, or commercialize our product candidates, if approved.

Our collaborators also may breach their agreements with us or otherwise fail to perform to our satisfaction, which could impact the development timeline of our product candidates.

If we continue to progress the development of our product candidates, we will continue to rely on third parties to conduct, supervise, and monitor our preclinical studies and clinical trials. If we fail to effectively oversee and manage these third parties, if they do not successfully carry out their contractual duties, or if they perform in an unsatisfactory manner, it may harm our business.

We rely, and will continue to rely, on CROs, CRO-contracted vendors, and clinical trial sites to ensure the proper and timely conduct of our clinical trials. Our reliance on CROs for clinical development activities limits our control over these activities, but we remain responsible for ensuring that each of our trials is conducted in accordance with the applicable protocol and legal, regulatory, and scientific standards.

We and our CROs will be required to comply with the GLP requirements for our preclinical studies and GCP requirements for our clinical trials. Regulatory authorities enforce GCP requirements through periodic inspections of trial sponsors, principal investigators, and clinical trial sites. If we, or our CROs, fail to comply with GCP requirements, the clinical data generated in our clinical trials may be deemed unreliable and the FDA, EMA or other comparable foreign regulatory authorities may require us to perform additional clinical trials before approving our marketing applications. We cannot assure you that upon inspection by a given regulatory authority, such regulatory authority will determine that any of our clinical trials comply with GCP requirements and may require a large number of patients. Our failure or any failure by our CROs, investigators, CMOs or other third parties to comply with regulatory requirements or to recruit enough patients may delay ongoing or planned clinical trials or require us to repeat clinical trials, which would delay the regulatory approval process. Failure by us or by third parties we engage to comply with regulatory requirements can also result in fines, adverse publicity, and civil and criminal sanctions. Moreover, our business may be implicated if any of these third parties violates federal or state fraud and abuse or false claims laws and regulations or healthcare privacy and security laws.

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Our CROs, vendors and clinical trial investigators are not our employees, and we do not control whether they devote sufficient time and resources to our clinical trials. These third parties may also have relationships with other commercial entities, including our competitors, for whom they may also be conducting clinical trials, or other drug development activities, which could harm our competitive position. We face the risk of potential unauthorized disclosure or misappropriation of our intellectual property by CROs and other third parties involved in our preclinical studies and clinical trials, which may reduce our trade secret protection and allow our potential competitors to access and exploit our proprietary technology. If our CROs and other third parties involved in our trials do not successfully carry out their contractual duties or obligations, or fail to meet expected deadlines, or if the quality or accuracy of the clinical data they obtain is compromised due to the failure to adhere to our clinical protocols or regulatory requirements or for any other reason, our clinical trials may be extended, delayed or terminated, and we may not be able to obtain regulatory approval for, or successfully commercialize, any product candidates that we develop. As a result, our financial results and the commercial prospects for any product candidates that we develop would be harmed, our costs could increase, and our ability to generate revenue could be delayed.

If our relationship with any CRO terminates, we may not be able to enter into arrangements with alternative CROs or do so on commercially reasonable terms. Switching or adding additional CROs involves substantial cost and requires management’s time and focus. In addition, there is a natural transition period when a new CRO commences work. As a result, delays occur, which can materially impact our ability to meet our desired clinical development timelines. Though we intend to carefully manage our relationships with our CROs, there can be no assurance that we will not encounter challenges or delays in the future or that these delays or challenges will not have an adverse impact on our business, financial condition, and prospects.

Risks Related to Healthcare Laws and Other Legal Compliance Matters

If we continue to progress the development of our product candidates, enacted and future healthcare legislation may increase the difficulty and cost for us to obtain marketing approval of and commercialize our product candidates, if approved, and may affect the prices we may set.

In the United States and other jurisdictions, there have been, and we expect there will continue to be, a number of legislative and regulatory changes, and additional proposed changes, to the healthcare system that could affect our future results of operations. In particular, there have been and continue to be a number of initiatives at the U.S. federal and state levels that seek to reduce healthcare costs and improve the quality of health care. As an earlier example with longstanding impact, in March 2010, the ACA was enacted, which substantially changed the way healthcare is financed by both governmental and private insurers. The ACA expanded health care coverage through a Medicaid eligibility expansion and the implementation of the individual mandate for health insurance coverage. The ACA also imposed an annual fee payable on manufacturers of branded prescription drugs and biologic agents (other than those designated as orphan drugs) and implemented changes to the coverage and reimbursement of drug products under government healthcare programs, including an expansion in the Medicaid drug rebate program, an increase in the statutory minimum rebates a manufacturer must pay under the Medicaid drug rebate program, and the establishment of a new Medicare Part D coverage gap discount program.

