iologics treat many complex, chronic conditions. In the US, biologics account for around 2% of prescriptions but close to 50% of overall drug spending. Biosimilars, clinically equivalent but lower-cost alternatives, offer an efficient solution to reduce healthcare costs and expand access. Despite their potential, biosimilars continue to face significant regulatory and market challenges that limit their impact. In a world of escalating biologic costs, many patients are priced out. Biosimilars could offer an answer, but obstacles persist.

Breaking Down Regulatory Barriers to Biosimilar Adoption

Patent Thickets: A Legal Maze Hindering Timely Access

One of the most pressing barriers to biosimilar entry is the proliferation of overlapping patents, commonly referred to as patent thickets. Compared to other countries, the US stands out dramatically. One co-author (Goode) conducted an extensive review of patent thickets and showed that litigation against the same 30 biosimilars involved 377 patents in the US versus just 24 in the UK and 46 in Canada. This disparity correlated with significantly longer times to biosimilar market launch: an average of 34 months after regulatory approval in the US compared to 4–7 months elsewhere.

A key contributor to this issue is how the US Patent and Trademark Office (USPTO) handles “obviousness-type double patenting.” By allowing terminal disclaimers (formal commitments by applicants to limit a patent’s term to the expiration date of an earlier related patent), the USPTO enables originators to file duplicative claims across multiple patents, thereby avoiding double patenting rejections. These clusters, often referred to as “rings,” inflate the scope of litigation without extending patent life, creating costly and time-consuming hurdles for biosimilar challengers.

The economic imbalance is stark. Obtaining a new drug patent typically costs between $10,000 to $50,000, but challenging a patent through litigation typically costs over $1 million. With dozens or even hundreds of overlapping patents, biosimilar developers face impractical litigation burdens that delay patient access and stifle competition.

A pragmatic reform could allow originators to file as many patents as they wish but litigate only one per duplicative cluster. This “ring representative” approach would preserve incentives for genuine innovation while streamlining litigation and accelerating biosimilar availability. By reducing legal complexity and litigation costs, this change could shorten time to market and improve affordability for patients.

This proposal is gaining traction among policymakers. The Eliminating Thickets to Increase Competition (ETHIC) Act (S.2276/H.R.3269), introduced in Congress in 2025, would limit the assertion of duplicative patents and reduce litigation burden. If enacted, it could significantly improve biosimilar competition while maintaining protections for meaningful innovation.

Interchangeability: A Regulatory Signal with Market Consequences

Interchangeability is another key factor influencing biosimilar adoption. In the US, the interchangeability designation allows pharmacies to substitute biosimilars for their reference biologics without the need for a new prescription, subject to state law. Differently from small molecule generic drugs, by law and regulation not all biosimilars become interchangeable for the reference biologic upon approval. In order to receive an interchangeability designation, biosimilars are required to submit additional clinical trials demonstrating that they could be expected to produce the same clinical result as the reference product.

The regulatory requirements for interchangeability add costs and can further delay biosimilar development. While more than 75 biosimilars have been approved in the US by the FDA, the FDA had approved only 26 interchangeable biosimilars as of July 2025, and 46 states permit pharmacist substitution. In 2024, FDA guidance made interchangeability more accessible by reducing reliance on formal switching trials and emphasizing analytical data. In October 2025, the FDA released additional draft guidance allowing biosimilar sponsors to consider a streamlined approach to demonstrating biosimilarity where a clinical comparative effectiveness study may not be necessary. In this case, certain biosimilar applications could be submitted without a clinical comparative study in humans. Although this would not be the standard for all applications, it would offer a pathway to streamline biosimilar development, accelerating development time and lowering costs.

Although these recent regulatory policies can help lower biosimilar development costs and accelerate approval timelines, market dynamics reveal that interchangeability alone may not guarantee sustained uptake or savings. A case study comparing two long-acting insulins (one the reference insulin and the other an interchangeable) led by the other two co-authors (Trujillo and Socal) showed that biosimilar prices rose post-designation and then stabilized, while reference product prices dropped via rebates and formulary tactics. Biosimilar utilization spiked initially but then plateaued, and patient out-of-pocket costs sometimes increased.

Encouraging one-step approvals that combine biosimilarity and interchangeability, in line with the 2024 FDA guidance, could reduce uncertainty and transaction costs. With more sponsors seeking interchangeability at the time of initial biologics license application (BLA), rather than as a follow-up, these policies could accelerate the availability of interchangeable biosimilars and expand the competitive landscape, especially for some high-cost biologics used to treat autoimmune and inflammatory conditions. However, to ensure that interchangeability delivers on its promise, stakeholders must align payer and pharmacy incentives. Greater transparency around rebates, coupons, and formulary decisions would also help ensure that lower-cost options are prioritized.

Call to Action for Policy Makers, Regulators, and Payers

Policy makers have a pivotal role to play in unlocking biosimilar potential. Legislative efforts such as the ETHIC Act, which limits assertion to one patent per duplicative family, represent a critical step toward curbing patent thickets and fostering competition.

But legislative reform alone is not enough. Stakeholders across the healthcare ecosystem must also act. Providers and pharmacists need clear, consistent education on biosimilar safety, efficacy, and substitution practices. Patients must be empowered with transparent information to make informed choices. Payers and pharmacy benefit managers (PBMs) should align formulary and reimbursement policies to support biosimilar adoption. Policy makers must advance legislation that balances innovation with access and affordability.

Collaborative efforts, such as educational campaigns or transparent pricing models, can help overcome inertia and dispel misconceptions. Evidence has shown that, when patients are told that they do not need to obtain a new prescription in order to get the biosimilar, they demonstrate greater interest in taking a biosimilar product. Patient interest in the biosimilar was driven by their perception that the biosimilar was clinically comparable to the biologic; patients who were told that they needed a new prescription were less likely to perceive the two drugs as comparable. Patient education efforts are especially important in therapeutic areas where biosimilars have the potential to dramatically reduce costs and improve outcomes, such as oncology, rheumatology, and endocrinology.

By working together, stakeholders can overcome inertia, dispel misconceptions, and create a more equitable and sustainable biosimilar market. The opportunity is clear, and the time to act is now.