THRX Theseus Pharmaceuticals Inc

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934 (Amendment No.  )

Filed by the Registrant ☒

Filed by a Party other than the Registrant ☐

Check the appropriate box:

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April 25, 2022

To the Stockholders of Theseus Pharmaceuticals, Inc.:

It is my pleasure to invite you to attend the 2022 Annual Meeting of Stockholders (the “Annual Meeting”) of Theseus Pharmaceuticals, Inc., to be held on Friday, June 10, 2022 at 10:00 a.m. (Eastern Daylight Time). The Annual Meeting will be completely virtual. You may attend the virtual meeting, submit questions, and vote your shares electronically during the meeting via live webcast by visiting www.virtualshareholdermeeting.com/THRX2022 in advance of the meeting. In order to be able to attend the Annual Meeting, you will need the 16-digit control number, which is located on your Notice, on your proxy card or in the instructions accompanying your proxy materials. Instructions on how to participate in the Annual Meeting are also posted online at www.proxyvote.com.

Details regarding the business to be conducted at the Annual Meeting are more fully described in the accompanying Notice of Annual Meeting of Stockholders and Proxy Statement.

We are pleased to take advantage of the Securities and Exchange Commission rules that allow companies to furnish proxy materials to their stockholders on the internet. On or around April 25, 2022, we expect to mail to our stockholders an Important Notice Regarding the Availability of Proxy Materials (the “Notice”) containing instructions on how to access our proxy statement for the Annual Meeting and our Annual Report on Form 10-K for the fiscal year ended December 31, 2021. The Notice also provides instructions on how to vote online or by telephone, how to access the virtual Annual Meeting, and how to receive a paper copy of the proxy materials by mail.

Whether or not you plan to virtually attend the meeting, your vote is very important and we encourage you to vote promptly. You may vote by proxy over the internet or by telephone, or, if you received paper copies of the proxy materials by mail, you can also vote by mail by following the instructions on your proxy card (if you requested and received a printed copy of the proxy materials). If you virtually attend the meeting you will have the right to revoke your proxy and vote electronically during the meeting via the live webcast. If you hold your shares through an account with a brokerage firm, bank or other nominee, please follow the instructions you receive from your brokerage firm, bank or other nominee to vote your shares.

On behalf of your Board of Directors, thank you for your continued support and interest.

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314 Main Street

Cambridge, Massachusetts 02142

T (857)-400-9491

www.theseusrx.com

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Theseus Pharmaceuticals, Inc.

314 Main Street

Cambridge, Massachusetts 02142

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Theseus Pharmaceuticals, Inc.

314 Main Street

Cambridge, Massachusetts 02142

FOR THE 2022 ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD ON JUNE 10, 2022

This proxy statement (this “Proxy Statement”) and proxy card are furnished in connection with the solicitation of proxies by our Board of Directors to be voted at the 2022 Annual Meeting of Stockholders (the “Annual Meeting”) of Theseus Pharmaceuticals, Inc. (sometimes referred to as “we,” “us,” the “Company” or “Theseus”), which will be held virtually on Friday, June 10, 2022, at 10:00 a.m. (Eastern Daylight Time) via live webcast by visiting www.virtualshareholdermeeting.com/THRX2022 in advance of the meeting. In order to be able to attend the Annual Meeting, you will need the 16-digit control number, which is located on your Notice, on your proxy card or in the instructions accompanying your proxy materials. Instructions on how to participate in the Annual Meeting are also posted online at www.proxyvote.com.

INTERNET AVAILABILITY OF PROXY MATERIALS

We are making this Proxy Statement and our annual report available to stockholders primarily via the internet, instead of mailing printed copies of those materials to each stockholder. This Proxy Statement, the Notice of Annual Meeting of Stockholders, our form of proxy card and our Annual Report on Form 10-K for the fiscal year ended December 31, 2021 (our “2021 Annual Report”) are available for viewing, printing and downloading at http://materials.proxyvote.com. On or around April 25, 2022, we intend to mail to our stockholders the Notice Regarding Availability of Proxy Materials (the “Notice”) containing instructions on how to access and review this Proxy Statement and our 2021 Annual Report. The Notice also instructs you how you may submit your proxy over the internet or via telephone and how to vote online at the Annual Meeting. If you received a Notice and would like to receive a printed copy of our proxy materials, you should follow the instructions for requesting those materials included in the Notice.

Additionally, you can find a copy of our 2021 Annual Report, which includes our financial statements for the fiscal year ended December 31, 2021, on the website of the Securities and Exchange Commission, at www.sec.gov, or in the “SEC Filings” section of the “Investors & Media” section of our website located at www.theseusrx.com. You may also obtain a printed copy of our 2021 Annual Report, including our financial statements, free of charge, from us by sending a written request to Attention: Corporate Secretary, Theseus Pharmaceuticals, Inc., 314 Main Street, Cambridge, Massachusetts 02142. Exhibits will be provided upon written request and payment of an appropriate processing fee.

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IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE

STOCKHOLDER MEETING TO BE HELD ON JUNE 10, 2022.

This Proxy Statement and the 2021 Annual Report are available on-line at www.proxyvote.com.

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QUESTIONS AND ANSWERS ABOUT THIS PROXY MATERIAL AND VOTING

Why am I receiving these materials?

You have received these proxy materials because the Board of Directors (our “Board of Directors”) of Theseus Pharmaceuticals, Inc. (“we,” “us,” “our,” the “Company” or “Theseus”) is soliciting your proxy to vote at the 2022 Annual Meeting (the “Annual Meeting”). This proxy statement (this “Proxy Statement”), along with the accompanying Notice of Annual Meeting of Stockholders, summarizes the purposes of the meeting and the information you need to know to vote at the Annual Meeting. We have made available to you on the internet this Proxy Statement, the Notice of Annual Meeting of Stockholders, the proxy card and a copy of our Annual Report on Form 10-K for the fiscal year ended December 31, 2021 (our “2021 Annual Report”) because you owned shares of our common stock (“Common Stock”) on the record date of April 14, 2022.

Why did I receive an Important Notice of Regarding the Availability of Proxy Materials in the mail instead of a printed set of proxy materials?

Pursuant to rules adopted by the Securities and Exchange Commission (the “SEC”), we are permitted to furnish our proxy materials over the internet to our stockholders by delivering an Important Notice Regarding the Availability of Proxy Materials (the “Notice”) in the mail rather than mailing printed copies of a full set of proxy materials. The Notice instructs stockholders on how to access and review this Proxy Statement and Annual Report on Form 10-K over the internet at http://materials.proxyvote.com. The Notice also instructs stockholders on how they may submit their proxy over the telephone or internet and vote online at the Annual Meeting. If a stockholder who received a Notice would like to receive a printed copy of our proxy materials, such stockholder should follow the instructions for requesting these materials contained in the Notice.

You can find directions on how to instruct us to send future proxy materials to you by email at www.proxyvote.com. Choosing to receive future proxy materials by email will save us the cost of printing and mailing documents to you and will reduce the impact of our annual meetings on the environment. If you choose to receive future proxy materials by email, you will receive an email message next year with instructions containing a link to those materials and a link to the proxy voting website. Your election to receive proxy materials by email will remain in effect until you terminate it.

What is a virtual Annual Meeting?

The Annual Meeting will be conducted as a virtual meeting of stockholders by means of a live webcast. We believe that hosting a virtual meeting will enable greater stockholder attendance and participation from any location, improved communication and cost savings to our stockholders and support the health of our stockholders and employees given the public health impact of the ongoing COVID-19 pandemic. You can virtually attend the Annual Meeting by visiting www.virtualshareholdermeeting.com/THRX2022 in advance of the meeting. In order to be able to attend the Annual Meeting, you will need the 16-digit control number, which is located on your Notice, on your proxy card or in the instructions accompanying your proxy materials. Instructions on how to participate in the Annual Meeting are also posted online at www.proxyvote.com. There will not be a physical meeting location and you will not be able to attend in person.

We invite you to virtually attend the Annual Meeting and request that you vote on the proposals described in this Proxy Statement. However, you do not need to attend the virtual meeting to vote your shares. Instead, you may vote by internet, by telephone, or, if you requested and received paper copies of the proxy materials by mail, you may also vote by completing and mailing your proxy card.

The Annual Meeting starts at 10:00 a.m. (Eastern Daylight Time) on Friday, June 10, 2022. We encourage you to access the meeting website prior to the start time to allow time for check in. If you encounter any difficulties accessing the virtual meeting during the check-in or meeting time, please call the technical support number that will be posted on the virtual stockholder meeting log-in page.

