The approval of biosimilars in the EU 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.

However, according to the report from Decision Resources, physician attitudes about indication extrapolation vary by country. French physicians were found to be the most conservative when asked about extrapolation of biosimilar indications compared to German and US physicians.

Rheumatologists, nephrologists and gastroenterologists surveyed for the report were either against indication extrapolation or stated that it should be done carefully because of minute differences between the biosimilar and the branded product that may be clinically significant. This was not surprising to the report’s authors since ‘these specialists have expressed a moderately conservative approach to biosimilars’.

The authors of the report therefore believe that in order to meet physician expectations, biosimilar manufacturers will most likely need to conduct clinical trials in several indications, focusing on therapeutic areas and drug classes that physicians find most acceptable for extrapolation, such as granulocyte colony-stimulating factors in oncology.

If this proves to be the case, and extra clinical trials for additional indications need to be carried out, the extra costs may become cost-prohibitive for many, especially smaller companies, to enter the biosimilars market.

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