The FDA is doubling down on its goal to increase biosimilar drug availability in the U.S. with a fresh draft guidance proposing more changes to streamline development of the cheaper biologic copies.
The newly proposed guidance (PDF) focuses on clinical pharmacokinetic (PK) testing, a core aspect of biosimilar drug testing that serves as a key comparative test to weigh a proposed biosimilar against the approved product it references.
In its draft guidance, the FDA offers recommendations for streamlining unnecessary PK testing when “scientifically justified,” a change that could save biosimilar drugmakers up to 50% of their PK study costs, which equates to about $20 million, the agency said in a press release.
“Streamlining biosimilar development reflects our ongoing commitment to lowering drug costs for everyday Americans,” FDA Commissioner Marty Makary, M.D., commented in the release. “Using common sense, we are embracing more precise analytical testing approaches than have been used in the past.”
The FDA’s biosimilar stance is written out in Q&A form, with the newest update listed as the fourth revision to its official biosimilar guidance. The draft guidance lists three Q&A’s that were revised in March 2026 and one draft from 2018.
In the new proposed regulations, the FDA clarifies circumstances under which biosimilar makers could leverage data from a comparator product that’s only approved outside of the U.S. to prove how a proposed biosimilar is similar to a U.S.-licensed reference product. In certain situations, this could allow biosimilar applicants to rely solely on clinical data from outside of the U.S., as opposed to needing additional data from a three-way PK study.
The draft guidance also removes an earlier requirement for at least one clinical PK study that directly stacks a proposed biosim against a U.S. reference product, allowing a study using a product approved that’s outside of the U.S. if “scientifically justified,” the FDA said.
With the new update, the FDA is also cleaning up its archive of biosimilar guidelines, scrapping a 2015 final guidance that was issued after the agency approved its first biosimilar product that “no longer represents the FDA’s current thinking,” it said.
After signing off on now 82 biosimilars to date, the agency explained that it has “gained significant experience” in the way of biosimilars, adding that its “scientific thinking has evolved.”
FDA’s broader biosim efforts
With the U.S. drug market now having had more than 10 years to adjust to biosimilar availability, the FDA is still searching for ways to foster broader growth for the cheaper meds. While biologic drugs make up 5% of overall drug prescriptions in the U.S., they also represent 51% of drug spending and can cost “hundreds of thousands of dollars per year,” the agency points out.
In October, the FDA drew up a plan to reduce clinical testing burdens for biologic drug copies and to slap an interchangeability tag on all approved biosims. The framework specifically looks to eliminate switching studies that are currently necessary to categorize a biosimilar as “interchangeable” to the reference product, a label that allows pharmacists to freely substitute a biosimilar for a pricier brand-name drug at the pharmacy counter without a doctor’s sign-off.
The comparative efficacy studies targeted in the FDA’s October draft guidance can take one to three years and cost $24 million, according to the agency.
Regulatory action on biosimilars has been a long time coming, with lawmakers and advocates pushing for updates on the current interchangeability structure to clear up confusion for patients. Changes in biosimilar regulations would be especially timely considering the upcoming “biosimilar void,” a term that describes the dozens of biologic drugs that are set to go off patent in the coming years with no biosimilars in line to launch.
“The pathway to reducing the biosimilar void begins with regulatory modernization,” leading biosimilar maker Sandoz said in a January report.
The company pointed to costly phase 3 clinical efficacy trials as a primary hindrance to current biosimilar development, explaining that streamlined regulatory pathways “retain rigorous analytical studies and pharmacokinetic characterization while eliminating expensive, time-consuming phase 3 trials.”
Biosimilars have so far generated savings of more than $56 billion since first cracking open the U.S. market in 2015, according to the Biosimilars Council. However, broader cost savings in the U.S. are often held up by a lack of widespread biosimilar awareness and payer dynamics as well as the regulatory concerns, experts have said.
