MREO Mereo BioPharma Group PLC

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

Filed by the Registrant ☒

Filed by a Party other than the Registrant ☐

Check the appropriate box:

MEREO BIOPHARMA GROUP PLC

(Name of Registrant as Specified In Its Charter)

N/A

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

MEREO BIOPHARMA GROUP PLC

Registered office: 4th Floor, One Cavendish Place, London, W1G 0QF, United Kingdom

Incorporated in England and Wales with registered no. 09481161

April 8, 2025

Dear Shareholder,

2025 Annual General Meeting of Mereo BioPharma Group plc (the “AGM” or the “Meeting”)

This letter, the notice of the AGM set out in this document (the “Notice”) and associated materials for the AGM are being sent or supplied to you because, as of 6:00 p.m. (British Summer Time) (1:00 p.m. Eastern Time) on Friday, April 4, 2025 (being the latest practicable date before the circulation of this document), you are registered in the register of members of Mereo BioPharma Group plc (the “Company”) as a holder of ordinary shares in the capital of the Company. However, this letter, the Notice and associated materials will also be available to holders of American Depositary Shares (“ADS”) representing ordinary shares and contains information relevant to holders of ADSs.

I am pleased to confirm that our AGM will take place at 2:00 p.m. (British Summer Time) (9:00 a.m. Eastern Time) on Tuesday, May 13, 2025 at 5th Floor, One Cavendish Place, London W1G 0QF, United Kingdom. The Notice is set out in this document and it contains the resolutions to be proposed at the AGM (the “Resolutions”).

Action to be taken by holders of ordinary shares

If you are a holder of ADSs, please ignore this section and refer instead to the section below — “Action to be taken by holders of American Depositary Shares.”

If you are a holder of ordinary shares and are planning to attend the AGM in person (or by way of corporate representative) it would be helpful if you could inform the Company’s registrar, MUFG Corporate Markets, in advance by submitting a proxy vote electronically via the Investor Centre app or by accessing the web browser at https://uk.investorcentre.mpms.mufg.com/.

Holders of ordinary shares are entitled to appoint a proxy to exercise all or any of their rights to attend and to speak and vote on their behalf at the AGM. Proxy appointment instructions may be submitted electronically via the Investor Centre app or by accessing the web browser at

https://uk.investorcentre.mpms.mufg.com/ by completing and returning the form of proxy enclosed with this document.

In order to be valid, proxy appointment instructions must be submitted using the Investor Centre, or by completing and returning a form of proxy (together with any power of attorney or other authority, if any, under which it is signed or a duly certified copy thereof) in accordance with the instructions printed

thereon to the Company’s registrar, MUFG Corporate Markets at PXS 1, Central Square, 29 Wellington Street, Leeds LS1 4DL, United Kingdom, in each case so as to be received by no later than 2:00 p.m. (British Summer Time) (9:00 a.m. Eastern Time) on Friday, May 9, 2025 or 48 hours before any adjourned meeting.

If you require additional forms of proxy or assistance with how to complete, sign and return your form of proxy or assistance in submitting your proxy appointment electronically, please email shareholderenquiries@cm.mpms.mufg.com or call MUFG Corporate Markets' portal team on

+44 (0) 371 664 0391. Calls are charged at the standard geographic rate and will vary by provider. Calls from outside the U.K. will be charged at the applicable international rate. Lines are open 9:00 a.m. to 5:30 p.m. (British Summer Time), Monday to Friday, excluding public holidays in England and Wales.

If you hold your ordinary shares in uncertificated form (i.e. in CREST), you may appoint a proxy for the AGM by completing and transmitting a CREST Proxy Instruction in accordance with the procedures set out in the CREST Manual issued by Euroclear so that it is received by the Company’s registrar (under CREST Participation ID RA10) by no later than 2:00 p.m. (British Summer Time) (9:00 a.m. Eastern Time) on Friday, May 9, 2025 or 48 hours before any adjourned meeting. The time of receipt will be taken to be the time from which MUFG Corporate Markets is able to retrieve the message by enquiry to CREST in the manner proscribed by CREST.

If you are an institutional investor you may also be able to appoint a proxy electronically via the Proxymity platform, a process which has been agreed by the Company and approved by the Registrar. For further information regarding Proxymity, please go to www.proxymity.io.

In order to attend and vote at the AGM as an ordinary shareholder or for your proxy appointment instructions to remain valid, you must continue to be registered as a holder of ordinary shares in the Company’s register of members as of 6:00 p.m. (British Summer Time) (1:00 p.m. Eastern Time) on Friday, May 9, 2025 (or, if the AGM is adjourned, of 6:00 p.m. (British Summer Time) (1:00 p.m. Eastern Time) on the date which is two business days prior to the adjourned meeting). If you sell or transfer your ordinary shares on or prior to such time, any proxy appointment instructions that you submit (whether before or after you sell or transfer your ordinary shares) will be treated as invalid. Please pass this document to the person who arranged the sale or transfer for delivery to the purchaser or transferee.

The appointment of a proxy will not preclude you from attending, speaking and voting at the AGM should you wish and be entitled to do so. Please refer to the notes to the Notice for further information relating to your entitlement to attend and vote at the AGM and to appoint a proxy to attend and to speak and vote on your behalf at the AGM.

Should you elect to convert your holding of ordinary shares into an interest in the capital of the Company represented by ADSs before the AGM, you will cease to be a holder of ordinary shares in your own name and will not be entitled to vote, whether in person or by proxy, at the AGM as an ordinary shareholder. However, you may be able to exercise your vote as a holder of an interest in the capital of the Company represented by ADSs — please refer to the next section — “Action to be taken by holders of American Depositary Shares.”

Action to be taken by holders of American Depositary Shares

In order to exercise your vote as a holder of an interest in ordinary shares represented by ADSs, you or your bank, broker or nominee must be registered as a holder of ADSs in the ADS register as of 5:00 p.m. Eastern Time (10:00 p.m. British Summer Time) on Tuesday, April 8, 2025 (the “ADS Record Date”).

If you hold ADSs through a bank, broker or nominee as of 5:00 p.m. Eastern Time on the ADS Record Date, the materials for ADS holders, including this proxy statement, the Annual Report on Form 10-K and an ADS proxy card, will be sent to such bank, broker or nominee who should forward the materials to you – you should contact them to provide your voting instructions.

Please note that ADS proxy cards submitted by ADS holders must be received by Citibank, N.A. no later than 10:00 a.m. Eastern Time (3:00 p.m. British Summer Time) on Wednesday, May 7, 2025.

Contact for holders of American Depositary Shares

If you have queries about how you can deliver voting instructions, please contact Citibank, N.A. — ADR Shareholder Services by telephone on +1-877-248-4237 (toll free within the United States) or +1-781-575-4555 (for international callers) or by emailing citibank@shareholders-online.com or by mail to Citibank Shareholder Services, P.O. Box 43077, Providence, RI 02940-3077.

Contact at Mereo BioPharma

If at any point you require guidance, please contact Charles Sermon, Mereo BioPharma Group plc Company Secretary, by emailing legal@mereobiopharma.com.

Recommendation

You will find an explanatory note in relation to each of the Resolutions in the attached proxy statement. Your Board of Directors consider that each Resolution is in the best interests of the Company and is likely to promote the success of the Company for the benefit of its members as a whole. Accordingly, your directors unanimously recommend that you vote FOR the Resolutions as each of the directors with personal holdings of ordinary shares or ADSs intends to do.

Thank you for your ongoing support of Mereo BioPharma Group plc.

Yours faithfully,

Michael Wyzga

Chairman

Mereo BioPharma Group plc

4th Floor, One Cavendish Place, London, W1G 0QF,

United Kingdom

Registered Company No. 09481161

NOTICE OF 2025 ANNUAL GENERAL MEETING OF SHAREHOLDERS TO BE HELD ON TUESDAY, MAY 13, 2025

NOTICE IS HEREBY GIVEN that the Annual General Meeting of Mereo BioPharma Group plc, a public limited company incorporated under the laws of England and Wales (the “Company,” “we,” “us” and “our”), will be held on Tuesday, May 13, 2025, at 2:00 p.m. (British Summer Time) (9:00 a.m. Eastern Time) at 5th Floor, One Cavendish Place, London W1G 0QF, United Kingdom to consider and, if thought fit, to pass resolutions 1 to 9 below, in each case as an ordinary resolution.

Ordinary resolutions

Notes:

The following notes apply to ordinary shareholders. Holders of ADSs should review the information in the section of the letter accompanying this Notice titled “Action to be taken by holders of American Depositary Shares” for voting and other relevant information for the Meeting.

