CAMBRIDGE, Mass.--(BUSINESS WIRE)--Alnylam Pharmaceuticals, Inc. (Nasdaq: ALNY), a leading RNAi therapeutics company, announced today that it has initiated dosing in its Phase I clinical trial with ALN-PCS, an RNAi therapeutic targeting proprotein convertase subtilisin/kexin type 9, or PCSK9, for the treatment of severe hypercholesterolemia. The study is aimed at evaluating the safety and tolerability of ALN-PCS in subjects with elevated low-density lipoprotein cholesterol (LDLc, or “bad” cholesterol). In addition, the study will evaluate clinical activity of ALN-PCS based on measurements of plasma PCSK9 protein and serum LDLc levels. Alnylam expects to present data from this study at year’s end.