Biosimilar Competition Reduces Adalimumab Spending but Faces Challenges in Uptake
In the first year of biosimilar competition for adalimumab, spending on the drug decreased by nearly 50%, yet biosimilars accounted for less than 2% of prescriptions in the US, according to a study published in JAMA Health Forum.
“In this cross-sectional study, we examined the use of and spending on Humira [adalimumab] and 9 adalimumab biosimilars in the 4 quarters before and after the first biosimilar entered the US market in January 2023,” explained Benjamin Rome, MD, MPH, Program on Regulation, Therapeutics, and Law, Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School in Boston, Massachusetts, and coauthors.
The researchers analyzed quarterly data from 2022 to 2023, tracking prescriptions, spending, and pricing trends for adalimumab and its 9 biosimilar competitors. The total number of prescriptions remained stable at approximately 1 million per quarter, but biosimilar uptake increased modestly, from 0.03% in Q1 to 1.35% in Q4 of 2023. The single interchangeable biosimilar, adalimumab-adbm, represented only 2.35% of biosimilar prescriptions in 2023.
Despite the low uptake, competition drove significant cost reductions. Net sales for adalimumab dropped from $5 billion in Q4 of 2022 to $2.8 billion in Q4 of 2023. Similarly, the average net price per prescription decreased by 43%, from $5007 to $2837. Interestingly, by Q4 of 2023, adalimumab’s net price ($2798 per prescription) was lower than that of its biosimilar competitors, which ranged from $3452 to $4793. This pricing trend likely reflects aggressive rebate strategies by AbbVie, adalimumab’s manufacturer, to maintain formulary dominance.
The slow adoption of biosimilars contrasts sharply with the rapid uptake of generic drugs, which typically achieve 66% market share within a year of exclusivity loss. Barriers to biosimilar substitution include stricter US Food and Drug Administration (FDA) requirements for interchangeability and state laws limiting automatic pharmacy substitution. Policy changes, such as eliminating the FDA’s interchangeable designation for biosimilars, could streamline substitution and improve uptake.
Additionally, nearly all Medicare Part D plans covered adalimumab by January 2024, while only half covered biosimilars, and less than 2% preferred them. “To prevent manufacturers from leveraging confidential rebates to maintain exclusive preferred formulary status, policymakers could prohibit such rebates for biologics after initiation of biosimilar competition, facilitating direct price competition and possibly lowering patient out-of-pocket costs,” concluded the study authors. CVS Health’s recent decision to replace adalimumab with a biosimilar on its formularies could signal a shift, but its impact remains to be seen.
Reference
Rome BN, Bhaskar A, Kesselheim AS. Use, spending, and prices of adalimumab following biosimilar competition. JAMA Health Forum. 2024;5(12):e243964. doi:10.1001/jamahealthforum.2024.3964