Entitlement to Attend and Vote

Appointment of Proxies

Appointment of Proxy Using Hard Copy Proxy Form

Appointment of a Proxy Online

Appointment of Proxies Through CREST

Appointment of Proxies via Proxymity

Appointment of Proxy by Joint Members

Changing Proxy Instructions

Termination of Proxy Appointments

Corporate Representatives

Issued Shares and Total Voting Rights

Electronic Address

Website Publication of Audit Concerns

TABLE OF CONTENTS

i

Mereo BioPharma Group plc

4th Floor, One Cavendish Place, London, W1G 0QF, United Kingdom Registered Company No. 09481161

PROXY STATEMENT FOR THE 2025 ANNUAL GENERAL MEETING OF SHAREHOLDERS TO BE HELD ON, TUESDAY MAY 13, 2025

INFORMATION CONCERNING PROXY SOLICITATION AND VOTING

We have sent you this proxy statement and the enclosed form of proxy because the Board of Directors of Mereo BioPharma Group plc (referred to herein as the “Company”, “Mereo”, “we”, “us” or “our”) is soliciting your proxy to vote at our annual general meeting of shareholders (referred to herein as the “Meeting” or the “AGM”) to be held on Tuesday, May 13, 2025, at 2:00 p.m. (British Summer Time) (9:00 a.m. Eastern Time), at 5th Floor, One Cavendish Place, London W1G 0QF, United Kingdom.

In addition to solicitations by mail, our directors, officers and regular employees, without additional remuneration, may solicit proxies by telephone, e-mail, internet and personal solicitation. All costs of solicitation of proxies will be covered by us.

We are mailing the Notice, this proxy statement and the form of proxy to our ordinary shareholders of record as of 6:00 p.m. (British Summer Time) (1:00 p.m. Eastern Time) on Friday, April 4, 2025 (being the latest practicable date before the circulation of this document) for the first time on or about Tuesday, April 8, 2025. We are also including our annual report on Form 10-K for the year ended December 31, 2024 (the “Annual Report on Form 10-K”). This includes mailing or supplying our proxy materials, including the Notice, this proxy statement and the accompanying form of proxy, and the Annual Report on Form 10-K, to relevant brokers, dealers, bankers and their nominees in their capacity as shareholders of record, so that they can supply these materials to the relevant beneficial owners of ordinary shares.

While this document is being sent or supplied to our ordinary shareholders of record, this document will also be made available to holders of American Depositary Shares (“ADSs”) and contains information relevant to holders of ADSs.

Important Notice Regarding the Availability of Proxy Materials for the Shareholder Meeting to be Held on Tuesday, May 13, 2025

Our Notice, this proxy statement and the accompanying form of proxy and the Annual Report on Form 10-K

are available in the Investors section of our website at: http://www.mereobiopharma.com/agm2025.

QUESTIONS AND ANSWERS ABOUT VOTING AT THE ANNUAL GENERAL MEETING Why am I receiving these materials?

We have sent you this proxy statement and the enclosed form of proxy because you are an ordinary shareholder of record and our Board of Directors (the “Board” or “Board of Directors”) is soliciting your vote at the Meeting, including at any adjournments or postponements of the Meeting. You are invited to attend the Meeting to vote on the proposals described in this proxy statement. However, you do not need to attend the

Meeting to vote your shares. Instead, please submit your proxy online using the Investor Centre app or at https://uk.investorcentre.mpms.mufg.com/ (see instructions in the explanatory notes to the Notice). Alternatively, you may simply complete, sign and return the enclosed form of proxy in accordance with the instructions printed thereon. CREST members may appoint a proxy by using the CREST electronic proxy appointment service. If you

are an institutional investor you may also be able to appoint a proxy electronically via the Proxymity platform. All proxies, however submitted, must be received by our registrar, MUFG Corporate Markets, by no later than 2:00 p.m. (British Summer Time) (9:00 a.m. Eastern Time) on Friday, May 9, 2025 or 48 hours before any adjourned meeting.

We intend to mail this proxy statement, the accompanying form of proxy and the Annual Report on Form

10-K on or about Tuesday, April 8, 2025 to all ordinary shareholders of record as of 6:00 p.m. (British

Summer Time) (1:00 p.m. Eastern Time) on Friday, April 4, 2025.

Materials for ADS holders of record, including this proxy statement, the Annual Report on Form 10-K and the ADS proxy card, will be mailed on or about Friday, April 11, 2025 to all ADS holders, including banks, brokers and nominees, who are registered as holders of ADSs in the ADS register by 5:00 p.m. Eastern Time (10:00 p.m. British Summer Time) on Tuesday, April 8, 2025 (the "ADS Record Date").

Who can vote at the Meeting?

Ordinary shareholders

Only ordinary shareholders of record registered in the register of members at 6:00 p.m. (British Summer Time) (1:00 p.m. Eastern Time) on Friday, May 9, 2025 will be entitled to attend and vote in person at the Meeting. As of Friday, April 4, 2025 (being the last practicable date before the circulation of this proxy statement) there were 795,001,444 ordinary shares issued and outstanding and entitled to vote.

All proxies must be received by our registrar, MUFG Corporate Markets, by no later than 2:00 p.m. (British Summer Time) (9:00 a.m. Eastern Time) on Friday, May 9, 2025 or 48 hours before any adjourned meeting.

If you sell or transfer your ordinary shares in the Company on or prior to Friday, May 9, 2025, your form of proxy can no longer be used and if submitted (whether before or after you sell or transfer your ordinary shares) will be treated as invalid. Please pass this document to the person who arranged the sale or transfer for delivery to the purchaser or transferee. The purchaser or transferee should contact the Company’s registrar, MUFG Corporate Markets, using the details set out in the Notice, to request a new form of proxy for its use.

Beneficial owners of ordinary shares which are registered in the name of a broker, bank or other agent

If, on Friday, April 4, 2025, your ordinary shares were held in an account at a brokerage firm, bank or other similar organization and you are the beneficial owner of shares, these proxy materials should be forwarded to you by that organization. The organization holding your account is considered the shareholder of record for purposes of voting at the Meeting by proxy. You are encouraged to provide voting instructions to your broker or other agent so that they may submit a proxy.

Holders of American Depositary Shares

You are entitled to exercise your vote as a holder of an interest in the capital of the Company represented by

ADSs if you or your brokerage firm, bank or nominee is registered as a holder of ADSs in the ADS register as of

the ADS Record Date.

If you hold ADSs through a brokerage firm, bank or nominee on the ADS Record Date, the materials for ADS holders, including this proxy statement, the Annual Report on Form 10-K and the ADS proxy card, will be

sent to that organization. The organization holding your account is considered the ADS holder of record. Please reach out to that organization to provide your voting instructions.

Please note that ADS proxy cards submitted by ADS holders must be received by Citibank, N.A. by no later than 10:00 a.m. Eastern Time (3:00 p.m. British Summer Time) on Wednesday, May 7, 2025.

Citibank, N.A. will collate all votes properly submitted by ADS holders and submit a vote on behalf of all ADS holders.

What are the differences between ADS holders and ordinary shareholders?

We are requesting Citibank, N.A., which holds the ordinary shares represented by the ADSs, to seek ADS holders’ instructions for voting at the Meeting. As a result, ADS holders may instruct Citibank, N.A., as Depositary, to vote the ordinary shares represented by their ADSs.

Because we have asked Citibank, N.A. to seek the instructions of ADS holders, Citibank, N.A. will notify ADS holders of the upcoming vote and arrange to deliver the proxy materials to them. Citibank, N.A., as Depositary, then tries, as far as practicable, to vote the ordinary shares as our ADS holders instruct. We cannot guarantee that ADS holders will receive this proxy statement and the other proxy materials from Citibank, N.A. in time to permit them to instruct Citibank, N.A., as Depositary, to vote their shares. In addition, there may be other circumstances in which ADS holders may not be able to exercise voting rights. Furthermore, ADS holders can exercise their right to vote the ordinary shares underlying their ADSs by exchanging their ADSs for ordinary shares. However, even though we are subject to U.S. domestic issuer proxy rules, ADS holders may not receive proxy materials about the AGM early enough to exchange their ADSs for ordinary shares. ADS holders are not required to be treated as holders of ordinary shares and do not have the rights of holders of ordinary shares.

What is the difference between a shareholder of record and a beneficial owner?

These terms describe how your ordinary shares are held. If your ordinary shares are registered directly in our register of members, you are a shareholder of record and the proxy materials are being sent directly, or otherwise being made available, to you. If your ordinary shares are held in the name of a broker, bank, or other nominee, you are a beneficial owner of the shares held by your broker, bank or other nominee and the proxy materials are being made available or forwarded to you by your broker, bank, or other nominee, who is treated as the shareholder of record. As the beneficial owner, you have the right to direct your broker, bank, or other nominee on how to vote your ordinary shares by following the instructions on the voting instructions provided to you by such broker, bank or other nominee.

Who do I contact regarding my ADS holdings?

