Dynamics of biological markets with multiple biosimilar competitors in the United States.

Background: The dynamics of biological markets with multiple biosimilar competitors in the United States are poorly understood. Moreover, due to confidentiality issues, the relationship between originator biologic net prices, rebates, and biosimilar entry is largely unexplored.

Research design and methods: We conducted a review of the Food Drug Administration (FDA) purple book and manufacturer websites to identify all originator biologics with multiple competitors and their characteristics. We leveraged a novel data source to examine originator biologic net prices and rebates over time and used descriptive statistics and interrupted time-series analyses to assess their relationship with biosimilar entry.

Results: By December 2022, only five originator biologics had three or more available biosimilar competitors. Mean time between biosimilar approval and biosimilar launch was 9 months (SD = 7.04 months). By third biosimilar competitor, entry net prices for originator biologics had decreased by 9.34% to 50.93%, while rebates had increased by 25.35% to 89.71%.

Conclusions: Very few originator biologics have multiple available biosimilar competitors. Barrier to biosimilar availability seems to be at the approval level as the time between approval and launch is relatively short. However, originator biologics respond quickly to biosimilar competition, mainly through an increase in rebates.