Trastuzumab Biosimilar Adoption Increased in Japan Due to Reimbursement

Trastuzumab biosimilars saw significant market uptake in Japan after reimbursement incentives were implemented, but bevacizumab biosimilars did not experience a similar response. | Image Credit: Shevon - stock.adobe.com

Reimbursement incentives significantly increased the market uptake of trastuzumab biosimilars for cancer treatment but failed to produce a similar effect for bevacizumab biosimilars, suggesting policy makers design reimbursement strategies tailored to each biosimilar to optimize effectiveness, according to a time series analysis published in Value in Health Regional Issues.¹

Novel cancer drug costs are continuously rising, and health care systems are looking to rely on the entry of biosimilars to lead them to significant cost reductions. Patients receiving cancer treatment in Japan have an estimated annual economic burden of about $12.6 million (¥1296 million), including $11 million (¥1128 million) for targeted therapy, $1.3 million (¥130 million) for nontargeted therapy, and $0.4 million (¥38 million) for anticancer therapy–related costs.² 

The Japanese government is focusing more on reimbursement incentive policies to promote biosimilar adoption within the health care system.¹ The biosimilar adoption incentive policy will offer medical institutions a premium of approximately $10 (¥1500) per prescription for up to 3 months.

Researchers aimed to determine the effectiveness of this policy intervention for oncology drugs, specifically trastuzumab and bevacizumab, in outpatient settings using an interrupted time series analysis. They utilized health insurance claims data from January 1, 2005, to March 31, 2023, for Tokyo, Japan.

Trastuzumab insurance claims (22,440) for treating breast or gastric cancer and bevacizumab claims (14,022) for treating colorectal or lung cancer were utliized for this analysis. There were 11,622 claims in the preintervention period for trastuzumab (April 2021-March 2022) and 10,818 in the postintervention period (April 2022-March 2023). Bevacizumab had 6973 claims prior to intervention and 7049 afterward.

For trastuzumab, 97% of the claims were from female patients in both periods while for bevacizumab, 42% of claims were for female patients before the policy change and 43% afterward. There were also more trastuzumab claims for treating breast cancer (96%) than gastric cancer (4%). Bevacizumab was used at the treatment for 86% to 87% of the claims for colorectal cancer and 13% to 14% of the claims for lung cancer in both observed periods.

The time series analysis demonstrated a significant preintervention monthly increase in biosimilar use of 0.65% (95% CI, 0.48%-0.83%). The postintervention slope change of 0.33% (95% CI, 0.07%-0.58%) and the overall postintervention slope of 0.98% per month (95% CI, 0.8%-1.16%) also were significant, showing a continued increase in biosimilar uptake.

Bevacizumab had a significant increase in biosimilar usage before the policy intervention, with a slope of 1.56% per month (95% CI, 1.44%-1.69%). The level change postintervention was 0.16% (95% CI, –1.52% to 1.83%). The slope change postintervention was –0.18% (95% CI, –0.41% to 0.06%), which was not significant. The postintervention slope remained positive and significant at 1.38% per month (95% CI, 1.17%-1.60%).

The prices for the originator and biosimilar versions of trastuzumab, as of April 2022, were $231 (¥34,670) and $127 (¥19,118) for 150 mg, respectively. Bevacizumab’s originator and biosimilar were priced at $811 (¥121,608) and $363 (¥54,403) for 400 mg, respectively.

The results may not be fully representative of the overall Japanese population, and the medications may not have been analyzed long enough to capture the effects of the policy over the long term. Also, the outcomes are tied to specific characteristics of Japanese health care and reimbursement systems that might not be directly applicable to the differing health care infrastructures, regulatory environments, and approaches to biosimilar promotion of other countries. The study also is limited by the external validity of our conclusions, especially since each country has a unique policy landscape that could influence the effectiveness of similar interventions.

“It is crucial for policy makers to design reimbursement strategies that are specifically tailored to the characteristics of each biosimilar to optimize their effectiveness,” study authors concluded.

References

1. Mamiya H, Fukasawa T, Kawakami K. Effects of reimbursement add-on policies on trastuzumab and bevacizumab biosimilar adoption in Japanese oncology setting. Value Health Reg Issues. 2025;46:101090. doi:10.1016/j.vhri.2025.101090

2. Yusuke Kajimoto, Honda K, Nozawa K, Mukai M, Teng L, Igarashi A. Use of anticancer therapies and economic burden near the end of life in Japan: results from claims database. JCO Global Oncology. 2022;8:e2200227. doi:10.1200/go.22.00227