Isis Pharmaceuticals and Sanofi unit Genzyme obtained FDA approval to market Kynamro, or mipomersen, as an add-on treatment to lipid-lowering drugs and diet for patients with homozygous familial hypercholesterolemia. Due to risks of liver problems, the once-weekly injectable drug will carry a boxed warning. The approval triggers the payment of a $25 million milestone fee from Genzyme to Isis.