Biosimilar Uptake of Filgrastim and Impact on Spending in Medicare Part D from 2015 to 2019

A retrospective, cross-sectional review reported significant uptake of biosimilar filgrastim products in Medicare Part D from 2015 to 2019 being associated with a small decrease in aggregate spending, essentially unchanged per-unit spending, and increased spending per beneficiary on filgrastim products, all attributed to the inability of Medicare Part D to directly negotiate prices with manufacturers.

A retrospective, cross-sectional review evaluated utilization trends of filgrastim biosimilars and impact on spending among Medicare Part D beneficiaries. The results of the analysis were presented at the 2021 American Society of Clinical Oncology Annual Meeting.

Using the 2015 to 2019 Medicare Part D Prescription Drug Event data, this study assessed annual spending, number of beneficiaries, number of claims, spending per beneficiary, and spending per dosage unit of filgrastim, as well as per the biosimilars filgrastim-sndz and tbo-filgrastim.

The total aggregate Part D spending on filgrastim products was $78 million in 2019, of which the biosimilars share was $44 million (56%); that increased from $1.8 million (2%) in 2015. From 2015 to 2019, total spending on filgrastim reference decreased by 58%. Whereas biosimilar uptake progressively increased every year, total aggregate spending on all filgrastim forms decreased only 7% from 2015 to 2019 ($84 million to $78 million). From 2015 to 2019, for all 3 filgrastim forms, trends in spending were average spending per claim ($3193-$2549; –20%), average spending per beneficiary ($5880-$6722; +15%), and average spending per dosage unit of filgrastim ($583 vs $571; –2%).

Based on these results, the significant uptake of biosimilar filgrastim products in Medicare Part D from 2015 to 2019 was associated with a small decrease in aggregate spending, essentially unchanged per-unit spending, and increased spending per beneficiary on filgrastim products, all attributed to the inability of Medicare Part D to directly negotiate prices with manufacturers. These results are in contrast with the significant cost-savings associated with biosimilar filgrastim uptake in Medicare Part B and Medicaid programs.

Source: Hussaini S, Gupta A, Anderson KE, et al. Biosimilar uptake of filgrastim and impact on spending in Medicare Part D from 2015 to 2019. J Clin Oncol. 2021;39(suppl_28):67.