Abstract 17913: Inhibition of CETP by Dalcetrapib Results in a Modest Increase in Cholesterol Efflux Capacity Associated With an Increase in Large HDL Particles, but Does Not Impact Carotid Intima-Media Thickness in a dal-PLAQUE-2 Substudy

Inhibition of cholesteryl ester transfer protein (CETP) is an approach aiming at raising HDL-cholesterol levels and reducing cardiovascular risk. The dal-PLAQUE-2 phase III study recruited 988 subjects with stable coronary artery disease. Its primary objective was to evaluate the effect of dalcetrapib on the progression of carotid atherosclerotic disease measured by intima-media thickness after one year of therapy. As dalcetrapib showed a neutral effect on cardiovascular risk in the dal-OUTCOMES study, our objective was to evaluate its effect on cIMT and markers of HDL mass, lipoprotein subclass distribution and HDL function. All subjects from dal-PLAQUE-2 who had provided serum samples at baseline and one year were included in our substudy of 193 subjects on placebo and 186 subjects on dalcetrapib. Comparisons between groups at one year were made by ANCOVA after adjustment for baseline levels. No significant differences between groups for all variables considered were observed at baseline. Dalcetrapib reduced CETP activity as measured by a fluorescent method by 30% after 1 year (p<0.001), which resulted in increases in HDL-cholesterol and apoA-I levels by 32% and 11%, respectively (both p<0.001). Dalcetrapib markedly increased the concentration of large HDL particles measured by NMR profiling (+59%, p<0.001), at the expense of small HDL particles (-9.5%, p<0.001). Cholesterol efflux capacity of serum was measured from J774 macrophages under basal conditions and after cAMP stimulation. Dalcetrapib increased basal and stimulated efflux by 7.1% and 5.5% (both p<0.001), but was without effect on the ABCA1-dependent component (p=0.26). Despite these effects, dalcetrapib had no impact on mean and maximal cIMT (p=0.98 and p=0.85). While the change in cIMT was inversely correlated with basal cholesterol efflux in the placebo group (Spearman r=-0.163, p<0.05), such a relationship was not found in the dalcetrapib group. Moreover, the change in total HDL particles concentration was inversely correlated with change in cIMT (r=0.181, p<0.05) in the placebo arm only. In conclusion, dalcetrapib raised HDL-C and larger HDL, but this had minimal effects on cholesterol efflux capacity of patients’ serum and had a neutral effect on carotid artery plaque burden.