Developing oncology biosimilars: an essential approach for the future.

The treatment of many diseases, particularly cancer, has been profoundly impacted by the introduction of biologic therapies (biologics), which are incorporated into the treatment algorithms of most oncology clinical practice guidelines. Biologics are large molecular weight, structurally complex proteins that are produced via complex manufacturing processes. With the patents of key biologics, including many widely used in oncology, set to expire in the near future, a number of pharmaceutical companies have focused on developing biosimilars. While the goal of development is to demonstrate that the biosimilar product is highly similar to the reference biologic product, biosimilars should not be viewed as "generic" biologics. Generic drugs are small chemical moieties that are identical to the patent-expired "reference" small-molecule drugs. It is not possible to produce an identical copy of a biologic, so the term "biosimilar" was chosen to define an appropriately similar biologic product. Improving patient access to cancer therapies such as biologics and reducing healthcare costs are key initiatives of the US Government; the integration of approved biosimilars into clinical practice will be instrumental in accomplishing these goals.