FDA Issues Draft Guidance Aimed at Cutting Expenses for Biosimilar PK Studies

Persons living with cancer, rheumatoid arthritis, or other conditions requiring costly biologic therapies may one day pay less for their medications—if a cascade of federal regulatory changes translates into meaningful market competition.

On March 9, 2026, the FDA issued new draft guidance aimed at further reducing the time and expense of bringing biosimilars to market, the latest in a series of actions taken under the current administration to lower the cost of biologic drugs.1

What the New Guidance Does

The draft guidance, titled "New and Revised Draft Q&As on Biosimilar Development and the BPCI Act (Revision 4)," recommends streamlining unnecessary clinical pharmacokinetic (PK) testing when scientifically justified.

PK studies evaluate how the body processes a drug and have traditionally been required as part of demonstrating that a biosimilar behaves like its reference product. The FDA stated this change could save biosimilar developers up to 50% of their PK study costs, or approximately $20 million per program.

The March guidance also revises how developers may use international data. Specifically, it provided updated recommendations to biosimilar applicants seeking to use data from a comparator product approved outside the US as evidence that a proposed product is biosimilar to the US-licensed product—describing scenarios in which a biosimilar applicant may use such clinical data without conducting an additional 3-way PK study involving the proposed biosimilar, the US-licensed reference product, and the non–US-licensed comparator.

In a related action, the FDA withdrew its 2015 final guidance on demonstrating biosimilarity to a reference product, stating it no longer represents the agency's current thinking.

Building on October 2025 Action

The March announcement builds on a prior FDA effort in October 2025, when FDA Commissioner Marty Makary, MD, MPH, announced draft guidance reducing certain unnecessary comparative efficacy studies (CES), which can require 1 to 3 years and cost $24 million.

That earlier guidance drew wide attention for proposing a significant shift in how biosimilarity is demonstrated. The FDA emphasized that current analytical technologies offer sufficiently sensitive tools to characterize highly purified therapeutic proteins and, in many cases, can detect minor differences more precisely than a clinical trial.2 Under that framework, a well-conducted comparative analytical assessment (CAA) is often more sensitive than a CES, whose outcomes may be affected by factors such as dose selection, patient population variability, or trial design.3

Weighing Market Urgency With Cautious Optimism

The urgency behind these actions is grounded in a stark spending imbalance. Biosimilars make up just 5% of prescriptions in the US but accounted for 51% of total drug spending in 2024, and only about 10% of reference biologics that will lose patent protection in the next decade currently have a biosimilar in development.4

Congress established the approval pathway for biosimilars in 2010 through the Biologics Price Competition and Innovation Act, and the FDA has since approved 82 biosimilars, providing additional treatment options for conditions such as cancer, rheumatoid arthritis, diabetes, Crohn disease, and osteoporosis—although that figure represents a small fraction of approved biologics overall.5

Industry stakeholders and patient advocates largely welcomed the October and March guidance. The Biosimilars Forum described the October guidance as addressing the affordability crisis in prescription medicines, and Makary emphasized that regulatory barriers have prevented greater biosimilar entry into the US market and that expanding competition is essential to driving down biologic prices and improving patient access.2

Still, analysts and health policy experts cautioned against reading the regulatory changes as a near-term solution to drug costs.

Taking the New Guidance With a Grain of Salt

Regulatory streamlining addresses only one of several layers of friction slowing biosimilar uptake in the US. Even with lower development costs and shortened timelines, significant structural barriers remain. Manufacturers have shown hesitation to invest in biosimilars for small patient populations where return on investment is limited, manufacturing complexity for advanced biologics continues to require specialized facilities and expertise, and even with streamlined guidance, bringing a biosimilar to market can take nearly a decade.3

Patent protections pose a particularly stubborn challenge. A GlobalData health care analyst noted that branded biologics will still control the market through patents, which act as a bottleneck to market entry for biosimilars, meaning the guidance will not, on its own, improve patient access to biosimilars.6

The guidance has also attracted pushback from organizations focused on biologic safety. The Alliance for Safe Biologic Medicines submitted comments to the FDA expressing strong concern over what it characterized as the "genericizing" of biosimilars, stating that the proposed shifts would be "scientifically inappropriate and potentially harmful to patient confidence" and urging the agency to regulate in a manner consistent with the recognition that biosimilars are not generics.7

Without additional reforms—such as addressing rebate structures, patent thickets, prescriber incentives, biosimilar education gaps, and pharmacy benefit manager transparency—the US may not realize the full potential of biosimilar competition.3 The benefits of these regulatory reforms could take years to materialize, underscoring that policy change alone will not close the biosimilar access gap.2

The FDA is accepting public comments on the March 9 draft guidance, and developers and payers alike are expected to weigh in before the guidance is finalized.1

References

1. FDA takes further steps to streamline biosimilar development and make medicines more affordable. News release. FDA. March 9, 2026. Accessed March 9, 2026. https://www.fda.gov/news-events/press-announcements/fda-takes-further-steps-streamline-biosimilar-development-and-make-medicines-more-affordable
2. Jeremias S. FDA guidance to remove one of the largest barriers to biosimilar development. AJMC®️. October 29, 2025. Accessed March 9, 2026. https://www.ajmc.com/view/fda-guidance-to-remove-one-of-the-largest-barriers-to-biosimilar-development
3. Jeremias S. A closer look at new FDA guidance removing barriers to biosimilar development. The Center for Biosimilars®️. October 30, 2025. Accessed March 9, 2026. https://www.centerforbiosimilars.com/view/a-closer-look-at-new-fda-guidance-removing-barriers-to-biosimilar-development
4. Jeremias S. The biosimilar void: 90% of biologics coming off patent will lack biosimilars. The Center for Biosimilars. February 5, 2025. Accessed March 9, 2026. https://www.centerforbiosimilars.com/view/the-biosimilar-void-90-of-biologics-coming-off-patent-will-lack-biosimilars
5. The Center for Biosimilars. Biosimilar approvals. Updated December 22, 2025. Accessed March 9, 2026. https://www.centerforbiosimilars.com/biosimilar-approvals
6. Allen AK. FDA looks to simplify biosimilar development with new draft guidance. Clinical Trials Arena. October 30, 2025. Accessed March 9, 2026. https://www.clinicaltrialsarena.com/news/fda-biosimilar-approval-draft-guidance-2025
7. Worcester S. FDA aims to streamline biosimilar drug development. Medscape. November 21, 2025. Accessed March 9, 2026. https://www.medscape.com/viewarticle/fda-aims-streamline-biosimilar-drug-development-2025a1000whe