On November 26, 2010, the European Medicines Agency released its proposed guideline for regulatory approval of similar biological medicinal products containing monoclonal antibodies ("Guideline"). Although the EMA has had a framework for approving biosimilar medicines for several years, and has approved over a dozen biosimilar products, to date it has not approved any biosimilar antibodies. The long-awaited Guideline sets forth the non-clinical and clinical requirements for monoclonal antibody-containing medicinal products claiming to be similar to another one already marketed, i.e., biosimilars. The Agency will be accepting public comments on the proposed Guideline until May 31, 2011. On the same day the Guideline for biosimilar monoclonal antibodies ("mAbs") was released, the Agency also released a related guideline on the immunogenicity assessment of monoclonal antibodies intended for in vivo clinical use. That guideline is applicable to all biological medicinal products contaning mAbs, not just biosimilars.

In general, the Guideline requires that a biosimilar antibody not be inferior to the reference antibody, which is a lesser standard than for a new non-generic drug. In particular, the Guideline states that "[t]he focus of the biosimilarity exercise is to demonstrate similar efficacy and safety compared to the reference product, not patient benefit per se, which has already been established by the reference product." Deviations from the Guideline are permissible only if scientifically justified. Clinical trials will be required, including safety trials. The Guideline stresses that the scope and amount of testing, both in vitro and in vivo, will be determined on a case-by-case basis. Click here for a summary of the Guideline or click here for the full Guideline.