Rare incidence of immune-related gastritis and duodenitis in a single tertiary medical center: A diagnostic challenge.

Abstract

e24118 Background: Cancer immunotherapy has emerged as a cornerstone of modern cancer treatment. While generally considered well-tolerated, some immune-related adverse events (irAEs) can impact patient care, making accurate diagnosis essential. Immune-related gastritis and duodenitis (irGD) are two rare side effects of immunotherapy. Since these conditions affect only a small number of patients, standardized diagnostic criteria and evidence-based treatment guidelines are lacking. Methods: We conducted a retrospective analysis of patients undergoing esophagogastroduodenoscopy (EGD) while receiving immune checkpoint inhibitors (ICIs). For this study, a diagnosis of irGD required meeting at least two of three criteria to qualify as GD (suggestive symptoms, EGD findings, or pathology findings) and at least one criterion supporting a causal link to ICI treatment. Patients with irGD were compared to those without irGD. Results: Of 2,553 patients treated with ICI, 62 (2.4%) underwent EGD and were eligible for our study, of whom nine (0.4%) met the diagnostic criteria for irGD. An additional, nine patients (0.4%) had gastritis or duodenitis unrelated to ICI treatment. Notably, three of the nine patients (33%) with irGD had pre-existing inflammatory gastrointestinal conditions including inflammatory bowel disease or celiac disease, compared to two of 53 patients (4%) in the non-irGD cohort (P = 0.019). Patients with irGD were significantly more symptomatic (100% vs 58%, P = 0.009). However, no single symptom was specific for irGD, including epigastric pain (33% vs. 19%, P = 0.38), nausea (44% vs. 15%, P = 0.062) and gastrointestinal bleeding (33% vs. 17%, P = 0.357). While all patients with irGD were treated with proton pump inhibitors, only three (33%) required steroid treatment. Treatment discontinuation was more common in patients with irGD (44% vs. 6%, P = 0.001). Symptom resolution was recorded in all patients, and three patients successfully underwent rechallenge, including one with grade 3 irGD, after completing a course of steroid treatment. Conclusions: irGD is a rare irAE that is challenging to distinguish from GD caused by other etiologies. Upon diagnosis, clinicians may consider non-steroid treatment regimen and, in selected patients, even ICI rechallenge.