Evaluation of drug lag and drug loss in Japan: participation in global phase III oncology trials.

Background: Despite efforts to mitigate drug lag, discrepancies in drug approval timelines persist between Japan and the US, and increase in unapproved drugs has become a significant challenge. This study aimed to evaluate potential drug lag and drug loss by assessing Japan's participation in global phase III multinational/multiregional clinical trials (MRCTs) targeted cancers.

Methods: Phase III MRCTs of anticancer drugs initiated between 2008 and 2022 were collected. Information of participant countries, study sponsor, study design, and cancer type were collected and analyzed by logistic regression analysis to identify factors affected Japan's participation.

Results: Of 999 phase III MRCTs, Japan's participation every 5 years increased over 15 years (2008-2012: 34.3%, 2013-2017: 51.6%, 2018-2022: 60.2%), while Japan's non-participation numbers did not change (2008-2012: 157, 2013-2017: 167, 2018-2022: 165). In the multivariate logistic regression analysis, the absence of an operational base in Japan and minor cancers were negatively associated with Japan's participation in phase III MRCTs. Japan's participation was also associated with some cancer organs and drug modalities.

Conclusion: Potential future drug lag and increases of unapproved drugs were expected to increase. Since the inclusion of Japan in MRCTs results in shorter or no approval lag, Japan should promote to make circumstances where small overseas companies can include Japan in MRCTs.