Sec Form 3 Filing - RA CAPITAL MANAGEMENT, L.P. @ PepGen Inc. - 2022-05-05

FORM 3 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person RA CAPITAL MANAGEMENT, L.P. 2. Issuer Name and Ticker or Trading Symbol PepGen Inc. [ PEPG] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 200 BERKELEY STREET, 18TH FLOOR, 3. Date of Earliest Transaction (MM/DD/YY) 05/05/2022 (Street) BOSTON, MA02116 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Series A-2 Preferred Stock ( 1 ) ( 1 ) ( 1 ) Common Stock 2,160,845( 2 ) I See footnotes( 2 )( 5 ) Series A-2 Preferred Stock ( 1 ) ( 1 ) ( 1 ) Common Stock 417,972( 3 ) I See footnotes( 3 )( 5 ) Series A-2 Preferred Stock ( 1 ) ( 1 ) ( 1 ) Common Stock 207,672( 4 ) I See footnotes( 4 )( 5 ) Series B Preferred Stock ( 1 ) ( 1 ) ( 1 ) Common Stock 1,481,383( 2 ) I See footnotes( 2 )( 5 ) Series B Preferred Stock ( 1 ) ( 1 ) ( 1 ) Common Stock 634,878( 3 ) I See footnotes( 3 )( 5 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other RA CAPITAL MANAGEMENT, L.P. 200 BERKELEY STREET, 18TH FLOOR BOSTON, MA02116 X X RA Capital Healthcare Fund LP 200 BERKELEY STREET 18TH FLOOR BOSTON, MA02116 X X RA Capital Nexus Fund II, L.P. 200 BERKELEY STREET, 18TH FLOOR BOSTON, MA02116 X X Kolchinsky Peter 200 BERKELEY STREET 18TH FLOOR BOSTON, MA02116 X X Shah Rajeev M. 200 BERKELEY STREET 18TH FLOOR BOSTON, MA02116 X X Signatures /s/ Peter Kolchinsky, Manager of RA Capital Management, L.P. 05/05/2022 Signature of Reporting Person Date /s/ Peter Kolchinsky, Manager of RA Capital Healthcare Fund GP, LLC the General Partner of RA Capital Healthcare Fund, L.P. 05/05/2022 Signature of Reporting Person Date /s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund II GP, LLC the General Partner of RA Capital Nexus Fund II, L.P. 05/05/2022 Signature of Reporting Person Date /s/ Peter Kolchinsky, individually 05/05/2022 Signature of Reporting Person Date /s/ Rajeev Shah, individually 05/05/2022 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The Issuer effected a 1.018-for-1 reverse stock split of its Common Stock on April 29, 2022 ("Reverse Split"). After giving effect to the Reverse Split, the shares of Series A-1 Preferred Stock, Series A-2 Preferred Stock and Series B Preferred Stock are convertible, at any time, at the holder's election, into shares of the Issuer's common stock at a ratio of 1.018-for-1. In addition, effective immediately prior to the closing of the Issuer's initial public offering of its common stock, each share of Series A-1 Preferred Stock, Series A-2 Preferred Stock and Series B Preferred Stock will automatically convert into shares of the Issuer's common stock at a ratio of 1.018-for-1. The Series A-1 Preferred Stock, Series A-2 Preferred Stock and Series B Preferred Stock have no expiration date. ( 2 )These securities are held directly by RA Capital Healthcare Fund, L.P. (the "Fund"). ( 3 )These securities are held directly by RA Capital Nexus Fund II, L.P. ("Nexus Fund II"). ( 4 )These securities are held directly by a separately managed account. (the "Account"). ( 5 )RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund, Nexus Fund II and the Account. The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Adviser, the Adviser GP, Dr. Kolchinsky, and Mr. Shah disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.

Remarks: Dr. Joshua Resnick, a Managing Director of the Adviser, serves on the Issuer's board of directors.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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