S3974 A Case of Pembrolizumab-Related Duodenopathy

Introduction: Checkpoint inhibitors have been associated with a variety of autoimmune diseases. Here we present a case of celiac-like duodenopathy attributed to pembrolizumab. Case Description/Methods: Case: A 48-year-old man with clear cell renal cell carcinoma on pembrolizumab presents with episodic nausea, vomiting, and abdominal pain that started about 6 months after initiation of pembrolizumab. He has noticed that symptoms tend to occur with gluten ingestion. He did not have any chronic GI symptoms prior to immunotherapy initiation. His past medical history other than his cancer is notable for essential hypertension. Medications include losartan, vitamin D, fish oil and turmeric supplements. He is allergic to penicillins. He is married with 3 children, works as a supply chain manager, is a former smoker and consumes 1 glass of wine weekly. On physical examination, he is in no acute distress. Abdomen is soft, non-distended and non-tender to palpation, with active bowel sounds. Laboratory studies reveal normal hemoglobin and normal tissue transglutaminase IgA, and normal total IgA. EGD on a gluten-containing diet reveals normal esophagus, stomach, and duodenum, and duodenal biopsies showed intraepithelial lymphocytes. The patient was placed on a gluten-free diet with resolution of symptoms, and follow up TTG IgA 2 weeks later was negative. HLA typing subsequently was positive for HLA-DQB1*02. Discussion: Several case reports have described a clinical syndrome resembling celiac disease in patients receiving checkpoint inhibitor therapy. Some patients respond to a gluten-free diet, while others require steroids or even other treatments such as vedolizumab. Checkpoint inhibitor duodenopathy remains a poorly understood entity but is likely due to enhanced immunity. It warrants further study to elucidate pathogenesis.