Safety and Efficacy of a Monoclonal Antibody to Proprotein Convertase Subtilisin/Kexin Type 9 Serine Protease, SAR236553/REGN727, in Patients With Primary Hypercholesterolemia Receiving Ongoing Stable Atorvastatin Therapy

OBJECTIVES: The primary objective of this study was to evaluate the low-density lipoprotein cholesterol (LDL-C)-lowering efficacy of 5 SAR236553/REGN727 (SAR236553) dosing regimens versus placebo at week 12 in patients with LDL-C ≥100 mg/dl on stable atorvastatin therapy. Secondary objectives included evaluation of effects on other lipid parameters and the attainment of LDL-C treatment goals of <100 mg/dl (2.59 mmol/l) and <70 mg/dl (1.81 mmol/l). BACKGROUND: Serum proprotein convertase subtilisin kexin 9 (PCSK9) binds to low-density lipoprotein receptors, increasing serum LDL-C. SAR236553 is a fully human monoclonal antibody to PCSK9. METHODS: This double-blind, parallel-group, placebo-controlled trial randomized 183 patients with LDL-C ≥100 mg/dl (2.59 mmol/l) on stable-dose atorvastatin 10, 20, or 40 mg for ≥6 weeks to: subcutaneous placebo every 2 weeks (Q2W); SAR236553 50, 100, or 150 mg Q2W; or SAR236553 200 or 300 mg every 4 weeks (Q4W), alternating with placebo for a total treatment period of 12 weeks. RESULTS: SAR236553 demonstrated a clear dose-response relationship with respect to percentage LDL-C lowering for both Q2W and Q4W administration: 40%, 64%, and 72% with 50, 100, and 150 mg Q2W, respectively, and 43% and 48% with 200 and 300 mg Q4W. LDL-C reduction with placebo at week 12 was 5%. SAR236553 also substantially reduced non-high-density lipoprotein cholesterol, apolipoprotein B, and lipoprotein(a). SAR236553 was generally well tolerated. One patient on SAR236553 experienced a serious adverse event of leukocytoclastic vasculitis. CONCLUSIONS: When added to atorvastatin, PCSK9 inhibition with SAR236553 further reduces LDL-C by 40% to 72%. These additional reductions are both dose- and dosing frequency-dependent. (Efficacy and Safety Evaluation of SAR236553 [REGN727] in Patients With Primary Hypercholesterolemia and LDL-cholesterol on Stable Atorvastatin Therapy; NCT01288443).