Trends in and Determinants of Approval Lag for Anticancer Drugs in Japan and the US: Role of Multi‐Regional Trials and Concurrent Approvals

Timely access to treatment for cancer patients requires the accelerated approval of new anticancer therapies. However, the lengthy pharmaceutical approval process in Japan has contributed to what is known as "drug lag." Although recent efforts to promote international multi-regional clinical trials (MRCTs) involving Japan and to advance strategies for concurrent approval in Japan and the United States have helped shorten time to approval, the individual effects of these approaches have not been fully quantified. This study analyzed trends in the timing of drug application, review, and approval for anticancer agents approved in Japan and the United States, and evaluated the influence of MRCT participation, concurrent approval, company origin, cancer type, and regulatory programs through multivariate analysis. We examined 142 anticancer agents approved between October 2004 and March 2025 by the Pharmaceuticals and Medical Devices Agency in Japan and the U.S. Food and Drug Administration. The median approval lag was 774 days (interquartile range: 217-1370), but decreased markedly to about 100 days by the 2020s. Approval lag was significantly shorter for drugs developed through MRCTs and those approved concurrently in both countries (both p < 0.001), whereas company origin, cancer type, and regulatory program use were not significantly associated (p > 0.05). Multivariate analysis confirmed that MRCTs and concurrent approval were independently associated with shorter approval lag. These findings support early international development and synchronized submission timing to further reduce approval lag. They provide updated evidence based on recent data and offer novel insights by quantifying the effects of MRCT implementation and concurrent approval.