This guidance is intended to provide advice on the evaluation of analytical similarity to sponsors interested in developing biosimilar products for licensure under section 351(k) of the Public Health Service Act (PHS Act) (42 U.S.C. 262(k)). This evaluation is to support the demonstration that a proposed biosimilar product (hereinafter proposed biosimilar or biosimilar) is highly similar to a  reference product licensed under section 351(a) of the PHS Act. Specifically, this guidance describes  the type of information a sponsor of a proposed biosimilar product should obtain about the  structural/physicochemical and functional attributes of the reference product, how that information is used in the development of an analytical similarity assessment plan for the proposed biosimilar, and the statistical approaches recommended for evaluating analytical similarity.

FDA Statistical Approaches to Evaluate Analytical Similarity .Guidance for Industry