A Life-Threatening Cause of Diarrhea: A Case of Immune Checkpoint Inhibitor Colitis

Introduction: Immune checkpoint inhibitor induced colitis (ICI colitis) is among the most commonly seen immune related adverse event in cancer patients on ICI therapy. Initial evaluation involves ruling out infectious etiologies and diagnostic colonoscopy. Management includes initiation of steroids and escalation to immunotherapy based on severity of ICI colitis. In our case, we highlight the rapid progression of a patient’s ICI colitis and the significance of early multidisciplinary collaboration and initiation of immunotherapy for optimal management. Case description/methods: A 68-year-old man with a history of chronic kidney disease, diabetes, hypertension, and renal cell carcinoma status post right nephrectomy, presented acutely with diarrhea in the setting of recent ICI therapy. Labs were negative for infectious etiology. He was started on solumedrol for suspected ICI colitis and was discharged after clinical improvement as patient declined colonoscopy. He returned 12 days later with worsening diarrhea with imaging concerning for recurrent colitis. He was restarted on solumedrol and later had hematochezia and underwent a colonoscopy confirming active ICI colitis and was given a one-time dose of infliximab. Hospital course was further complicated by colonic perforation requiring emergent colectomy and post-operative respiratory failure requiring intubation, with elevated troponin concerning for ICI pneumonitis and myocarditis. The patient continued to decline with progressive multiorgan failure and expired. Discussion: This case raises awareness of the importance of considering ICI colitis in cancer patients on ICI therapy who report having diarrhea. Early recognition of symptoms, diagnosis, and initiation of treatment is essential to determining a patient’s clinical outcome. More importantly, this case also illustrates the greater need for awareness of when to consider steroid-refractory ICI colitis and the need for alternative therapies such as infliximab. Our patient’s ICI colitis unfortunately progressed from grade 2 to grades 3 and 4 while being treated with steroids resulting in hemorrhagic shock, colonic perforation, and death. It is unclear whether early recognition of steroid refractory ICI colitis and early initiation of immunotherapy such as infliximab would have changed this patient’s clinical course. Future research should look into predictors of patients at higher risk for ICI colitis, prevention of ICI colitis, and efficacy in alternative immunotherapies as treatment for ICI colitis.Figure 1.: Endoscopic findings and histology of colon. (a, b) Colonoscopy images demonstrating moderate inflammation with altered vascularity, erosions, friability and aphthous ulcerations. (c, d). H&E staining of colon demonstrated focal active colitis (yellow arrow) with cryptitis and abscess formation (red arrow). There were no architectural changes to suggest inflammatory bowel disease.Table 1.: Grading of ICI colitis and trajectory of this patient’s clinical progression.