Trends in usage and drug costs of immune checkpoint inhibitors in Japan

Abstract Background Immune checkpoint inhibitors (ICI) have recently been developed and launched in Japan, at the same time, soaring national healthcare costs have become one of the major social issues. We investigated the volume of prescriptions and the drug costs of ICIs using National Database (NDB) open data. Methods This is a retrospective cohort study; we used aggregate data between fiscal year (FY)2015 and FY2022 (April 2015–March 2023) from the NDB. The drugs of interest included nivolumab, ipilimumab, pembrolizumab, avelumab, atezolizumab, and durvalumab. Findings are presented as descriptive statistics. Results Since the introduction of ICIs, prescription volume of all ICIs increased overtime. Overall ICI drug costs increased from 16 898 million yen in FY2015 to 419 615 million yen in FY2022; the total of ICI drug costs from FY2015 to FY2022 was over 1 793 billion yen. For each drug, 70% of drug costs were generally for patients aged 65 years or older. In addition, total drug costs tended to increase over the years among those aged 75 and over. Conclusions Drug costs for ICIs are significantly increasing despite the Japanese government’s frequent efforts to reduce ICI drug prices. The elderly population made up a particularly high proportion of those burdened with the higher costs. Healthcare economic policies are warranted to ensure efficient distribution of budgetary resources.