Statistical analysis
The main statistical considerations for the primary analysis have been reported previously (Shitara et al. All randomized patients (intention-to-treat population) were included in efficacy analyses, and all patients who had received ≥ 1 dose of study treatment (as-treated population) were included in the safety analysis.Comparisons of OS, PFS, and time to ECOG ≥ 2 between treatment groups in each subgroup were conducted using the stratified log-rank test, with median values calculated using the Kaplan–Meier method and associated HRs and 95% CIs calculated using a Cox proportional hazards model; 