Nivolumab-Induced Refractory Hemorrhagic Gastritis and Duodenitis Requiring Multimodal Biologic Therapy.

Rising immune checkpoint inhibitor use in modern cancer therapy has increased the incidence of immune-related adverse events. Although isolated upper gastrointestinal immune-related adverse events including gastritis and duodenitis are uncommon, they may be severe and potentially life-threatening. The heterogeneous presentation of immune-related gastritis and duodenitis causes diagnostic and therapeutic challenges. We present a rare case of severe hemorrhagic gastritis and duodenitis occurring 2 months after completion of nivolumab therapy for stage III melanoma. The disease proved refractory to intravenous pantoprazole, steroids, and infliximab alone, ultimately requiring the addition of vedolizumab in the short term. Complete clinical and biochemical remission was achieved after 12 months of infliximab, which was ceased a month later. Following cessation of immunomodulatory therapy, there was no recurrence of disease at 12-month follow-up.