Patient safety advocates and brand-name drug makers lined up against companies that make generic drugs over just how flexible the standards should be for the clinical testing of biosimilars.

These drugs, also known as biogenerics, follow-on biologics and subsequent entry biologics, are officially approved subsequent versions of biopharmaceutical products following patent and exclusivity expiration on the original product. Until now, only a handful of biosimilars have been approved in the U.S., but that is about to change.