If you have queries about how you can deliver voting instructions, please contact Citibank, N.A. — ADR Shareholder Services at tel: +1-877-248-4237 (toll free within the United States) or +1-781-575-4555 (for international callers) or by email: citibank@shareholders-online.com or at Citibank Shareholder Services, P.O. Box 43077, Providence, RI 02940-3077.

What do I do if I have additional questions?

If at any point you require guidance, please contact Charles Sermon, Company Secretary, by email:

legal@mereobiopharma.com, or telephone: +44 (0) 333 023 7300.

What are the requirements to elect the directors and approve each of the proposals?

The proposed resolutions will be subject to vote on a poll. This results in a more accurate reflection of the views of shareholders ensuring that votes by proxy will be fully counted. On a poll, each shareholder has one vote for every share held.

Proposals 1 through 9 will be proposed as ordinary resolutions. On a poll, assuming that a quorum is present, an ordinary resolution is passed on a show of hands if it is approved by a simple majority (more than 50%) of the votes cast by shareholders present (in person or by proxy) at the Meeting and entitled to vote.

What are the voting recommendations of our Board regarding the election of directors and other proposals?

The following table summarizes the items that will be brought for a vote of our shareholders at the Meeting, along with the Board’s voting recommendations.

What constitutes a quorum?

For the purposes of the Meeting, the quorum requirement is a minimum of two shareholders entitled to vote at the meeting and present in person or by proxy or, in the case of a shareholder which is a corporation, represented by a duly authorized representative. In addition, in accordance with the applicable Nasdaq rules, under the Articles of Association for a shareholders’ meeting to be quorate at least 33 1/3 per cent. of the Company’s issued and outstanding ordinary shares must be present at such meeting, whether represented in person (including, in the case of a corporate member, by a duly authorized representative) or by a duly appointed proxy. If you are an ordinary shareholder of record, your shares will be counted towards the quorum only if you are present in person or represented by proxy at the Meeting. If you are a beneficial owner of ordinary shares

held in an account at a brokerage firm, bank or other similar organization your shares will be counted towards the quorum if your broker or nominee submits a proxy for those shares and the proxy represents the holder at the Meeting. A member represented by a proxy at the Meeting will be counted towards the quorum requirement even where the proxy abstains from voting. If a form of proxy does not instruct the proxy how to vote, the proxy may

vote as he or she sees fit or abstain in relation to any business of the Meeting, but the member represented by that proxy at the Meeting will be counted towards the quorum requirement.

Where Citibank N.A. submits votes on behalf of any ADS holders, the number of ordinary shares represented by the ADSs held by the relevant ADS holders will count towards the quorum.

How do I vote my shares?

You may vote “for” or “against” or abstain from voting on the applicable resolutions. The procedures for voting are as follows:

Ordinary shareholders

If you are an ordinary shareholder of record, you may appoint a proxy to vote on your behalf:

All proxies (however submitted) must be received by our registrar (MUFG Corporate Markets) by no later than 2:00 p.m. (British Summer time) (9:00 a.m. Eastern Time) on Friday, May 9, 2025.

If you properly give instructions as to your proxy appointment by executing and returning a form of proxy, or by submitting your proxy online or CREST or Proxymity, and your proxy appointment is not subsequently revoked, your shares will be voted by the attendance of your proxy at the Meeting and your proxy voting in accordance with your instructions.

If your ordinary shares are held in an account at a brokerage firm, bank or similar organization, you should follow directions provided by your broker, bank or other nominee.

Holders of American Depositary Shares

If you are a holder of record of ADSs, you can return your executed ADS proxy card to Citibank, N.A. for tabulation. If you hold your ADSs through a broker, bank or other organization, that organization can return the ADS proxy card to Citibank, N.A. following your instruction. Citibank, N.A. will submit your votes to MUFG Corporate Markets for tabulation.

Please note that ADS proxy cards submitted by ADS holders must be received by Citibank, N.A. no later than 10:00 a.m. Eastern Time- (3:00 p.m. British Summer Time) on Wednesday, May 7, 2025.

How will my shares be voted if I do not specify how they should be voted?

If you are an ordinary shareholder and you sign and send your form of proxy but do not indicate how you want your shares to be voted, your shares may be voted by the person that you appoint as your proxy as he or she sees fit or such person may abstain in relation to any business of the Meeting.

If a holder of ADSs does not submit an ADS proxy card to Citibank, N.A. by the deadline specified, the ADS holder shall be deemed to have instructed Citibank, N.A. to give a discretionary proxy to a person designated by us to vote the ordinary shares represented by his or her ADSs (provided that no such discretionary proxy shall be given if we inform Citibank, N.A. that we do not want such proxy to be given, substantial opposition exists or the rights of ADS holders may be adversely affected). If the ADS proxy card is signed but is missing voting instructions with respect to any resolution, then Citibank, N.A. will deem the ADS holder to have instructed it to vote in favor of such unvoted resolution(s).

Can I change my vote or revoke a proxy?

To change your proxy instructions simply submit a new proxy appointment using the methods set out above prior to the relevant deadline or attend the Meeting and vote in-person.

In order to revoke a proxy instruction, you will need to inform the Company by sending a signed hard copy notice clearly stating your intention to revoke your proxy appointment to MUFG Corporate Markets, at MUFG Corporate Markets, PXS1, Central Square, 29 Wellington Street, Leeds LS1 4DL, United Kingdom. The revocation notice, together with the accompanying material set out in the notes to the Notice, must be received by MUFG Corporate Markets no later than 48 hours before the meeting.

If your ordinary shares are held in an account at a brokerage firm, bank or similar organization, you may change or revoke your voting instructions by contacting the broker, bank or other nominee holding the shares.

If you hold ADSs, directly or through a broker, bank or other nominee, you must follow the instructions provided by Citibank, N.A. or such broker, bank or other nominee if you wish to change your vote. The last instructions you submit prior to the deadline indicated by Citibank, N.A. or the broker, bank or other nominee, as applicable, will be used to instruct Citibank, N.A. how to vote your ADSs.

Who counts the votes?

MUFG Corporate Markets has been engaged as our independent agent to tabulate shareholder votes. If you are an ordinary shareholder of record, you may submit your proxy to MUFG Corporate Markets online, via CREST, via Proxymity, or return the form of proxy to MUFG Corporate Markets prior to the relevant deadline above.

If you hold your ordinary shares through a broker, your broker will directly submit your proxy to MUFG Corporate Markets online, via CREST, via Proxymity, or return the form of proxy to MUFG Corporate Markets prior to the relevant deadline above.

If you are a holder of record of ADSs, you can return your executed ADS proxy card to Citibank, N.A. prior to the relevant deadline above for tabulation. If you hold your ADSs through a broker, bank or other organization, that organization can return the ADS proxy card to Citibank, N.A. prior to such deadline following your instruction. Citibank, N.A. will submit your votes to MUFG Corporate Markets for tabulation.

How are votes counted?

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

How many votes do I have?

On a poll, each shareholder present in person or by proxy or (being a corporation) by a duly authorized representative has one vote for each share held by the shareholder.

What about joint holders?

In the case of joint holders of record of an ordinary share, the vote of the senior holder who tenders the vote

(whether in person or by proxy) will be accepted to the exclusion of the votes of any other joint holders. For these purposes, seniority shall be determined by the order in which the names stand in the register of members of the company in respect of the joint holding (with the first named being the most senior).

What if I plan to attend the Meeting?

Attendance at the Meeting will be limited to ordinary shareholders of record as of 6:00 p.m. (British Summer Time) (1:00 p.m. Eastern Time) on Friday, May 9, 2025. In order to obtain admittance to the Meeting each shareholder may be asked to present valid picture identification, such as a driver’s license or passport.

How do you solicit proxies?

We will solicit proxies and will bear the entire cost of this solicitation. The initial solicitation of proxies may be supplemented by additional mail communications and by telephone, fax, e-mail, internet and personal solicitation by our directors, officers or other employees. No additional compensation for soliciting proxies will be paid to our directors, officers or other employees for their proxy solicitation efforts. We also reimburse Citibank, N.A. for their expenses in sending materials, including ADS proxy cards, to ADS holders of record.

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

If you hold your ordinary shares in more than one account, you will receive a form of proxy for each

account. To ensure that all of your shares are voted, please sign, date and return all forms of proxy. Please be sure to vote all of your shares.

If you hold ADSs in your own name registered on the books of Citibank, N.A., as Depositary, you are considered the registered holder of the ADSs and will receive a form of proxy from Citibank, N.A. If you hold ADSs through a broker, bank or other nominee, you are considered the beneficial owner of the ADSs and you will receive a form of proxy from your broker, bank or other nominee.

Will there be any other business conducted at the Meeting?

No. In accordance with our Articles of Association, other than with respect to procedural matters in relation to the Meeting, no business other than proposals 1 through 9 may be presented at this Meeting. We have not been notified of, and our Board is not aware of, any other matters to be presented for action at the Meeting.