To access the Annual Meeting, follow the instructions on your Notice or proxy card (if you requested and received a printed copy of the proxy materials). If your shares are not registered in your own name and you plan to vote your shares

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in person at the Annual Meeting, you should contact your broker or agent to obtain a legal proxy or broker’s proxy card and bring it to the Annual Meeting in order to vote.

If you wish to submit a question the day of the Annual Meeting, you may log in to the virtual meeting platform at www.virtualshareholdermeeting.com/THRX2022 using the procedure described above, type your question into the “Ask a Question” field, and click “Submit.” Questions pertinent to meeting matters will be answered during the Annual Meeting, subject to time constraints. Questions regarding personal matters, including those related to employment, are not pertinent to annual meeting matters and, therefore, will not be answered.

What is the difference between holding shares as a stockholder of record and as a beneficial owner?

Stockholders of record - If your shares are registered directly in your name with our transfer agent, ComputerShare Trust Company, N.A., you are considered, with respect to those shares, the “stockholder of record,” and the Notice was provided to you directly by us. As the stockholder of record, you have the right to grant your voting proxy directly to the individuals listed on the proxy card or to vote in person at the Annual Meeting.

Beneficial owners - Many Theseus stockholders hold their shares through a broker, trustee or other nominee, rather than directly in their own name. If your shares are held in a brokerage account or by a bank or another nominee (commonly referred to as being held in “street name”), you are considered the “beneficial owner” of such shares. The Notice was forwarded to you by your broker, trustee or nominee who is considered, with respect to those shares, the stockholder of record.

As the beneficial owner, you have the right to direct your broker, trustee or nominee on how to vote your shares. Beneficial owners are also invited to attend the Annual Meeting. However, since beneficial owners are not stockholders of record, you may not vote your shares in person at the Annual Meeting unless you follow your broker’s procedures for obtaining a legal proxy. If you request a printed copy of the proxy materials by mail, your broker or nominee will provide a voting instruction card for you to use.

How many shares must be present or represented to conduct business at the Annual Meeting?

A quorum of stockholders is necessary to hold a valid meeting. A quorum will be present if a majority of all shares of Common Stock outstanding on April 14, 2022, the record date, are represented at the meeting by stockholders present online or by proxy. On the record date, there were in the aggregate 38,702,650 shares of Common Stock outstanding and entitled to vote. Thus, 19,351,326 shares of Common Stock must be represented by stockholders present at the Annual Meeting or by proxy to have a quorum.

Your shares will be counted towards the quorum only if you submit a valid proxy vote or vote at the Annual Meeting. Abstentions and broker non-votes will be counted towards the quorum requirement.

Who can vote at the Annual Meeting?

Only stockholders of record at the close of business on April 14, 2022 will be entitled to vote at the Annual Meeting. On this record date, there were 38,702,650 shares of Common Stock outstanding, our only class of voting stock. The holders of our Common Stock have the right to one vote for each share of Common Stock they held as of the record date. We do not have cumulative voting rights for the election of directors.

In accordance with Delaware law, a list of stockholders entitled to vote at the meeting will be accessible for ten days prior to the meeting at our principal place of business, 314 Main Street, Cambridge, Massachusetts 02142, between the hours of 9:00 a.m. and 5:00 p.m. (Eastern Daylight Time).

How are votes counted?

Each share of Common Stock is entitled to one vote. Votes will be counted by the inspector of elections appointed for the Annual Meeting. Prior to the Annual Meeting, the inspector will sign an oath to perform their duties in an impartial manner and according to the best of their ability. The inspector will determine the number of shares represented at the

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Annual Meeting and the validity of proxies and ballots, count all votes and ballots and perform certain other duties. The determination of the inspector of elections as to the validity of proxies will be final and binding

How do I vote?

Stockholder of Record: Shares Registered in Your Name

If on April 14, 2022, your shares were registered directly in your name with our transfer agent, ComputerShare Trust Company, N.A., then you are a stockholder of record. Stockholders of record may vote at the Annual Meeting or vote by proxy. Whether or not you plan to attend the Annual Meeting, we urge you to vote by proxy on the internet or via telephone as instructed below or submit your proxy card to ensure your vote is counted.

If you are a stockholder of record, you may vote at the Annual Meeting or by one of the following methods:

The method you use to vote will not limit your right to vote at the Annual Meeting if you decide to virtually attend the Annual Meeting.

We provide internet proxy voting to allow you to vote your shares on-line, with procedures designed to ensure the authenticity and correctness of your proxy vote. 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.

Beneficial Owner: Shares Registered in the Name of a Broker or Bank

If on April 14, 2022, your shares were held in an account at a brokerage firm, bank, dealer or other similar organization, then you are the beneficial owner of shares held in “street name” and these proxy materials are being forwarded to you by that organization. The organization holding your account is considered the stockholder of record for purposes of voting at the Annual Meeting. As a beneficial owner, you may direct your broker or other agent on how to vote the shares in your account. Instructions for granting proxies with these proxy materials from that organization rather than from us. A number of brokers and banks participate in a program provided through Broadridge Financial Services that enables beneficial holders to grant proxies to vote shares via telephone or the internet. If your shares are held by a broker or bank that participates in the Broadridge program, you may grant a proxy to vote those shares telephonically by calling the telephone number on the instructions received from your broker or bank, or via the internet at Broadridge’s website at www.proxyvote.com. To vote by internet during the Annual Meeting, you must obtain your 16-digit control number from your broker, bank, or other agent.

You do not need to attend the virtual Annual Meeting to vote your shares. Shares represented by valid proxies, received in time for the Annual Meeting and not revoked prior to the Annual Meeting, will be voted at the Annual Meeting. For instructions on how to change or revoke your proxy, see “Can I change or revoke my vote after submitting my proxy?” below.

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How will my shares be voted if I mark “Abstain” on my proxy card or when voting on the internet or via telephone?

We will count a properly executed proxy card or submitted vote marked “Abstain” as present for purposes of determining whether a quorum is present, but the represented shares will not be voted at the Annual Meeting for the proposals so marked.

What happens if I do not give specific voting instructions?

Stockholder of Record: Shares Registered in Your Name

If you are a stockholder of record and you:

your shares will be voted (i) “For” the election of both director nominees for Class I director and (ii) “For” ratification of the appointment of Ernst & Young LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2022, as disclosed herein. If any other matter is properly presented at the meeting, your proxy (one of the individuals named on your proxy card) will vote your shares using their best judgment.

Beneficial Owner: Shares Registered in the Name of a Broker or Bank

If you are not a record holder, such as where your shares are held through a broker, nominee, fiduciary or other custodian, and do not provide voting instructions to the record holder of the shares in accordance with the record holder’s requirements the organization that holds your shares may generally vote your shares with respect to “discretionary” items, but not with respect to “non-discretionary” items. Discretionary items are proposals considered routine under the rules of the New York Stock Exchange (“NYSE”) on which your broker may vote shares held in street name without your voting instructions. On non-discretionary items for which you do not give your broker instructions, the shares will be treated as broker non-votes. Under current NYSE rules, any election of a member of our Board of Directors, whether contested or uncontested, is considered “non-discretionary” and therefore brokers are not permitted to vote your shares held in street name for the election of directors in the absence of instructions from you. Proposal 1 is a non-discretionary matter and therefore if you hold your shares through a broker, nominee, fiduciary or other custodian, your shares will not be voted on those proposals unless you provide voting instructions to the record holder. Proposal 2 is a discretionary matter therefore brokers are permitted to vote your shares held in street name for the election of directors in the absence of instructions from you. However several large brokerage firms, such as Charles Schwab and TD Ameritrade, have recently announced that they have eliminated discretionary voting even for “routine” matters. Therefore, if you hold your shares through a broker, nominee, fiduciary or other custodian, then your shares might not be voted, even for “routine” matters if you do not give voting instructions to your broker.

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What proposals will be voted on at the Annual Meeting?

The following chart sets for the proposals scheduled for a vote at the Annual Meeting, our Board of Directors recommendation with respect to such proposals, the vote required for such proposals to be approved and whether broker discretionary voting is allowed on such proposal.

“Plurality” means that the nominees for director receiving the greatest number of “FOR” votes will be elected. Withheld votes and “broker non-votes” will have no effect on the election of a nominee.

“Majority Voted” means the affirmative (“FOR”) vote of the majority of the outstanding shares of Common Stock that are present at the Annual Meeting or represented by proxy and cast affirmatively or negatively on such proposal. Abstentions and broker non-votes will not be counted “For” or “Against” this proposal and will have no effect on this proposal.

Broker Discretionary Voting occurs when a broker does not receive voting instructions from the beneficial owner and votes those shares in its discretion on any proposal on which it is permitted to vote.

