Biosimilars are biologic medicines highly similar to the reference product with no meaningful clinical differences in terms of safety, purity, and potency. All biologic medicines are produced by living cells, resulting in an inherent heterogeneity in their higher order structures and post-translational modifications. In 2010, the US Congress enacted legislation to streamline the approval process for biosimilars of products losing patent protection, with the goal of decreasing costs and improving patient access to therapeutically important but expensive biologic agents.