Is a Biologic Produced 15 Years Ago a Biosimilar of Itself Today?

Much of the testing required for the regulatory approval of a biosimilar is focused on proving that the new drug is sufficiently similar to the reference biologic in structure, pharmacokinetics or pharmacodynamics, clinical efficacy, and safety. However, the reference drug may itself have gone through some changes in the years since its approval, including those caused by alterations in the manufacturing process. Do these changes increase the risk that the reference drug may cause unexpected outcomes? It is up to the US Food and Drug Administration to decide whether the changes merit the need for additional studies to confirm that the drug meets the structural or clinical outcomes standard for the reference agent. Although it is extremely rare, a change in the production of one biologic drug (ie, epoetin alfa) did result in unanticipated serious immunologic side effects.