Pembrolizumab-Induced Immune-Mediated Colitis in a Patient with Concurrent Clostridium Difficile Infection.

Pembrolizumab is a programmed death receptor-1 (PD-1) inhibitor that has been approved for treatment of a wide variety of malignancies. Immune-mediated colitis is a known but uncommon adverse effect of pembrolizumab. Symptoms of immune-mediated colitis can be similar to those of many other gastrointestinal illnesses, including Clostridium difficile infection (CDI).