SLATE MEDICINES, INC., a Delaware corporation having its principal place of business at 200 Berkeley St., 18th Floor, Boston, MA 02116 (the “Company”);

SLATE MEDICINES UK LIMITED, a private company limited by shares incorporated under the laws of England and Wales under company registration number 17032838 having its registered office at 3rd Floor 1 Ashley Road, Altrincham, Cheshire, United Kingdom, WA14 2DT (the “Subsidiary” and, together with the Company, the “Group”); and

FORBION VENTURES FUND VII COÖPERATIEF U.A and FORDD VENTURES VII B.V., each having its registered office at Gooimeer 2 – 35, 1411 DC Naarden, The Netherlands (collectively, the “Investor”).

The Company is, as at the date hereof, the current shareholder of the Subsidiary.

The Investor has agreed to invest an aggregate amount of US $34,999,997.71 in three tranches, US $2,692,307.18 at the Initial Closing (as defined in the Purchase Agreement (as defined below)), US $14,807,691.68 at the Tranche 2 Closing (as defined in the Purchase Agreement) and US $17,499,998.85 at the Tranche 3 Closing (as defined in the Purchase Agreement) in the Group pursuant to that certain Series A Preferred Stock Purchase Agreement, dated as of the date of this Agreement (the “Initial Closing Date”), among the Company, the Subsidiary and the investors listed in the schedule of purchasers in Exhibit A of such agreement (as amended and/or restated from time to time, the “Purchase Agreement”).

The Investor has determined that it is in its best interests to invest in the Subsidiary rather than in the Company and shall subscribe for certain B ordinary shares of US$0.00001 each in the capital of the Subsidiary (the “Subsidiary Shares”) and certain shares of Series A-2 Preferred Stock in the Company (the “Company Series A-2 Preferred Stock”), provided that the Investor shall have the option to exchange, and the Company shall have the option to require the exchange of, the Subsidiary Shares for certain securities in the Company, in each case in accordance with and subject to the terms and conditions set out in this Agreement (as applicable, the “Exchange”).

The Company wishes to provide for the right to require the Investor to complete the Exchange subject to the terms and conditions set forth in this Agreement.

In the event that the Exchange is exercised and completed, the shares of Company Series A¬2 Preferred Stock held by the Investor shall be redeemed by the Company in accordance with Article Fourth, Part B, Section 6 of the Company’s Amended and Restated Certificate of Incorporation (as amended and/or restated from time to time, the “Restated Certificate”).

GRANT OF OPTIONS; EXCHANGE ON TRANSFER

Put Option

Call Option

Subject to the terms and conditions of this Agreement, the Investor hereby grants to the Company an irrevocable right and option (the “Call Option” and, together with the Put Option, the “Options”) to cause the Investor to exchange all (but not less than all) of the Subsidiary Shares held by the Investor for shares of the Relevant Company Stock at the Exchange Ratio. The Call Option shall be exercisable only at the times and upon the occurrence of the events specified in Section 1.2(b).

The Call Option under Section 1.2(a) shall be deemed exercised by the Company:

if the Selling Investors (as defined in Section 3.2 of that certain Amended and Restated Voting Agreement by and among the Company and the other parties thereto, dated as of the Initial Closing Date (as amended and/or restated from time to time, the “Voting Agreement”)) and the Board of Directors of the Company (the “Board”) approve in writing a Sale of the Company (as defined in the Voting Agreement), specifying that Section 3 of the Voting Agreement shall apply to such transaction, immediately prior to the closing of such Sale of the Company;

immediately prior to the automatic conversion of all shares of Company Series A-1 Preferred Stock (as defined below) into shares of the Company Common Stock (as defined below) in accordance with Article Fourth, Part B, Section 5 of the Restated Certificate;

immediately prior to the consummation of a Deemed Liquidation Event (as defined in and subject to the provisions of Article Fourth, Part B, Section 2.3.1 of the Restated Certificate);

upon the Investor taking any action in contravention of Section 1.4 or Section 4.1, provided that the Company has provided the Investor with notice of such action and has been provided at least fifteen (15) U.S. business days to cure or otherwise rectify any such action to the reasonable satisfaction of the Company; or

immediately upon a Special Mandatory Conversion (as defined in the Restated Certificate) involving the Investor’s Company Series A-2 Preferred Stock in accordance with Article Fourth, Part B, Section 5A of the Restated Certificate.

