S4979 The Use of IVIG in Drug Induced Colitis

Introduction: Drug-induced colitis (DiC) accounts for ∼10% of new colitis cases. While often linked to NSAIDs, immune checkpoint inhibitors, and mycophenolate, many other agents have also been implicated. Evidence regarding DiC management is limited. We report a case of severe DiC treated successfully with intravenous immunoglobulin (IVIG). Case Description/Methods: A 58-year-old man with metastatic adenocarcinoma of unknown primary presented with abdominal pain and emesis 1 month after FOLFIRINOX initiation. Computed tomography showed large bowel obstruction at the splenic flexure. Laparotomy revealed peritoneal carcinomatosis and an extrinsic mass compressing the colon. A colo-colonic bypass was performed. Post-operatively, he developed intra-abdominal abscesses requiring drainage and antibiotics. On day 20, he developed hematochezia, hemodynamic instability (HR 118, BP 90/55), and a hemoglobin drop from 9.2 to 6.9. Sigmoidoscopy revealed multifocal ulcerations in the sigmoid and rectum. Histology showed crypt dropout and increased apoptosis, consistent with DiC. Medication review identified 5-FU and oxaliplatin as potential culprits. Despite cessation and supportive care, bleeding recurred. Repeat colonoscopy showed diffuse ulceration with ongoing histologic evidence of DiC. Given his critical condition and recent infections, corticosteroids were deferred. After multidisciplinary discussion, IVIG (1 g/kg × 2 days) was administered. Within 48 hours, stools became non-bloody and formed. He was discharged 1 week later. Discussion: DiC is typically managed with drug cessation and supportive care. In refractory cases, corticosteroids may be used, but data on alternatives when steroids are contraindicated are limited. The pathophysiology of DiC remains poorly understood but may involve mucosal cytotoxicity, barrier disruption, or ischemia-like injury. Given this mechanistic heterogeneity, limited research exists to guide therapy. In practice, DiC treatment is often extrapolated from IBD and immune checkpoint inhibitors colitis literature, though these approaches may not always be appropriate. In this case, IVIG was used instead of corticosteroids due to its relatively low immunosuppressive profile. IVIG is commonly used in immunodeficiency and immune-mediated diseases. In gastroenterology, IVIG has shown some success in refractory IBD and C. difficile colitis, though data remain limited. This case suggests IVIG may be a viable option for severe, steroid-contraindicated DiC. Further studies are needed to clarify its safety and efficacy in DiC management.