What is the role of PwC?

PwC is our auditor for the year ended December 31, 2024 and our Audit and Risk Committee has selected PwC as our independent registered public accounting firm for the fiscal year ending December 31, 2025, and has further directed that we submit the selection of PwC for approval by our shareholders at the Meeting. Proposal 2 seeks your approval of the re-appointment of PwC to serve as our auditor, to hold office until the conclusion of the next annual general meeting of shareholders at which our annual report and accounts are presented.

PwC is entitled to attend any general meeting of the Company and be heard on any part of the business of the meeting that concerns them as auditors.

What is MUFG Corporate Markets’ role?

MUFG Corporate Markets is our registrar. All communications concerning ordinary shareholder of record accounts, including address changes, name changes, ordinary share transfer requirements and similar issues can be handled by contacting MUFG Corporate Markets via email shareholderenquiries@cm.mpms.mufg.com or by

telephone to the general helpline: +44 (0) 371 664 0391 (if calling from overseas, please ensure the country code is used) or by writing to MUFG Corporate Markets, PXS1, Central Square, 29 Wellington Street, Leeds LS1 4DL, United Kingdom.

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

Voting results will be announced by the filing of a current report on Form 8-K within four business days after the Meeting. If final voting results are unavailable at that time, we will file an amended current report on Form 8-K within four business days of the day the final results are available.

Directions to Meeting

Directions to our Meeting, which is to be held at 5th Floor, One Cavendish Place, London, W1G 0QF, United Kingdom, are available in the Contact Us section of our website at: https://www.mereobiopharma.com.

PROPOSAL 1 — RESOLUTION TO ADOPT THE COMPANY’S U.K. STATUTORY ANNUAL REPORT AND ACCOUNTS

At the Meeting, our Board of Directors will present our U.K. statutory annual report and accounts for the period January 1, 2024 through December 31, 2024, which includes the directors’ report and independent auditor’s report thereon. We will provide our shareholders with an opportunity to review the U.K. statutory annual report and accounts and to adopt them.

THE BOARD OF DIRECTORS RECOMMENDS A VOTE

FOR THE RESOLUTION TO RECEIVE AND ADOPT THE COMPANY’S U.K. STATUTORY ANNUAL REPORT AND ACCOUNTS

PROPOSAL 2 — RE-APPOINTMENT OF PRICEWATERHOUSECOOPERS LLP AS OUR AUDITORS, TO HOLD OFFICE UNTIL THE CONCLUSION OF THE NEXT ANNUAL GENERAL MEETING OF SHAREHOLDERS

Proposal 2 seeks your approval of the re-appointment of PricewaterhouseCoopers LLP to serve as our auditor, to hold office until the conclusion of the next annual general meeting of shareholders. In the event this proposal does not receive the affirmative vote of the shareholders by the requisite majority set out above, the Board of Directors may appoint an auditor to fill the vacancy.

Background to Proposal 2

Our Audit and Risk Committee has selected PricewaterhouseCoopers LLP (“PwC”) as our independent registered public accounting firm for the fiscal year ending December 31, 2025, and has further directed that we submit the selection of PwC for approval by our shareholders at the Meeting.

The Audit and Risk Committee approves PwC’s and its affiliates audit and non-audit services in advance as required under Sarbanes-Oxley and SEC rules. Before the commencement of each fiscal year, the Audit and Risk Committee appoints the independent auditor to perform audit services that we expect to be performed for the fiscal year and appoints the auditor to perform audit-related, tax and other permitted non-audit services. In addition, our Audit and Risk Committee approves the terms of the engagement letter to be entered into by us with the independent auditor. The Audit and Risk Committee has also delegated to its chairman the authority, from time to time, to pre-approve audit-related and non-audit services not prohibited by law to be performed by our independent auditors and associated fees, provided that the chairman shall report any decisions to pre-approve such audit-related and non-audit services and fees to our full Audit and Risk Committee at its next regular meeting. Additional information concerning the Audit and Risk Committee and its activities can be found in the following sections of this proxy statement: “Board Committees” and “Audit and Risk Committee Report.”

Fees for Independent Registered Public Accounting Firm — PwC

On September 20, 2023, our Board, following the recommendation of the Audit and Risk Committee, dismissed BDO LLP (“BDO”) as our independent registered public accounting firm and appointed PwC as our new independent registered public accounting firm effective immediately.

BDO had served as our independent registered public accounting firm for the year ended December 31,

2022 and until September 20, 2023 while we reported as a foreign private issuer and prepared our financial statements in accordance with IFRS.

PwC has served as our independent registered public accountants since September 20, 2023, and was appointed by our Board to act as our independent auditor for the fiscal year ending December 31, 2023. PwC's appointment as our independent auditor for the fiscal year ending December 31, 2024 was approved by shareholders at our 2024 Annual General Meeting. PwC has audited our U.K. statutory annual report and accounts prepared in accordance with UK-adopted International Financial Reporting Standards ("IFRS") for the fiscal year 2024 and has audited our financial statements prepared in accordance with U.S. GAAP included in our Annual Report on Form 10-K for the years ended December 31, 2024 and 2023.

The table below sets forth a summary of the fees billed to the Company by our auditors for professional services rendered for the fiscal years ended December 31, 2024 and December 31, 2023. All such audit and audit-related services were pre-approved by the Audit and Risk Committee.

(1) Fees paid to the auditors are denominated in pounds sterling. For the purposes of this table, all 2024 amounts have been converted based on the pound sterling/U.S. dollar exchange rate in effect as of December 31, 2024 (£1/$1.2546) and all 2023 amounts have been converted based on the pound Sterling/U.S. dollar exchange rate in effect as of December 31, 2023 (£1/$1.2103).

(2) There was a change in registered auditor during the year ended December 31, 2023. Of the 2023 amount, $1.0 million was in relation to the current auditors and includes amounts paid for the Company’s transition from IFRS to U.S. GAAP.

(3) In the year ended December 31, 2024, these fees were in relation to the current auditors while in the year ended December 31, 2023, these fees were in relation to the former auditors. All such fees were approved by the Audit and Risk Committee pursuant to its pre-approval policies.

(4) All of these fees were approved by the Audit and Risk Committee pursuant to its pre-approval policies.

THE BOARD OF DIRECTORS RECOMMENDS A VOTE

FOR THE RE-APPOINTMENT OF PRICEWATERHOUSECOOPERS LLP AS OUR AUDITORS, TO HOLD OFFICE UNTIL THE CONCLUSION OF THE NEXT ANNUAL GENERAL MEETING OF SHAREHOLDERS

PROPOSAL 3 — AUTHORIZATION FOR THE AUDIT AND RISK COMMITTEE TO DETERMINE THE AUDITORS’ REMUNERATION FOR THE FISCAL YEAR ENDING DECEMBER 31, 2025

Proposal 3 authorizes the Audit and Risk Committee to determine our auditors’ remuneration for the fiscal year ending December 31, 2025. Fees for PwC, our independent registered public accounting firm and U.K. statutory auditors, in respect of the year ended December 31, 2024 are set forth in Proposal 2 above.

THE BOARD OF DIRECTORS RECOMMENDS A VOTE

FOR THE AUTHORIZATION OF OUR AUDIT AND RISK COMMITTEE TO DETERMINE OUR AUDITORS’ REMUNERATION FOR THE FISCAL YEAR ENDING DECEMBER 31, 2025

PROPOSAL 4 — APPROVAL OF OUR U.K. DIRECTORS’ ANNUAL REPORT ON REMUNERATION ON AN ADVISORY (NON-BINDING) BASIS

Our U.K. directors’ remuneration report will be set out in our 2024 U.K. Annual Report. This document describes in detail our remuneration policies and procedures and explains how these policies and procedures help to achieve our compensation objectives with regard to our directors and the retention of high- quality directors. Our Board of Directors and the Remuneration Committee believe that the policies and procedures as articulated in the directors’ remuneration report are effective and that as a result of these policies and procedures we have and will continue to have high-quality directors. Our Board of Directors has approved and signed the report in accordance with English law.

At the Meeting, the shareholders will vote on the annual report on remuneration. This vote is advisory and non-binding. Although non-binding, our Board of Directors and Remuneration Committee will review and consider the voting results when making future decisions regarding our director remuneration program.