Notwithstanding the foregoing, in the event of a Deemed Liquidation Event, the Company agrees that, upon request of the Investor given at least fifteen (15) U.S. business days prior to the consummation of such Deemed Liquidation Event (the Investor having been given written notice by the Company at least twenty (20) U.S. business days prior to the consummation of the Deemed Liquidation Event), the Company shall use its commercially reasonable efforts to obtain the agreement of the counterparty to such Deemed Liquidation Event to a transaction structure that would permit the Investor to transfer its Subsidiary Shares to such counterparty in lieu of the Investor consummating the Exchange and transferring the shares of the Relevant Company Stock to such counterparty, without any impairment in the amount of consideration to be received by the Investor in such Deemed Liquidation Event as compared to the amount payable with respect to the shares of the Relevant Company Stock issuable upon the consummation of the Exchange.

Transfer Documents; Power of Attorney

Upon issuance to the Investor of any Subsidiary Shares, the Investor shall deliver to the Company:

a duly completed and signed share transfer form as the Company deems reasonably necessary or appropriate to effectuate the transfers contemplated hereunder and vest in the Company all right, title and interest in and to all the Subsidiary Shares owned by the Investor upon the Closing Date (as defined below) (the “Stock Transfer Form”); and

to the extent not already held by the Company, the original share certificate(s) in respect of all of the Subsidiary Shares issued to the Investor (or a duly executed indemnity for lost share certificate in a form acceptable to the Board) (the “Share Certificate” and, together with the Stock Transfer Form, the “Transfer Documents”).

The Investor hereby irrevocably and unconditionally grants a power of attorney to the Company, acting as escrow agent, to duly date the Transfer Documents as of the Closing Date and to release the Share Certificate to the Company. The transfer of ownership shall take place on the date of delivery of the Transfer Documents.

Transfer Restrictions

No Subsidiary Shares may be transferred by the Investor without the prior written consent of the Company, which consent shall be granted or denied in the sole discretion of the Company; provided, however, that the Investor may transfer the Subsidiary Shares to an Affiliate (as defined in, and pursuant to the restrictions set forth in, the Purchase Agreement) with prior written notice to the Company provided that any transferee agrees to be bound by terms and conditions substantially similar to those set forth in this Agreement. To the extent granted, any such consent may be expressly conditioned on such terms as necessary, in the Company’s sole judgement, to protect the rights of the Company hereunder (including, without limitation, requiring that any transferee agree to be bound by terms and conditions substantially similar to those set forth in this Agreement).

For the purposes of this Agreement, a reference to the “transfer” of a Subsidiary Share includes:

the transfer or assignment of a beneficial or other interest in that Subsidiary Share or the creation of a trust or encumbrance over that Subsidiary Share, or in each case, of a beneficial or other interest in a Subsidiary Share; and

the transfer of a Subsidiary Share pursuant to a merger or scheme of arrangement and any provision of such merger or scheme of arrangement by which a shareholder thereby ceases to be interested in shares in the Subsidiary (or any surviving or successor entity to the Subsidiary) (whether by way of cancellation or otherwise), and the terms “transferring”, “transferor” and other derivatives shall be construed accordingly.

Any attempted transfer of Subsidiary Shares that is not made in full compliance with this Section 1.4 shall be null and void and the parties hereto agree that such attempted transfer shall not be given effect in the company books and records of the Subsidiary. The Subsidiary hereby agrees and undertakes to the Company that it shall not take any action to effectuate any such attempted transfer if it is not in full compliance with this Section 1.4.

