X0609 4 2026-10-26 0 0001620463 LeonaBio, Inc. LONA 0002126186 Portman David J. false 250 E. BROAD ST., SUITE 250 COLUMBUS OH 43215 0 0 1 0 0 Common Stock 2026-10-26 2026-10-26 4 P 0 3149470 3149.47 A 3149470 I See note Warrant 0.001 2026-10-26 2026-10-26 4 P 0 5502402 3149.47 D 2026-10-26 Common Stock 5502402 0 I See note The shares are held by Sermonix Pharmaceuticals, Inc. of which Dr. Portman is the Chief Executive Officer. This Form 4 is being filed to report Dr. Portman's voting control over such securities, but Dr. Portman's personal indirect beneficial ownership does not exceed 10% of the stock in the Issuer. The Warrant does not expire. The Warrant was held by Sermonix Pharmaceuticals, Inc. of which Dr. Portman is the Chief Executive Officer. The Warrant was exercised on October 26, 2026, in part, into 3,149,740 Common Shares of Issuer, and the balance of the Warrant was assigned to Perceptive Xentogeny Venture Fund II, LP as a distribution-in-kind pursuant to a plan of distribution to the Sermonix Pharmaceuticals equity holders. Following the partial exercise and the assignment of the remaining Warrant rights, Sermonix Pharmaceuticals holds 3,149,740 Common Shares of Issuer. David J. Portman 2026-10-28