S3938 Gastrointestinal Toxicity of Dupilumab: A Case of Drug-Induced Colitis

Introduction: Dupilumab is a monoclonal antibody that is used to treat conditions such as atopic dermatitis and asthma. Although it has transformed the management of these conditions, its association with gastrointestinal adverse events is emerging in clinical practice. Case Description/Methods: A 32-year-old man with history of asthma and atopic dermatitis on Dupilumab presented with a 3-week history of subacute diarrhea. He reported up to 10 episodes of loose stools daily, associated with crampy abdominal pain, 5 lb weight loss, and occasional hematochezia. Initial workup revealed leukocytosis with eosinophilia, elevated C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and a fecal calprotectin level of 1390 µg/g. Fecal leukocytes were positive, while stool cultures, including C. difficile, Strongyloides, and Toxocara, were negative. Computed tomography abdomen showed findings concerning for infectious or inflammatory enterocolitis. Colonoscopy showed diffuse severe inflammation in the rectum, sigmoid, and transverse colon, along with patchy inflammation in the ascending colon and cecum. Biopsy results confirmed active colitis with focal ulceration and prominent eosinophilic infiltration, without granulomas. The patient was started on 1 mg/kg per day of prednisone with great improvement in his symptoms. Discussion: The patient’s clinical course and histologic findings were most consistent with dupilumab-induced colitis. Although inflammatory bowel disease shares overlapping clinical and endoscopic features, the temporal relationship to dupilumab initiation and lack of chronic architectural distortion on biopsy supports the former diagnosis. This case highlights the importance of recognizing dupilumab as a potential cause of colitis in patients who present with unexplained diarrhea and eosinophilia following its initiation.