Impact of market entry of biosimilars in the US on cancer biologics' pricing strategies, market share, and payer costs.

Abstract

11073 Background: Biosimilars have been anticipated to lower the financial burden of cancer for payors as well as patients. As of 2025, 42% (n=13 from three product lines: bevacizumab, rituximab, and trastuzumab) of physician-administered biosimilars launched in the US were indicated for cancer. These three product lines accounted for approximately $5.35 billion healthcare expenditure at clinics and nonfederal hospitals in 2024. Methods: Using MarketScan claims data and Average Sales Price (ASP) data from the Centers for Medicare & Medicaid Services, we calculated quarterly ASP of reference products to compare the pricing strategies of reference biologics for cancer vs. non-cancer treatment. We also compared the market share between cancer vs. non-cancer biologics and estimated the average monthly payor costs of the three cancer product lines 12 months before biosimilar entry versus 2023. We identified biologics using Healthcare Common Procedure Coding System codes and adjusted costs to 2025 USD using the prescription drugs Consumer Price Index. Results: Analyses included 8,252,400 claims of 8 reference products and 27 biosimilars. All three cancer biologics experienced biosimilar market entry starting late 2019. On average, the ASP of reference biologics for cancer decreased by 4.3% annually after biosimilar entry, contrasting to 17.2% decrease for non-cancer reference biologics. Meanwhile, the market share of reference biologics decreased on average 39.3%, 34.2%, and 35.4% annually for bevacizumab, rituximab, and trastuzumab, respectively, contrasting to 15.4% decrease for non-cancer reference biologics. Compared to monthly payor costs averaging over 12 months before the first biosimilar launch, monthly payor costs of biologics (including reference and biosimilars) in 2023 fell for all three cancer biologics in the commercial and Medicare market. The annual decrease rate in monthly payor costs was on average 45.1%, 52.0%, and 34.6% for bevacizumab, rituximab, and trastuzumab, respectively. Conclusions: After biosimilar entry, reference biologics for cancer reduced prices at a slower pace than non-cancer reference biologics, this pricing strategy led to a much faster decrease in their market share. Biosimilars for cancer, by gaining larger market share over time, has significantly reduced payor costs of cancer biologics for commercial and Medicare insurers. Drug Reference product ASP annual change Reference product market share annual change Commercial insurance mean monthly payor costs Medicare Part B mean monthly payor costs Before biosimilar entry 2023 Change Before biosimilar entry 2023 Change bevacizumab -2.1% -39.3% $5,261.9 $2,823.0 -46.4% $2,720.0 $1,526.8 -43.9% rituximab -4.4% -34.2% $7,187.4 $3,799.2 -47.1% $3,977.7 $1,717.1 -56.8% trastuzumab -6.5% -35.4% $4,781.6 $3,302.7 -30.9% $2,401.6 $1,485.0 -38.2%