The foregoing transfer restrictions shall not apply to transfers of the Subsidiary Shares by the Investor to the Company pursuant to the exercise of either of the Options in accordance with the terms of this Agreement.

Exercise of Options

At any time, the Investor may exercise the Put Option by giving written notice (in the form set out in Schedule 1 hereto) of such exercise (the “Put Option Exercise Notice”) to the Company.

The Company may exercise the Call Option by giving written notice (in the form set out in Schedule 2 hereto) of such exercise (which notice may be given in advance of the applicable triggering event) (the “Call Option Exercise Notice”) to the Investor; provided, however, that upon an exercise of its Call Option pursuant to Section 1(b)(iv), the Company may exercise the Call Option as set forth herein only after the applicable cure period has run. The Call Option Exercise Notice shall identify the Section of this Agreement pursuant to which the Call Option is being exercised and the proposed Closing Date.

Completion of the Exchange

The completion of the Exchange shall take place remotely via the exchange of documents and signatures on:

with respect to the exercise by the Investor of the Put Option pursuant to Section 1.1, the next U.S. business day following the receipt of the Put Option Exercise Notice by the Company; and

with respect to the exercise by the Company of the Call Option pursuant to Section 1.2(b), either (i) the next U.S. business day following the sending or transmission of the Call Option Exercise Notice by the Company (in the event of an exercise of the Call Option pursuant to Section 1.2(b)(iv)), (ii) immediately prior to the event as specified by the Company in the Call Option Exercise Notice or (iii) immediately upon the event as specified by the Company in the Call Option Exercise Notice; or on such other date and time as agreed in writing by the Investor and the Company (the “Closing Date”).

The following shall occur at the completion of the Exchange to effect the transfer and delivery to the Company of the Subsidiary Shares that are to be exchanged pursuant to the Exchange and the issuance to the Investor of the shares of the Relevant Company Stock pursuant to the Exchange:

the Investor shall deliver to the Company the Transfer Documents (or, to the extent such documents have been previously delivered by the Investor to the Company and held in escrow, such Transfer Documents shall be deemed released from escrow to the Company without any further action on the part of the Investor);

the Company shall deliver to the Investor certificates representing the number of shares of the Relevant Company Stock being exchanged for the Subsidiary Shares pursuant to and in accordance with Section 1.1 or 1.2, as the case may be;

the Group shall redeem, retire, and cancel any Share Certificate evidencing the Subsidiary Shares held by the Investor (for no additional consideration and without any further action required on the part of the Investor); and

the Investor shall deliver to the Company any and all instruments of conveyance in addition to the Transfer Documents held by the Company in escrow as the Company shall deem reasonably necessary or appropriate to vest in the Company all right, title and interest in and to the Subsidiary Shares being exchanged.

Scope of Subsidiary Shares

Status of Subsidiary Shares Prior to the Exercise

Until such time as the Put Option or Call Option is exercised in accordance with the terms of this Agreement, the Subsidiary Shares shall continue to be equity securities of the Subsidiary, with all of the rights and privileges appurtenant thereto under the applicable governing documents of the Subsidiary or the Company (as applicable), subject to the restrictions contained herein (including in Sections 1.4 and 4.1).

In the event the Company, at any time when any Subsidiary Shares are held by the Investor, declares and pays a dividend on the shares of the Relevant Company Stock pursuant to the Restated Certificate, the Company covenants and agrees to set aside sufficient funds to pay a comparable per share dividend on each Subsidiary Share (and to issue shares of Relevant Company Stock to the Investor in an Exchange with previously accrued and/or declared dividends accounted for as set forth in the Restated Certificate) and to use its commercially reasonable efforts to cause the Subsidiary (in accordance with, and not in duplication of, Article 29 (Dividend) of the articles of association of the Subsidiary, as may be amended and/or restated from time to time) to issue and pay such dividend as promptly as practicable thereafter; provided, however, that to the extent that the payment of such dividends by the Subsidiary is not then permitted under applicable English law, the Company shall, at the election of the Investor, either pay such amounts directly to the Investor or hold such funds for the benefit of the Investor until such time as the Subsidiary may be permitted to pay such dividend.

