A Phase 3 Study to Investigate the Efficacy and Safety of SHR0302 With Moderately to Severely Active Ulcerative Colitis

This study consists of a screening period followed by a placebo-controlled Part 1 phase and then a placebo-controlled Part 2 phase. An open label Part 3 phase is open to subjects who: complete the Part 2, are considered non-responders following the Part 1, or have disease worsening during Part 2.