A Phase 2b, Double-Blind, Placebo-Controlled, Multicenter Proof of Concept Clinical Study to Evaluate the Efficacy and Safety of ATH-063 Induction Therapy in Patients With Biologic Relapsed/Refractory Moderately to Severely Active Ulcerative Colitis (UC)

The trial will consist of a 4-week screening period, a 12-week double-blind treatment period, and an open-label extension. Following completion of the 12-week double-blind period, participants who wish to continue into the open-label extension will be unblinded. Participants who do not wish to continue into the extension will remain blinded and proceed to posttreatment follow-up at Weeks 16 and 24 (via telephone calls). Unblinded participants who are revealed to have been randomized to receive ATH-063 will also proceed to posttreatment follow-up at Weeks 16 and 24 (via telephone calls). Unbli…