Statistical analysis
deaths, death
DISEASE PROGRESSION
The Kaplan–Meier method was used to estimate the median and distribution of PFS, OS and DOR; stratified log-rank tests were used to assess between-group differences, and the stratified Cox proportional hazard model was used to calculate HRs and associated 95% CIs. The Cochran–Mantel–Haenszel test was used to assess between-group differences in ORR. Pre-specified multiplicity adjustment methods were used to control the overall one-sided type I error rate at 0.025. Efficacy boundaries were calculated based on the information fraction at the time of analysis. The reported 95% CIs describe the precision of the point estimates and may not correspond to the significance of the test. The study aimed to enroll 500 patients. The final analysis of PFS was planned when 300 patients experienced disease progression or death to provide 93.4% power to detect a between-group difference with the assumption of median PFS of 9 months with zolbetuximab plus CAPOX versus 6 months with placebo plus CAPOX (HR = 0.67) at an overall one-sided alpha level of 0.025. An interim analysis of OS was planned at the final PFS analysis, and a final analysis of OS was planned after 386 deaths to provide 80% power to detect a between-group difference with the assumption of median OS of 14.7 months with zolbetuximab plus CAPOX versus 11 months with placebo plus CAPOX (HR = 0.75) at an overall one-sided alpha level of 0.025. An efficacy boundary was calculated for the interim OS based on the information fraction at the time of the interim analysis; a one-sided level of significance of 0.0135 was used with an 82.4% information fraction. To strictly control the type I error rate at an alpha level of 0.025, OS was tested only if the null hypothesis of the final PFS analysis was rejected. Full details of the statistical analysis plan are provided in the protocol (Collected data were entered using the RAVE electronic data collection system. Sample size calculations were performed with East version 6.4 software. Statistical data analyses were performed with SAS version 9.3 or higher software.