Pemafibrate has a novel mechanism of action to lower LDL-C and ApoB in patients with higher LDL-C levels: Insights from a phase 2 exploratory clinical pharmacology crossover study

Abstract

Abstract Background Pemafibrate, a selective PPARα modulator (SPPARMα), decreases plasma TG and increases HDL-C. The effects of pemafibrate on cardiovascular outcomes were examined in patients with type 2 diabetes, moderately high TG, and low HDL-C who were on statin therapy (the PROMINENT trial) [1]. Against our expectation, the intervention with pemafibrate did not reduce the outcomes. The increases in LDL-C and ApoB observed in the trial may have mitigated the beneficial effects of lowering TG and remnants. On the contrary, pemafibrate decreased LDL-C and ApoB in some of the clinical trials conducted in Japanese population [2, 3], suggesting that the effects of pemafibrate on LDL-C and ApoB may vary depending on the target patient population. Purpose To clarify the mechanisms behind the LDL-C-lowering effects of pemafibrate, we evaluated the effects of pemafibrate on serum levels of lathosterol, beta-sitosterol and campesterol, surrogate markers for cholesterol synthesis and absorption. Methods This is a post hoc analysis of a Phase 2 study comparing a once-daily extended-release formulation (ER) of pemafibrate to a twice-daily immediate-release formulation (IR). The study was a multicentre, randomized, single-blind, 3-treatment, 2-period crossover clinical trial. Patients with fasting serum TG >150 mg/dL were treated with IR 0.2 mg/day (IR0.2), ER 0.4 mg/day (ER0.4), or ER 0.8 mg/day (ER0.8) for 4 weeks in each treatment period. We measured serum levels of TG, LDL-C, ApoB, lathosterol (a cholesterol synthesis marker), and beta-sitosterol and campesterol (cholesterol absorption markers) before and after the intervention and evaluated their correlations. Results Among 63 patients randomized, 60 received the study drug. At baseline, the mean TG was 221.3 mg/dL, LDL-C was 134.5 mg/dL, and 10% of patients were concomitantly treated with a statin. The least squares mean percentage changes from baseline at 4 weeks were -43.6%, -41.1%, and -39.7% for TG, -3.5%, -7.0%, and -11.3% for LDL-C, and -9.8%, -11.9%, and -13.4% for ApoB with IR0.2, ER0.4, and ER0.8, respectively, which were significant except for LDL-C with IR0.2. Lathosterol, beta-sitosterol, and campesterol significantly decreased with each dose (see Fig.). The percentage change in LDL-C was positively correlated with those in the synthesis and absorption markers. There was a trend that the reductions in LDL-C and lathosterol increased in a dose-dependent manner. The reduction in LDL-C was larger in the subgroup with higher baseline levels than those with lower baseline levels. Conclusion Pemafibrate reduced serum levels of LDL-C and ApoB. In parallel, they reduced serum markers for cholesterol synthesis and absorption. Because the percentage changes in LDL-C were significantly correlated with those in the absorption and synthesis markers, we would propose that pemafibrate reduced LDL-C by inhibiting both synthesis and absorption of cholesterol.