That FDA has apparently been issuing more refusal to file decisions, particularly to big pharma, is "yet another possible indication that [the agency] is getting still tougher with its approval process," Pharmalot's Ed Silverman says. "Among big drug-makers receiving an RTF [refusal to file notice] in the last two years were Pfizer, Novartis, Roche and Merck, as well as Gilead Sciences, one of the largest biotechs," Silverman adds.