From High Cost to High Access: The Impact of Generic Abiraterone on Medicare Part D Spending in Advanced Prostate...

Advanced prostate cancer treatments carry substantial financial toxicity, which may be mitigated by generic alternatives. We characterize Medicare spending trends on branded vs generic abiraterone to estimate the impact of generic adoption on cost and access.

Medicare Part D data (2013-2023) were analyzed for all abiraterone formulations and compared with enzalutamide, which carries similar indications but no generic alternative. Annual percent change (APC) was analyzed using joinpoint regression.

Generic abiraterone became available in 2018. Medicare spending on all abiraterone formulations increased from $470 million to $1.5 billion from 2013 to 2018 (APC 19.3%, P = .02) and then decreased from $1.5 billion to $910 million from 2018 to 2023 (APC -10.4%, P = .06). From 2013 to 2023, the number of beneficiaries receiving abiraterone annually increased from 14,188 to 46,411 (APC 12.3%, P < .01). From 2013 to 2017, the annual cost per beneficiary grew from $33,094 to $48,978 (APC 12.2%, P = .02) and then decreased to $19,610 in 2023 (APC -17.7%, P < .01). The per-refill cost of generic abiraterone decreased significantly after its introduction in 2018 (APC -17.2%, P = .01). Generic abiraterone adoption yielded total Medicare cost savings of $7.3 billion from 2018 to 2023. By contrast, enzalutamide displayed steady increases in total Medicare spending (APC 18.5%, P < .01) and per-beneficiary cost (APC 9.3%, P < .01) throughout the study period.

Generic abiraterone adoption led to significant reductions in Medicare spending and cost per beneficiary, while maintaining a trend of increased utilization. These benefits were not seen with enzalutamide, which does not have a generic alternative. These findings underscore the importance of timely generic entry in controlling Medicare spending while preserving access to life-prolonging therapeutics.