Oncology drug lag in Japan: has it improved over the last decade?

Background Existing studies and statistics on the drug lag between Japan and the United States (US) for anti-cancer drugs indicate that it has decreased, whereas more drugs are left unapproved in Japan. This study aimed to quantify the impact of unapproved drugs on the drug lag. Methods Information on 136 anti-cancer drugs approved in the US between 2011 and 2022 was collected. The approval lag, defined as the number of days from the date of approval in the US to the date of approval in Japan, was calculated for all selected drugs, and the median was calculated using the Kaplan–Meier method. The approval lag for drugs not approved in Japan was treated as censored data. Factors potentially associated with the approval lag were explored using Cox regression analysis. Results The median approval lags for the first half-period (2011–2016) and the last half-period (2017–2022) were 961 days (2.6 years) and 1547 days (4.2 years), respectively (Log-rank test: p = 0.0687). The participation of Japan in the global pivotal trial was associated with a shorter approval lag, and new drug applications by non-Japanese companies that did not rank in the global sales top 20 were associated with a longer approval lag. Conclusions Drug lag has not decreased over the last decade. The percentage of pivotal trials for US approval that included Japan has increased but should be further increased in the future. Japan may require a scheme to encourage smaller non-Japanese companies to include Japan in their global clinical development plan.