For therapeutic categories with comparable biosimilar products approved in both markets, European countries have generally achieved substantially higher biosimilar market share than the United States — a gap that has drawn sustained attention from health policy researchers trying to understand what structural differences actually explain the disparity, given that both markets have functioning regulatory approval pathways for biosimilars.
Different Healthcare System Structures
Many European countries operate healthcare systems with centralized or national purchasing authority — a single national health system or insurance fund negotiating directly with manufacturers and, in many cases, actively steering prescribing toward the lowest-cost clinically appropriate option through tendering processes that award exclusive or preferred supply contracts to the winning biosimilar manufacturer. This centralized purchasing leverage, largely absent from the more fragmented U.S. system of multiple competing insurers and pharmacy benefit managers, has allowed several European health systems to drive rapid, decisive biosimilar uptake once a product is approved.
The U.S. Rebate System Distortion
As with the broader insulin pricing story, the U.S. pharmacy benefit manager rebate system creates a structural dynamic that can actually favor the more expensive reference biologic over a lower-priced biosimilar — if the reference product manufacturer offers a larger rebate to secure favorable formulary placement, the PBM or insurer may have limited financial incentive to favor the objectively cheaper biosimilar, even though the biosimilar's lower list price would benefit patients paying coinsurance or facing a high deductible. This dynamic has been specifically identified by health policy researchers as a meaningful contributor to the U.S. biosimilar adoption gap.
Physician and Patient Familiarity
Surveys of U.S. physicians have found meaningfully lower comfort and familiarity with biosimilar switching compared to physicians in markets with longer, more established biosimilar usage history — a knowledge and comfort gap that tends to close over time as physicians gain direct clinical experience, but that has genuinely slowed early-stage adoption in the U.S. market relative to markets where biosimilars have been standard practice for longer.
Patent Litigation and Delayed Entry
Reference biologic manufacturers have employed sophisticated patent portfolio strategies — sometimes described as "patent thickets," involving dozens of secondary patents covering manufacturing processes, formulations, and delivery devices beyond the core molecule patent — that have in several documented cases delayed biosimilar market entry well beyond the core patent's expiration, through negotiated settlement agreements between reference and biosimilar manufacturers that industry critics argue function similarly to the "pay for delay" settlements previously scrutinized in the small-molecule generic drug context.
Signs of Acceleration
Despite the persistent gap, several U.S. biosimilar categories have shown accelerating adoption in more recent years as cumulative clinical experience has grown, as more biosimilar competitors have entered specific categories increasing competitive pressure, and as some large employer and payer purchasing coalitions have begun implementing more assertive biosimilar-preferred formulary strategies modeled loosely on European purchasing approaches.
Conclusion
The U.S.-Europe biosimilar adoption gap reflects genuine structural differences in healthcare purchasing power and formulary incentive design, not simply slower regulatory approval or inferior products. Closing that gap meaningfully will likely require addressing the underlying rebate and formulary incentive structures that have, in specific documented cases, worked against biosimilar adoption despite their clear cost advantage.