THE BOARD RECOMMENDS YOU VOTE, ON AN ADVISORY (NON-BINDING) BASIS

FOR THE APPROVAL OF OUR U.K. DIRECTORS’ ANNUAL REPORT ON REMUNERATION

PROPOSAL 5 — APPROVAL OF THE COMPENSATION OF THE COMPANY’S NAMED EXECUTIVE OFFICERS ON AN ADVISORY (NON-BINDING) BASIS

Pursuant to the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 (the “Dodd-Frank Act”) and Section 14A of the Exchange Act, we are asking our shareholders to vote to approve, on a non-binding, advisory basis, the compensation paid to our named executive officers in the year ended December 31, 2024, as disclosed in this proxy statement. This advisory vote, commonly known as a “say-on-pay” vote, gives our shareholders the opportunity to express their views on the Company’s executive compensation policies and programs and the compensation paid to our named executive officers in the year ended December 31, 2024. Although this advisory vote is non-binding, our Board of Directors will review and consider the voting results when making future decisions regarding our named executive officer compensation and related executive compensation programs.

We are asking that our shareholders to indicate their support of our executive compensation as described in this proxy statement. This vote is not intended to address any specific item of compensation, but rather the overall compensation of our named executive officers and the philosophy, policies and practices described in this proxy statement. We encourage shareholders to read the “Executive Compensation” section in this proxy statement, including the compensation tables and the related narrative disclosure, which describes the structure and amounts of the compensation of our named executive officers in the year ended December 31, 2024. As further discussed in the “Executive Compensation” section, the compensation of our named executive officers is designed to enable us to attract and retain talented and experienced executives to lead us successfully in a competitive environment. The Board of Directors will determine when the next “say-on-pay” advisory vote will be held after considering the results of the advisory vote on the frequency of future advisory votes on executive compensation (see Proposal 6).

THE BOARD RECOMMENDS YOU VOTE, ON AN ADVISORY (NON-BINDING) BASIS, FOR THE APPROVAL OF THE COMPENSATION OF OUR NAMED EXECUTIVE OFFICERS AS SET FORTH IN THIS PROXY STATEMENT

PROPOSAL 6 — APPROVAL OF THE FREQUENCY OF FUTURE ADVISORY VOTES ON THE COMPENSATION OF THE COMPANY’S NAMED EXECUTIVE OFFICERS ON AN ADVISORY (NON-BINDING) BASIS

As required by the Dodd-Frank Act and Section 14A of the Exchange Act, we are asking our shareholders to provide their input with regard to the frequency of future advisory votes on the compensation of our named executive officers, such as Proposal 5 of this proxy statement. In particular, we are asking whether the advisory vote on executive compensation should occur once every year, every two years or every three years.

The Board of Directors has determined that an advisory vote on executive compensation that occurs once every three years is the most appropriate alternative for the Company and therefore the Board recommends that you vote for a three-year interval for the advisory vote on executive compensation. In determining to recommend that shareholders vote for a frequency of once every three years, the Board considered how an advisory vote at this frequency will provide our shareholders with sufficient time to evaluate the effectiveness of our overall compensation philosophy, policies and practices in the context of our long-term business results for the corresponding period, while avoiding over-emphasis on short-term variations in compensation and business results. An advisory vote occurring once every three years will also permit our shareholders to observe and evaluate the effect of any changes to our executive compensation policies and practices which have occurred since the last advisory vote on executive compensation, including changes made in response to the outcome of a prior advisory vote on executive compensation. This approach will also allow the Board and the Remuneration Committee sufficient time to thoughtfully evaluate shareholder feedback, engage with shareholders, and make any appropriate adjustments to the executive compensation program.

You may cast your vote for your preferred voting frequency by choosing the option of one year, two years, or three years or electing to withhold your vote. The frequency that receives the affirmative vote of shareholders representing a simple majority of the total voting rights of shareholders present (in person or by proxy) who (being entitled to vote) vote on the proposal will be the frequency recommended by shareholders. If no frequency receives the foregoing level of support, then the Board of Director will consider the option of one year, two years, or three years that receives the highest number of votes cast to be the frequency recommended by shareholders. Withheld votes are not considered to be votes cast and, accordingly, will have no effect on the outcome of the vote on this proposal.

Your vote on this proposal is advisory, and therefore not binding on the Company or the Board, and will not be interpreted as overruling a decision by, or creating or implying any additional fiduciary duty for, the Board. Shareholders are not voting to approve or disapprove the Board of Directors’ recommendation. Rather, shareholders are being asked to express their preference regarding the frequency of future advisory votes to approve executive compensation. Although this vote is advisory and not binding, the Board will carefully review the results of the vote in making the determination as to the frequency of future advisory votes on our executive compensation.

THE BOARD OF DIRECTORS RECOMMENDS YOU VOTE, ON AN ADVISORY (NON-BINDING) BASIS, FOR THE OPTION OF ONCE EVERY THREE YEARS AS THE FREQUENCY WITH WHICH SHAREHOLDERS ARE PROVIDED AN ADVISORY VOTE ON EXECUTIVE COMPENSATION

ELECTION OF

DIRECTORS

Our Board of Directors currently consists of ten directors.

Our Articles of Association require any director (i) in office who has been appointed by the Board since the previous general meeting, or (ii) for whom it is the third annual general meeting following the annual general meeting at which they were elected or last re-elected, to retire from office and (if they wish to continue to serve on the Board) stand for re-election by our shareholders. This is a constitutional arrangement that is routinely adopted by public limited companies incorporated in the United Kingdom. These provisions apply equally to all directors and ensure that each director is required to stand for re-election by our shareholders at regular intervals. For the avoidance of doubt, this arrangement does not amount to a “classified board” or “staggered board” structure of the sort adopted by some U.S. public companies, which typically have the intention of entrenching the positions of certain directors on a board.

Having carried out an evaluation of the individual performance of each of Dr. Deepika Pakianathan, Dr. Pierre Jacquet and Michael Wyzga with the support of the Nomination and Corporate Governance Committee, the Board is satisfied that their performance continues to be effective and that they continue to demonstrate commitment to their roles. The Board considers that it is entirely appropriate for each of Dr. Deepika Pakianathan, Dr. Pierre Jacquet and Michael Wyzga to seek re-election at the Meeting.

Each of the above directors has been nominated for re-election and no other nominees for directors have been presented. Therefore, it is anticipated that following the Meeting, if all of the above directors are re-elected, the Board of Directors will be comprised of ten members.

In connection with proposals 7 through 9, we set forth the biographical information for the nominees to our Board of Directors. For biographical information for the other directors see the section titled “Board of Directors and Corporate Governance.”

PROPOSAL 7 — RE-ELECTION OF DR. DEEPIKA PAKIANATHAN TO THE BOARD OF DIRECTORS

Dr. Deepika Pakianathan is currently a member of our Board of Directors and has been nominated for

re-election as a director. If elected, she will hold office from the date of her election until the third annual general meeting following this annual general meeting of shareholders upon which she must retire by rotation and offer herself for re-election, or until her earlier death, resignation or removal. Dr. Deepika Pakianathan has agreed to serve if elected, and we have no reason to believe that she will be unable to serve.

Dr. Pakianathan has served on our Board of Directors since April 2019 following completion of the merger of the Company with OncoMed Pharmaceuticals, Inc. (the “Merger”) and served as a director of OncoMed since December 2008 until the closing of the Merger. Since 2001, Dr. Pakianathan has been a Managing Member at Delphi Ventures, a venture capital firm focused on biotechnology and medical device investments. Dr. Pakianathan is also the Chief Executive Officer of a privately held start-up biotechnology company operating in stealth mode. Dr. Pakianathan serves on the boards of directors of Karyopharm Therapeutics, Inc. and Theravance Biopharma, Inc., and previously served on the boards of directors of Calithera Biosciences, Foresite Development Corp II, Alder Biopharmaceuticals, Inc., Foresite Development Corp I. and Relypsa, Inc. Dr. Pakianathan received a B.Sc. from the University of Bombay, India, a M.Sc. from The Cancer Research Institute at the University of Bombay, India, and an M.S. and Ph.D. from Wake Forest University.

Based on her extensive experience as a senior executive and board member in the pharmaceutical and healthcare sectors, the Nomination and Corporate Governance Committee concluded that Dr. Deepika Pakianathan is qualified to serve on our Board of Directors.

THE BOARD OF DIRECTORS RECOMMENDS A VOTE

FOR THE RE-ELECTION OF DR. DEEPIKA PAKIANATHAN TO THE BOARD OF DIRECTORS

PROPOSAL 8 — RE-ELECTION OF DR. PIERRE JACQUET TO THE BOARD OF DIRECTORS

Dr. Pierre Jacquet is currently a member of our Board of Directors and has been nominated for re-election as a director. If elected, he will hold office from the date of his election until the third annual general meeting following this annual general meeting of shareholders upon which he must retire by rotation and offer himself for re-election, or until his earlier death, resignation or removal. Dr. Jacquet has agreed to serve if elected, and we have no reason to believe that he will be unable to serve.

