Therapeutic monoclonal antibodies: strategies and challenges for biosimilars development

Biosimilar medicines already on the market may have a primary structure identical to their reference products (e.g., amino acid sequences should be identical). In the case of monoclonal antibodies (mAbs), and due to their more complex structure, a greater level of demand would be in order and identity at other levels (e.g., post-translational modifications within the Fc region of the molecule) should be proved to establish "similarity". These requirements would lead to a greater development in the process and tighter quality controls during the production of biosimilar mAbs. The following issues should be taken into account in the comparability exercise: - The designs of the studies carried out to obtain approval of the reference product are not always adequate to show that safety and efficacy of the biosimilar mAbs are comparable. A similar efficacy does not necessarily imply a similar safety profile between the innovator and biosimilar products. - The design of clinical tests to demonstrate comparability must be flexible and adaptable throughout the development of the product. - The European Medicines Agency (EMA) will consider suitable goals in the evaluation of biosimilar mAbs for their approval (e.g., to specify whether their goal is to check similarity with the reference product or to show that the treatment is effective at a clinical level).