PepGen Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

(Rule 14a-101)

INFORMATION REQUIRED IN PROXY STATEMENT

SCHEDULE 14A INFORMATION

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:

(Exact name of registrant as specified in its charter)

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

Payment of Filing Fee (Check all boxes that apply):

Boston, MA 02118

NOTICE OF 2025 ANNUAL MEETING OF STOCKHOLDERS

To be held June 4, 2025

Dear Stockholders:

You are cordially invited to attend the 2025 Annual Meeting of Stockholders, or the Annual Meeting, of PepGen Inc. to be held on Wednesday, June 4, 2025, at 12:00 p.m. Eastern Daylight Time, virtually via live webcast at www.proxydocs.com/PEPG, where you will be able to vote electronically and submit questions, as described below. We encourage you to access the Annual Meeting before it begins. The purpose of the Annual Meeting is the following:

to elect three Class III directors to our board of directors, to serve until the 2028 annual meeting of stockholders and until his or her successor has been duly elected and qualified, or until his or her earlier death, resignation or removal;

to ratify the appointment of KPMG LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2025; and

to transact any other business properly brought before the Annual Meeting or any adjournment or postponement of the Annual Meeting.

The proposal for the election of directors relates solely to the election of Class III directors nominated by the board of directors.

Only PepGen Inc. stockholders of record at the close of business on April 8, 2025 will be entitled to vote during the Annual Meeting and any adjournment or postponement thereof. In order to attend the Annual Meeting, you must register in advance at www.proxydocs.com/PEPG prior to the commencement of the Annual Meeting. Upon completing your registration, you will receive further instructions via email, including your unique links that will allow you access to the meeting and will permit you to submit questions. You will not be able to attend the Annual Meeting in person.

We are pleased to take advantage of Securities and Exchange Commission rules that allow companies to furnish their proxy materials over the Internet. We are mailing to our stockholders a Notice of Internet Availability of Proxy Materials, or the Notice, instead of a paper copy of our proxy materials and our Annual Report to Stockholders for the fiscal year ended December 31, 2024, or 2024 Annual Report. The Notice contains instructions on how to access those documents and to cast your vote via the Internet. The Notice also contains instructions on how to request a paper copy of our proxy materials and our 2024 Annual Report, which are available to you free of charge. This “Notice and Access” internet process that we have elected to follow allows us to provide our stockholders with necessary information on a more timely basis, while reducing the environmental impact and lowering the costs of printing and distributing our proxy materials. The Annual Meeting items of business noted above are more fully described in the proxy materials we are furnishing over the Internet.

Your vote is important. Whether or not you are able to attend the virtual Annual Meeting, it is important that your shares be represented. To ensure that your vote is recorded promptly, please vote as soon as possible, even if you plan to attend the virtual Annual Meeting. You may vote by submitting your proxy via the Internet, by telephone, or by mail (if you received paper copies of the proxy materials) by following the instructions on the proxy card or voting instruction card. Voting over the Internet or by telephone, written proxy or voting instruction card will ensure your representation at the virtual Annual Meeting regardless of whether you attend.

On behalf of our Board of Directors and all our employees, thank you for your continued support and investment in PepGen Inc.

By order of the Board of Directors,

James McArthur, Ph.D.

President and Chief Executive Officer

Boston, Massachusetts

April 25, 2025

Table of Contents

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Boston, MA 02118

PROXY STATEMENT

FOR THE 2025 ANNUAL MEETING OF STOCKHOLDERS

To be held on Wednesday, June 4, 2025

This proxy statement contains information about the 2025 Annual Meeting of Stockholders, or the Annual Meeting, of PepGen Inc., which will be held virtually on Wednesday, June 4, 2025 at 12:00 p.m. Eastern Daylight Time. The Annual Meeting will be a virtual stockholders meeting held at www.proxydocs.com/PEPG. The board of directors of PepGen Inc. is using this proxy statement to solicit proxies for use at the Annual Meeting. In this proxy statement, the terms “PepGen,” “Company,” “we,” “us,” and “our” refer to PepGen Inc. The mailing address of our principal executive offices is 321 Harrison Avenue, 8th Floor, Boston, Massachusetts 02118.

All properly submitted proxies will be voted in accordance with the instructions contained in those proxies. If no instructions are specified, the proxies will be voted in accordance with the recommendation of our board of directors with respect to each of the matters set forth in the accompanying Notice of the Annual Meeting. You may revoke your proxy at any time before it is exercised at the meeting by (1) following the instructions on the Notice and entering a new vote by mail that we receive before the start of the Annual Meeting or over the Internet by the cutoff time of 12:00 p.m. Eastern Daylight Time on June 4, 2025, (2) attending and voting at the virtual Annual Meeting (although attendance at the virtual Annual Meeting will not in and of itself revoke a proxy), or (3) filing an instrument in writing revoking the proxy or another duly executed proxy bearing a later date with our Corporate Secretary. Any written notice of revocation or subsequent proxy card must be received by our proxy tabulator prior to the taking of the vote at the Annual Meeting. Any such written notice of revocation or subsequent proxy card should be delivered by mail, for delivery prior to the above-referenced cutoff time, to PepGen Inc., Attn: Corporate Secretary, 321 Harrison Avenue, 8th Floor, Boston, Massachusetts 02118.

We made this proxy statement and our Annual Report to Stockholders for the fiscal year ended December 31, 2024, or 2024 Annual Report, available to stockholders on or about April 25, 2025.

We are an “emerging growth company” under applicable federal securities laws and therefore permitted to conform with certain reduced public company reporting requirements. As an emerging growth company, we provide in this proxy statement the scaled disclosure permitted under the Jumpstart Our Business Startups Act of 2012, or the JOBS Act, including the compensation disclosures required of a “smaller reporting company,” as that term is defined in Rule 12b-2 promulgated under the Securities Exchange Act of 1934, as amended, or the Exchange Act. In addition, as an emerging growth company, we are not required to conduct votes seeking approval, on an advisory basis, of the compensation of our named executive officers or the frequency with which such votes must be conducted. We will remain an “emerging growth company” until the earliest of (i) the last day of the fiscal year following the fifth anniversary of our May 2022 initial public offering; (ii) the last day of the fiscal year in which our total annual gross revenue is equal to or more than $1.235 billion; (iii) the date on which we have issued more than $1 billion in nonconvertible debt during the previous three years; or (iv) the date on which we are deemed to be a large accelerated filer under the rules of the Securities and Exchange Commission, or SEC. Even after we are no longer an “emerging growth company,” we may remain a “smaller reporting company.”

Important Notice Regarding the Availability of Proxy Materials for

the Annual Meeting of Stockholders to Be Held on Wednesday, June 4, 2025:

This proxy statement and our 2024 Annual Report are

available for viewing, printing and downloading at www.proxydocs.com/PEPG.

A copy of our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, as filed with the SEC, except for exhibits, will be furnished without charge to any stockholder upon written request to PepGen Inc., 321 Harrison Avenue, 8th Floor, Boston, MA 02118, Attention: Corporate Secretary. This proxy statement and our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, are also available on the SEC’s website at www.sec.gov, or on our website athttps://investors.pepgen.com/financial-information/sec-filings.

PEPGEN inc.

PROXY STATEMENT

FOR THE 2025 ANNUAL MEETING OF STOCKHOLDERS