Dr. Jacquet has served on our Board of Directors since September 2021. Dr. Jacquet is currently Managing Director and Vice Chairman of L.E.K. Consulting’s Global Healthcare practice. He has served in a variety of leadership roles over 20 years at L.E.K., including Global Head, Healthcare Practice, Global Leadership Team, the Americas management committee, and various partner operating committees. Prior to joining L.E.K. in 2001, Dr. Jacquet was trained as a surgical resident at University of Liege, Belgium and served as a Fellow at the Washington Cancer Institute, where he authored over 40 publications and presentations. In addition to serving on Mereo’s Board of Directors, Dr. Jacquet is a Director of Neurvati Neurosciences, on the Advisory Board of Life Science Cares, and previously served as a Director of Exact Sciences Corporation and Osprey Pharmaceuticals. He earned a Master of Business Administration from the Darden Graduate School at the University of Virginia, graduated Magna Cum Laude in Medicine from the University of Liege in Belgium and was awarded a Summa Cum Laude Doctor of Philosophy in biomedical sciences from the University of Liege in Belgium.

Based on his extensive experience as a senior executive and board member in the pharmaceutical and healthcare sectors, the Nomination and Corporate Governance Committee concluded that Dr. Jacquet is qualified to serve on our Board of Directors.

THE BOARD OF DIRECTORS RECOMMENDS A VOTE

FOR THE RE-ELECTION OF DR. PIERRE JACQUET TO THE BOARD OF DIRECTORS

PROPOSAL 9 — RE-ELECTION OF MICHAEL WYZGA TO THE BOARD OF DIRECTORS

Michael Wyzga is currently a member of our Board of Directors and has been nominated for

re-election as a director. If elected, he will hold office from the date of his election until the third annual general meeting following this annual general meeting of shareholders upon which he must retire by rotation and offer himself for re-election, or until his earlier death, resignation or removal. Michael Wyzga has agreed to serve if elected, and we have no reason to believe that he will be unable to serve.

Mr. Wyzga has served on our Board of Directors since April 2019 following completion of the Merger and had served as a director of OncoMed since October 2013 until the closing of the Merger. On May 14, 2020, we entered into the Consulting and Interim Chief Financial Officer Agreement with MSW Consulting Inc. and Michael Wyzga by which Mr. Wyzga served as Interim Chief Financial Officer from August 1, 2020 to January 4, 2021. Mr. Wyzga is currently the President of MSW Consulting Inc., a strategic consulting group focused in the life sciences area. From December 2011 until November 2013, Mr. Wyzga served as President and Chief Executive Officer and a member of the board of directors of Radius Health, Inc. Prior to that, Mr. Wyzga served in various senior management positions at Genzyme Corporation, including as Chief Financial Officer from July 1999 until November 2011. Mr. Wyzga was previously a member of the boards of directors of Adagio Therapeutics Corporation and LogicBio. He is currently Chairman of the board of directors of GenSight Biologics S.A. and of X4 Biologics. Mr. Wyzga previously served as a member of the boards of directors of Exact Sciences Corporation, Idenix Pharmaceuticals, Inc. and Altus Pharmaceuticals, Inc., and as a member of the supervisory board of Prosensa Holding B.V. He received an M.B.A. from Providence College and a B.S. from Suffolk University.

Based on his extensive experience as a senior executive and board member in the pharmaceutical and healthcare sectors, the Nomination and Corporate Governance Committee concluded that Michael Wyzga is qualified to serve on our Board of Directors.

THE BOARD OF DIRECTORS RECOMMENDS A VOTE

FOR THE RE-ELECTION OF MICHAEL WYZGA TO THE BOARD OF DIRECTORS

BOARD OF DIRECTORS AND CORPORATE GOVERNANCE

Below is a list of our directors and their positions and ages as of the date of this proxy statement.

During the year ended December 31, 2024, there were five meetings of our Board, six meetings of our Audit and Risk Committee, five meetings of our Remuneration Committee and no meetings of either our Nomination and Corporate Governance Committee or our Research and Development Committee. All of our then Directors attended a minimum of 75% of the aggregate of the meetings of the Board and meetings of the committees of which he or she was a member during 2024.

Director Nominees

The biographical information for Dr. Deepika Pakianathan, Dr. Pierre Jacquet and Michael Wyzga, the nominees to our Board, is provided in “Proposal 7 — Re-election of Dr. Deepika Pakianathan to the Board of Directors,” “Proposal 8 — Re-election of Dr. Pierre Jacquet to the Board of Directors,” and “Proposal 9 — Re-election of Michael Wyzga to the Board of Directors.”

Continuing Directors

Biographical information for those directors who are not standing for re-election at this Meeting and who will remain seated following the Meeting follows below.

Dr. Denise Scots-Knight. Dr. Scots-Knight has served as our Chief Executive Officer since July 2015 and as a member of our Board of Directors since our formation. From 2010 until joining us, Dr. Scots-Knight was the Managing Partner of Phase4 Partners Ltd. (“Phase4”), a global life science venture capital firm. Dr. Scots-Knight is currently a board member of Elanco Animal Health Incorporated (NYSE: ELAN). Dr. Scots-Knight previously served as a member of the board of directors of Idenix Pharmaceuticals (acquired by Merck), Albireo (acquired by Ipsen) and OncoMed and was an observer on the board of Proteolix (acquired by Onyx Pharma). Dr. Scots-Knight holds a B.Sc. (Hons.) and a Ph.D. from Birmingham University and was a Fulbright scholar at the University of Berkeley California.

Dr. Jeremy Bender. Dr. Bender has served on our Board of Directors since October 2020. Dr. Bender is Chief Executive Officer and President of DayOne Biopharmaceuticals, Inc. (NASDAQ: DAWN). Dr. Bender also serves on the board of directors of Fusion Pharmaceuticals, Inc. Previously he served as Vice President of Corporate Development at Gilead Sciences, Inc., where he was responsible for development and negotiation of partnerships, alliances, joint ventures, equity investments, licensing agreements and M&A transactions. Dr. Bender joined Gilead from Tizona Therapeutics, Inc., where he was Chief Operating Officer. Prior to Tizona, he was Chief Business Officer of Sutro Biopharma, Inc. Dr. Bender received his undergraduate degree in Biological Sciences from Stanford University and his Ph.D. in Microbiology & Immunology from the University of Colorado. He also holds an M.B.A. from the MIT Sloan School of Management.

Dr. Anders Ekblom. Dr. Ekblom has served on our Board of Directors since July 2015. Dr. Ekblom has held a number of executive positions at AstraZeneca, including Executive Vice President Global Drug Development, Executive Vice President Global Medicines Development, Global Head Clinical Development and Chief Executive Officer of AstraZeneca AB Sweden. He currently serves as Chairman of the Board of Alligator Bioscience AB, Atrogi AB, Elypta AB and Xspray Pharma AB, and on the boards of directors of AnaMar AB, Flerie AB and Synerkine Pharma Bv. Dr. Ekblom is a board-certified medical doctor and an Associate Professor at the Karolinska Institutet. Dr. Ekblom holds a M.D., Ph.D. and a D.D.S. from Karolinska Institutet.

Dr. Annalisa Jenkins. Dr. Jenkins has served on our Board of Directors since November 2022. Dr. Jenkins served as president and CEO of Dimension Therapeutics, a leading NASDAQ listed gene therapy company that was acquired by Ultragenyx in November 2017. Prior leadership roles have included the head of global research and development at Merck Serono and SVP, Global Development at Bristol Myers-Squibb. Dr. Jenkins is a board member of Compass Pathways plc, Affimed GmbH and Skye Bioscience, Inc., as well as serving on the board, as a trustee or advisor to a number of public and private health and life science companies globally. She is also a board member of Genomics England and a trustee of The Kings Fund and The British Heart Foundation. Dr. Jenkins graduated with a degree in medicine from St. Bartholomew’s Hospital in the University of London and served as a Surgeon Lieutenant Commander in the British Royal Navy.

Justin Roberts. Justin Roberts has served on our Board of Directors since November 2022.

Mr. Roberts is a Partner at Rubric Capital Management LP, a role he has held since the formation of the company in 2016. Before Rubric he spent seven years at Point72 Asset Management. Mr. Roberts currently serves on the board of directors of TherapeuticsMD, Inc. and has also held roles at ZS Associates, Moore Capital Management, and began his career at Lehman Brothers as an investment banker in their M&A practice. Mr. Roberts graduated with honors from Johns Hopkins University.

Dr. Daniel Shames. Dr. Shames has served on our Board of Directors since November 2022. Dr. Shames has served as President of Daniel A. Shames Consulting, providing regulatory services to over 100 biotechnology and pharmaceutical clients. Prior to starting his consultancy Dr. Shames spent 12 years at the FDA during which time he was involved in the safety and efficacy review of hundreds of drugs. Most recently Dr. Shames served as Deputy Director, Office of Drug Evaluation III from 2006 to 2008, while also serving as Director of the Division of Gastroenterology and Inborn Error Products. Prior to that he was Director of Reproductive and Urologic Drugs from 2001 to 2006. Before joining the FDA, Dr. Shames founded Carolina Urocorp, operated a private medical practice, and was as Major in the U.S. Army Medical Corps. Dr. Shames received his undergraduate degree from Brandeis University, his MD from Georgetown University School of Medicine, and did his urology residency at the University of Pennsylvania.

