Other items provided in the guidance documents are clear definitions for "protein" and "chemically synthesized polypeptides."
These definitions are crucial because the pathway legislation added "protein" to the definition of a biological product for
the first time.
Also noted are pediatric assessments, which the draft guidance states are required for a biosimilar product that is not deemed
"interchangeable." Pediatric study plans should therefore be part of IND applications.
Overall, FDA is focusing on a step-wise approach for manufacturers and a "totality-of-the-evidence" approach for regulatory
assessment for biosimilars. Essentially, the manufacturer needs to look at each step of biosimilarity demonstration, starting
with extensive structural and functional characterization of both the proposed product and the reference product, to evaluate
"the extent to which there is residual uncertainty about the biosimilarity of the proposed product" and then "identify next
steps to try to address that uncertainty." For FDA's part, the agency will be reviewing the "totality of data and information
submitted in the application...."
Looking ahead, Sherman noted during the February press briefing that FDA still plans to address naming and tracking standards
for biosimilars as well as additional exclusivity issues, which are addressed only briefly in the Q&A draft guidance.
Also on the docket for the future: standards for "interchangeability." Once a product is proved to be biosimilar, a sponsor
can work to demonstrate interchangeability, meaning that the biosimilar product produces the same clinical result as the reference
product in any given patient, explained Sherman.
Public comments on the draft guidance documents are due to FDA through the Federal Register and will be used to shape the final guidance—hopefully sooner rather than later. The European Union has been ahead of the
US in the biosimilar game for years, with approximately 14 approved products under its regional belt. It will be interesting
to watch how the global market reacts to FDA's long-anticipated movement forward in this area.
Angie Drakulich is editorial director of Pharmaceutical Technology. Send your thoughts and story ideas to firstname.lastname@example.org