Beyond the ACA, there have been ongoing healthcare reform efforts, including efforts focused on drug pricing and payment. For example, the Inflation Reduction Act (“IRA”) of 2022 includes a number of changes intended to address rising prescription drug prices in Medicare Parts B and D. These changes include caps on Medicare Part D out-of-pocket costs, Medicare Part B and Part D drug price inflation rebates, a new Medicare Part D manufacturer discount drug program (replacing the ACA Medicare Part D coverage gap discount program) and a drug price negotiation program for certain high spend Medicare Part B and D drugs (with negotiated prices for the first set of drugs taking effect in 2026). The IRA has had and will likely continue to have a significant impact on the pharmaceutical industry. Additionally, changes to Medicaid effective in 2024 eliminated the Medicaid rebate cap. And changes to certain Medicare price reporting requirements for drugs beginning in 2026 will likely increase the administrative and compliance burden for manufacturers.

Recently, drug pricing and payment has been subject to a number of reform initiatives. For example, President Trump issued an Executive Order in April 2025 with multiple directives aimed at lowering drug prices, including refining the Medicare drug price negotiation program established by the IRA; accelerating competition for high-cost prescription drugs by accelerating approval of generics and biosimilars and facilitating the process for re-classifying

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prescription drugs as over-the-counter drugs; and increasing drug importation. In May 2025, President Trump issued another Executive Order that directed government agencies and officials to identify most-favored nation pricing targets for prescription drugs (and looked to pharmaceutical manufacturers to make significant progress towards delivering target prices to patients); prevent foreign countries from disproportionately shifting the cost of global pharmaceutical research and development to the United States; and facilitate direct-to-consumer purchasing programs for pharmaceutical manufacturers to sell their products to patients at the most-favored-nation price. In the wake of the Executive Orders and related executive initiatives, a number of pharmaceutical manufacturers have announced direct-to-consumer offerings with discounted prices and/or reached agreement with the federal government regarding pricing for drugs, including prices for Medicaid drugs and newly launched products. A website sponsored by the federal government that is anticipated to offer pharmaceutical direct-to-consumer channels in the future has also been launched. Federal agencies are developing new drug pricing pilot programs, such as a voluntary Medicaid initiative which would authorize the federal government to negotiate Medicaid supplemental rebates with participating manufacturers on behalf of state Medicaid programs, in exchange for standardized coverage criteria for participating manufacturer drugs, and proposed Medicare Part B and D pilot models that, if finalized as proposed, would replace existing inflation-based Medicare rebates with rebates determined on the basis of international prices, for drugs and patients subject to the model. Many of these reform initiatives would require additional legal and/or administrative action to implement and may be subject to legal challenge.

Other federal healthcare reform efforts or actions may affect access to healthcare coverage or the funding of health care benefits, although the full impact of such efforts or actions cannot be predicted. For example, the Congressional Budget Office has estimated that Medicaid provisions in the 2025 budget reconciliation legislation, including restrictions in eligibility and funding for Medicaid, as well as changes to the healthcare marketplace such as the elimination of certain subsidies, will increase the number of uninsured.

Individual states in the United States have also become increasingly aggressive in passing legislation and implementing regulations designed to control pharmaceutical and biological product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, measures designed to encourage importation from other countries and bulk purchasing.

Healthcare reform efforts have been and may continue to be subject to scrutiny, legal challenge and subsequent amendment, creating further uncertainty.

Other recent government actions may also affect prices or payments for prescription drugs. For example, the Trump Administration’s recently announced tariff on branded or patented drugs may increase the cost of drug products that are imported from abroad or manufactured using products or materials imported from abroad. The timeline for implementation of this tariff has not yet been finalized. As another example, the Budget Control Act, as amended, resulted in the imposition of reductions in Medicare (but not Medicaid) payments to providers in 2013 and will remain in effect through 2032 unless additional Congressional action is taken. Any significant spending reductions affecting Medicare, Medicaid or other publicly funded or subsidized health programs that may be implemented and/or any significant taxes or fees that may be imposed on us could have an adverse impact on our results of operations.

