This study is to evaluate the efficacy and safety of induction and maintenance therapy with TD-1473, an orally administered drug, in patients with moderate-to-severe active Ulcerative Colitis (UC). Designed to provide an alternative treatment for patients with UC designed to act directly at the site of inflammation in the intestinal wall, avoiding systemic effects.

Eligible participants must be male or female over 18 years of age or older.

They must have at least 3 months prior history of UC, been diagnosed by a physician with UC, present with UC symptoms and have previously failed biological treatments (anti-TNF or anti-integrin).