Post-Marketing Requirements for Anticancer Drugs Approved in Japan, 2001-2024: A Cross-Sectional Analysis.

The accelerated development of innovative anticancer therapies has led to the early approval of an increasing number of drugs. However, clinical evidence available at the time of approval is often limited, necessitating additional post-marketing studies to supplement safety and efficacy data. Therefore, post-marketing requirements (PMRs) have gained greater regulatory importance. Nevertheless, the current landscape of PMRs for anticancer drugs in Japan has not been clearly characterized. In this study, we aimed to characterize the status, content, and trends of PMRs for anticancer drugs approved in Japan. We reviewed publicly available regulatory documents for anticancer drugs approved in Japan between 2001 and 2024 and extracted data on background characteristics and PMRs. Analysis of 471 anticancer agents identified 328 (69.6%) drugs requiring at least one PMR. The temporal trend analysis showed a consistent increase in the number of drugs requiring PMRs after 2011. Among 453 PMR assignments, the development and implementation of a risk management plan (RMP) was the most frequent PMR type (n = 254, 56.1%), followed by post-marketing all-case surveillance (n = 147, 32.5%). Twelve drugs (2.6%) required post-marketing clinical trials, among which one (0.2%) involved dose optimization. In conclusion, our findings show that PMRs for anticancer drugs in Japan are predominantly focused on safety monitoring, and that only one PMR was related to dose optimization. These findings suggest that further consideration may be needed in Japan to strengthen post-approval evidence generation for dose setting and to support more evidence-based dose selection.