Statistical Considerations on Clinical Efficacy Studies of Biosimilar for PMDA Submission

In general, similar to FDA and other health authorities, the PMDA requires clinical efficacy study(ies) to evaluate equivalence between a reference biological product and a Biosimilar product for new drug applications. Even if an identical clinical efficacy study is included in both of PMDA and FDA submissions, the coefficients of confidence interval (CI) used for comparison with the equivalence margins could be different between the two submissions (e.g., 95% CI vs. 90% CI). In this article, we will focus on clinical efficacy studies of Biosimilar products and provide an overview of the two one-sided tests (TOST) and the type I error rate for equivalence design. Then, we summarize published PMDA review reports of Biosimilar products in terms of the coefficients of CI and other elements of the primary endpoints, and explain some Japanese guidelines of Biosimilar and Statistics behind the difference between PMDA and FDA submissions. In addition, we discuss how to use statistical methods correctly and efficiently for PMDA submissions.