2555 Immune Check Point Inhibitor Enteritis: A Case of Severe Duodenitis From Nivolumab Therapy

Abstract

INTRODUCTION: Nivolumab, an immune checkpoint inhibitor, is an immunotherapy that has shown remarkable benefit in treating a wide range of cancers. However, by activating the immune system, these agents can cause immune-related adverse events (irAE). The gastrointestinal (GI) system is commonly affected, and typically presents with lower GI inflammation, such as colitis. Upper GI involvement is rarely reported. We present a case of nivolumab-associated duodenitis refractory to systemic corticosteroids but resolved after treatment with infliximab. CASE DESCRIPTION/METHODS: A 61-year-old man with a history of squamous cell carcinoma of the head and neck presented with intense cramping abdominal pain several weeks after nivolumab initiation. Given concerns for an irAE, he was initially treated with prednisone for 2 weeks, with minimal improvement in symptoms. He underwent esophagogastroduodenoscopy (EGD), which showed granularity and erythema of the duodenum with pathology consistent with duodenitis. He was referred to our institution, and treated with a course of IV solumedrol, which resulted in worsening abdominal pain and severe (grade 3) watery diarrhea. He was admitted to the hospital, and infliximab 5 mg/kg was initiated for suspected steroid-resistant immune checkpoint inhibitor-associated duodenitis/enterocolitis. He was noted to have rapid improvement in diarrhea and abdominal pain within 24 hours, with total resolution within nine days. After a second infusion of infliximab, he underwent a small bowel enteroscopy, which was unremarkable. His rapid improvement following infliximab further confirmed suspicion for an immune-checkpoint inhibitor medicated duodenitis/enterocolitis. DISCUSSION: As the use of checkpoint inhibitor immunotherapy grows, it is imperative that gastroenterologists be able to recognize and promptly treat GI immune-related adverse events, especially less common presentations involving the upper GI tract. Our case of nivolumab-associated duodenitis is an example of a rare immune-related adverse event that was refractory to steroids but responded to infliximab. Given no clear guidelines for duration of infliximab treatment, recommendations were extrapolated from IBD literature, with subsequent infusions recommended at two and six weeks. It has been reported that one-third to two-thirds of patients with immune-related GI toxicities do not respond to high dose systemic steroids or experience a relapse of symptoms. These are the patients that should be considered for infliximab.