Immune-Mediated Colitis with Novel Immunotherapy : PD1 Inhibitor Associated Gastrointestinal Toxicity

T-cell checkpoint blockade is showing great promise in treatment of advanced melanoma and noncell lung cancer [NSCLC]. Nivolumab is a monoclonal antibody that selectively inhibits programmed cell death one [PD1], a coinhibitory receptor allowing immune system to mount an effective antitumor response (1). Other immunomodulatory antibodies like Ipilimumab, a CTLA4 inhibitor have also been used to enhance immune system. Although therapeutic advances have improved prognosis of advanced melanoma, immune- related adverse events [AE] of gastrointestinal [GI] tract are commonly seen. While studies have reported GI toxicities with Ipilimumab, very few cases of Nivolumabinduced colitis are reported.