Marc Yoskowitz. Mr. Yoskowitz has served on our Board of Directors since November 2022. Mr. Yoskowitz is Chief Executive Officer of Evozyne, Inc. and a Non-Executive Director of Endo, Inc. Previously he served as EVP and Chief Strategy Officer, Life Sciences at Tempus, Inc. Prior to Tempus, Mr. Yoskowitz was Chief Business Officer, Pfizer Essential Health, leading a range of corporate initiatives within the Pfizer portfolio. Prior to Pfizer, he served as SVP, Strategy and Corporate Development at Hospira and was a member of the Executive Committee. Earlier in his career, Mr. Yoskowitz led business development at a specialty pharmaceutical company, spent eight years at McKinsey & Company where he was an Associate Principal, and began his career as an M&A lawyer at Davis, Polk & Wardwell in New York. Mr. Yoskowitz received a bachelor’s degree magna cum laude from Washington University in St. Louis and holds a JD from Columbia University School of Law.

CORPORATE GOVERNANCE

Structure of the Mereo Board

The leadership structure of our Board of Directors separates the positions of Chief Executive Officer and Chairman of the Board in order to ensure independent leadership of the Board. Our Board believes that this separation is appropriate for the Company at this time because it allows for a division of responsibilities, with our CEO focused on leading the Company while the Chairman can focus on leading the Board in its fundamental role of providing advice to and independent oversight of management. Specifically, the Chair presides over meetings of the Board, facilitates communications between management and the Board and assists with other corporate governance matters. We believe that having a non-executive Chair can enhance the effectiveness of the Board as

a whole.

Composition of the Mereo Board

Our Board currently consists of ten members. We are required to have a board that is composed of a majority of independent directors, as defined under the Nasdaq Stock Market rules. In making the determination of whether a member of the board is independent, our Board considers, among other things, the information provided by the directors with regards to each director’s business and personal activities and any relationships they have with the Company or management, including with respect to their ownership of the Company’s ordinary shares. On the basis of such review and its understanding of such relationships and transactions, our Board affirmatively determined that Michael Wyzga, Jeremy Bender, Anders Ekblom, Pierre Jacquet, Annalisa Jenkins, Deepika Pakianathan, Justin Roberts, Daniel Shames and Marc Yoskowitz are “independent directors” as defined under the applicable rules and regulations of the SEC and the listing requirements and rules of the Nasdaq Stock Market, representing nine of our ten directors. Dr. Denise Scots-Knight is not an independent director due to her employment as Chief Executive Officer of the Company.

Board Oversight of Risk Management

Our management is primarily responsible for assessing and managing risk, while our Board

of Directors is responsible for overseeing management’s execution of its responsibilities. Our Board of Directors is supported by its committees in fulfillment of this responsibility.

Board Committees

The Mereo Board has four standing committees: the Audit and Risk Committee, the Remuneration Committee, the Nomination and Corporate Governance Committee, and the Research and Development Committee.

Audit and Risk Committee

The Audit and Risk Committee which consists of Deepika Pakianathan, Annalisa Jenkins, Michael Wyzga and Jeremy Bender, assists the board in overseeing our accounting and financial reporting processes and the audits of our financial statements. Dr. Pakianathan serves as Chair of the committee. The Audit and Risk Committee consists exclusively of members of our Board who are financially literate, and Dr. Pakianathan is considered an “audit committee financial expert” as defined by applicable SEC rules and has the requisite financial sophistication as defined under the applicable Nasdaq rules and regulations. Our Board has determined that all of the members of the Audit and Risk Committee satisfy the “independence” requirements set forth in Rule 10A-3 under the Exchange Act. The Audit and Risk Committee is governed by a charter that complies with Nasdaq rules, which is available on our website, at: https://www.mereobiopharma.com/investors/corporategovernance/.

The Audit and Risk Committee’s responsibilities include:

The Audit and Risk Committee will meet as often as one or more members of the Audit and Risk Committee deem necessary, but in any event will meet at least four times per year. The Audit and Risk Committee will meet at least once per year with our independent accountant, without our senior management being present.

Remuneration Committee

The Remuneration Committee which consists of Deepika Pakianathan, Justin Roberts and Anders Ekblom, assists the board in determining senior management compensation. Dr. Ekblom serves as Chairman of the committee. Under Nasdaq rules, there are heightened independence standards for members of the Remuneration Committee, including a prohibition against the receipt of any compensation from us other than standard board member fees. Our Board has determined that Dr. Pakianathan, Mr. Roberts and Dr. Ekblom meet this heightened standard. The Remuneration Committee is governed by a charter that complies with Nasdaq rules, which is available on our website, at: https://www.mereobiopharma.com/investors/corporategovernance.

The Remuneration Committee’s responsibilities include:

Remuneration Committee Processes and Procedures

The Remuneration Committee is required to meet at least twice per year, with additional meetings convened as necessary by the Committee Chair. In 2024, the Remuneration Committee met five times. The agenda for each meeting is agreed with the Chair of the Remuneration Committee, in consultation with the appropriate members of the management team, with input from the compensation consultants or other external advisors, and other members of the Committee. The Remuneration Committee meets regularly in executive sessions, and only Remuneration Committee members have the right to attend these meetings. However, other individuals, such as the CEO, other executives, and external advisors, may be invited to attend when appropriate and necessary. The CEO is excluded from participating in deliberations or voting on their own compensation, though they may be invited to attend meetings where other executive compensation matters are discussed.

The Remuneration Committee is authorized to delegate authority to one or more subcommittees as deemed appropriate. The Committee also has the authority to retain or obtain the advice of compensation consultants, legal counsel, or other external advisors, including the selection, retention, and approval of fees and other retention terms at the Company's expense. When retaining such advisors, the Remuneration Committee considers factors affecting their independence, in line with the applicable Nasdaq rules. While the Committee must consider these factors, it is free to select or receive advice from a consultant that may not be independent. The Committee is directly responsible for overseeing the work of any consultants or advisors it engages.

Nomination and Corporate Governance Committee

The Nomination and Corporate Governance Committee which consists of Michael Wyzga, Jeremy Bender, Pierre Jacquet, and Justin Roberts, assists our Board in identifying individuals qualified to become members of our Board and senior management consistent with criteria established by our Board and in developing our corporate governance principles. Mr. Wyzga serves as Chair of the Nomination and Corporate Governance Committee. The Nomination and Corporate Governance Committee is governed by a charter that complies with Nasdaq rules, which is available on our website, at: https://www.mereobiopharma.com/investors/corporategovernance/.

The Nomination and Corporate Governance Committee’s responsibilities include:

Research and Development Committee

The Research and Development Committee, which consists of Pierre Jacquet, Daniel Shames, Marc Yoskowitz and Anders Ekblom, assists our senior management with oversight and guidance related to strategic research and development matters and provides guidance and makes recommendations to our Board regarding strategic research and development matters. Dr. Ekblom serves as Chair of the Research and Development Committee.

The Research and Development Committee’s responsibilities include oversight of:

In addition, the Research and Development Committee is tasked with keeping informed of strategic issues (regulatory, competitive landscape and commercial) affecting our development programs and potential product acquisitions.

Code of Business Conduct and Ethics

The Company currently maintains a Code of Business Conduct and Ethics which applies to all directors, officers, and employees. A copy of our Code of Business Conduct and Ethics can be found on our website at www.mereobiopharma.com in the “Investors” section under “Corporate Governance.” We intend to satisfy the disclosure requirement under Item 5.05 of Form 8-K regarding amendments to, or waivers from, a provision of our Code of Business Conduct and Ethics, as well as Nasdaq’s requirement to disclose waivers with respect to directors and executive officers, by posting such information on our website at the address and location specified above.

Delinquent Section 16(a) Reports

During the year ended December 31, 2024, based solely on a review of the reports furnished to the Company, or written representations by persons subject to Section 16(a), the Company believes that all executive officers and directors complied with Section 16(a) filing requirements applicable to us.

Policy Prohibiting Hedging and Pledging

Pursuant to our Insider Trading Policy, our officers, directors, and employees are prohibited from engaging in speculative trading, including hedging transactions or short sale transactions with respect to Company securities.

Clawback Policy

The Company has adopted a compensation recovery policy as required by Rule 10D-1 under the Securities Exchange Act of 1934, as amended, and the corresponding listing standards of the Nasdaq Stock Exchange. This policy provides for the mandatory recovery (subject to limited exceptions) from current and former officers of incentive-based compensation that was erroneously received during the three years preceding the date that the Company is required to prepare an accounting restatement. The amount required to be recovered

is the excess of the amount of incentive-based compensation received over the amount that otherwise would have been received had it been determined based on the restated financial measure.

