FDA Proposes a Change in Biosimilar Switching Study Requirements 

The US Food and Drug Administration (FDA) has proposed that manufacturers of biosimilar drugs seeking the agency’s interchangeable designation will no longer be required to perform switching studies.

Current Biosimilar Interchangeability Dynamics 

The FDA’s initial guidance to industry Considerations in Demonstrating Interchangeability With a Reference Product was published in May 2019.  Under this guidance, biosimilar manufacturers were required to conduct switching studies to establish safety and efficacy when a reference brand product is switched to a biosimilar version.   

The interchangeability designation in the product label allows for a biosimilar to be switched for a reference product without the pharmacist having to obtain permission from the prescriber.  According to the American Journal of Managed Care’s Center for Biosimilars, only 13 of approved biosimilars have received the interchangeable designation.  Of these, 6 were approved without switching data either because they are administered intravitreally or because the FDA waived the requirement for insulin biosimilars.

Proposed Switching Study Changes 

According to the FDA draft guidance document, “Since publication of the Interchangeability Guidance, experience has shown that for products approved as biosimilars to date, the risk in terms of safety or diminished efficacy is insignificant following single or multiple switches between a reference product and a biosimilar product.  Accordingly, FDA’s scientific approach to when a switching study or studies may be needed to support a demonstration of interchangeability has evolved.” 

Applicants with a pending 351 (k) biologics license application (BLA) for a proposed biosimilar product may choose to submit an amendment to their pending BLA with a assessment of why comparative analytical and clinical data provided in the application or supplement support a showing  that the switching standard set forth in section 351 (k) (4)(B) of the Public Health Service act has been met and request that their BLA be reviewed as a proposed interchangeable biosimilar.   

The FDA is requesting for comments from interested parties on proposed changes to biosimilar switching study requirements.  The deadline for submission of comments to the FDA is September 20, 2024.   

Implications 

Switching studies impose a significant cost burden on the biosimilar manufacturer.  As such, most biosimilar manufacturers have not conducted these studies in order to receive the interchangeability designation.  If the switching study requirement were to be removed, this would even the playing field among all biosimilars and support faster biosimilar market uptake.  For reference brand manufacturers, the change would likely result in faster erosion of market share which should be considered in an updated brand forecast scenario.   

From the payer perspective, the new guidance would allow for potential cost savings as legacy reference brands are more easily substituted with biosimilar versions.  However, the question of reference brand rebates complicates the situation as payers may be reluctant to disadvantage reference brands which are competitive with biosimilars on a net cost basis.   

For patients, the change would remove existing burden around switching to a biosimilar and likely provide greater access to biosimilars which offer a potentially lower out-of-pocket cost option to a reference brand when coinsurance is required as part of the benefit design. 

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