This is a Phase 2, randomized, double-blinded, placebo-controlled 3-arm, multi-center, parallel-group study with an open-label extension (OLE) period. The study includes a Screening Period (of up to 28 days) and a 12-week Double-Blind Period (Day 1 through Day 85) for all subjects. Subjects completing the Double-Blind Period through Day 85 will be provided the opportunity to continue in the OLE Period of the study to receive treatment through approximately one year. Subjects who do not participate in the OLE Period will be followed for 84 days in a Safety Follow-up Period.
The study will assess the efficacy and safety of oral MT-1303 compared to placebo at 12 weeks as the induction treatment in subjects with active mild to moderate ulcerative colitis (UC), as well as maintenance treatment with open-label MT-1303 for up to 36 weeks.