Healthcare or other reform initiatives could affect demand for, or pricing of, any future products if approved for sale. We cannot, however, predict the ultimate content, timing or effect of any federal and state reform efforts. There is no assurance that federal or state health care reform will not adversely affect our future business and financial results.

In markets outside of the United States, reimbursement and healthcare payment systems vary significantly by country, and many countries have instituted price ceilings on specific products and therapies. We cannot predict the likelihood, nature, or extent of government regulation that may arise from future legislation or administrative action in the United States or any other jurisdiction. If we, or any third parties we may engage, are slow or unable to adapt to changes in existing requirements or the adoption of new requirements or policies, or if we or such third parties are not able to maintain regulatory compliance, our product candidates may lose any regulatory approval that may have been obtained and we may not achieve or sustain profitability.

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If we continue to progress the development of our product candidates, our business operations and current and future relationships with contractors, investigators, healthcare professionals, consultants, third-party payors, patient organizations, customers, and others will be subject to applicable healthcare regulatory laws, which could expose us to penalties.

Our business operations and current and future arrangements with contractors, investigators, healthcare professionals, consultants, third-party payors, patient organizations, and customers may expose us to broadly applicable fraud and abuse and other healthcare laws and regulations. These laws may constrain the business or financial arrangements and relationships through which we conduct our operations, including how we research, market, sell, and distribute our product candidates, if approved. Such laws, some of which may apply only after our products are approved for marketing, include:

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Efforts to ensure that our business arrangements with third parties will comply with applicable healthcare and other laws and regulations will involve substantial costs. Given the breadth of the laws and regulations and narrowness of any exceptions, limited guidance for certain laws and regulations and evolving government interpretations of the laws and regulations, regulatory authorities may possibly conclude that our business practices may not comply with healthcare laws and regulations, including our consulting agreements and other relationships with healthcare providers.

If our operations are found to be in violation of any of the laws described above or any other governmental laws and regulations that may apply to us, we may be subject to actions including the imposition of civil, criminal, and administrative penalties, damages, disgorgement, monetary fines, possible exclusion from participation in Medicare, Medicaid, and other federal healthcare programs, individual imprisonment, contractual damages, reputational harm, diminished profits and future earnings, additional reporting requirements, or oversight if we become subject to a corporate integrity agreement or similar agreement to resolve allegations of non-compliance with these laws, and curtailment or restructuring of our operations, any of which could adversely affect our ability to operate our business and our results of operations. Further, defending against any such actions can be costly, time consuming, and may require significant personnel resources. Therefore, even if we are successful in defending against any such actions that may be brought against us, our business may be impaired.

Our business operations may subject us to data protection laws, including the GDPR, the UK GDPR, the CCPA and other similar laws.

The GDPR and UK GDPR apply to companies established in the EEA and UK, respectively, as well as to companies that are not established in the EEA or UK, respectively, and which collect and use personal data in relation to (i) offering goods or services to, or (ii) monitoring the behavior of, individuals located in the EEA or UK, respectively. If we conduct clinical trial programs in the EEA or UK (whether the trials are conducted directly by us or through a clinical vendor or collaborator), enter into research collaborations involving the monitoring of individuals in the EEA or UK, or market our products to individuals in the EEA or UK, we will be subject to the GDPR or UK GDPR, as applicable, which place stringent operational requirements for processors and controllers of personal data of individuals in the EEA and UK, respectively. If our or our collaborators’ or service providers’ privacy or data security measures fail to comply with the GDPR or UK GDPR requirements, we may be subject to litigation, regulatory investigations, enforcement notices requiring us to change the way we use personal data, temporary or definitive bans on data processing, or fines of up to 20 million Euros in the case of GDPR or £17.5 million in the case of UK GDPR or, in each case, up to 4% of our total worldwide annual revenue of the preceding financial year, whichever is higher, as well as compensation claims by affected individuals, including class-action type litigation, negative publicity, reputational harm and a potential loss of business and goodwill.

