X0508 4 2025-12-04 0001829802 Sensei Biotherapeutics, Inc. SNSE 0001843594 Peyer James 228 PARK AVENUE S. #66643 NEW YORK NY 10003 true true See remarks below false Common Stock 2025-12-04 4 S 0 5000 9.06 D 177654 I See footnote Common Stock 2025-12-05 4 S 0 14508 11.4 D 163146 I See footnote Common Stock 2025-12-05 4 S 0 1745 12.29 D 161401 I See footnote Common Stock 2025-12-05 4 S 0 42 13.16 D 161359 I See footnote The price reported in Column 4 is a weighted average price. The prices sold ranged from $9.00 to $9.54. The reporting person will provide the issuer, any security holder of the issuer, or the SEC staff, upon request, full information regarding the number of shares sold at each separate price within the range. The amount shown reflects the number of shares held following the reported transaction, as adjusted for a 1-for-20 stock split effectuated by the issuer. These shares are held by Cambrian Biopharma Inc, a Delaware corporation ("Cambrian"). The Reporting Person is the Chief Executive Officer of Cambrian and in such capacity may direct the voting and disposition of the shares held by Cambrian, subject in certain instances to the approval of Cambrian's Board of Directors. Mr. Peyer disclaims beneficial ownership of such shares. The price reported in Column 4 is a weighted average price. The prices sold ranged from $11.00 to $12.00. The reporting person will provide the issuer, any security holder of the issuer, or the SEC staff, upon request, full information regarding the number of shares sold at each separate price within the range. The price reported in Column 4 is a weighted average price. The prices sold ranged from $12.02 to $12.95. The reporting person will provide the issuer, any security holder of the issuer, or the SEC staff, upon request, full information regarding the number of shares sold at each separate price within the range. The price reported in Column 4 is a weighted average price. The prices sold ranged from $13.00 to $13.26. The reporting person will provide the issuer, any security holder of the issuer, or the SEC staff, upon request, full information regarding the number of shares sold at each separate price within the range. /s/ James Peyer 2025-12-08