LeonaBio, Inc.

FOR 2026 ANNUAL MEETING OF STOCKHOLDERS

To be Held at 8:00 a.m., Pacific Time, on June 22, 2026

The board of directors of LeonaBio, Inc., a Delaware corporation (“we,” “us,” “our,” the “Company” or “LeonaBio”), is soliciting proxies to be used at our 2026 annual meeting of stockholders (together with any postponement, adjournment or continuation thereof, the “Annual Meeting”). The Annual Meeting will be held on June 22, 2026, at 8:00 a.m., Pacific Time. The Annual Meeting will be conducted virtually via live audio webcast. You will be able to attend the Annual Meeting virtually by visiting www.virtualshareholdermeeting.com/LONA2026, where you will be able to listen to the meeting live, submit questions and vote online during the meeting.

The Notice of Internet Availability of Proxy Materials (the “Notice of Internet Availability”), containing instructions on how to access this proxy statement, the accompanying notice of annual meeting and form of proxy, and our annual report, is first being sent or given on or about May 11, 2026 to all stockholders of record as of May 1, 2026. The proxy materials and our annual report can be accessed as of May 11, 2026 by visiting www.proxyvote.com. If you receive a Notice of Internet Availability, then you will not receive a printed copy of the proxy materials or our annual report in the mail unless you specifically request these materials. Instructions for requesting a printed copy of the proxy materials and our annual report are set forth in the Notice of Internet Availability.

The information provided in the “question and answer” format below is for your convenience only and is merely a summary of the information contained in this proxy statement. You should read this entire proxy statement carefully.