A Multicentre Randomized, Double-blind, Placebo-controlled Phase 2 Study to Evaluate the Safety, Tolerability, Efficacy, Dose-response, Pharmacokinetics and Pharmacodynamics of Repeat Dosing of an Anti-LAG3 Cell Depleting Monoclonal Antibody (GSK2831781) in Patients With Active Ulcerative Colitis

This is a Phase 2, multicenter, randomized, double-blind, parallel group, placebo-controlled
study to investigate the safety, tolerability, efficacy and dose-response of GSK2831781 in
participants with moderate to severe active ulcerative colitis. The study consists of a
5-week screening window, 10-week Induction Phase, 30-week double-blind Extended Treatment
Phase (ETP) with 42-week Follow-Up Phase. Non-Responders identified following the Week 10
assessment will be allocated to open label treatment, consisting of Induction (Weeks 12 to
22), an Open label ETP (Weeks 22 to 42) and a follow-Up to Week 54.