Chronic gastrointestinal immune-related adverse events in patients exposed to immune checkpoint inhibitors

: Immune checkpoint inhibitors (ICI) cause acute gastrointestinal (GI) immune-related adverse events (IrAEs). We aimed to report and describe chronic GI IrAEs. : We included consecutive patients addressed to a single center between October 2010 and March 2022 for endoscopic and/or histological GI inflammation persisting at least six months after the last dose of ICI. : Among a total of 178 patients addressed for GI IrAE, 14 met the inclusion criteria (8%). The median follow-up was 13 months after discontinuation of ICI. The most common symptom was watery diarrhea (54%). Ten (77%) patients had colonic involvement and three patients (21%) had ileal involvement. Ten patients (77%) had inflammatory lesions, two patients (15%) had fistulas and one patient had (8%) a stricture. All patients had lymphoplasmacytic infiltrate and basal plasmacytosis, and seven (54%) had crypt distortions. Nine patients (69%) received medical therapy, including five patients treated with vedolizumab, two patients (15%) underwent intestinal resection. At the last follow-up, seven of the 13 patients were receiving maintenance therapy. Endoscopic lesions persisted one year after discontinuing ICI in 4/6 patients, and two years after discontinuation in 3/4 patients. : Chronic GI IrAEs exist after ICI use.