Biosimilars: how similar?

As patents expire on biological agents for the treatment of rheumatic diseases, we have the opportunity to develop non-proprietary biologic agents, biosimilars. The development and approval of these agents present novel challenges to both pharma and regulatory agencies although there is great promise of high quality, less expensive biologic agents for the treatment of rheumatic diseases. Here, we review the definitions of biosimilars, the regulatory challenges to approval of these agents and the record of approvals of biosimilars to date.