Characteristics of Clinical Trials for the US Food and Drug Administration Accelerated Approval and Subsequent Confirmatory Trials: Implications for Drug Approval in Japan.

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The Accelerated Approval (AA) Program of the United States (US) Food and Drug Administration (FDA) was established to facilitate and expedite access to new drugs for serious or life-threatening conditions. Although many drugs have granted AAs in the US, the number of approvals under the conditional approval system in Japan remains limited. This study aimed to examine whether confirmatory trials after the US AA are conducted in accordance with the design of postmarketing requirements and assess the timing of regular approval (RA) in Japan for drugs that have been granted US AA. Utilizing FDA databases and Japanese regulatory data from 1992 to 2023, we analyzed indications, postmarketing requirements, and clinical trial designs. Our findings indicate that the AA program in the US is well-managed as most AAs were converted to RAs based on confirmatory study data that met the designations. From the Japanese perspective, our findings show that the over half of Japanese RAs can be obtained without waiting for confirmatory trial results. By granting RA, instead of conditional approval, based on exploratory trial data in the US AA, the opportunity to evaluate postmarketing confirmatory trial results might be lost in Japan. Therefore, further improvements are needed to actively utilize the conditional approval system, which could allow for the rapid introduction of innovative drugs and also the verification of their efficacy and safety at an appropriate time.