Geographic heterogeneity in the outcomes of patients receiving immune checkpoint inhibitors for advanced solid tumors: a meta-analysis

BACKGROUND: Little is known about the effect of geographic location on efficacy of immune checkpoint inhibitors (ICI). We performed a systematic review and meta-analysis to assess the heterogeneity of ICI efficacy between different geographic locations. METHODS: We searched PubMed, EMBASE, and the Cochrane Library through October 2019 for phase III randomized controlled trials (RCT) that provided sufficient data for hazard ratio (HR) and 95% confidence interval (CI) of overall survival (OS) or progression-free survival (PFS) according to designated geographic region. We calculated pooled HRs and 95% CIs for North American, European and Asian cancer patients, and assessed data heterogeneity using subgroup and sensitivity analysis. The INPLASY registration number was INPLASY202050062. RESULTS: Of 10151 publications identified in our research, 17 RCTs including 7462 patients met our selection criteria. The pooled HRs for OS of North American, European and Asian patients were 0.67 (95% CI: 0.57 to 0.78), 0.72 (95% CI: 0.64 to 0.81), and 0.74 (95% CI: 0.66 to 0.84) respectively; the pooled HRs for PFS of North American, European and Asian patients were 0.58 (95% CI: 0.49 to 0.69), 0.61 (95% CI: 0.41 to 0.90), and 0.87 (95% CI: 0.38 to 1.99) respectively. Both anti-PD-1 inhibitors and anti-PD-L1 inhibitors showed clinical benefit in North American and European arms while anti-PD-L1 inhibitors failed to show benefit in Asian arms. CONCLUSIONS: Our meta-analysis indicates that the magnitude of benefit from ICI varies in North America, Europe, and Asia. Asian patients experience inferior outcomes compared to Western patients. Notably, anti-PD-L1 therapies do not result in survival improvements in Asian patients.