FDA updates biosimilar development guidance as review experience accumulates

On March 9, 2026, the FDA issued draft guidance revising how biosimilar developers may use clinical pharmacokinetic data, alongside withdrawing a 2015 final guidance that the agency said no longer reflects its current thinking after years of review experience.

The new document, New and Revised Draft Q&As on Biosimilar Development and the BPCI Act (Revision 4), replaces a September 17, 2021 revision and is intended to inform prospective applicants developing proposed biosimilars and interchangeable biosimilars.

The immediate operational change is a narrower approach to certain pharmacokinetic (PK) study expectations. The FDA said developers may, in some cases, use clinical data from a comparator product approved outside the United States without additional data from a three-way PK study involving the proposed biosimilar, the U.S.-licensed reference product, and the foreign comparator. The agency also removed its earlier recommendation for at least one clinical PK study directly comparing the proposed biosimilar with the U.S.-licensed reference product, stating that a PK study may instead use a non-U.S. comparator if scientifically justified.

For biosimilar developers, the agency said the revised approach could cut PK study costs by up to 50%, or about $20 million. The move builds on an October draft guidance that, according to the FDA, reduced certain unnecessary comparative efficacy studies that can require one to three years and cost about $24 million.

The policy matters because biologics account for 51% of drug spending despite representing about 5% of prescriptions, according to the FDA. The agency said it has approved 82 biosimilars in the U.S., covering conditions including cancer and autoimmune diseases, and listed a request for comment alongside the new draft guidance.

Sources: Reuters, FDA