Risk of immune-related colitis with PD-1/PD-L1 inhibitors vs chemotherapy in solid tumors: systems assessment

Background: We performed a meta-analysis to evaluate the risk of immune-related colitis associated with PD1/PD-L1 inhibitors as compared to chemotherapy in solid tumor patients. Methods: Eligible studies were identified through a comprehensive search of multiple databases and included solid tumor patients in randomized controlled trials (RCTs) with PD-1/PD-L1 inhibitors. The data was analyzed by Stata version 12.0 software. Results: After exclusion of ineligible studies, 11 clinical trials were considered eligible for the meta-analysis, including 5751 patients. Compared with chemotherapy, the risk ratios (RRs) of all-grade colitis were significant for the PD-1 inhibitor subgroup (RR 2.69, 95% confidence interval (CI): 1.15-6.29, p=0.023), and for pembrolizumab subgroup (RR 3.17, 95% CI: 1.08-9.37, p=0.037), but not for nivolumab treatment and PD-L1 inhibitor (atezolizumab) treatment (RR 2.05, 95% CI: 0.52-8.13, p=0.305; RR 4.75,95% CI: 0.56-40.50, p=0.154, respectively). The RR of all-grade colitis was significant for PD-1/PD-L1 inhibitor in NSCLC (RR 4.34, 95% CI: 1.37-13.82, p=0.013), and not significant in melanoma (RR 2.11, 95% CI: 0.54-8.34, p=0.285). Moreover, the RRs of all-grade diarrhea were significant for the PD-1 inhibitor subgroup (RR 0.61, 95% CI: 0.44-0.83, p=0.002), for the nivolumab subgroup (RR 0.54, 95% CI: 0.34-0.87, p=0.012), and for atezolizumab subgroup (RR 0.48, 95% CI: 0.25-0.89, p=0.021). The RR of high-grade diarrhea was significant for atezolizumab subgroup (RR 0.34, 95% CI: 0.12-0.94, p=0.037). Conclusions: Our meta-analysis demonstrates that compared with chemotherapy, pembrolizumab may result in a higher risk of all-grade immune-mediated colitis. PD-1/PD-L1 inhibitor treatment in NSCLC patients, but not in melanoma patients, increases the risk of all-grade colitis incidence.