S6415 A Rare Cause of Abdominal Pain: Immune Checkpoint Inhibitor Gastritis

Introduction: Immune checkpoint inhibitors (ICIs) are becoming more widely used for the treatment of numerous cancers. There have been increasing reports regarding immune-related adverse events (irAEs) of ICIs due to an unchecked immune system, prompting an autoimmune like process in the body. Here we present a rare case of ICI related gastritis and subsequent gastric intestinal metaplasia (GIM). Case Description/Methods: A 55-year-old woman with a history of recurrent stage III cervical squamous cell carcinoma status post chemoradiation and undergoing active immunotherapy (PD-1/CTLA-4 combination) presented to the hospital with abdominal pain, decreased oral intake, nausea, and vomiting for about 2 weeks. Computed tomography scan of the abdomen showed findings consistent with gastritis. An esophagogastroduodenoscopy (EGD) showed severe diffuse hemorrhagic gastritis with gastric biopsies noting marked active chronic gastritis with ulceration, suspicious for ICI gastritis per pathologist’s interpretation. She was started on a long steroid taper and omeprazole with quick symptom improvement. She was re-admitted 2 months later for hematemesis after finishing steroids. Repeat EGD showed persistent but improved hemorrhagic gastritis. Gastric biopsies again revealed severe gastritis. She was restarted on a steroid taper with improvement in symptoms and her ICI was discontinued due to recurrent toxicity. Repeat EGD 4 months later showed dramatic improvement in gastritis, but did reveal atrophic appearing gastric mucosa. Gastric mapping biopsies showed limited complete type intestinal metaplasia, marked chronic active gastritis, and was negative for H. pylori. She remained asymptomatic at time of last follow up. Discussion: While ICIs have therapeutic potential for various cancers, this class of medication has also been associated with significant irAEs involving nearly any body system. ICI related gastritis is quite rare when compared to the more common GI-related irAEs like colitis and hepatitis. ICI gastritis can be managed by stopping the ICI, initiating proton-pump inhibitors, and steroids. Some cases require immunomodulators such as infliximab and vedolizumab. There is not currently any known literature on the relationship between ICI gastritis and GIM, which warrants further investigation. We present this case as an example of a rare but severe adverse effect of ICIs, highlighting the need for a lower threshold to perform an EGD in patients with GI symptoms who are undergoing ICI therapy.