What happens if additional matters are presented at the Annual Meeting?

If any other matters are properly presented for consideration at the Annual Meeting, including, among other things, consideration of a motion to adjourn the Annual Meeting to another time or place (including, without limitation, for the purpose of soliciting additional proxies), the persons named in the proxy card and acting thereunder will have discretion to vote on those matters in accordance with their best judgment. We do not currently anticipate that any other matters will be raised at the Annual Meeting.

Can I change or revoke my vote after submitting my proxy?

Yes. You can revoke your proxy at any time before the final vote at the Annual Meeting.

If you are a stockholder of record, you may change or revoke your proxy in any one of four ways:

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If you are a beneficial owner of shares held in street name, you may change your vote (1) by submitting new voting instructions to your broker, trustee or other nominee or (2) if you have obtained a legal proxy from the broker, trustee or other nominee that holds your shares giving you the right to vote the shares, by attending the Annual Meeting and voting in person.

Who will solicit proxies on behalf of our Board of Directors?

Proxies may be solicited on behalf of our Board of Directors, without additional compensation, by the Company’s directors and employees.

The original solicitation of proxies by mail may be supplemented by telephone, telegram, facsimile, electronic mail, and personal solicitation by our directors and officers (who will receive no additional compensation for such solicitation activities). You may also be solicited by advertisements in periodicals, press releases issued by us and postings on our corporate website at www.theseusrx.com. Unless expressly indicated otherwise, information contained on our corporate website is not part of this Proxy Statement.

Who will bear the cost of soliciting votes for the Annual Meeting?

We will bear all expenses of this solicitation, including the cost of preparing and mailing these proxy materials. We may reimburse brokerage firms, custodians, nominees, fiduciaries and other persons representing beneficial owners of Common Stock for their reasonable expenses in forwarding solicitation material to such beneficial owners. Directors, officers and employees of Theseus may also solicit proxies in person or by other means of communication. Such directors, officers and employees will not be additionally compensated but may be reimbursed for reasonable out-of-pocket expenses in connection with such solicitation. We may engage the services of a professional proxy solicitation firm to aid in the solicitation of proxies from certain brokers, bank nominees and other institutional owners. Our costs for such services, if retained, will not be significant.

What does it mean if I receive more than one proxy card or Notice?

If you receive more than one proxy card or Notice, your shares are registered in more than one name or are registered in different accounts. Please complete, sign and return each proxy card or submit a proxy for each Notice to ensure that all of your shares are voted.

What if I share an address with another stockholder of Theseus?

If you reside at the same address as another Theseus stockholder, you and other Theseus stockholders residing at the same address may receive a single copy of the Notice. This process, which has been approved by the SEC, is called “householding.” Once you receive notice from your broker or other nominee record holder that it will be “householding” our proxy materials, the practice will continue until you are otherwise notified or until you notify them that you no longer want to participate in the practice. Stockholders who participate in householding will continue to have access to and utilize separate proxy voting instructions.

If you wish to receive a separate copy of the Notice, you may do so by making a written or oral request to: Theseus Pharmaceuticals, Inc., 314 Main Street, Cambridge, Massachusetts 02142, Attention: Corporate Secretary, or by calling (857) 400-9491. Upon your written or oral request, we will promptly deliver a separate copy to you. If you want to receive your own set of our proxy materials in the future or, if you share an address with another stockholder and together both of you would like to receive only a single set of proxy materials, you should contact your broker or other nominee record holder directly or you may contact us at the above address and phone number. The Annual Report, Proxy Statement and Notice are also available at http://materials.proxyvote.com.

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Is my vote confidential?

Proxy instructions, ballots, and voting tabulations that identify individual stockholders are handled in a manner that protects your voting privacy. Your vote will not be disclosed either within Theseus or to third parties, except as necessary to meet applicable legal requirements, to allow for the tabulation of votes and certification of the vote, or to facilitate a successful proxy solicitation.

How can I find out the results of the voting at the Annual Meeting?

Preliminary voting results will be announced at the Annual Meeting. Final voting results will be available on a Current Report on Form 8-K filed with the SEC within four business days after the end of the Annual Meeting.

When are stockholder proposals and nominations for director due for next year’s Annual Meeting?

If you wish to submit a proposal to be considered for inclusion in next year’s proxy materials, your proposal must be in proper form according to SEC Regulation 14A, Rule 14a-8 and received by the Corporate Secretary of the Company on or before December 31, 2022. If you wish to submit a proposal to be presented at the 2023 Annual Meeting of Stockholders, but which will not be included in the Company’s proxy materials, including to nominate a director, your notice must be received by the Corporate Secretary of the Company at Theseus Pharmaceuticals, Inc., 314 Main Street, Cambridge, Massachusetts 02142, Attention: Corporate Secretary, no earlier than February 10, 2023 and no later than March 12, 2023. Proposals that are not received in a timely manner will not be voted on at the 2023 annual meeting of stockholders. If a proposal is received on time, the proxies that management solicits for the meeting may still exercise discretionary voting authority on the proposal under circumstances consistent with the proxy rules of the SEC. You are advised to review our amended and restated bylaws (the “bylaws”), which contain additional requirements about advance notice of stockholder proposals and director nominations. Stockholders may request a free copy of our bylaws from contacting our Corporate Secretary at 314 Main Street, Cambridge, Massachusetts 02142, Attention: Corporate Secretary.

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Executive Officers

Timothy P. Clackson, Ph.D. has served as our President and Chief Executive Officer and as a member of our Board of Directors since April 2021. From May 2018 until April 2021, Dr. Clackson was President, Chief Technology Officer and Executive Vice President of Research and Development at Xilio Therapeutics Inc. Prior to joining Xilio, Dr. Clackson served as President of Research and Development and Chief Scientific Officer at ARIAD Pharmaceuticals, Inc., which was acquired by Takeda Pharmaceutical Company Limited in February 2017, from June 2010 to May 2017. Prior to that, Dr. Clackson served as ARIAD’s Senior Vice President and Chief Scientific Officer from 2003, and in other roles from December 1994. Dr. Clackson has served as both a member of the board of directors of Elevation Oncology, Inc. (Nasdaq: ELEV) since May 2020, and as a member of the board of directors of Forma Therapeutics Holdings, Inc. (Nasdaq: FMTX) since March 2018. Dr. Clackson has also served as a member of the board of the Massachusetts Biotechnology Council since March 2014. During the past five years, Dr. Clackson served as a member of the board of directors of Spring Bank Pharmaceuticals, Inc., until the business combination with F-star Therapeutics Limited in November 2020 (formerly Nasdaq: SBPH). Dr. Clackson holds a Bachelor of Arts, with Honors, in Biochemistry from Oxford University and a Doctorate in Biology from the University of Cambridge. We believe that Dr. Clackson is qualified to serve on our Board of Directors because of the perspective and experience he provides as our President and Chief Executive Officer, in addition to his extensive leadership experience in our industry and his educational background in biology and biochemistry.

Bradford D. Dahms has served as our Chief Financial Officer since May 2021. From September 2019 to May 2021, Mr. Dahms served as Chief Financial Officer of Selecta Biosciences Inc. (Nasdaq: SELB). Prior to joining Selecta, Mr. Dahms served as Senior Vice President—Healthcare Investment Banking at Cantor Fitzgerald & Co., an investment bank, from April 2014 to August 2019. He also served as an analyst at RBC Capital Markets from 2012 to 2014, and at JPMorgan Chase & Co. from 2010 to 2012, and at JPMorgan Chase & Co. from 2010 to 2012. Mr. Dahms holds a Bachelor of Science degree in Economics, with honors, from The Ohio State University.

William C. Shakespeare, Ph.D. is a founding member of Theseus Pharmaceuticals, Inc. and has served as our President of Research and Development since May 2018. From May 2018 to April 2021, Dr. Shakespeare served as a member of our Board of Directors. From 2009 to January 2017, Dr. Shakespeare was Vice President of Drug Discovery at ARIAD Pharmaceuticals, Inc., which was acquired by Takeda Pharmaceutical Company Limited in February 2017. Dr. Shakespeare holds a Doctorate in Chemistry from the University of New Hampshire and a Bachelor of Science in Chemistry from Gettysburg College.

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David C. Dalgarno, D.Phil. is a founding member of Theseus Pharmaceuticals, Inc. and has served as our Chief Technical Officer since June 2018. From March 1992 to February 2017, Dr. Dalgarno held several roles at ARIAD Pharmaceuticals, Inc., which was acquired by Takeda Pharmaceutical Company Limited in February 2017, including most recently as Vice President of the Research Technologies Discovery Group. Dr. Dalgarno holds a Doctorate in Chemistry and a Bachelor of Arts in Chemistry from the University of Oxford.

