Ozanimod (previously known as RPC-1063) is a selective immune-inflammatory modulator of the G protein-coupled receptors sphingosine 1-phosphate 1 and 5, which are part of the sphingosine 1-phosphate (S1P) receptor family. Treatment with S1P receptor modulators interferes with S1P signaling and blocks the response of lymphocytes (a type of white blood cell) to exit signals from the lymph nodes, sequestering them within the nodes. The result is a downward modulation of circulating lymphocytes and anti-inflammatory activity by inhibiting cell migration to sites of inflammation. Ozanimod is currently in phase III clinical trials for the treatment of relapsing multiple sclerosis (RMS) and ulcerative colitis, and also in phase II clinical trials to determine whether it is effective in the treatment of Crohn's disease.