Biosimilar Uptake Lags in US Despite Potential Cost Savings

This article was originally published by The American Journal of Managed Care^®.

Biosimilar uptake in the US has not met the expectations of many health care professionals who believe biosimilars can lead to reduced spending, according to a study published in Health Affairs.¹

As prices have increased for biologic drugs, these medications made up 46% of US prescription drug spending in 2022, despite only making up 3% of prescriptions. Originally, the assumption about biosimilars was they would help lower costs and improve patient access to biologic therapies through market competition. However, the first decade following the Biologics Price Competition and Innovation Act of 2009, which established an FDA approval pathway for biosimilars, did not have successful biosimilar competition as policy makers expected. Within the first 2 years, biosimilars had less than 30% of the market share compared with most biologic drugs facing competition.

In 2023 alone, specialty medicines accounted for 54% of spending, an increase from 49% in 2018.² Market uptake of biosimilars has ranged based on the medication, from 8% for insulin lispro to 82% for bevacizumab. By the end of last year, adalimumab biosimilars accounted for 2% of volume, likely due to contracts the originator products are under and the differences in biosimilar formulations.

Economic factors that hinder biosimilar uptake in the US include the absence of financial rebates for biosimilars, leaving payers disinterested in supporting biosimilars.³ Additional factors like access to health insurance, clinics, and transportation can also hinder biosimilars.

Noneconomic factors, such as complex naming conventions, health care provider knowledge gaps, and safety concerns, have hindered biosimilar uptake in the US. Despite these challenges, global studies demonstrate increased patient access and treatment options through biosimilar utilization.

“The reasons for slow biosimilar uptake remain unclear,” the authors of the new study wrote.¹ “Existing studies have suggested that there may be important variation in biosimilar initiation across patient characteristics and sites of care, but these studies have been limited in terms of the number and types of biosimilars investigated.”

Their study aimed to provide a better understanding of the reasons for inadequate biosimilar uptake in the US by analyzing characteristics of patients and prescribers initiating biosimilars for 7 biologic drugs from 2013-2022.

The cross-sectional study began on November 1, 2013, when the first biosimilar entered the market, and ended on March 31, 2022. Patients initiated 1 of 7 biologic medications—filgrastim, bevacizumab, epoetin alfa, trastuzumab, pegfilgrastim, infliximab, or rituximab—or corresponding biosimilars. The primary outcome was the proportion of patients who initiated the reference biologic or a biosimilar version.

Trends in Biosimilar Uptake in the US

A total of 196,766 patients initiated 1 of the 7 biologics or corresponding biosimilar versions during the study period. Most patients identified as White (69%) and women (58%), with an average age of 68.8 years. Patients were more likely to be enrolled in a Medicare Advantage plan (74%), receive biologic treatment in an office compared with other locations (62%), and have biologic drugs prescribed by a specialist (49%). While uptake varied between drugs, only 27% of patients overall initiated a biosimilar version.

The first biosimilar market entry dates in the US ranged from filgrastim in November 2013 to rituximab in November 2019. Patients who initiated a biosimilar increased from less than 1% in 2013 to 34% in 2022.

In 2022, more than half of patients who initiated filgrastim, trastuzumab, infliximab, rituximab, and epoetin alfa used biosimilar versions. However, less than 30% of patients initiated biosimilar versions of pegfilgrastim and bevacizumab.

Characteristics Associated With Biosimilar Initiation

The study found several patient factors that were independently associated with higher odds of initiating a biosimilar. Patients under 18 years of age were less likely to initiate a biosimilar (adjusted OR [aOR], 0.33) compared with patients 45 to 64 years old (aOR, 1.12). The only significant difference in race and ethnicity was among patients who identified as Black, who were less likely to initiate a biosimilar (aOR, 0.9) compared with patients who identified as White.

Lower odds of biosimilar initiation were associated with treatment in physician offices compared with hospital outpatient settings (aOR, 0.65). Patients who were prescribed biologics by a primary care clinician were more likely to initiate a biosimilar version compared with biologics prescribed by a specialist (aOR, 1.17). Regarding geographic variations, the highest rates of biosimilar initiation were seen in the Southern region (aOR, 1.26) and the West (aOR, 1.36) compared with the Northeast.

Initiation also varied among the 7 drugs and was associated with patient and prescriber characteristics. Patients under 18 years old were less likely than patients 65 years or older to initiate biosimilars for all drugs, except pegfilgrastim (aOR, 3.94). The study excluded 77% of the bevacizumab initiators with ophthalmologic diagnoses, and the overall number of patients initiating biosimilars increased from 27% to 37%.

Study limitations included reliance on biologic and biosimilar initiators, limited racial and ethnic data, and exclusion of other potential uptake factors. Future research should consider these factors to improve generalizability.

“Biosimilar uptake among new users has been less robust than expected in the US,” the authors concluded. “We identified that biosimilar initiation varied by patient age, insurance type, geography, and site of care, and by prescriber specialty. Targeted policy solutions to increase biosimilar uptake could result in substantial savings to patients and the health care system.”

References

1. Hong D, Kesselheim AS, Ameet Sarpatwari, Rome BN. Biosimilar uptake in the US: patient and prescriber factors. Health Aff. 2024;43(8):1159-1164. doi:10.1377/hlthaff.2023.01215

2. Jeremias S. Overcoming economic, noneconomic barriers to biosimilar adoption in oncology. The Center for Biosimilars®. June 20, 2024. Accessed August 13, 2024. https://www.centerforbiosimilars.com/view/overcoming-economic-noneconomic-barriers-to-biosimilar-adoption-in-oncology

3. Jeremias S. Biosimilars account for 23% market share, with wide uptake disparities across molecules. The Center for Biosimilars. May 22, 2024. Accessed August 13, 2024. https://www.centerforbiosimilars.com/view/biosimilars-account-for-23-market-share-with-wide-uptake-disparities-across-molecules