When biotech proteins go off-patent.

The patents of the first generation of biopharmaceuticals derived from recombinant DNA such as interferons, growth hormone and epoietins are expiring, opening up the possibility for competitors to introduce biosimilar products. The concept of generics that applies to classical drugs and allows market admission on limited documentation cannot be extrapolated to these "off-patent biologics". Physicochemical characterization, bioassays and animals studies do not predict completely the efficacy and safety of therapeutic proteins. Clinical studies will nearly always be necessary to obtain marketing authorization for off-patent biologics. Immunogenicity is considered to be the main problem with therapeutic proteins. The recent upsurge of pure red cell aplasia (PRCA), a severe form of anemia associated with the use of epoietin-alpha, highlights both the unpredictability and the severe consequences of immunogenicity. A risk-based approach can be used to evaluate the potential induction of antibodies by off-patent biologics.