[Immune-related colitis after immune checkpoint inhibitor rechallenging: a case report].

Immune-related adverse events (irAE) are treatment-associated complications that single or multiple systems could be involved after immune checkpoint inhibitors(ICI), ranging from mild to life-threatening diseases, with significant heterogeneity. This is an important factor which might affect continuous ICI treatment. Patients who have experienced mild to moderate irAE could try ICI rechallenge after they recovered from irAE. However, patients would suffer from same or different irAE during ICI rechallenge. Our patient who was diagnosed with maxillary sinus carcinoma experienced checkpoint inhibitor pneumonitis (CIP) after anti-PD-1 therapy with combined chemotherapy and radiotherapy. Under closely follow-up, he tried same ICI rechallenge. Although he did not suffer from refractory CIP, he was diagnosed with immune-related colitis, which was recovered from ICI discontinuation and treatment of probiotics and Mesalazine.