Biosimilars--science, status, and strategic perspective.

Biopharmaceuticals based on recombinant proteins have started to go off-patent, opening the way for other manufacturers to place follow-on products to the market. Meanwhile it has been recognized by all stakeholders that there are fundamental differences between conventional small-molecule based drugs and biopharmaceuticals. This has led to the adoption of distinct legal and regulatory frameworks for biosimilars (follow-on products to biopharmaceuticals) in various parts of the world. This review gives an overview on the scientific basis for the approval requirements, the regulatory and market status, open issues, and the strategic perspective.