<b>BACKGROUND</b>: Ozanimod (RPC1063) is an oral agonist of the sphingosine-1-phosphate receptor subtypes 1 and 5 that induces peripheral lymphocyte sequestration, potentially decreasing the number of activated lymphocytes circulating to the gastrointestinal tract.<br><b>METHODS</b>: We conducted a double-blind, placebo-controlled phase 2 trial of ozanimod in 197 adults with moderate-to-severe ulcerative colitis.