Refinements to the analytical testing of biosimilar candidates to verify similarity were worked into 2019 guidance from the FDA. These changes offer what the author considers a more "rational approach."
Analytical similarity assessment of biosimilar candidates is the backbone for establishing biosimilarity, a primary requirement for the licensing of biosimilars. After withdrawing its pivotal final guideline on analytical similarity testing, the FDA issued new guidance (Development of Therapeutic Protein Biosimilars: Comparative Analytical Assessment and Other Quality-Related Considerations), with many apparent and subtle differences, primarily based on my citizen petition to the FDA. For example, few people noticed that the FDA replaced “testing” with “assessment.” To assess is to test the value of something using various tools. Testing is when something is put through a series of trials to determine its value. Thus, testing is one of the ways to assess something. In this paper, I will draw attention to both substantive and subtle changes to help reduce the cost and time for the approval of biosimilars.
We have come a long way from the early days of superfluous testing of biosimilars; the new FDA guidance should be read carefully between lines; it is a more rational approach to achieving the demonstration of biosimilarity, but the FDA is like any other agency—if you keep offering to assess ad infinitum, they will have no objection to it. Manufacturers must learn the difference between “testing” and “assessment.”