Republicans on the Senate HELP Committee are taking the FDA to task for failing to shore up policies on biosimilar naming and interchangeability before approving the first biosimilar drug nearly two months ago.

Sandoz made history in March when the FDA approved Zarxio (filgrastim-sndz), a biosimilar version of Amgen’s Neupogen (filgrastim) chemotherapy drug. Though the drug has a unique name, the FDA made clear at the time that the name was just a placeholder and that it would decide later whether biosimilars should get unique names or use international nonproprietary names.

In a letter to Acting FDA Commissioner Stephen Ostroff, HELP Chairman Lamar Alexander (R-Tenn.) and seven other senators expressed confusion about what a placeholder name is and asked the agency to explain what kind of legal authority it has to issue that name and/or change it later.

The senators also want the FDA to explain exactly how it will go about changing a placeholder name and how the agency and the manufacturer will avoid confusing patients and healthcare workers.

The FDA’s ability to draft and finalize guidance also came in for criticism. While the agency issued several final guidances on demonstrating biosimilarity recently, much of its biosimilars guidances remain drafts, the senators charge.

The senators gave the FDA until May 22 to respond to their questions. In the meantime, they want to see a schedule of the biosimilars guidances the agency intends to finalize.

The agency did not respond to a request for comments by press time. Read the letter at www.fdanews.com/04-30-15-biosimilarsletter.pdf. — Lena Freund