Biosimilars: are they ready for primetime in the United States?

The introduction of alternative versions of biologic products, also known as biosimilars, into the United States market has been gaining increasing visibility as patents for many agents are nearing expiration. Unlike generics, which are regulated under the Hatch-Waxman legislation passed in 1984, the approval process for biosimilars in the United States has not been defined. In 2004, the European Union established a regulatory pathway for these agents, and the FDA is now following suit. The economic implications are large, with $66.9 billion spent on the top 20 biologics in 2009. Of the top 10 biologics, 6 are routinely used in oncology. As the regulatory requirements are debated, several critical issues must be resolved. The most obvious is that the agents must be shown to be comparable to the original biologic they intend to replace. Knowledge of pharmacokinetic parameters alone will not be adequate, but the amount of clinical data required by the FDA remains unclear. The regulations will define the ease with which a biosimilar can be brought to market, and the associated costs of trials will influence the ultimate price of the medications. Balancing the needs of the relevant stakeholders is critical to ensure patient safety while controlling costs, improving access, and encouraging innovation. This is not an easy balance to strike.