Reduction of triglyceride-rich lipoproteins with retatrutide in type 2 diabetes may be explained by concurrent reduction in ANGPTL3/8 levels

Abstract Background/Introduction In the recent phase 2 study (NCT04867785) in patients with type 2 diabetes (T2D), retatrutide, an agonist of glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide 1 (GLP-1), and glucagon receptors, reduced triglycerides (TG) and non-high-density lipoprotein cholesterol (non-HDL-C) up to 35.0% and 20.7%, respectively. The angiopoietin-like 3/8 complex (ANGPTL3/8) is the most potent circulating inhibitor of lipoprotein lipase (LPL), and its serum levels have been shown to be directly correlated with TG and low-density lipoprotein cholesterol (LDL-C). Purpose In the aforementioned phase 2 study, we examined the effects of retatrutide on circulating ANGPTL3/8 complex concentrations to help understand the mechanism by which retatrutide reduced TG and non-HDL-C. Methods Patients with T2D were randomly assigned to receive once-weekly injections of placebo, 1.5 mg dulaglutide, or retatrutide doses of 0.5 mg, 4 mg, 8 mg, or 12 mg. Fasting serum samples were collected at baseline, week 2, week 4, week 8, week 12, week 16, and week 24, and ANGPTL3/8 levels were measured at all time points using a sensitive and selective immunoassay. Plasma PCSK9 levels were also measured at baseline and 24 weeks. Data were analyzed using a mixed model for repeated measures with log-transformation. Results Baseline ANGPTL3/8 levels (mean 26.3 ng/mL, IQR 17.4-33.0 ng/mL) were not different among all study groups. Mean percent changes of ANGPTL3/8 from baseline at week 24 were -1.3%, -12.0%, -48.7% and -51.0% in 0.5 mg, 4 mg, 8 mg and 12 mg retatrutide groups, respectively (Figure). Percent changes of ANGPTL3/8 in 8 mg and 12 mg retatrutide groups were significantly different from placebo group (p < 0.0001). Mean percent changes of PCSK9 levels from baseline to 24 weeks were not different from placebo for any treatment arm (+6.2%, -3.9%, -3.8% and -9.6% for retatrutide 0.5 mg, 4 mg, 8 mg and 12 mg groups, respectively, and -1.5% for dulaglutide and -6.5% for placebo). Conclusions In patients with T2D, retatrutide dose-dependently decreased serum concentrations of ANGPTL3/8, the most potent circulating LPL inhibitor. These data suggest that retatrutide may reduce TG-rich lipoproteins by decreasing ANGPTL3/8 levels.