We used PubMed, EMBASE, and the Cochrane Library to retrieve phase II or III randomized controlled trials (RCTs) of ICIs that specified the number of all-grade (grade 1-5) colitis and high-grade (grade 3-5) colitis events through January 2020. The pooled relative risk (RR) and 95% confidence intervals (CIs) were calculated to compare the risk of colitis among various therapeutic regimens.
The search strategy identified 40 RCTs involving 26,893 patients. The risk of all-grade and high-grade colitis after PD-1/PD-L1 inhibitor was significantly lower than that of CTLA-4 inhibitor (0.18 and 0.14 relative risk respectively). The risk of all-grade and high-grade colitis was dose-dependent for CTLA-4 inhibitor therapy, but not for PD-1/PD-L1 inhibitor therapy. The relative risk of all-grade and high-grade colitis after combination therapy with PD-1/PD-L1 inhibitor and CTLA-4 inhibitor compared to PD-1/PD-L1 inhibitor alone was 9.25 and 12.00 respectively. No significant difference was found between PD-1/PD-L1 inhibitor combined with chemotherapy or targeted therapy and PD-1/PD-L1 inhibitor alone for either all-grade or high-grade colitis.
Our meta-analysis indicates that CTLA-4 inhibitor is associated with a higher risk of colitis compared with PD-1/PD-L1 inhibitor, whether used as a monotherapy or combination immunotherapy. Importantly, the combination of PD-1/PD-L1 inhibitor with chemotherapy or targeted therapy may not increase the risk of colitis significantly compared to PD-1/PD-L1 inhibitor alone.
Copyright © 2020 Elsevier B.V. All rights reserved.