Comparison of efficacy outcomes of anticancer drugs between Japanese patients and the overall population

Background It is important to recognize regional and racial differences in drug efficacy and safety when performing multi-regional clinical trials (MRCTs). To understand regional differences, we compared the efficacy results in Japanese patients and the overall population in the MRCTs of anticancer drugs. Methods All new approvals of oncology drugs in Japan from January 2009 to December 2018 were searched using the Pharmaceuticals and Medical Devices Agency web site to find phase 3 MRCTs for the analysis. As the supporting data source, a literature search was performed in PubMed and Google Scholar. Linear regression analysis was performed and Pearson correlation coefficients ( r ) were calculated to compare the overall survival (OS), progression-free survival (PFS), and objective response rate (ORR) between Japanese patients and the overall population. Results Seventy MRCTs were identified. The correlation of hazard ratios (HRs) for OS between Japanese patients and the overall population was moderate ( r = 0.45), and OS was 1.31 times longer in Japanese patients than in the overall population, although the correlation of median OS was strong ( r = 0.91). The HRs for PFS were moderately correlated ( r = 0.70) and the correlation of median PFS was strong ( r = 0.90). The correlation of ORR was very strong ( r = 0.96). Conclusion The PFS and ORR were consistent between Japanese patients and the overall population. A longer median OS was observed in Japanese patients. Our results would be a useful reference when planning and conducting MRCTs that include Japan for global simultaneous drug development.