X0609 4 2026-06-26 0001984086 Septerna, Inc. SEPN 0001377202 Sharp Shalini false C/O SEPTERNA, INC. 250 EAST GRAND AVENUE SOUTH SAN FRANCISCO CA 94080 true false false false false Stock Option (Right to Buy) 37.34 2026-06-26 4 A false 15000 0 A 2036-06-25 Common Stock 15000 15000 D The shares underlying the stock option vest in full upon the earlier of (i) June 26, 2027 or (ii) the date of the Issuer's next annual meeting of stockholders, subject to the Reporting Person's continued service to the Issuer through such vesting date. Exhibit 24.2 - Substitute Power of Attorney /s/ Mark A. Wilson, Attorney-in-Fact 2026-06-30