Victor M. Rivera, Ph.D. is a founding member of Theseus Pharmaceuticals, Inc. and has served as our Chief Scientific Officer since June 2018. From February 1993 to February 2017, Dr. Rivera held several roles at ARIAD Pharmaceuticals, Inc., which was acquired by Takeda Pharmaceutical Company Limited in February 2017, including most recently as Vice President, Preclinical and Translational Research. Dr. Rivera holds a Doctorate in Microbiology and Molecular Genetics from Harvard Medical School and a Bachelor of Arts in Molecular Biology, magna cum laude, from Princeton University.

David P. Kerstein, M.D. has served as our Chief Medical Officer since October 2020. From November 2018 to July 2020, Dr. Kerstein served as Chief Medical Officer of Achiano Therapeutics Ltd. Dr. Kerstein also served as Senior Medical Director of Oncology Clinical Research at Takeda Pharmaceutical Company Limited, from February 2017 to November 2018. From 2014 to 2017, Dr. Kerstein was Medical Director and then Senior Medical Director of Clinical Research at ARIAD Pharmaceuticals, Inc. (which was acquired by Takeda in February 2017). Prior to that, Dr. Kerstein was Director of Clinical Development and Regulatory Affairs at Boston Biomedical, Inc., a wholly-owned subsidiary of Sumitomo Dainippon Pharma Co. Ltd. Dr. Kerstein holds a Doctorate of Medicine from Tufts University School of Medicine and a Bachelor of Science in Biology, summa cum laude, from Tufts University.

Non-Employee Directors

Iain D. Dukes, MA, D.Phil. is a founding member of Theseus Pharmaceuticals, Inc. and has served as our Chairman since May 2021 and as a member of our Board of Directors since June 2018. From June 2018 until April 2021, Dr. Dukes served as our Chief Executive Officer. Dr. Dukes is a Venture Partner at OrbiMed Advisors LLC, an investment firm, which he joined in August 2016. Dr. Dukes has served as the Chief Executive Officer of Viriom Inc. since February 2019 and has also served as the Executive Chairman of Angiex Inc. since February 2020. In September 2017, Dr. Dukes co-founded Kartos Therapeutics, Inc. and currently serves as President. Dr. Dukes previously served as Senior Vice President and Head of Business Development and Licensing for Merck Research Laboratories from August 2013 through May 2016. Prior to joining Merck, Dr. Dukes was Vice President of External Research & Development at Amgen, Inc. (Nasdaq: AMGN) from August 2010 to August 2013. From October 2017 to July 2020, Dr. Dukes was a board member and Chairman of KaNDy Therapeutics Ltd., which was acquired by Bayer AG in September 2020. From January 2020 to June 2020, Dr. Dukes also co-founded Telios Pharmaceuticals, Inc., where he serves as President. Dr. Dukes currently serves on the board of directors of NeRRe Therapeutics Ltd., ReViral Limited, ENYO Pharma SA and Ikena Oncology, Inc. (Nasdaq: IKNA). Since August 2016, Dr. Dukes has also served as chairman of the board of directors of Iovance Biotherapeutics Inc. (Nasdaq: IOVA). Dr. Dukes holds Master of Jurisprudence and Doctor of Philosophy degrees from the University of Oxford, a Master of Science degree in Cardiovascular Studies from the University of Leeds and a Bachelor of Science degree in Pharmacology from the University of Bath. We believe that Dr. Dukes is qualified to serve as a member of our Board of Directors because of his valuable and extensive experience gained from prior service as our Chief Executive Officer, as well as his extensive experience in the pharmaceutical industry, including his service in senior management roles.

Carl Gordon, CFA, Ph.D. has served as a member of our Board of Directors since June 2018. Dr. Gordon is a founding member, Managing Partner, and Co-Head of Global Private Equity at OrbiMed Advisors LLC, an investment firm. Dr. Gordon currently serves on the boards of directors of Adicet Bio, Inc. (Nasdaq: ACET), Compass Therapeutics Inc. (Nasdaq: CMPX), Gemini Therapeutics Inc. (Nasdaq: GMTX), Keros Therapeutics Inc. (Nasdaq: KROS), Kinnate Biopharma, Inc. (Nasdaq: KNTE) and Terns Pharmaceuticals, Inc. (Nasdaq: TERN), as well as several private companies. Dr. Gordon previously served on the boards of directors of several companies, including Alector Inc. (Nasdaq: ALEC), ARMO Biosciences, Inc. (formerly Nasdaq: ARMO), Arsanis, Inc. (which merged with X4 Pharmaceuticals, Inc.) (formerly Nasdaq: ASNS), Intellia Therapeutics, Inc. (Nasdaq: NTLA), Passage Bio Inc., Prevail Therapeutics Inc. (formerly Nasdaq: PRVL), Selecta Biosciences, Inc. (Nasdaq: SELB), SpringWorks Therapeutics Inc. (Nasdaq: SWTX) and Turning Point Therapeutics, Inc. (Nasdaq: TPTX). Dr. Gordon received a Bachelor of Arts in Chemistry from Harvard College, a Doctorate in Molecular Biology from the Massachusetts Institute of Technology and

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was a Fellow at The Rockefeller University. We believe that Dr. Gordon is qualified to serve on our Board of Directors due to his extensive business experience, and experience in venture capital and the life science industry.

Michael Rome, Ph.D. has served as a member of our Board of Directors since January 2021. Dr. Rome has served in various roles with Foresite Capital Management, an investment firm, since August 2016, including serving as Managing Director since May 2020. Prior to that, he served as an Analyst at DAFNA Capital Management LLC, a healthcare hedge fund, from September 2015 to July 2016. Dr. Rome also worked in early-stage drug development as a Senior Scientist for Vault Pharma, an academic start-up out of the California NanoSystems Institute at the University of California, Los Angeles from April 2014 to September 2015. Dr. Rome currently serves on the board of directors of Kinnate Biopharma Inc. (Nasdaq: KNTE) and a privately held company, Remix Therapeutics Inc. Dr. Rome has also held board observer roles (past and present) at Turning Point Therapeutics, Inc. (Nasdaq: TPTX), Nurix Therapeutics, Inc. (Nasdaq: NRIX) and several privately held companies, including Maze Therapeutics, Inc. and PACT Pharma, Inc. Dr. Rome holds a Bachelor of Science in Molecular, Cellular and Developmental Biology from the University of California, Los Angeles and a Doctorate in Biochemistry, Biophysics and Molecular Biology from the California Institute of Technology. We believe Dr. Rome is qualified to serve on our Board of Directors because of his extensive experience in investing in diverse biotechnology companies and his depth of knowledge and substantial experience as a research scientist.

Kathy Yi, MBA has served as a member of our Board of Directors since June 2021. Ms. Yi serves as Chief Operating and Financial Officer of Affini-T Therapeutics. Previously Ms. Yi has served as Chief Financial officer of Cerevel Therapeutics Holdings, Inc. (Nasdaq: CERE) from June 2019 to November 2021. Previously, Ms. Yi served as Executive Vice President, Chief Financial Officer and Secretary of Sangamo Therapeutics, Inc. (Nasdaq: SGMO), from February 2017 to June 2019. Prior to Sangamo Therapeutics, Ms. Yi was Head of Finance at Novartis Pharmaceutical Corporation (NYSE: NVS) from February 2014 to February 2017. From 2007 to 2014, Ms. Yi held various financial management positions of increasing seniority at Life Technologies Corp., which was acquired by Thermo Fisher Scientific in 2014, including Finance Leader, Corporate FP&A from 2012 to 2014, Director of Finance, M&A/Corporate Development, from 2010 to 2012, and Director of Finance, Global Manufacturing Operations, from 2007 to 2010. From 2001 to 2007, Ms. Yi held increasing roles of responsibilities in corporate finance at Intel Corporation. Ms. Yi holds a Bachelor of Science in Chemical Engineering from the University of California at Berkeley and a Master of Business Administration from Columbia Business School. We believe Ms. Yi is qualified to serve on our Board of Directors due to her extensive business, financial and accounting experience as an executive in the pharmaceutical industry.

