When a brand new class of cholesterol-lowering drugs called PCSK9 inhibitors won Food and Drug Administration (FDA) approval in 2015, it was heralded as the biggest advance in battling heart disease since the invention of statins. The launch of PCSK9 inhibitors was accompanied by billion-dollar-plus predictions for sales. However, revenue has fallen far shy of blockbuster status, leaving drugmakers Amgen Inc.(NASDAQ:AMGN), Regeneron Pharmaceuticals(NASDAQ:REGN), and Sanofi SA(NYSE:SNY) in the lurch.