Recent legal developments in Europe have created complexity and uncertainty regarding transfers of personal data from the EEA and the UK to the United States. On July 16, 2020, the Court of Justice of the European Union (“CJEU”) invalidated the EU-US Privacy Shield Framework (the “Privacy Shield”) under which personal data could be transferred from the EEA to US entities who had self-certified under the Privacy Shield scheme. This framework has been replaced by the E.U.-U.S. Data Privacy Framework, for which the EC adopted an adequacy decision in July 2023, and the UK Extension to the E.U.-U.S. Data Privacy Framework, which took effect in October 2023. While we do not currently rely upon these frameworks, we expect there to be legal challenges to this framework in the future, which could draw into question the legitimacy of other cross-border transfer mechanisms, including the standard contractual clauses on which we rely to transfer personal data from the EEA and UK to the U.S. and other jurisdictions. On June 4, 2021, the EC released two revised sets of standard contractual clauses for transfers of personal data from the EEA to the U.S. and has indicated that it will release additional revised standard contractual clauses in the future.

These recent developments may require us to review and amend the legal mechanisms by which we make and/or receive personal data transfers to/in the United States. Other countries outside of the EEA and UK maintain different privacy laws that we are subject to which may further increase our costs of compliance and expose us to greater legal risk.

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There are numerous U.S. federal and state laws and regulations related to the privacy and security of personal information. In particular, regulations promulgated pursuant to HIPAA establish privacy and security standards that limit the use and disclosure of individually identifiable health information, or protected health information, and require the implementation of administrative, physical and technological safeguards to protect the privacy of protected health information and ensure the confidentiality, integrity and availability of electronic protected health information. Determining whether protected health information has been handled in compliance with applicable privacy standards and our contractual obligations can be complex and may be subject to changing interpretation. While we do not believe that we are directly subject to HIPAA as either a “covered entity” or “business associate,” U.S. sites at which we conduct clinical trials are likely to be covered entities and thus must ensure that they obtain adequate patient authorization or establish another basis under HIPAA to disclose a clinical trial subject’s individually identifiable health information to us and other entities participating in our clinical trials.

In the United States, the CCPA imposes many obligations for the collection, processing, and sharing of personal information of California residents. The CCPA provides for civil penalties for violations, as well as a private right of action for data breaches that is expected to increase data breach litigation. Because we have not yet generated revenue and do not meet the CCPA’s other jurisdictional tests, we do not yet meet the applicable threshold for the CCPA to apply to our business. If our business becomes subject to CCPA in the future, it could increase our compliance costs and potential liability. Similar laws have been proposed or passed in more than half of the states in the U.S. and in the U.S. Congress. In addition, Washington state enacted the My Health, My Data Act, a health-focused consumer privacy law, which took effect in March 2024. This law imposes obligations related to the collection and sharing of certain health-related information that is not subject to HIPAA and that does not fall within certain other exceptions in the law. Other states have enacted, or are in the process of enacting, similar health-focused consumer privacy laws. Furthermore, all fifty U.S. states, the District of Columbia, Puerto Rico, and other U.S. territories have enacted data breach notification laws that require, among other things, notifications to state governments and/or the affected individuals in the event of a data breach. Such laws differ from one another, and may impose significant compliance burden. Further, we may at times fail, or be perceived to have failed, to have complied with such laws. This could result in significant consequences, which include, but are not limited to, the imposition of fines and penalties, government enforcement actions, investigations and other proceedings, as well as additional reporting requirements and/or oversight.

Also of note, in June 2024, the Protecting Americans’ Data from Foreign Adversaries Act of 2024 took effect. This law prohibits data brokers from making available certain personally identifiable sensitive data of U.S. individuals to “foreign adversary” countries, such as the People’s Republic of China (“PRC”), and entities controlled by such countries. Additionally, in January 2025, the DOJ published a final rule implementing President Biden’s Executive Order 14117, “Preventing Access to Americans’ Bulk Sensitive Personal Data and United States Government-Related Data by Countries of Concern,” which became effective in April 2025. This final rule prohibits certain data brokerage transactions and transactions involving certain bulk human ‘omic data, including human genomic data and biospecimens from which such data can be derived, with restricted jurisdictions, such as the PRC, and “covered persons” that have certain ties to such restricted jurisdictions. The final rule also places restrictions on certain vendor, employment and investment agreements with such jurisdictions. These restrictions may affect our ability to engage in collaborations or license agreements with entities in restricted countries or with a nexus to such countries going forward. As such, we will need to review periodically our operations in comparison to developments in such laws. Achieving and sustaining compliance with applicable international, federal and state privacy, security, and breach reporting laws may prove time-consuming and costly. Failure to comply with any of these legal requirements could have a material adverse effect on our reputation, business, or financial condition, including but not limited to: interruptions or stoppages in our business operations, including our clinical studies; inability to process personal data or to operate in certain jurisdictions; limited ability to develop or commercialize our products; expenditure of time and resources to defend any claim or inquiry; adverse publicity; or revision or restructuring of our operations.

