ABSTRACT
BACKGROUND: The 'Questions and Answers (Q&A)' document regarding Japanese biosimilar guideline elucidated that Japanese participant enrollment in at least one comparative clinical study was required for the marketing authorization application (MAA) of biosimilars in Japan. RESEARCH DESIGN AND METHODS: To discuss the requirement of Japanese clinical study data for biosimilar development, the trend in comparative clinical studies conducted for approved biosimilars of monoclonal antibodies and fusion proteins was analyzed, and the consistency of the results between the overall population and the Japanese population according to the publicly available information was reviewed. RESULTS: The number of comparative clinical studies enrolling Japanese participants was 25 cases, and the type and percentage were 13 (52%) and 12 (48%) cases of comparative pharmacokinetic study and comparative efficacy study, respectively. In all comparative clinical studies, consistent results between the overall population and the Japanese population were shown. CONCLUSIONS: Our study indicated that Japanese participant enrollment in comparative clinical studies may not always be necessary for biosimilar development when certain conditions are satisfied. This has been described in the revised Q&A document published by the Ministry of Health, Labour and Welfare in January 2024.