X0508 4 2024-07-18 0001835597 PepGen Inc. PEPG 0001923040 Mellion Michelle L 321 HARRISON AVE., 8TH FLOOR C/O PEPGEN INC. BOSTON MA 02118 1 Chief Medical Officer 1 Common Stock 2024-07-18 4 M 0 12625 10.21 A 12625 D Common Stock 2024-07-18 4 S 0 12625 18.2023 D 0 D Stock Option (Right to Buy) 10.21 2024-07-18 4 M 0 12625 0 D 2032-06-30 Common Stock 12625 57772 D The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on January 19, 2024. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $18.00 to $18.56, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. This option shall vest as follows: twenty-five percent (25%) on the one-year anniversary of the Grant Date and the remainder vesting in thirty-six (36) equal monthly installments, subject to the option recipient's continued service or employment with the Company on each applicable vesting date. /s/ Noel Donnelly, as Attorney-in-Fact 2024-07-19