We are subject to environmental, health and safety laws and regulations, and we may become exposed to liability and substantial expenses in connection with environmental compliance or remediation activities.

Our operations, including our development, testing and manufacturing activities, are subject to numerous environmental, health and safety laws and regulations. These laws and regulations govern, among other things, the controlled use, handling, release, and disposal of and the maintenance of a registry for, hazardous materials and

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biological materials, such as chemical solvents, human cells, carcinogenic compounds, mutagenic compounds, and compounds that have a toxic effect on reproduction, laboratory procedures and exposure to blood-borne pathogens. If we fail to comply with such laws and regulations, we could be subject to fines or other sanctions.

As with other companies engaged in activities similar to ours, we face a risk of environmental liability inherent in our current and historical activities, including liability relating to releases of or exposure to hazardous or biological materials. Environmental, health and safety laws and regulations are becoming more stringent. We may be required to incur substantial expenses in connection with future environmental compliance or remediation activities, in which case, the production efforts of our third-party manufacturers or our development efforts may be interrupted or delayed.

Risks Related to Our Intellectual Property

If we are unable to obtain, maintain and enforce patent protection for our technology and product candidates, or if the scope of the patent protection obtained is not sufficiently broad, our competitors could develop and commercialize similar or identical technology and products, and our ability to successfully develop and commercialize our technology and product candidates may be adversely affected.

Our success depends in large part on our ability to obtain and maintain intellectual property, particularly patents, in the United States and other countries, with respect to any proprietary technology and product candidates we develop. If we are unable to obtain or maintain patent protection of proprietary technology or product candidates by filing patent applications and/or in-licensing related intellectual property in commercially relevant jurisdictions, our business, financial condition, results of operations and prospects could be materially harmed.

The patent prosecution process is expensive, time-consuming and complex, and we may not be able to identify, file, prosecute, maintain, defend or license all necessary or desirable patent applications at a reasonable cost or in a timely manner. In some circumstances involving technology that we license from third parties, we do not have the sole right to control the preparation, filing and prosecution of patent applications or to maintain, enforce and defend the in-licensed patents. Therefore, these in-licensed patents and applications may not be prepared, filed, prosecuted, maintained, defended and enforced in a manner consistent with the best interests of our business.

The patent rights of pharmaceutical and biotechnology companies generally are highly uncertain, involve complex legal and factual questions and have been the subject of much litigation in recent years. No consistent policy regarding the breadth of claims allowed in biotechnology and pharmaceutical patents has emerged in the United States or in numerous foreign jurisdictions. Various courts, including the U.S. Supreme Court, have rendered decisions that affect the scope of patent eligibility of certain inventions or discoveries relating to biotechnology. These decisions conclude, among other things, that abstract ideas, natural phenomena and laws of nature are not themselves patent eligible subject matter.

Precisely what constitutes a law of nature or abstract idea is uncertain, and certain aspects of our technology could be considered ineligible for patenting under applicable law. In addition, the scope of patent protection outside the United States is uncertain, and laws of foreign countries may not protect our rights to the same extent as the laws of the United States or vice versa. For example, European patent law precludes the patentability of methods of treatment of the human body. With respect to both owned and in-licensed patent rights, we cannot predict whether the patent applications we and our licensors are currently pursuing will issue as patents that protect our technology and product candidates, in whole or in part, in any particular jurisdiction or whether the claims of any issued patents will provide sufficient protection from competitors. Changes in either the patent laws or interpretation of the patent laws in the United States or other countries may diminish the value of our patents and our ability to obtain, protect, maintain, defend and enforce our patent rights, narrow the scope of our patent protection and, more generally, affect the value or narrow the scope of our patent rights.

