Incidence of immune checkpoint inhibitor-related colitis in solid tumor patients: A systematic review and meta-analysis

Background: With the rising use of immune checkpoint inhibitors (ICI) across varying tumors types, immune-related colitis is an increasingly encountered, serious adverse event requiring appropriate management. The incidence across ICI treatment regimens and tumor types is unclear. Objective: To characterize the incidence of immune-related colitis among various ICI regimens and tumor types. Methods: Thirty-four original studies of prospective ICI trials were identified based on a PubMed search completed on November 1st, 2016. Seventeen studies compared incidences across tumor types. The incidences of all-grade, grade 3-4 (severe) colitis, and grade 3-4 (severe) diarrhea were collected. Results: Thirty-four studies containing 8863 patients were included in the meta-analysis. The overall incidence during ipilimumab monotherapy was 9.1% for all-grade colitis, 6.8% for severe colitis, and 7.9% for severe diarrhea. The incidence was lowest during PD-1/PD-L1 inhibitor monotherapy with 1.3% for allgrade colitis, 0.9% for severe colitis and 1.2% for severe diarrhea, while combination ipilimumab and nivolumab resulted in the highest incidences of all-grade colitis (13.6%), severe colitis (9.4%) and severe diarrhea (9.2%) among ICIs. Among melanoma, NSCLC, RCC patients, incidences of colitis and diarrhea with PD-1/PD-L1 inhibitor monotherapy did not significantly differ. Severe colitis incidence was similar with ipilimumab monotherapy at 3 mg/kg and 10 mg/kg (7.1% vs 5.1%, respectively), but significantly higher for severe diarrhea with 10mg/kg (11.5% vs 5.2%). Conclusions: The incidence of immune-related colitis and severe diarrhea was higher with ipilimumab-containing regimens compared with PD-1/PD-L1 inhibitors. There was no significant difference in immune-related colitis between different tumor types with PD-1/L1 inhibitors.