Less than four months after accepting Alnylam Pharmaceuticals Inc.'s NDA for Givlaari (givosiran), the FDA has approved the new RNAi therapy for the treatment of adults with the rare genetic disorder acute hepatic porphyria (AHP). The condition is defined by a buildup of toxic porphyrin molecules formed during the production of heme. That buildup can cause incidents of severe pain and paralysis, respiratory failure, seizures and mental status changes, according to the agency.