Publications of discoveries in the scientific literature often lag behind the actual discoveries, and patent applications in the United States and other jurisdictions are typically not published until 18 months after filing, or, in some cases, are not published at all. Therefore, neither we nor our licensors can know with certainty whether either we or our licensors were the first to make the inventions claimed in the patents and patent applications we own or in-license now or in the future, or that either we or our licensors were the first to file for patent protection of such inventions. As a result, the issuance, scope, validity, enforceability and commercial value of our owned and

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in-licensed patent rights are uncertain. In addition, the scope of patent protection outside the United States is uncertain, and laws of foreign countries might not protect our rights to the same extent as the laws of the United States or vice versa.

Additionally, the coverage claimed in a patent application can be significantly reduced before the patent is issued, and its scope can be reinterpreted after issuance. Even if our patent applications issue as patents, they might not issue in a form that will provide us with any competitive advantage. The issuance of a patent is not conclusive as to its inventorship, scope, validity or enforceability, and our patents might be challenged in a variety of proceedings before courts or patent offices in the United States and abroad. Such challenges might result in loss of exclusivity or in patent claims being narrowed, invalidated or held unenforceable, which could reduce the scope of, or invalidate, our patent rights, allow third parties to commercialize our technology without payment to us, and/or limit the duration of the patent protection of our technology and product candidates. If the breadth or strength of our patents and patent applications is threatened, regardless of the outcome, it could dissuade companies from collaborating with us to license, develop or commercialize current or future product candidates.

For these reasons, our patent portfolio might not provide us with sufficient rights to exclude others from using or commercializing technology and products similar or identical to our technology and product candidates.

Obtaining and maintaining patent protection depends on compliance with various procedural requirements imposed by governmental patent agencies, and our patent protection could be reduced or eliminated for non-compliance with these requirements.

The United States Patent and Trademark Office (“USPTO”) and foreign patent offices have a number of procedural and documentary requirements that must be complied with during the patent application and prosecution process. Periodic fees must be paid to the USPTO and foreign patent offices at several stages or annually over the lifetime of issued patents and pending patent applications. In certain circumstances, we might rely on our licensing partners to meet procedural, documentary, and fee requirements of the relevant patent agency. With respect to our patents, we rely outside counsel to remind us of the due dates and to make payment after we instruct them to do so. While an inadvertent lapse can in many cases be cured, there are situations in which noncompliance can result in abandonment or lapse of the patent or patent application, resulting in partial or complete loss of patent rights in the relevant jurisdiction. If we or our licensors fail to maintain current and future patents and patent applications covering our product candidates, our competitors might be able to enter the market with similar or identical products or technology, which would have a material adverse effect on our business, financial condition, results of operations, and prospects.

We may not be able to protect our intellectual property and proprietary rights throughout the world.

Filing, prosecuting, and defending patents on product candidates in all countries throughout the world would be prohibitively expensive. In addition, the laws of some foreign countries do not protect intellectual property rights to the same extent as federal and state laws in the United States, and even where such protection is available, adequate judicial and governmental enforcement of such intellectual property rights may be lacking. Consequently, third parties may attempt to develop and/or commercialize competitive products in foreign countries where we do not have any patent protection and/or where legal recourse may be limited. Further, we may not be able to prevent third parties from importing products made using our inventions into the United States or other jurisdictions. This may have a significant commercial impact on our business operations.

Proceedings to enforce our intellectual property rights in foreign jurisdictions could result in substantial costs and divert our efforts and attention from other aspects of our business, could put our patents at risk of being invalidated or interpreted narrowly, could put our patent applications at risk of not issuing, and could provoke third parties to assert claims against us. We may not prevail in any lawsuits that we initiate, and even if we do prevail, the damages or other remedies awarded, if any, may not be commercially meaningful. Accordingly, our efforts to enforce our intellectual property and proprietary rights around the world may be inadequate to obtain a significant commercial advantage from the intellectual property that we develop or license.

Many countries, including India, China and certain countries in Europe, have compulsory licensing laws under which a patent owner may be compelled to grant licenses to third parties. In addition, many countries limit the enforceability of patents against government agencies or government contractors. In these countries, the patent

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owner may have limited remedies, which could materially diminish the value of such patents. If we or any of our licensors are forced to grant a license to third parties with respect to any patents relevant to our business, our competitive position may be impaired and our business, financial condition, results of operations, and prospects may be adversely affected.

Changes to patent laws in the United States and other jurisdictions could diminish the value of our patents, thereby impairing our ability to protect our products.

