The FDA released a draft guidance titled Considerations in Demonstrating Interchangeability With a Reference Product: Update (here), which acknowledges the FDA’s continued evaluation of the biosimilar data collected to date and worldwide acknowledgement that if a biosimilar is approved using the analytical methods required for approval, including appropriate in vitro testing, there should be no need for switching studies for products to be substituted.

The guidance discusses the revised FDA thinking, but also notes that this is a draft guidance not for implementation! The FDA says that it will accept comments on the guidance and expects to finalize it once the comments are reviewed. The information in this guidance will serve to revise portions of the May 2019 guidance titled Considerations in Demonstrating Interchangeability With a Reference Product (here) that deals with interchangeability of biosimilars.

Because the FDA has indicated that the guidance is a draft, it is not fully known how or whether the FDA will implement the provisions of the new draft guidance before its finalization; however, given the FDA’s public discussion regarding its views on interchangeability, it is possible that the Agency will adopt the tenets and spirit of the guidance in its review of therapeutic protein biosimilar product applications that contain the required data. Remember, the FDA has already approved a number of biosimilar products, either with or without interchangeability studies, and has found no safety or efficacy issues with the any of the products that it has approved. In addition, other countries have acknowledged that a product that is found to be biosimilar through rigorous analytical and in vitro testing by virtue of its approval to be interchangeable, despite the lack of switching studies. Keep your eyes peeled for further information from the Agency on this important issue.