Reservation of Company Shares

as are necessary to allow for the exchange of all Subsidiary Shares issued and outstanding and the issuance of the shares of the Relevant Company Stock to the Investor following the Exchange; and

as are now and may hereafter be required to enable and permit the Company to meet its obligations hereunder.

Stamp Duty

Adjustments

The Exchange Ratio shall be proportionately adjusted, as may be necessary, from time to time in the event that the Company or the Subsidiary shall effect any subdivision, combination, recapitalization, stock dividend, anti-dilution adjustment or other similar transaction with respect to the stock of the Company or the shares of the Subsidiary.

If there shall occur any capital reorganization or reclassification of the stock of the Company, or any consolidation or merger of the Company with or into another corporation, whether or not the Company is the surviving corporation (other than a transaction or action covered under Section 1.2(b)), then, as part of any such reorganization, reclassification, consolidation, or merger, as the case may be, lawful provision shall be made so that the Investor shall have the right thereafter to receive upon the Exchange the kind and amount of shares of stock or other securities or property that the Investor would have been entitled to receive if, immediately prior to any such reorganization, reclassification, consolidation, or merger, as the case may be, the Investor had held the number of shares of the Relevant Company Stock after giving effect to the Exchange set forth herein.

Definitions. In addition to the terms defined herein, the following terms used in this Agreement shall be construed to have the meanings set forth or referenced below:

“Exchange Ratio” means one share of the Relevant Company Stock in exchange for one Subsidiary Share, except that, if the Investor is a Defaulting Purchaser (as defined in the Purchase Agreement), it shall mean a number of shares of Relevant Company Stock equal to the aggregate number of votes the shares of Company Series A-2 Preferred Stock held by the Investor and any of its Affiliates, in the aggregate, are entitled to cast, in exchange for all Subsidiary Shares (in each case subject to any adjustment pursuant to Section 1.11).

“Relevant Company Stock” means the Series A-1 Preferred Stock of the Company, US $0.00001 par value per share (the “Company Series A-1 Preferred Stock”), except that, if the Investor is a Defaulting Purchaser, it shall mean shares of Common Stock of the Company, $0.00001 par value per share (the “Company Common Stock”).

REPRESENTATIONS AND WARRANTIES OF THE GROUP

Due Organisation

The Company:

is a corporation duly organized, validly existing and in good standing under the laws of the State of Delaware; and

has all requisite corporate power and authority to own, lease and operate its properties and to carry on its businesses.

The Subsidiary:

is a private company limited by shares duly organized and validly existing under the laws of England and Wales; and

has all requisite corporate power and authority to own, lease and operate properties and to carry on its businesses.

Authority; Binding Nature of Agreement

REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE INVESTOR

Authority

Required Filings and Consents

Other Agreements

The Investor agrees that it:

will not transfer or assign this Agreement or any of its interest herein in contravention of this Agreement;

may not cancel, terminate or revoke this Agreement, and this Agreement shall be binding upon its successors, assigns, legal representatives, heirs, legatees and distributees; and

will not sell, transfer, dispose of, hypothecate or otherwise encumber the Subsidiary Shares at any time or take any other action that would cause any of its representations or warranties hereunder to be untrue.

MISCELLANEOUS

Further Assurance

Amendments and Waivers

Benefit; Successors and Assigns

Notices

Headings

Severability

Entire Agreement

Governing Law; Dispute Resolution

This Agreement shall be construed in accordance with, and governed in all respects by, the laws of the State of Delaware (without giving effect to principles of conflicts of laws); provided, however, that the transfer of ownership of the Subsidiary Shares to the Company upon exercise of the Call Option or the Put Option, as the case may be, in accordance with the terms hereof, shall be governed by, and construed in accordance with, the laws of England and Wales.

Each of the parties to this Agreement consents to personal jurisdiction for any equitable action sought in the U.S. District Court for the District of Delaware or any court of the State of Delaware having subject matter jurisdiction.

