Statistical Assessment of Biosimilarity Based on the Relative Distance Between Follow-on Biologics for Time-to-Event Endpoints

The two-arm parallel design that is commonly used to assess biosimilarity has the drawback that it does not take into account the inherent variability within the reference products. The three-arm parallel design was proposed to solve this problem. The purpose of this article was to extend the previous results to the time-to-event endpoints in the exponential model, the Cox proportional hazard model, and the restricted mean survival time. The relative distance is defined, and the corresponding test procedures are developed based on asymptotic theory. The Type I error rates and powers are investigated theoretically and empirically. Supplementary materials for this article are available online.