Uptake and cost of biosimilar filgrastim among Medicare and Medicaid populations in 2015-2018

BACKGROUND: The first biosimilar product filgrastim-sndz was approved by the FDA in 2015, but real-world evaluations of its uptake and cost in nationally representative populations are limited. OBJECTIVE: To evaluate the uptake and cost of filgrastim-sndz, relative to its originator filgrastim and alternative biologic tbofilgrastim, among Medicare and Medicaid populations. METHODS: Using the annually aggregated, product-level utilization and cost data of biologic and biosimilar filgrastim products in 2015-2018 from CMS drug spending data, total number of claims and costs for all 3 filgrastim products were identified and extracted for Medicare Part B, Part D, and Medicaid reimbursement. Annual average cost per claim and per beneficiary of individual filgrastim products were also extracted, and their annual growth rates were calculated. RESULTS: Three years after entering the US market, use of filgrastim-sndz increased to 49.1% and 46.0% of all filgrastim claims paid by Medicare Parts B and D, respectively, and to 38.7% of filgrastim Medicaid claims in 2018. Total cost for filgrastim-sndz also reached 42.8%, 41.8%, and 26.9% of all filgrastim products paid by Medicare Parts B and D and Medicaid, respectively. Significant reductions in average cost per claim for filgrastim-sndz in 2017 and 2018 were observed in Medicare Part B and Medicaid. CONCLUSIONS: Significant uptake of biosimilar filgrastim in Medicare and Medicaid programs occurred during the first 3 years of marketing. Policymakers may use the evidence to evaluate existing barriers and policies regarding biosimilar adoption.