Study notes disparities in new drugs approved in the US and Japan

Almost half of US-approved drugs remained unavailable in Japan, highlighting a “substantial” disparity in available drugs between the two countries, according to a recent research article published in the JAMA Network. Oncology drugs and biologics were approved more in Japan than other drugs, reflecting their “clinical importance and market demand.”

The study, authored by Shingo Kasahara, a professor at Keio University in Yokohama, examined a cross-section of new molecular entities and biologics first approved in the US or Japan between 2005 and 2022. The research evaluated the approval status of each drug as of 31 December 31 2024, allowing for a two-year window for subsequent approvals. This timeframe was based on prior research indicating that the median approval interval between US and Japanese drug approvals is typically 1-2 years.

The study found that 711 drugs were approved in either the US or Japan during the study period. Out of these, 633 received approval in the US, while 280 (44.2%) were not approved in Japan. Conversely, among the 431 drugs approved in Japan, 78 (18.1%) were not approved in the US. These 78 drugs were classified as local drugs and were excluded from the regression analysis.

A limitation of this study is that label expansions were not studied, suggesting some approval disparities may be overlooked at the indication level.

The study leveraged data from public databases such as the Food and Drug Administration’s Drugs@FDA, Japan’s Pharmaceuticals and Medical Devices Agency (PMDA), and Kyoto’s Encyclopedia of Genes and Genomes.

This finding contrasts with other markets, where US-approved drugs are approved at a higher rate. For example, 74.2% of US-approved drugs between 2004 and 2018 were available in Germany.

“Our findings suggest that optimizing approval pathways for smaller and foreign companies could help reduce these disparities and improve patient access to innovative treatments in Japan, the authors wrote. “Addressing these issues could also provide valuable insights for other countries facing similar challenges.”

Earlier this year, Japan’s Pharmaceutical and Medical Devices Agency (PMDA) launched a website to promote launching products in the Japanese market (RELATED: Asia-Pacific Roundup: PMDA website promotes bringing products to Japanese market, Regulatory Focus 3 March 2025).

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