This phase III study protocol includes an induction study for 6 weeks and a maintenance study for an additional 45 weeks.~In the induction study there will be an initial phase to explore the best dose, between cobitolimod 250 mg and cobitolimod 500 mg using adaptive design.
The purpose of the study is to evaluate the efficacy of cobitolimod treatment compared to placebo in inducing clinical remission, in participants with moderate to severe active left-sided UC and to evaluate the efficacy of cobitolimod maintenance treatment compared to placebo in inducing or maintaining clinical remission at week 52, in participants with clinical response at week 6 after induction treatment with cobitolimod.