Low-density lipoprotein cholesterol (LDL-C) levels are significantly associated with atherosclerotic cardiovascular disease (ASCVD) risk, and studies using interventions that lower LDL-C levels have been shown to reduce the risk of ASCVD events and mortality. Statin treatment is the current first-line therapy for lowering LDL-C and reducing ASCVD risk. However, many patients are still unable to reach recommended LDL-C goals on maximally tolerated statin therapy. Monoclonal antibodies that inhibit proprotein convertase subtilisin/kexin type 9, including evolocumab (previously AMG 145), dramatically lowered LDL-C in phase 2 clinical trials when administered alone or in combination with a statin. The aim of this phase 3 study is to evaluate the efficacy of 12 weeks of subcutaneous evolocumab (vs placebo) administered every 2 weeks or every month in combination with a statin in patients with hypercholesterolemia and mixed dyslipidemia. This study will also provide comparative efficacy, safety, and tolerability data between evolocumab and ezetimibe when added to background atorvastatin therapy. © 2014 Wiley Periodicals, Inc.