Amgen, Inc. (NASDAQ: AMGN) and Sanofi SA (NYSE: SNY) are locked in a heated patent battle, and a judge’s decision to halt sales of Sanofi’s cholesterol-lowering drug, Praluent, which is co-marketed by Regeneron Pharmaceuticals Inc. (NASDAQ: REGN), puts Amgen firmly in the driver’s seat in what could be a multibillion-dollar market for next-generation cholesterol-lowering medicine.