Changes in either the patent laws or interpretation of patent laws in the United States or other jurisdictions could increase the uncertainties and costs surrounding the prosecution of our patent applications and the maintenance, enforcement or defense of our issued patents, all of which could have a material adverse effect on our business. For example, in 2023, patent reform in the EU created a unitary patent and established a Unified Patent Court (“UPC”). The unitary patent facilitates validation of a patent granted by the European Patent Office in the EU member states that participate in the unitary patent. The UPC is a centralized body with jurisdiction over actions for preliminary injunctions, infringement, and revocation of patents granted by the European Patent Office. While the UPC has exclusive jurisdiction over unitary patents, patentees that do not utilize the unitary patent for validation can opt existing or future patents out of the jurisdiction of the UPC. There are both risks and benefits associated with pursuing Unitary Patents and with submitting to the jurisdiction of the UPC in the absence of a Unitary Patent. For example, because the UPC is a relatively new forum, little precedent exists, and the manner in which European patent law will be applied by the UPC is unpredictable, which presents potential risks to a patent’s scope and enforceability. In addition, an unfavorable outcome before the UPC could result in a European patent being invalidated in all participating member states. In comparison, European patents that are not under the jurisdiction of the UPC must be litigated separately in each member state, which causes patent challengers to incur additional costs and leaves open the possibility that a challenged patent could be affirmed in some member states, even if it is invalidated in others. From an enforcement perspective, the ability to assert patents against infringers under the UPC system could have significant financial benefits for a patentee, due to the ability to litigate in a single forum, rather than in each individual member state.

Currently, we do not have any unitary patents and we have opted out of UPC jurisdiction for our existing European patents. While we have and will continue to make case-by-case decisions about whether to pursue unitary patents or to elect the jurisdiction of the UPC, we cannot be certain that a more favorable outcome could be achieved if the opposite decision were made. We also cannot be certain whether the legal precedent of the UPC will evolve in a manner that is more or less favorable to us than the precedent of individual member states in a given situation or for a given patent.

In addition to legislative changes, recent U.S. Supreme Court rulings have narrowed the scope of patent protection available in certain circumstances and weakened the rights of patent owners in certain situations. This combination of events has increased uncertainty with respect to the validity and enforceability of patents once obtained. Similarly, foreign courts have made, and will likely continue to make, changes in how the patent laws in their respective jurisdictions are interpreted. Further, political changes in government leadership both within and outside of the U.S. could result in changes to national patent laws and regulations or multi-country intellectual property treaties, which could impact patent enforcement in the U.S. and internationally. We cannot predict future changes in the interpretation of patent laws or changes to patent laws that might be enacted into law by U.S. and foreign legislative bodies. Those changes may materially affect our patents or patent applications and our ability to obtain additional patent protection in the future.

If we are unable to obtain licenses from third parties on commercially reasonable terms, our business could be harmed.

In addition to our existing licensing agreements, it may be necessary for us to use the patented or proprietary technology of third parties to commercialize our products, if approved, in which case we would be required to obtain a license from these third parties. The in-licensing and acquisition of third-party intellectual property rights is a competitive area, and a number of more established companies are also pursuing strategies to in-license or acquire third-party intellectual property rights that we may consider attractive or necessary. These established companies may have a competitive advantage over us due to their size, cash resources and greater clinical development and commercialization capabilities. Furthermore, companies that perceive us to be a competitor may be unwilling to assign or license rights to us. These factors might mean fewer suitable licensing opportunities for us, as well as higher acquisition or licensing costs.

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If we are unable to obtain a necessary license, the third parties owning such intellectual property rights could seek an injunction prohibiting our development and/or commercialization of the affected product candidates. Even if we are able to obtain a license, the terms may be unfavorable; for example, it may require substantial licensing or royalty payments, or be non-exclusive, thereby giving our competitors access to the same technologies licensed to us.

If we are unable to obtain third-party intellectual property rights or to maintain our existing intellectual property rights, we may be required to expend significant time and resources to redesign our technology, product candidates, or the methods for manufacturing them or to develop or license replacement technology, all of which may not be feasible on a technical or commercial basis. If we are unable to do so, we may be unable to develop or commercialize the affected technology and product candidates, which could harm our business, financial condition, results of operations, and prospects significantly.

