Let's discuss the cost of medicine. Are Japan's top-selling drugs really worth it?No. 139

Akihiko Ozaki, M.D., Ph.D. Physician at the Medical Governance Research Institute

In recent years, the breast cancer field, which the author is responsible for, has seen a continuous succession of new drug developments. In 2024, capivasertib ("Truqap") for hormone receptor-positive breast cancer with specific gene mutations (PIK3CA, AKT1, PTEN) was approved in March, sacituzumab govitecan ("Trodelvy") for triple-negative breast cancer in November, and datopotamab deruxtecan ("Dato-DXd," "Dato-way") for hormone receptor-positive breast cancer in December, all in quick succession. Tucatinib for HER2-positive breast cancer was applied for approval in March 2025.

The approval of new drugs is a boon for patients. The problem, however, lies in the drug prices. The monthly drug costs are approximately 1.68 million yen for Trodelvy, 1.66 million yen for Dato-DXd, and 0.86 million yen for Truqap (the price for tucatinib is yet to be determined).

In recent years, medical expenditure has been increasing by approximately 1 trillion yen annually, reaching 47 trillion yen in 2023. Appropriately evaluating whether new drugs have an efficacy commensurate with their prices is becoming increasingly crucial for maintaining a sustainable healthcare system.

To provide some answers to this point, we conducted a study with Hayase Hakariya, an active researcher in Germany, and others. I would like to introduce the paper, which was published on May 26 in Clinical and Translational Science, a journal issued by the American Society for Clinical Pharmacology & Therapeutics.

In this study, we targeted the top 50 drugs with the highest sales in Japan in fiscal year 2021 and collected and analyzed the evaluations of their usefulness by HTA (Health Technology Assessment) agencies in three countries: Canada, France, and Germany.

The analysis results showed that out of the 43 products for which evaluation data were available among the 50, 20 products (46.5%) were evaluated as having "limited additional therapeutic benefit." This is based on the "optimistic scenario" (where a "high" rating is given if at least one HTA agency provides a high evaluation). In the more cautious "pessimistic scenario" (where a "high" rating is given only if two or more agencies provide a high evaluation), 35 products (81.4%) received a low evaluation. By drug type, 15 out of 24 small-molecule drugs (62.5%) received a low evaluation, whereas 14 out of 19 biopharmaceuticals (73.7%) were rated highly, indicating a difference in evaluation trends between the types. Most of the subject drugs are used for severe diseases such as cancer and autoimmune diseases, but even in these areas, there were quite a few cases where the additional usefulness was deemed limited.

In countries like Canada, France, and Germany, a system is in place to adjust drug prices based on the HTA results, where drugs with small additional effects are assigned a suppressed price.

In contrast, in Japan, such cost-effectiveness evaluations by a third-party organization are not systematically incorporated into the drug price determination process. Furthermore, when new drugs are approved, a clear comparison with existing treatments or a definitive added benefit is not strictly required. As a result, there are numerous cases where drugs that are not significantly different from existing ones are sold at high prices, accelerating the increase in drug expenditure.

In Japan, the HTA specialized agency C2H was established in 2019, and the evaluation framework is gradually being developed. However, as of now, there are few evaluation achievements, and it is difficult to say that the results are fully and effectively reflected in drug prices.

Of course, evaluating usefulness is by no means easy. Evaluation standards and the perception of clinical importance differ across countries and cultures, and there are cases where evaluations diverge for the same drug. Nevertheless, systematically introducing the perspective of "additional therapeutic benefit" and setting prices commensurate with the drug's value is unavoidable for building a sustainable healthcare system in Japan.

Our research aims to challenge the common perception that "a best-selling drug equals an excellent drug" with data-driven evidence. We hope that the findings of this study will contribute to institutional improvement for healthcare professionals, patients, and policymakers alike.

This article was originally published in Japanese in Iyakukeizai (Pharmaceuticals and Economics) on Jun 15, 2025.