Immune-related gastritis: An orphan immune-related adverse event.

Abstract

e24138 Background: Immune checkpoint inhibitors (ICI) have revolutionized the field of oncology with a significant impact on patients' survival. However, they are not without shortcomings, with 70-90% of patients experiencing immune-related adverse events (irAEs(. Immune-related gastritis is a relatively uncommon irAE, literature publications are scarce and limited to case reports. We aimed to investigate this rare irAE to enhance understanding and improve patient care for oncologists and gastroenterologists. Methods: We performed a retrospective review of medical records of all cancer patients treated with ICI who completed upper gastrointestinal endoscopy during ICI treatment, at a single tertiary center between 2017 and 2023. Results: Of 2553 patients receiving immunotherapy at our medical center, 64 completed upper gastrointestinal endoscopy, and 18 (0.7%) had either endoscopic or microscopic gastritis or both. Overall, 17 (94%) patients with gastritis were symptomatic compared to only 31 of 46 patients (67%) without gastritis (p = 0.025). Epigastric pain was the most common symptom and was experienced by seven (39%) patients with gastritis, and eight (17%) patients without gastritis (P = 0.068). Other symptoms in patients with gastritis were gastrointestinal bleeding (28%), nausea (17%) and vomiting (11%). However, gastrointestinal bleeding (17%), nausea (9%), and vomiting (11%) were also experienced by patients without gastritis at similar rates (P > 0.05 for all comparisons). Two patients had grade 4 and two patients had grade 3 immune-related gastritis. Symptoms resolved in all patients, though most patients continued ICI (77%). Ten patients were treated with high-dose proton pump inhibitors (PPIs), and only four were treated with corticosteroids. Overall survival in patients experiencing gastritis was 40 months and did not differ from that of patients without gastritis (p = 0.929). Conclusions: Immune-related gastritis is an infrequent and non-lethal adverse event. Diagnosis is challenging due to non-specific symptoms, that are common among cancer patients undergoing antineoplastic therapies. Nonetheless, upon diagnosis, treatment with high doses PPIs with or without corticosteroids leads to prompt resolution.