Statistical analysis
Statistical analyses were performed using SAS version 9.4 (SAS Institute, Cary, NC, USA). Age was expressed as median (range), and categorical variables were expressed as frequency (percentage). The 95% CIs of ORR and DCR were calculated using Clopper-Pearson method. The 95% CIs of PFS and OS were calculated using Brookmeyer-Crowley method. PK parameters were expressed as mean (standard deviation) or median (range), and analyzed using Phoenix version 8.0 (Certara, LP, Princeton, NJ, USA). No imputation method was performed for missing data.