Biosimilar Use Among 38 ASCO PracticeNET Practices, 2019-2021.

Purpose: Biosimilars offer increased patient choice and potential cost-savings, compared with originator biologics. We studied 3 years of prescribed biologics among US physician practices to determine the relationship of practice type and payment source to oncology biosimilar use.

Methods: We acquired biologic utilization data from 38 practices participating in PracticeNET. We focused on six biologics (bevacizumab, epoetin alfa, filgrastim, pegfilgrastim, rituximab, and trastuzumab) for the period from 2019 to 2021. We complemented our quantitative analysis with a survey of PracticeNET participants (prescribers and practice leaders) to reveal potential motivators and barriers to biosimilar use. We implemented logistic regression to evaluate the biosimilar use for each biologic, with covariates including time, practice type, and payment source, and accounted for clusters of practices.

Results: Use of biosimilars increased over the 3-year period, reaching between 51% and 80% of administered doses by the fourth quarter of 2021, depending on the biologic. Biosimilar use varied by practice, with independent physician practices having higher use of biosimilars for epoetin alfa, filgrastim, rituximab, and trastuzumab. Compared with commercial health plans, Medicaid plans had lower biosimilar use for four biologics; traditional Medicare had lower use for five biologics. The average cost per dose decreased between 24% and 41%, dependent on the biologic.

Conclusion: Biosimilars have, through increased use, lowered the average cost per dose of the studied biologics. Biosimilar use differed by originator biologic, practice type, and payment source. There remains further opportunity for increases in biosimilar use among certain practices and payers.