Corporate Governance and Board of Directors Matters

Board of Directors Composition

Our business affairs are managed under the direction of our Board of Directors, which currently consists of five members. Our Board of Directors is divided into three classes with staggered three-year terms. At each annual meeting of stockholders, the successors to directors whose terms then expire will be elected to serve from the time of election and qualification until the third annual meeting following election. Our directors are divided among the three classes as follows:

Directors in a particular class will be elected for three-year terms at the annual meeting of stockholders in the year in which their terms expire. As a result, only one class of directors will be elected at each annual meeting of our stockholders, with the other classes continuing for the remainder of their respective three-year terms. Each director’s term continues until the election and qualification of their successor, or the earlier of their death, resignation or removal. The classification of our Board of Directors may have the effect of delaying or preventing changes in our control or management.

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Director Independence

Our Common Stock is listed on the Nasdaq Global Select Market (“Nasdaq”). Under the rules of Nasdaq, independent directors must comprise a majority of a listed company’s board of directors within 12 months from the date of listing. In addition, the rules of Nasdaq require that, subject to specified exceptions, (i) a majority of the members of a listed company’s audit, compensation and nominating and corporate governance committees be independent within 90 days from the date of listing and (ii) each member of such committees must be independent within 12 months from the date of listing. Audit committee members must also satisfy the independence criteria set forth in Rule 10A-3 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”). Under the rules of Nasdaq, a director will only qualify as an “independent director” if, in the opinion of that company’s board of directors, that person does not have a relationship that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director.

To be considered to be independent for purposes of Rule 10A-3 under the Exchange Act and under the rules of Nasdaq, a member of an audit committee of a listed company may not, other than in their capacity as a member of the audit committee, the board of directors or any other board committee: (1) accept, directly or indirectly, any consulting, advisory or other compensatory fee from the listed company or any of its subsidiaries or (2) be an affiliated person of the listed company or any of its subsidiaries. Each of Dr. Rome and Ms. Yi qualifies as an independent director pursuant to Rule 10A-3.

In March 2022, our Board of Directors undertook a review of its composition, the composition of its committees and the independence of our directors and considered whether any director has a material relationship with us that could compromise their ability to exercise independent judgment in carrying out their responsibilities. Based upon information requested from and provided by each director concerning their background, employment and affiliations, including family relationships, our Board of Directors, based in part on the recommendation of its nominating and corporate governance committee, has determined that each of Dr. Rome and Ms. Yi does not have a relationship that would interfere with the exercise of independent judgment in carrying out the responsibilities of a director and that each of these directors is “independent” as that term is defined under the applicable rules of Nasdaq. We currently rely on the phase-in period under these rules described above, which permits fewer than a majority of our Board of Directors to be independent, provided we satisfy such requirement within one year of the date of the listing of our Common Stock. Accordingly, we intend to have a majority of our Board of Directors consist of independent directors prior to October 7, 2022, the one year anniversary of the date our Common Stock was listed.

In making these determinations, our Board of Directors considered the current and prior relationships that each non-employee director has with our company and all other facts and circumstances our Board of Directors deemed relevant in determining independence, including the beneficial ownership of our capital stock by each non-employee director, and the transactions involving them described in the section titled “Certain Relationships and Related Party Transactions” elsewhere in this Proxy Statement. There are no family relationships among any of our directors or executive officers.

Board of Directors Leadership Structure

Our Board of Directors is currently chaired by Dr. Dukes. As a general policy, our Board of Directors believes that separation of the positions of Chairperson of our Board of Directors and Chief Executive Officer reinforces the independence of our Board of Directors from management, creates an environment that encourages objective oversight of management’s performance and enhances the effectiveness of our Board of Directors as a whole. As such, Dr. Clackson serves as our Chief Executive Officer while Dr. Dukes serves as the Chairman of our Board of Directors but is not an officer of the Company. We currently expect and intend the positions of Chairperson of our Board of Directors and Chief Executive Officer to continue to be held by two individuals in the future.

Meetings of Our Board of Directors

Our Board of Directors met 12 times during 2021. Each member of our Board of Directors attended at least 75% or more of the aggregate of the meetings of our Board of Directors and of the committees on which they served, held during the period for which such member was a director or committee member. Members of our Board of Directors and its committees also consulted informally with management from time to time and acted at various times by written consent

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without a meeting during 2021. While we do not have a formal policy regarding attendance by members of our Board of Directors at our annual meetings of stockholders, all directors are encouraged to attend.

Role of Our Board of Directors in Risk Oversight

One of the key functions of our Board of Directors is informed oversight of our risk management process. In particular, our Board of Directors is responsible for monitoring and assessing strategic risk exposure. Our executive officers are responsible for the day-to-day management of the material risks we face. Our Board of Directors administers its oversight function directly as a whole. Our Board of Directors also administers its oversight through various standing committees, that address risks inherent in their respective areas of oversight. For example, our audit committee is responsible for overseeing the management of risks associated with our financial reporting, accounting and auditing matters; our compensation committee oversees the management of risks associated with our compensation policies and programs; and our nominating and corporate governance committee oversees the management of risks associated with director independence, conflicts of interest, composition and organization of our Board of Directors and director succession planning.

Committees of Our Board of Directors

Our Board of Directors has established an audit committee, a compensation committee, a nominating and corporate governance committee and an equity awards committee. In the future, our Board of Directors may establish other committees to facilitate the management of our business. Our Board of Directors and its committees sets schedules for meeting throughout the year and can also hold special meetings and act by written consent from time to time, as appropriate. Members serve on these committees until their resignation or until otherwise determined by our Board of Directors.

Our Board of Directors has delegated various responsibilities and authority to committees as generally described below. The committees regularly report on their activities and actions to the full Board of Directors. Each committee of our Board of Directors has a written charter approved by our Board of Directors.

The following table provides membership information for each of such Board of Directors committees as of April 14, 2022, the record date for the Annual Meeting:

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Audit Committee

The members of our audit committee are Ms. Yi, Dr. Gordon and Dr. Rome. Ms. Yi is the chair of the audit committee. Each member of our audit committee can read and understand fundamental financial statements. Our Board of Directors has determined that Ms. Yi qualifies as an audit committee financial expert within the meaning of SEC regulations and meets the financial sophistication requirements of Nasdaq. The designation does not impose on Ms. Yi any duties, obligations or liability that are greater than are generally imposed on her as a member of our audit committee and our Board of Directors, and her designation as audit committee financial expert pursuant to this SEC requirement does not affect the duties, obligations or liability of any other member of our audit committee or our Board of Directors. The audit committee met four times during 2021.

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We currently rely on the phase-in rules of Rule 10A-3 under the Exchange Act and the Nasdaq rules with respect to the requirement that the audit committee be composed entirely of members of our Board of Directors who satisfy the standards of independence established for independent directors under the Nasdaq rules and the additional independence standards applicable to audit committee members established pursuant to Rule 10A-3 under the Exchange Act, as determined by our Board of Directors. We expect that by the first anniversary of our listing on Nasdaq, our audit committee will comply with the applicable independence requirements. Ms. Yi and Dr. Rome are independent under the rules and regulations of the SEC and the listing standards of Nasdaq applicable to audit committee members.

Our audit committee operates under a written charter that satisfies the applicable rules of the SEC and the listing standards of Nasdaq. Our audit committee charter can be found on the Investor Relations section of our website at https://theseusrx.com/. Our audit committee assists our Board of Directors with its oversight of the integrity of our financial statements; our compliance with legal and regulatory requirements; the qualifications, independence and performance of the independent registered public accounting firm; the design, implementation and performance of any internal audit function, if and when implemented; and our risk assessment and risk management. Among other things, our audit committee is responsible for reviewing and discussing with our management the adequacy and effectiveness of our disclosure controls and procedures. The audit committee discusses with our management and independent registered public accounting firm the annual audit plan and scope of audit activities, scope and timing of the annual audit of our financial statements, and the results of the audit, quarterly reviews of our financial statements and, as appropriate, initiate inquiries into certain aspects of our financial affairs. Our audit committee is responsible for establishing and overseeing procedures for the receipt, retention and treatment of any complaints regarding accounting, internal accounting controls or auditing matters, as well as for the confidential and anonymous submissions by our employees of concerns regarding questionable accounting or auditing matters. In addition, our audit committee has direct responsibility for the appointment, compensation, retention and oversight of the work of our independent registered public accounting firm. Our audit committee has sole authority to approve the hiring and discharging of our independent registered public accounting firm, all audit engagement terms and fees and all permissible non-audit engagements with the independent auditor. Our audit committee reviews and oversees all related person transactions in accordance with our policies and procedures.

Compensation Committee

The members of our compensation committee are Dr. Rome and Ms. Yi. Dr. Rome is the chair of the compensation committee.

