Statistical analyses
Descriptive analyses were conducted for the Japanese subpopulation. Hazard ratios (HRs) for OS and PFS were calculated using unstratified Cox proportional hazards model with treatment as the sole covariate. Two-sided 95% confidence intervals (CIs) for the HR were provided. Median OS, PFS, and duration of response for each treatment arms were estimated using the Kaplan–Meier method, and the corresponding 95% CIs were constructed based on a log–log transformed CI for the survivor function. OS and PFS rates at fixed time points were derived from the Kaplan–Meier estimate. The 95% CIs for proportions were calculated using the Clopper–Pearson method. Statistical analyses were performed using SAS software v9.2 to v9.4 (SAS Institute, Cary, USA) and R statistical software package.