A biosimilar product is a biological product that is approved based on a showing that it is highly similar to an FDA-approved biological product, known as a reference product, and has no clinically meaningful differences in terms of safety and effectiveness from the reference product. Only minor differences in clinically inactive components are allowable in biosimilar products.
An interchangeable biological product is biosimilar to an FDA-approved reference product and meets additional standards for interchangeability. An interchangeable biological product may be substituted for the reference product by a pharmacist without the intervention of the health care provider who prescribed the reference product.
FDA requires licensed biosimilar and interchangeable biological products to meet the Agency’s rigorous standards of safety and efficacy. That means patients and health care professionals will be able to rely upon the safety and effectiveness of the biosimilar or interchangeable product, just as they would the reference product.To date, the FDA has not established the formal guidelines for a biosimilar to earn the designation of “interchangeable;” Sandoz, among others, has called for such action. As a result, the full market scope of market competition contemplated for an age of “biotech generics” awaits further regulatory developments from the FDA. This contrasts with the fate of Zarxio in the European Union, where the biosimilar has been approved since 2009 and where an approval by the the European Medicines Agency (EMA) means that a physician could decide that a biosimilar is interchangeable as a function of professional judgment, rather than regulatory designation.
The entry of Zarxio into the U.S. market has been accompanied by a patent-related dispute between Sandoz and Amgen regarding what level of information exchange between biosimilar applicant and reference product sponsor is required by the BCPIA (the so-called "patent dance"). In 2014, Sandoz provided notice to Amgen that it had filed a Biologics License Application (BLA) with the FDA to produce a biosimilar of Neupogen. A legal scuffle followed this notice, with Amgen claiming that Sandoz did not provide the actual BLA application as required by the BCPIA. The district court agreed with Sandoz that the statute did not require the application to be provided, but it did recognize an obligation of the application to provide notice of commercial marketing to the sponsor after FDA approval. In July of this year, the Federal Circuit subsequently sided with Sandoz and did not require it to provide the application to Amgen, and interpreted the BCPIA to establish that the notice to Amgen triggered a 180-day delay of marketing for Sandoz, which is why Zarxio has just entered the market now despite its approval in March.The growing pains for the age of biotech generics continue on another front, as the FDA has just released proposed naming guidelines to distinguish follow-on products from the original reference drug.