In 2003, select families with familial hypercholesterolemia were first identified to have gain-of-function mutations for proprotein convertase subtilisin kexin type 9 (PCSK9) followed, in 2006, by the identification of those with lifelong low levels of LDL-C and lowered atherosclerotic cardiovascular disease (ASCVD) risk who had loss-of-function PCSK9 mutations. These discoveries led to the rapid development of PSCK9-targeted monoclonal antibody (PCSK9 mAb) therapies and, in 2015, 2 'fully-humanized' PCSK9 mAbs (alirocumab and evolocumab) were marketed in the United States, Europe, and other countries. In a wide range of high risk patients, with and without ASCVD, these PCSK9 mAbs, as once or twice monthly subcutaneous injections, potently reduce LDL-C 50-65% beyond levels achieved by maximally tolerated statin therapy; approximately one-third of patients achieve LDL-C levels <25 mg/dL. In the US, PCSK9 mAb therapy has current limited indications for persons with ASCVD or familial hypercholesterolemia requiring additional LDL-C reduction beyond maximally tolerated statin therapy. The first of the ASCVD outcomes-driven trials, the FOURIER trial has very recently shown in over 27,000 subjects randomized to evolocumab or placebo on top of moderate or high intensity statin therapy, a 15% risk reduction in the primary and 20% reduction in the secondary outcome over 2.2 years of treatment. Also of interest in patients with coronary artery disease on statin therapies, once-monthly evolocumab treatment, for only 76 weeks, resulted in significant plaque atheroma volume regression, as assessed by serial intravascular ultrasonography imaging, in approximately two-thirds of treated patients. Finally, in development is a highly durable RNA interference therapeutic inhibitor of PCSK9 synthesis which from a single dosage has been shown to maintain, for 6 months, a 75% reduction in PCSK9 levels and 50% reductions in LDL-C levels. The potential role of this vaccination-like product, as well as currently available PCSK9 mAb therapies, represents significant therapeutic advances to address ASCVD residual risk.

A stronger association for low-density lipoprotein particle (LDL-P) and high-density lipoprotein particle (HDL-P) versus cholesterol concentrations (LDL-C and HDL-C) in predicting coronary heart disease (CHD) has been noted. We evaluate the role of these factors and extent of particle-cholesterol discordance in those with diabetes mellitus (DM) and metabolic syndrome (MetS) for event prediction. In the Multi-Ethnic Study of Atherosclerosis, we examined discordance of LDL and HDL (defined as a subject's difference between baseline particle and cholesterol percentiles), LDL-C, LDL-P, HDL-C, and HDL-P in relation to incident CHD and cardiovascular disease (CVD) events in subjects with DM, MetS (without DM), or neither condition using Cox regression. Of the 6,417 subjects with 10-year follow-up, those with MetS (n = 1,596) and DM (n = 838) had significantly greater LDL and HDL discordance compared with those without these conditions. In discordance models, only LDL discordance (per SD) within the MetS group was positively associated with CHD events (adjusted hazard ratio [HR] = 1.22, 95% confidence interval [CI] 1.01 to 1.48, p <0.05). In models with individual particle/cholesterol variables (per SD), within the DM group, HDL-P was inversely (HR 0.71, 95% CI 0.52 to 0.96, p <0.05) and LDL-C positively (HR 1.47, 95% CI 1.07 to 2.03, p <0.05) associated with CHD. In those with MetS, only LDL-P was positively associated with CHD (HR 1.34, 95% CI 1.00 to 1.78, p <0.05). Similar findings were also seen for CVD. LDL discordance and higher LDL-P in MetS, and higher LDL-C and lower HDL-P in DM, predict CHD and CVD, supporting a potential role for examining lipoprotein particles and discordances in those with MetS and DM.