Insider Trading Policy

The Company has adopted an insider trading policy governing the purchase, sale, and other dispositions of our securities by our directors, officers, employees, agents, consultants and other covered persons that we believe is reasonably designed to promote compliance with insider trading laws, rules, regulations, and applicable listing standards.

Director Nomination Process

The Nomination and Corporate Governance Committee of the Board of Directors reviews possible candidates for the Board and recommends the nominees for Directors to the Board for approval. The criteria that the Nomination and Corporate Governance Committee and the Board of Directors look for in determining candidates for election to the Board, include, among others:

It is the Nomination and Corporate Governance Committee’s policy that the composition of the Board of Directors reflect a range of talents, ages, skills, character, diversity and expertise, particularly in the areas of biotechnology and related industries, research and development and commercial leadership, accounting and finance, management, domestic and international capital markets, leadership and corporate governance sufficient to provide sound and prudent guidance with respect to the operations and interests of the Company. The independent directors of our Board of Directors believe that the current members of the Board of Directors

reflect an appropriate diversity of gender, age, race, geographical background and experience. Currently, 30% of our Board of Directors self-identified as female, 40% as male and 30% did not disclose. Furthermore, 10% of our Board of Directors self-identified as Asian, 60% as White and 30% did not disclose.

Shareholder Recommendations and Nominees

Our Nomination and Corporate Governance Committee considers both recommendations and nominations for candidates to the Board from shareholders so long as such recommendations and nominations comply with our Articles of Association, Nomination and Corporate Governance Committee charter and applicable laws, including the rules and regulations of the SEC. Shareholder recommendations for director candidates must include the nominee’s name and address of record, a representation that the shareholder is a holder of the Company’s securities, as well as the nominee’s detailed biographical data and qualifications for board membership, information regarding any arrangements or understandings between the shareholder and the recommended candidate, the consent of the proposed nominee to be named in the proxy statement and serve as a director if elected and any other information regarding the nominee that is required to be included in a proxy statement.

Following verification of the shareholder status of the person submitting the recommendation, all properly submitted recommendations will be promptly brought to the attention of the Nomination and Corporate Governance Committee. Shareholders who desire to nominate persons directly for election to the Board at an annual general meeting of shareholders must meet the deadlines and other requirements set forth under “Additional Information — Shareholder Proposals for 2026 Annual General Meeting”. Any vacancies on the Board of Directors occurring between our annual general meetings of shareholders may be filled by persons selected by a majority of the directors then in office, in which case any director so appointed will serve until the

next annual general meeting of shareholders when such director will offer himself/herself for re-election, or by persons elected by an ordinary resolution of the shareholders of the Company.

You may write to the Nomination and Corporate Governance Committee at:

c/o Charles Sermon

Company Secretary

Mereo BioPharma Group plc

4th Floor, One Cavendish Place, London, W1G 0QF

United Kingdom

Shareholder Communication with the Board of Directors

It is the policy of our Board of Directors to allow shareholders to communicate with its members. Communications may be addressed to the entire board or to any individual director. All such communications will initially be received and processed by our Company Secretary. Spam, junk mail, advertisements and threatening, hostile, illegal and similar unsuitable communications will not be delivered to the Board. Shareholders can contact members of the Board by writing to our Company Secretary at the Company’s registered office address.

DIRECTORS COMPENSATION

The following table presents the total compensation for each person who served as a non-executive member of our Board of Directors and received compensation for such service during the fiscal year ended December 31, 2024. Other than as set forth in the table and described more fully below, we did not pay any compensation, make any equity awards or awards to, or pay any other compensation to any of the members of our board of directors in 2024. We reimburse members of our Board of Directors for reasonable travel expenses. Dr. Scots-Knight, our Chief Executive Officer, did not receive any compensation for her service as a member of our board of directors in 2024. Dr. Scots-Knight’s compensation for service as a named executive officer (“NEO”) for fiscal years 2024 and 2023 is presented in “Executive Compensation—2024 Summary Compensation Table.”

(1) Compensation paid to all non-executive directors in 2024 was denominated in pounds sterling. For the purposes of this table, all 2024 amounts have been converted based on the pound sterling/U.S. dollar exchange rate in effect as of December 31, 2024 (£1/$1.2546).

(2) Amounts reflect the grant date fair value of awards granted in 2024 in accordance with the Financial Accounting Standards Board’s Accounting Standards Codification Topic 718, or ASC 718. Such grant date fair value does not take into account any estimated forfeitures related to service-vesting conditions. For information regarding assumptions underlying the valuation of equity awards, see note 15 to our financial statements for the year ended December 31, 2024. These amounts do not correspond to the actual value that may be recognized by the named executive officers upon vesting of applicable awards.

(3) Mr. Roberts has waived all remuneration in respect of his appointment as a non-executive director.

Non-Executive Director Compensation Policy

Our non-executive directors are eligible to earn cash fees for service on the board of directors and for service on each committee on which the director is a member. The chairperson of each committee receives a higher fee for such service. Non-executive directors may voluntarily elect to convert their annual cash fees into deferred restricted stock units ("Deferred RSUs") over ADSs. The number of Deferred RSUs granted is determined by dividing the amount of the annual cash compensation by the average closing trading price of the Company’s ADSs over the most recent 30 trading days as of the grant date. These Deferred RSUs are delivered under the terms of the existing 2019 Non-Employee Equity Incentive Plan (the “2019 NED EIP”) and they vest in substantially equal monthly installments over the plan year. Payment of Deferred RSUs in ADSs will generally be made 180 days following separation of service.

In addition to annual cash fees or Deferred RSUs, as elected, equity incentive awards are granted to non-executive directors in line with the 2019 NED EIP. In February 2024, a total of 45,000 equity incentive awards in the form of market value options over ADSs, were granted to each non-executive director at an exercise price of $3.87 per ADS, with a vesting period of one year; vesting is in equal monthly installments over the one-year period following grant date. No performance conditions were attached to the awards.

The fees payable to directors for service on the board of directors and for service on each committee of the board of directors on which the director is a member are as follows:

(1) Compensation in the form of annual cash fees or amounts to be granted in Deferred RSUs, as elected, paid to non-executive directors is denominated in pounds sterling. For the purposes of this table, all 2024 amounts have been converted based on the pound sterling/U.S. dollar exchange rate in effect as of December 31, 2024 (£1/$1.2546).

We also reimburse our non-executive directors for reasonable out-of-pocket expenses incurred in connection with attending our board of director and committee meetings.

Non-Executive Directors - Outstanding Equity Awards at 2024 Fiscal Year End Table

The following table presents information regarding all outstanding share awards and share options held by each of our non-executive directors as of December 31, 2024:

(1) Mr. Roberts has waived all remuneration in respect of his appointment as a non-executive director.

(2) These options vest in substantially equal monthly installments over a one year period from the February 8, 2024 grant date and fully vested on February 8, 2025.

(3) Each Deferred RSU was granted to non-executive directors who elected to receive them in the form of ADSs in lieu of annual cash compensation. Deferred RSUs vest in substantially equal monthly installments over the plan year following the grant date and became fully vested in January 2025. Payment of Deferred RSUs in ADSs will generally be made 180 days following separation of service.

Non-Executive Director Service Contracts

The remuneration of the non-executive directors is determined by the Board as a whole, based on a review of current practices in other companies. Mereo has entered into service contracts with Mereo’s

non-executive directors for their services, which are subject to a three-month termination period. There are no arrangements under which any non-executive director is entitled to receive compensation upon the early termination of his or her appointment.

SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

The following table sets forth information relating to the beneficial ownership of Mereo ordinary shares as of April 1, 2025 by each person known by Mereo to own beneficially 5% or more of the outstanding Mereo ordinary shares, its directors and NEOs.

The number of Mereo ordinary shares beneficially owned by each person is determined in accordance with the rules of the SEC, and the information is not necessarily indicative of beneficial ownership for any other purpose. Under such rules, beneficial ownership includes any shares over which the individual has sole or shared voting power or investment power as well as any shares that the individual has the right to acquire within 60 days through the exercise of any option, warrant or other right. Except as otherwise indicated, and subject to

applicable community property laws, the persons named in the table have sole voting and investment power with respect to all Mereo ordinary shares held by that person.

The percentage of Mereo ordinary shares beneficially owned as of April 1, 2025 is computed on the basis of 795,001,444 ordinary shares outstanding as of April 1, 2025. Mereo ordinary shares that a person has the right to acquire within 60 days of April 1, 2025 are deemed outstanding for purposes of computing the percentage ownership of the person holding such rights, but are not deemed outstanding for purposes of computing the percentage ownership of any other person.