The FDA is doubling down on its goal of increasing the availability of biosimilar drugs in the United States with new draft guidance proposing further changes to streamline the development of cheaper biologics.
The newly proposed guidance (PDF) focuses on clinical pharmacokinetic (PK) studies. This is a core aspect of biosimilar drug testing, serving as a critical comparative study to weigh a proposed biosimilar against the approved product it refers to.
In its draft guidance, the FDA offers recommendations to streamline unnecessary PK testing when “scientifically justified,” which could save biosimilar drug manufacturers up to 50% of PK testing costs, which equates to about $20 million, the agency said in a press release.
“Streamlining biosimilar development reflects our continued commitment to lowering drug costs for ordinary Americans,” FDA Commissioner Marty McCulley, MD, commented in the release. “Using common sense, we are adopting a more accurate analytical testing approach than has been used to date.”
The FDA’s stance on biosimilars is written in Q&A format, with the latest update listed as the fourth revised version of the official biosimilar guidance. The draft guidelines include three Q&As revised in March 2026 and one draft from 2018.
In the new proposed regulations, FDA is clarifying the circumstances in which biosimilar manufacturers may leverage data from comparable products approved only outside the United States to demonstrate how a proposed biosimilar is similar to a U.S.-approved reference product. In certain circumstances, this could allow biosimilar applicants to rely solely on clinical data from outside the United States, rather than requiring additional data from ternary PK studies.
The draft guidance also removes the previous requirement for at least one clinical PK study that directly compares the proposed biosim to a U.S. reference product, and allows studies using products approved outside the U.S. if “scientifically justified,” the FDA said.
With this new update, FDA also cleaned up its archive of biosimilar guidelines, rescinding the 2015 final guidance issued after the FDA approved the first biosimilar product, saying it “no longer represents FDA’s current thinking.”
After obtaining approval for 82 biosimilars to date, the agency explained that it had “gained significant experience” with biosimilars, adding that “scientific thinking has evolved.”
FDA’s Broad Biosim Initiatives
The U.S. drug market has taken more than a decade to adapt to the availability of biosimilars, and the FDA is still looking for ways to foster broader growth of cheaper drugs. Biologics account for 5% of all prescription drugs in the U.S., but they also account for 51% of drug spending and can cost “hundreds of thousands of dollars a year,” the agency said.
In October, the FDA developed a plan to reduce the burden of clinical trials on copies of biological drugs and to place a compatibility tag on all approved biosims. The framework specifically aims to eliminate the switching tests currently required to classify biosimilars as “interchangeable” with reference products. This label allows pharmacists to freely substitute biosimilars for more expensive brand-name drugs at the pharmacy counter without a doctor’s approval.
Comparative efficacy studies covered by the agency’s October draft guidance could take one to three years and cost $24 million, the FDA said.
Regulatory action on biosimilars has been a long time coming, and lawmakers and advocates are seeking an update on the current compatibility structure to eliminate confusion for patients. Changes to biosimilar regulations would be especially timely in light of the upcoming “biosimilar white space,” a term used to describe dozens of biologics scheduled to go off-patent in the next few years with no biosimilars scheduled for release.
“The path to reducing the biosimilar gap starts with regulatory modernization,” Sandoz, a leading biosimilar maker, said in a January report.
The company cited costly Phase 3 clinical efficacy trials as a major hurdle in current biosimilar development, explaining that the streamlined regulatory pathway “allows us to eliminate expensive and time-consuming Phase 3 trials while maintaining rigorous analytical studies and pharmacokinetic characterization.”
Since first entering the U.S. market in 2015, biosimilars have generated more than $56 billion in savings, according to the Biosimilars Council. But widespread cost savings in the U.S., however, are often hampered by a lack of broad awareness of biosimilars, payer trends and even regulatory concerns, experts say.
