Dear Commissioner Gottlieb: We appreciate the Food and Drug Administration’s (FDA) recent actions regarding biosimilars – specifically the FDA’s Biosimilars Action Plan. As you know, one of the most important ways the FDA can help increase marketplace competition is by finalizing its guidance, “Considerations in Demonstrating Interchangeability With a Reference Product” regarding the process a biosimilar manufacturer must follow to obtain an interchangeable designation. We appreciate that the FDA acknowledges that this guidance is needed to provide a clear and consistent pathway for demonstrating interchangeability, and ultimately achieving prescription drug cost savings in the biological product market, and we urge you to finalize the guidance as soon as possible.