(14) Recent Biosimilar Uptake in the United States

Publication Number: 1059

Background: In 2018, biologics accounted for approximately 40% of US pharmaceutical spending, despite being used by only 2% of patients. Biosimilar availability has the potential to lower costs and increase access. The Biologics Price Competition and Innovation Act was passed in 2010, and the FDA’s Biosimilars Action Plan was published in 2018.

Objectives: To describe recent trends of biosimilar uptake in the United States.

Methods: Using National Drug Codes and Healthcare Common Procedure Coding System (HCPCS) codes, we identified biologic and biosimilar use from January 2015 to September 2021 in Optum’s de-identified Clinformatics® Data Mart Database. When applicable, code modifiers were used in addition to unspecified HCPCS to identify biosimilars. Biosimilars either newly marketed or blocked due to patent litigation were not evaluated. Patients were required to have at least one day of enrollment to be included. Annual dispensings for 24 biosimilars and their 8 referent products were evaluated. Percent market share was also evaluated as total number of biosimilar dispensings divided by total number of product dispensings.

Results: We identified 1,587,360 total biologic dispensings among 303,690 patients in 2015, of which 173 (0.01%) were for biosimilars. By September 2021, there were 241,713 biosimilar dispensings (13.4% of all biologics) among 437,278 patients. Much of this growth in the proportion of biosimilar use occurred between 2019 and 2021 (4.2% to 13.4%).
Biosimilar use increased across all products, although with varying magnitude. Filgrastim biosimilars were first approved in 2015 and 2018 and had the highest market share, increasing steadily over time, reaching 94.6% market share in 2021. Biosimilars with similarly high uptake in 2021 included those for epoetin alfa, trastuzumab, and rituximab. Epoetin alfa biosimilar (2018) had rapid uptake and accounted for 81.2% of market share. Trastuzumab’s five biosimilars (2017-2019) accounted for 74.6% of all trastuzumab use, and three rituximab biosimilars (2018-2020) made up 76.4% of all rituximab dispensings. Three products had biosimilar uptake of less than 50% of market share in 2021: Infliximab biosimilars (n=4, 2016-2019) made up 48.2%; Bevacizumab biosimilars (n=2; 2017, 2019) accounted for 10.5%; and pegfilgrastim biosimilars (n=4; 2018-2020) was 20.3% of all pegfilgrastim use.

Conclusions: Biosimilar uptake increased the most between 2019 and 2021 perhaps spurred on by regulatory initiatives. Further exploration of the reasons for variations in biosimilar uptake among drug classes would be valuable.