If we fail to comply with our obligations in our intellectual property licenses with third parties, or otherwise experience disruptions to our business relationships with our licensors, we could lose intellectual property rights that are important to our business.

We are party to license agreements that impose upon us certain obligations, and we may enter into additional licensing and funding arrangements with third parties that may impose, among other things, diligence, development, and commercialization timelines, milestone and royalty payments, and insurance If we fail to comply with such obligations under current or future license and funding agreements, our counterparties may have the right to terminate these agreements, in which event we might be forced to cease developing, manufacturing or marketing any product that is covered by these agreements or may face other penalties under such agreements, or our counterparties may require us to grant them certain rights. Such an occurrence could materially adversely affect the value of any product candidate being developed under any such agreement.

Termination or reduction or elimination of our rights under these agreements, or restrictions on our ability to freely assign or sublicense our rights under such agreements may result in our loss of rights or our having to negotiate new or reinstated agreements with less favorable terms, which would impede, delay or prohibit the further development or commercialization of any product candidates that rely on such agreements.

Disputes may arise regarding intellectual property that is or becomes subject to a licensing agreement, including:

The resolution of any contract disagreement that may arise could narrow the scope of our rights to the relevant intellectual property or technology, could increase our financial or other obligations under the relevant agreement, or could result in loss of some or all rights under the license agreement. Moreover, if disputes over intellectual property that we have licensed prevent or impair our ability to maintain our current licensing arrangements on commercially acceptable terms, we may be unable to successfully develop and commercialize the affected technology and product candidates. Any of these outcomes could have a material adverse effect on our business, financial condition, results of operations and prospects.

Despite our efforts, our licensors or future licensors might conclude that we have materially breached our license agreements and might therefore terminate the license agreements, thereby removing our ability to develop and

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commercialize product candidates and technology covered by these license agreements. If these in-licenses are terminated, or if the underlying intellectual property fails to provide the intended exclusivity, competitors could seek regulatory approval for and market products and technologies identical to ours. This could have a material adverse effect on our competitive position, business, financial condition, results of operations and prospects.

Patent terms may not protect our competitive position for an adequate amount of time.

Patents have a limited lifespan. In the United States, if all maintenance fees are timely paid, the natural expiration of a patent is generally 20 years from its earliest U.S. non-provisional filing date. Various extensions may be available, but the life of a patent, and the protection it affords, is limited. Even if patents covering our product candidates are obtained, once the patent life has expired, we may be open to competition from competitive products, including generics or biosimilars. Given the amount of time required for the development, testing and regulatory review of new product candidates, patents protecting such candidates might expire before or shortly after such candidates are approved for use or commercialized. As a result, our patent portfolio may not provide us with sufficient rights to exclude others from commercializing products similar or identical to ours during periods when commercial exclusivity would be valuable to us.

If we do not obtain a patent term extension for any product candidates we might develop, our business might be materially harmed.

In the United States, the term of a patent that covers an FDA-approved drug may be eligible for a patent term extension (“PTE”) of up to five years beyond the expiration date of the patent, as compensation for the patent term lost during the FDA regulatory review process. The Drug Price Competition and Patent Term Restoration Act of 1984, also known as the Hatch-Waxman Act, permits a PTE of up to five years beyond the expiration date of the patent. The length of the PTE is related to the length of time the drug is under regulatory review, and cannot extend the remaining term of a patent beyond a total of 14 years from the date of product approval. The patent term of only one patent applicable to an approved drug may be extended, and only those claims covering the approved drug, a method for using it or a method for manufacturing it may be extended. Similar provisions are available in Europe and certain other jurisdictions. While we expect to apply for PTE on patents covering our product candidates, there is no guarantee that such extensions will be granted and, even if granted, the length of such extensions. We may not be granted PTE either in the United States or in any foreign country, even where that patent is eligible for PTE, if, for example, we fail to exercise due diligence during the testing phase or regulatory review process, fail to apply within applicable deadlines, fail to apply prior to expiration of relevant patents or otherwise fail to satisfy applicable requirements. Furthermore, for licensed patents, we might not be able to control whether a petition to obtain a PTE is filed or obtained from the USPTO and/or foreign patent office(s). If we are unable to obtain any PTE, or if the term of extension is less than we request, our business, financial condition, results of operations and prospects could be materially harmed.

If we are unable to protect the confidentiality of our trade secrets, our business and competitive position would be harmed.