G-CSF: Granulocyte-Colony Stimulating Factor

The EMA has also developed guidelines for immunogenicity assessment and for when there are changes in the manufacturing process. Looking to the future, it also has concept papers for biosimilars containing monoclonal antibodies, recombinant interferon beta and recombinant follicle stimulation hormone.

Because of the differences between biopharmaceutical products, the approval process varies according to the product. In particular, the amount of clinical data available may depend on the inherent variability of efficacy endpoints and the availability of validated surrogate markers.

The approval of biosimilars is based on demonstration of comparable efficacy and safety to an innovator reference product (i.e. ‘comparability’). EMA guidelines permit, with proper justification, the extrapolation of data from one therapeutic indication to another, allowing for the use of a biosimilar in indications for which it has not been formally studied.

Because biopharmaceuticals are sometimes, although infrequently, associated with serious adverse events, EMA guidelines also require immunogenicity testing and pharmacovigilance programmes to monitor the efficacy and safety of biosimilar products post-approval. The importance of immunogenicity testing and pharmacovigilance is illustrated by the biosimilar growth hormone Omnitrope. During development, production of this product was transferred from one facility to another. While qualitative testing demonstrated no notable differences between the end products of these facilities, a difference was observed with respect to immunogenicity, which was subsequently resolved by the manufacturer prior to approval.

There is currently no legal pathway in the US for the approval of biosimilars and, accordingly, the US FDA has not yet developed guidelines regarding these types of products. However in February 2010, the FDA agreed to review an application by Teva Pharmaceuticals to sell Neutroval, a biosimilar to boost white blood cells, that is similar to Amgen’s big-selling Neupogen (filgrastim [G-CSF]).

(see also The biosimilars challenge)

G-CSF: Granulocyte-Colony Stimulating Factor