Sandoz picked a relatively simple molecule for its first FDA biosimilars application, but the Novartis AG unit is presenting the agency with three tough regulatory challenges. Sandoz is asking FDA to allow it to share a non-proprietary name with the reference product, Neupogen filgrastim from Amgen Inc.; to extrapolate clinical data from a single indication to all five indications on the Neupogen label; and, sooner or later, to designate the Sandoz product as interchangeable with Neupogen.

The agency will face a more difficult scientific challenge when it reviews an application from Celltrion Inc. for its biosimilar version of Remicade infliximab, a mAb marketed by Johnson & Johnson and Merck & Co. Inc. Celltrion has publicly said it will submit an application in 2H14, and may have already done so.