We currently rely on the phase-in rules of Nasdaq with respect to the requirement that the compensation committee be composed entirely of members of our Board of Directors who satisfy the standards of independence established for independent directors under the Nasdaq rules, as determined by our Board of Directors. We expect that all members of our compensation committee will satisfy the applicable independence standards by the first anniversary of our listing on Nasdaq. Each of Dr. Rome and Ms. Yi is independent under the rules and regulations of the SEC and the listing standards of Nasdaq applicable to compensation committee members, is a “non-employee director,” as defined in Rule 16b-3 adopted under Section 16 of the Exchange Act and an “outside director” under Regulation Section 1.162-27 adopted under Section 162(m) of the Code of 1986, as amended.

Our compensation committee operates under a written charter that satisfies the applicable rules of the SEC and the listing standards of Nasdaq. Our compensation committee charter can be found on the Investor Relations section of our website at https://theseusrx.com/. The compensation committee, which was formed in October 2021 in connection with our initial public offering, held no meetings during 2021. Prior to our initial public offering, compensation matters were approved by our Board of Directors. Our compensation committee’s primary purpose is to assist our Board of Directors with its oversight of the forms and amount of compensation for our executive officers (including officers reporting under Section 16 of the Exchange Act), the administration of our equity and non-equity incentive plans for employees and other service providers and certain other matters related to our compensation programs. In addition, our compensation committee, among other responsibilities, establishes annual corporate performance goals and objectives relevant to the compensation of our executive officers, and evaluates the performance of our Chief Executive Officer and, in consultation with him, evaluates the performance of our other executive officers (including officers reporting under Section 16 of the Exchange Act); recommends to our Board of Directors the form and amount of cash- and equity-based and other compensation to non-employee members of the Board of Directors; review and make recommendations to our

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Board of Directors with respect to our equity and non-equity incentive plans; and assist our Board of Directors in its oversight of the development, implementation and effectiveness of our policies and strategies relating to our human capital management function. Our principal executive officer does not participate in the determination or discussion of his own compensation or the compensation of directors. However, our principal executive officer makes recommendations to the compensation committee regarding the amount and form of the compensation of the other executive officers, and participates in our compensation committee’s deliberations about their compensation. No other executive officers participate in the determination of the amount or form of the compensation of executive officers or directors.

Nominating and Corporate Governance Committee

The sole member and chair of our nominating and corporate governance committee is Ms. Yi. Ms. Yi is independent under the rules and regulations of the SEC and the listing standards of Nasdaq applicable to nominating and corporate governance committee members.

Our nominating and corporate governance committee operates under a written charter that satisfies the applicable rules of the SEC and the listing standards of Nasdaq. Our nominating and corporate governance committee charter can be found on the Investor Relations section of our website at https://theseusrx.com/. The nominating and corporate governance committee, which was formed in October 2021 in connection with our initial public offering, held no meetings during 2021. Our nominating and corporate governance committee assists our Board of Directors with its oversight of and identification of individuals qualified to become members of our Board of Directors, consistent with criteria approved by our Board of Directors, and selects, or recommends that our Board of Directors select, director nominees, develops and recommends to our Board of Directors a set of corporate governance guidelines and oversees the evaluation of our Board of Directors.

Our nominating and corporate governance committee considers the following factors, in no particular order of importance: (a) various and relevant career experience, (b) relevant skills, such as an understanding of our business, (c) financial expertise, (d) diversity and (e) local and community ties. However, our nominating and corporate governance committee retains the right to modify these qualifications from time to time.

Under our corporate governance guidelines diversity is one of several critical factors that the nominating and corporate governance committee considers when evaluating the composition of our Board of Directors, amongst other critical selection criteria. We consider various diversity factors when considering director candidates, including race, ethnicity, gender, national origin, and geography. Our Board of Directors currently includes directors with a range of diversity. We believe each director contributes to our Board of Directors’ overall diversity by providing a variety of perspectives based on distinct personal and professional experiences and backgrounds. We are committed to maintaining and enhancing the diversity of our Board of Directors and in furtherance of this, the nominating and corporate governance committee will conduct annual self-evaluations to assess its performance and effectiveness, which we expect will include its consideration of diversity and other selection criteria.

Our nominating and corporate governance committee will consider director candidates recommended by stockholders and evaluate them using the same criteria as candidates identified by our Board of Directors or our nominating and corporate governance committee for consideration. If a stockholder of the Company wishes to recommend a director candidate for consideration by our nominating and corporate governance committee, the stockholder recommendation should be delivered to the Corporate Secretary of the Company at the principal executive offices of the Company, and must include information regarding the candidate and the stockholder making the recommendation.

Equity Awards Committee

Our equity awards committee, which was formed in the first quarter of 2022, held no meetings during 2021. The members of our equity awards committee are our chief executive officer and chief financial officer. Pursuant to the equity awards committee charter, the function of this committee includes, among other things, granting stock options and restricted stock awards to non-executive employees under our 2021 Equity Incentive Plan within certain grant guidelines specified in the equity awards committee charter and equity awards grant policy or as adopted from time to time by our Board of Directors or compensation committee.

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Board Diversity Matrix

The following table provides information in a standardized matrix pursuant to NASDAQ Rule 5606 setting forth: (i) the total number of Company board members and (ii) how those board members self-identify regarding gender, predefined race and ethnicity categories and LGBTQ+ status.

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location on our website identified above and in public filings. Our code of conduct represents the standards by which we operate and reflects that we are an ethical, mindful and transparent business. The purpose of our code of conduct is to promote honest and ethical conduct, including with respect to actual or apparent conflicts of interest between personal and professional relationships, to promote full, fair, accurate, timely and understandable disclosure in periodic reports to be filed by us, to promote compliance with applicable governmental laws, rules and regulations, promoted the protection of the Company’s assets, including corporate opportunities and confidential information, promote fair dealing practices, deter wrongdoing, promote prompt internal reporting of violations of the code of conduct to an appropriate person(s) identified in the code of conduct, and ensure accountability for adherence to the code of conduct.

Hedging and Pledging Policies

Pursuant to our insider trading policy, all employees and agents, including our executive officers and directors, are prohibited from trading in publicly-traded options, such as puts or calls, or other derivative securities in our securities, including hedging or similar transactions designed to decrease the risks associated with holding our securities. Employees are also prohibited from including our securities in a margin account or pledging our securities as collateral for a loan. Further, it is against our insider trading policy for any employee (including any executive officers) to engage in short sales of our Common Stock. Any violation of the policies may result in disciplinary action, including dismissal for cause.

Stockholder Communications with our Board of Directors

Stockholders wishing to communicate with our Board of Directors or with an individual member of our Board of Directors may do so by writing to our Board of Directors or to the particular member of our Board of Directors, care of the Corporate Secretary by mail to our principal executive offices, Attention: Corporate Secretary. The envelope should indicate that it contains a stockholder communication. All clearly marked written communications, other than unsolicited advertising or promotional materials, are logged and copied, and forwarded to the director(s) to whom the communication was addressed. Please note that the foregoing communication procedure does not apply to (i) stockholder proposals pursuant to Exchange Act Rule 14a-8 and communications made in connection with such proposals or (ii) service of process or any other notice in a legal proceeding.

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based on the information contained in a Schedule 13D filed by FCM V, FCF V, FCOM V, FCOF V and Dr. Tananbaum on October 18, 2021.

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Investors’ Right Agreement

In connection with the sale of our Series B Preferred Stock, we entered into an amended and restated investors’ rights agreement, dated January 22, 2021 with certain holders of our preferred stock, including entities affiliated with OrbiMed Advisors, entities affiliated with Foresite Capital and ARIAD Pharmaceuticals, Inc. (“ARIAD”). These stockholders are entitled to rights with respect to the registration of their shares under the Securities Act of 1933, as amended. Other than these registration rights, all other terms of the amended and restated investors’ rights agreement terminated upon the completion of our initial public offering. Dr. Gordon is a member of OrbiMed Advisors and Dr. Dukes is a Venture Partner with OrbiMed Advisors. Dr. Rome is a Managing Director of Foresite Capital. Each of Dr. Gordon, Dr. Dukes and Dr. Rome are members of our Board of Directors.

