H.V.Raghunandan

  The imminent patent expiration of many biopharmaceutical products will produce the possibility for generic versions of these therapeutic agents (i.e. biosimilars). However, there are a number of issues that will make approval of biosimilars much more complicated than the approval of generic equivalents of conventional pharmaceuticals. These issues center on the intrinsic complexity of biopharmaceutical agents, which are recombinant proteins in most cases, and the heterogeneity of proteins produced by different manufacturing processes. The increased occurrence of antibody (Ab)-mediated pure red cell aplasia (PRCA) associated with change in the formulation of one particular epoetin-α product highlights the potential for increased immunogenicity of recombinant proteins with different formulations, or those manufactured by different processes. The subsequent production of ‘biosimilars’ has aroused interest within the pharmaceutical industry as biosimilar manufacturers strive to obtain part of an already large and rapidly growing market. The potential opportunity for price reductions versus the originator biopharmaceuticals remains to be determined, as the advantage of a slightly cheaper price may be outweighed by the hypothetical increased risk of side effects from biosimilar molecules that are not exact copies of their originators. This review focuses on the issues surrounding biosimilars, including quality control, clinical efficacy and side effects.