A U.S. FDA advisory committee’s backing keeps Alnylam Pharmaceuticals Inc.’s Onpattro (patisiran) on the road to a supplemental approval in treating a rare heart disease, but it couldn’t stop the company stock from sliding. Shares (NASDAQ:ALNY) closed Sept. 14 down 8.8% at $193.06, the day after the Cardiovascular and Renal Drugs Advisory Committee voted 9-3 that patisiran’s benefits outweigh the risks in treating cardiomyopathy of transthyretin-mediated amyloidosis.