Voting Agreement

In connection with the sale of our Series B Preferred Stock, we entered into an amended and restated voting agreement dated January 22, 2021 with certain holders of our preferred stock, including entities affiliated with OrbiMed Advisors, entities affiliated with Foresite Capital and ARIAD. Under our voting agreement, certain holders of our capital stock had agreed as to the manner in which they would vote their shares of our capital stock on certain matters, including with respect to the election of directors. The parties to the voting agreement had agreed, subject to certain conditions, to vote the shares of our capital stock held by them so as to elect the following individuals as directors: (i) one individual designated by OrbiMed Private Investments VII, LP (most recently, Dr. Gordon); (ii) one individual designated by Foresite Capital Fund V, L.P. (most recently, Dr. Rome); (iii) our Chief Executive Officer (most recently, Dr. Clackson); and (iv) one individual designated by the holders a majority of the outstanding shares of Common Stock held by the parties to the voting agreement (most recently, Dr. Dukes). The voting agreement terminated upon the completion of our initial public offering and there are no further contractual obligations regarding the manner in which shares are voted with respect to the election of our directors. Dr. Gordon is a member of OrbiMed Advisors and Dr. Dukes is a Venture Partner with OrbiMed Advisors. Dr. Rome is a Managing Director of Foresite Capital.

Right of First Refusal and Co-Sale Agreement

In connection with the sale of our Series B Preferred Stock, we entered into an amended and restated right of refusal and co-sale agreement, dated January 22, 2021 with certain holders of our preferred stock, including entities affiliated with OrbiMed Advisors, entities affiliated with Foresite Capital and ARIAD. Under our right of refusal and co-sale agreement, certain holders of our preferred stock had the right of first refusal and co-sale relating to the shares of Common Stock held by the parties to the agreement. The right of refusal and co-sale agreement terminated upon the completion of our initial public offering. Dr. Gordon is a member of OrbiMed Advisors and Dr. Dukes is a Venture Partner with OrbiMed Advisors. Dr. Rome is a Managing Director of Foresite Capital. Each of Dr. Gordon, Dr. Dukes and Dr. Rome are members of our Board of Directors.

Equity Grants to Executive Officers and Directors

We have agreements with and have granted stock options to certain of our executive officers and non-employee directors, including as described in the sections titled “Executive Compensation” and “Director Compensation.” Members of our Board of Directors are entitled to receive compensation under our non our compensation program for our non-employee directors, as described under the section titled “Director Compensation—Non-Employee Director Compensation Program.”

Employment Arrangements

We have entered into offer letters with our named executive officers. For more information regarding these agreements with our named executive officers, see the sections titled “Executive Compensation” and “Director Compensation.”

Retainer Agreement

We entered into a retainer agreement with Kathy Yi in May 2021 in connection with her appointment to our Board of Directors. Pursuant to the terms of the agreement, Ms. Yi received a cash retainer at an annual rate of $50,000. In connection with the commencement of her service on our Board of Directors, Ms. Yi received options to purchase

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99,634 shares of Common Stock under our 2018 Stock Plan. The retainer agreement has been superseded by our non-employee director compensation policy adopted in connection with our initial public offering.

Indemnification Agreements

We have entered into an indemnification agreement with each of our directors and executive officers. The indemnification agreements and our amended and restated certificate of incorporation and amended and restated bylaws require us to indemnify our directors and executive officers to the fullest extent permitted by Delaware law.

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Narrative Disclosure to Summary Compensation Table

During fiscal year 2021, the compensation of our named executive officers generally consisted of base salary, annual cash incentives and equity compensation. In making executive compensation decisions, our Board of Directors considers such factors as it deems appropriate in its exercise of discretion and business judgment, including a subjective assessment of the named executive officer’s performance, the amount of vested and unvested equity held by the named executive officer, amounts paid to our other executive officers and competitive market conditions.

2021 Salaries and Annual Incentive Opportunities

Our named executive officers each receive a base salary to compensate them for services rendered to us. The base salary payable to each named executive officer is intended to provide a fixed component of compensation reflecting the executive’s skill set, experience, role and responsibilities.

As of December 31, 2021, the annual salaries of Dr. Clackson, Dr. Shakespeare and Mr. Dahms were $540,000, $440,000, and $420,000, respectively, pursuant to the terms of their offer letters. During fiscal year 2021, Dr. Dukes earned an hourly fee of $600 for up to 20 hours per week of service pursuant to the terms of a consulting agreement that was terminated in April 2021. Thereafter, Dr. Dukes received a base salary at an annual rate of $250,000 under the terms of his offer letter that was terminated in September 2021. Upon termination, Dr. Dukes received $30,000 as compensation for his service to such date. See the section titled “—Employment Arrangements with our Named Executive Officers.” Our Board of Directors and compensation committee may adjust base salaries from time to time in their discretion.

Each of our executive officers is eligible to earn an incentive bonus for each of our fiscal years beginning with fiscal year 2021, with such bonus awarded based on individual performance goals, as well as corporate goals approved by our Board of Directors or the compensation committee. During fiscal year 2021, our named executive officers were eligible to earn cash incentive bonuses based on achievement of certain corporate goals. For fiscal year 2021, the target bonus rate (as a percentage of base salary) was 55% for Dr. Clackson and 40% for each of Dr. Shakespeare and Mr. Dahms. During fiscal year 2021, Dr. Dukes was eligible to earn a cash incentive bonuses based on achievement of certain corporate goals in consideration for his service as Executive Chairman from April 2021 to September 2021. For fiscal year 2021, Dr. Dukes received an annual incentive bonus of $44,000. No other non-employee directors were entitled to an annual incentive bonus for fiscal year 2021. Annual bonuses are pro-rated based on the number of days the named executive officer is employed during the fiscal year.

Stock-Based Compensation

Historically, the equity compensation granted to our named executive officers has consisted primarily of stock options. For further details regarding the stock options granted to our named executive officers for fiscal year 2021, see the table under the section titled “—Outstanding Equity Award.”

In April 2021, we granted Dr. Clackson an option to purchase 1,037,793 shares of Common Stock. The option vests as to 25% of the shares underlying the option on April 15, 2022 and the remainder vests monthly over the remaining 36 months, subject to Dr. Clackson’s continued service through the applicable vesting date. In April 2021, we granted Dr. Clackson an additional option to purchase 345,930 shares of Common Stock, which option was exercisable by Dr. Clackson prior to vesting and was fully exercised by Dr. Clackson. 25% of the unvested shares purchased by Dr. Clackson vest on April 15, 2022 and the remainder vests monthly over the remaining 36 months, subject to Dr. Clackson’s continued employment through the applicable vesting date and are subject to repurchase by us upon a termination of Dr. Clackson’s employment. In May 2021, we granted Dr. Clackson an additional option to purchase 110,790 shares of Common Stock. The additional option vests in 48 equal monthly installments over a four-year period, subject to Dr. Clackson’s continued employment through the applicable vesting date. Each of Dr. Clackson’s options have an exercise price of $4.03 per share.

In March and May 2021, we granted Dr. Dukes options to purchase 36,066 and 61,549 shares of Common Stock, respectively. Each option vests in 48 equal monthly installments over a four-year period, subject to Dr. Dukes’ continued service through the applicable vesting date and has an exercise price of $4.03 per share. In October 2021, following his

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transition out of his role as chief executive officer, we granted Dr. Dukes an additional option to purchase 22,678 shares of Common Stock. The additional option vests in 36 equal monthly installments over a three-year period, subject to Dr. Dukes’ continued service through the applicable vesting date, and has an exercise price of $16.00 per share.

In March and May 2021, we granted Dr. Shakespeare options to purchase 36,066 and 227,607 shares of Common Stock, respectively. Each option vests in 48 equal monthly installments over a four-year period, subject to Dr. Shakespeare’s continued employment through the applicable vesting date and has an exercise price of $4.03 per share.

In May 2021, we granted Mr. Dahms an option to purchase 332,114 shares of Common Stock. This option vests as to 25% of the shares underlying the option on May 25, 2022 and the remainder vests monthly over the remaining 36 months, subject to Mr. Dahms’ continued employment through the applicable vesting date, and has an exercise price of $4.03 per share. In August 2021, we granted Mr. Dahms an additional option to purchase 23,885 shares of Common Stock. The additional option vests as to 25% of the shares underlying the option on August 27, 2022 and the remainder vests monthly over the remaining 36 months, subject to Mr. Dahms’ continued employment through the applicable vesting date, and has an exercise price of $9.99 per share.

Although we do not have a formal policy with respect to equity compensation of our named executive officers, we believe that equity grants provide our executives with a strong link to our long-term performance, create an ownership culture and help to align the interests of our executives and our stockholders. In addition, we believe that equity grants promote executive retention because they incentivize our executive officers, including our named executive officers, to remain in our employment during the vesting period. Accordingly, our Board of Directors periodically reviews the equity compensation of our named executive officers and may grant equity incentive awards to them from time to time.

Health and Welfare Benefits

Our named executive officers are eligible to participate in our health and welfare plans to the same extent as other full-time employees generally. We generally do not provide our named executive officers with perquisites or other personal benefits. However, we do reimburse our named executive officers for their necessary and reasonable business and travel expenses incurred in connection with their services to us.

