Treatment of Immune Checkpoint Inhibitor Induced Colitis with Infliximab.

Several immunotherapeutic agents function against the T cell immune checkpoint inhibitor pathways thereby reestablishing immune response to elusive malignancies. Namely, the programmed death-1 co-receptor (PD-1) or ligand (PD-L1) and cytotoxic T lymphocyte- associated protein 4 (CTLA-4) are well known checkpoint targets of current FDA approved drugs. Among these drugs nivolumab, an IgG4 anti-PD-1 antibody, and ipilimumab, an anti-CTLA-4 antibody, are used to treat numerous malignancies but carry a large list of potential side effects termed immune-related adverse effects (irAEs). We describe the presentation, clinical course, and resolution of steroid-resistant immune checkpoint inhibitor-induced colitis secondary to administration of these two drugs in a 66-year-old female patient treated with infliximab.