WAIVER OF JURY TRIAL: EACH PARTY HEREBY WAIVES ITS RIGHTS TO A JURY TRIAL OF ANY CLAIM OR CAUSE OF ACTION BASED UPON OR ARISING OUT OF THIS AGREEMENT OR THE SUBJECT MATTER HEREOF. THE SCOPE OF THIS WAIVER IS INTENDED TO BE ALL-ENCOMPASSING OF ANY AND ALL DISPUTES THAT MAY BE FILED IN ANY COURT AND THAT RELATE TO THE SUBJECT MATTER OF THIS AGREEMENT, INCLUDING, WITHOUT LIMITATION, CONTRACT CLAIMS, TORT CLAIMS (INCLUDING NEGLIGENCE), BREACH OF DUTY CLAIMS, AND ALL OTHER COMMON LAW AND STATUTORY CLAIMS. THIS SECTION HAS BEEN FULLY DISCUSSED BY EACH OF THE PARTIES HERETO AND THESE PROVISIONS WILL NOT BE SUBJECT TO ANY EXCEPTIONS. EACH PARTY HERETO HEREBY FURTHER WARRANTS AND REPRESENTS THAT SUCH PARTY HAS REVIEWED THIS WAIVER WITH ITS LEGAL COUNSEL, AND THAT SUCH PARTY KNOWINGLY AND VOLUNTARILY WAIVES ITS JURY TRIAL RIGHTS FOLLOWING CONSULTATION WITH LEGAL COUNSEL.

Counterparts

Specific Performance

Termination

SLATE MEDICINES, INC.

/s/ Neil Buckley

/s/ Neil Buckley

For it: Forbion Ventures VII Management B.V.

For it: Rogier Rooswinkel, signing as
authorized proxy

/s/ Geert-Jan Mulder

/s/ Rogier Rooswinkel

For it: FCPM III Services B.V.

For it: Geert-Jan Mulder, signing as authorized proxy

For it: FCPM III Services B.V.

For it: Sander Slootweg, signing as authorized proxy

/s/ Geert-Jan Mulder

/s/ Sander Slootweg

We refer to the Agreement. This letter constitutes a Put Option Exercise Notice (the “Notice”). The terms defined in the Agreement shall have the same meaning in this Notice.

We hereby give you notice under and pursuant to Section 1.1 of the Agreement that we exercise the Put Option granted by you to us.

In accordance with Section 1.6(a)(i) of the Agreement, the exchange of the Subsidiary Shares for the Relevant Company Stock at the Exchange Ratio shall occur on the next U.S. business day following receipt of this Notice by the Company.

To the extent not already held by the Company, enclosed with this Notice are the Transfer Documents (duly executed by or on behalf of the Investor as required) to be held by the Company in escrow until the Closing Date.

This Notice is governed by the laws of the State of Delaware (without giving effect to principles of conflicts of laws).

For it: Forbion Ventures VII Management B.V.

For it: Rogier Rooswinkel, signing as
authorized proxy

We refer to the Agreement. This letter constitutes a Call Option Exercise Notice (this “Notice”). The terms defined in the Agreement shall have the same meaning in this Notice.

We hereby give you notice under and pursuant to Section 1.2(b)([●]) of the Agreement that the Call Option granted by you to us shall be deemed automatically exercised as a result of [●] (the “Event”).

In accordance with Sections 1.2(b)([●]) and 1.6(a)(ii) of the Agreement, the exchange of the Subsidiary Shares for the Relevant Company Stock at the Exchange Ratio shall occur [on the next U.S. business day following the sending or transmission of this Notice by the Company] OR [immediately prior to the Event] OR [immediately upon the Event] OR [other Closing Date, if applicable].

To the extent not already held by the Company, please provide the Transfer Documents (duly executed by or on behalf of the Investor as required) to be held by the Company in escrow until the Closing Date.

This Notice is governed by the laws of the State of Delaware (without giving effect to principles of conflicts of laws).