Employment Arrangements with our Named Executive Officers

Offer Letter with Dr. Clackson

We initially entered into an offer letter with Dr. Clackson in April 2021 in connection with the commencement of his employment, which was replaced by a new offer letter that became effective as of the date of our initial public offering. Pursuant to the terms of the new offer letter, Dr. Clackson receives a base salary at an annual rate of $540,000 and is eligible to receive an annual performance bonus of 55% of base salary, subject to the achievement of applicable performance metrics as determined by our board of directors.

The new offer letter provides Dr. Clackson with severance benefits if he undergoes an Involuntary Termination (as defined below), subject to his execution of a general release of claims with respect to us and our affiliates. If an Involuntary Termination occurs more than three months prior to, or more than 12 months after, the consummation of a Change in Control (as defined below), Dr. Clackson will be eligible to receive continued payments of base salary for 12 months following his termination date, a prorated annual target bonus, nine months of additional vesting on all outstanding equity awards, and payment by us of COBRA premiums at active employee rates for 12 months following his termination date. If an Involuntary Termination occurs within three months prior to, or within 12 months after, the consummation of a Change in Control, Dr. Clackson will be eligible to receive a severance payment equal to 1.5 times the sum of his base salary and annual target bonus, a prorated annual target bonus, full vesting on all outstanding equity awards, and payment by us of COBRA premiums at active employee rates for 18 months following his termination date.

Former Employment Arrangements with Dr. Dukes

We were previously party to a consulting agreement with Dr. Dukes setting forth the initial terms of his services. Dr. Dukes earned an hourly fee of $600 for up to 20 hours per week of service during the year ended December 31, 2020. In April 2021, the consulting agreement was terminated and we entered into an offer letter with Dr. Dukes in

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connection with his transition into his role as Executive Chairman. Pursuant to the terms of the offer letter, Dr. Dukes received a base salary at an annual rate of $250,000 and was eligible to receive an annual performance bonus with a target amount of 40% of base salary, subject to the achievement of performance metrics as determined by our board of directors. The offer letter was terminated in connection with Dr. Dukes’ transition into his current role of Chairman in September 2021, for which Dr. Dukes received $30,000 as compensation for his service as Executive Chairman to such date. Dr. Dukes is eligible to receive compensation as provided for under our compensation program for our non-employee directors, as described under the section titled “Director Compensation—Non-Employee Director Compensation Program.”

Offer Letter with Dr. Shakespeare

We initially entered into an offer letter with Dr. Shakespeare in May 2018 in connection with the commencement of his employment, which was replaced by a new offer letter that became effective as of the date of our initial public offering. Pursuant to the terms of this new offer letter, Dr. Shakespeare receives a base salary at an annual rate of $440,000 and is eligible to receive an annual performance bonus of 40% of base salary, subject to the achievement of performance metrics as determined by our Board of Directors.

The new offer letter provides Dr. Shakespeare with severance benefits if he undergoes an Involuntary Termination, subject to his execution of a general release of claims with respect to us and our affiliates. If an Involuntary Termination occurs more than three months prior to, or more than 12 months after, the consummation of a Change in Control, Dr. Shakespeare will be eligible to receive continued payments of base salary for nine months following his termination date, a prorated annual target bonus, nine months of additional vesting on all outstanding equity awards, and payment by us of COBRA premiums at active employee rates for nine months following Dr. Shakespeare’s termination date. If an Involuntary Termination occurs within three months prior to, or within 12 months after, the consummation of a Change in Control, Dr. Shakespeare will be eligible to receive a severance payment equal to 1.0 times the sum of Dr. Shakespeare’s base salary and annual target bonus, a prorated annual target bonus, full vesting on all outstanding equity awards, and payment by us of COBRA premiums at active employee rates for 12 months following his termination date.

Offer Letter with Mr. Dahms

We initially entered into an offer letter with Mr. Dahms in April 2021 in connection with the commencement of his employment, which was replaced by a new offer letter that became effective as of the date of our initial public offering. Pursuant to the terms of the new offer letter, Mr. Dahms receives a base salary at an annual rate of $420,000 and is eligible to receive an annual performance bonus of 40% of base salary, subject to the achievement of performance fmetrics as determined by our board of directors.

The new offer letter provides Mr. Dahms with severance benefits if he undergoes an Involuntary Termination, subject to his execution of a general release of claims with respect to us and our affiliates. If an Involuntary Termination occurs more than three months prior to, or more than 12 months after, the consummation of a Change in Control, Mr. Dahms will be eligible to receive continued payments of base salary for nine months following his termination date, a prorated annual target bonus, nine months of additional vesting on all outstanding equity awards, and payment by us of COBRA premiums at active employee rates for nine months following his termination date. If an Involuntary Termination occurs within three months prior to, or within 12 months after, the consummation of a Change in Control, Mr. Dahms will be eligible to receive a severance payment equal to 1.0 times the sum of his base salary and annual target bonus, a prorated annual target bonus, full vesting on all outstanding equity awards, and payment by us of COBRA premiums at active employee rates for 12 months following his termination date. The offering is not expected to be considered a Change in Control for purposes of these severance provisions.

Applicable Definitions under the Offer Letters

“Cause” generally means the executive’s material breach of an agreement (if not timely cured), gross negligence, willful misconduct or unauthorized disclosure of confidential information that causes material harm to us, material failure to comply with our policies, conviction of or plea of “guilty” to a felony, continuing failure to perform duties, or failure to cooperate with government or internal investigations.

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“Change in Control” generally means a sale of all or substantially all of our assets, a merger following which holders of our stock do not hold at least 50% of the voting power of the surviving or acquiring entity in substantially the same proportions, or any person becoming the beneficial owner of more than 50% of the voting power of our voting securities.

“Good Reason” generally means a resignation by the executive within 12 months following a diminution of base salary, a material diminution of duties or responsibilities, a required relocation of more than 50 miles, or our material breach of any agreement with the executive.

“Involuntary Termination” shall mean the executive’s involuntary discharge by us for reasons other than Cause, or the executive’s resignation for Good Reason.

Outstanding Equity Awards

The following table sets forth information regarding each unexercised option and all unvested restricted shares held by each of our named executive officers as of December 31, 2021.

The vesting schedule applicable to each outstanding award is described in the footnotes to the table below. For information regarding the vesting acceleration provisions applicable to the options and restricted shares held by our named executive officers, see the section titled “—Employment Arrangements with our Named Executive Officers.”

Options granted to certain of our named executive officers are immediately exercisable with respect to all of the option shares, subject to the continued vesting of the shares underlying any unvested options and to our repurchase right in the event the officer’s service terminates prior to vesting of such unvested shares.

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The non-employee members of our Board of Directors are also eligible for reimbursement of their reasonable expenses incurred in attending Board of Directors and committee meetings.

Equity Compensation

In April 2022, our Board of Directors amended the equity compensation component of our non-employee director compensation policy. Our non-employee directors receive both an initial equity award upon joining our Board of Directors and annual equity awards in connection with each annual meeting of our stockholders.

In addition, in April 2022, our Board of Directors approved a one-time grant of an option to purchase 15,000 shares of Common Stock under our 2021 Equity Incentive Plan to Dr. Dukes in connection with his prior transition to Board Chair. This option will be automatically granted following the conclusion of the Annual Meeting, subject to Dr. Dukes continuing to serve as Board Chair through such time.

The equity awards will also vest in full in the event of a “change of control” (as defined in our 2021 Equity Incentive Plan).

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The 2021 Plan provides for annual increases in the number of shares available for issuance thereunder on the first business day of each fiscal year, commencing in 2023, equal to the lesser of (a) 5% of the total number of shares of Common Stock outstanding on the last business day of the prior fiscal year, or (b) the number of shares determined by our Board of Directors. The ESPP provides for annual increases in the number of shares available for issuance thereunder on the first day of each fiscal year, commencing in 2023, equal to the lesser of: (1) 1% of the shares of Common Stock outstanding at that time; and (2) such other amount as our Board of Directors may determine.

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All fees described above were pre-approved by our audit committee.

Pre-approval Policies and Procedures

The audit committee’s policy is to pre-approve all audit and permissible non-audit services rendered by Ernst & Young LLP, our independent registered public accounting firm. The audit committee pre- approves specified services in defined categories of audit services, audit- related services and tax services up to specified amounts, as part of the audit committee’s approval of the scope of the engagement of Ernst & Young LLP or on an individual case-by-case basis before Ernst & Young LLP is engaged to provide a service. The audit committee has determined that the rendering of the services other than audit services by Ernst & Young LLP is compatible with maintaining the principal accountant’s independence.

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