Identification of 4-Aminopyrazolopyrimidine Metabolite That May Contribute to the Hypolipidemic Effects of LY2584702 in Long Evans Diet-Induced Obese Rats.

LY2584702 is an inhibitor of p70 S6 kinase-1 previously developed for the treatment of cancer. In two phase 1 trials in oncology patients, significant reductions of total cholesterol, low-density lipoprotein cholesterol (LDL-C), and triglyceride were observed. In the current study, we sought to understand the potential mechanism of action of this compound in regulating lipid metabolism. In Long Evans diet-induced obese (DIO) rats, oral administration of LY2584702 for 3-4 weeks led to robust reduction of LDL-C up to 60%. An unexpected finding of liver triglyceride (TG) increase implicated a metabolite of LY2584702, 4-aminopyrazolo[3,4-day]pyrimidine (4-APP), in modulation of lipid metabolism in these rats. We showed that low-dose 4-APP, when administered orally for 3-4 weeks to Long Evans DIO rats, produced lipoprotein profile changes that were strikingly similar to LY2584702. Kinetic studies suggested that both LY2584702 and 4-APP had no effect on chylomicron-TG secretion and only exerted a modest effect on hepatic very low-density lipoprotein (VLDL)-TG secretion. In human hepatoma HepG2 cells, 4-APP, but not LY2584702, increased LDL uptake. We hypothesize that generation of the 4-APP metabolite may contribute to the efficacy of LY2584702 in lowering LDL-C in rats and potentially in humans as well. This mechanism of LDL-C lowering may include inhibition of VLDL production and increase in LDL clearance.

Analysis of sphingolipids in extracted human plasma using liquid chromatography electrospray ionization tandem mass spectrometry.

We have developed an analytical method used to quantify sphingolipids, including deoxysphingoid bases, in lipid extracts prepared from human plasma. In total, 39 analytes were identified and analyzed in a single chromatographic run in less than 5 min. The new method is 4-8 times faster and more sensitive than previously published methods. We also describe a simple sample preparation method that allows medium-throughput screening of human plasma samples. Mass spectrometric analyses were performed online using liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) in the positive multiple reaction monitoring mode. Samples were extracted using a one-phase extraction method (methanol-dichloromethane) with appropriate internal standards. Sphingolipid analytes were linear over a wide range of concentrations, from 0.01 to 50 ng/ml, with a high correlation coefficient (r2 = 0.999). We successfully applied this method to analyze the levels of sphingolipid metabolites in healthy human plasma. The ceramide, dihydroceramide, hexosylceramide, and GM3 levels observed in females were slightly higher than those observed in males.

Evaluation of the Pharmacokinetic Profile of Ultra Rapid Lispro Administered Subcutaneously at Different Injection Sites.

PURPOSE: Ultra rapid lispro (URLi) is a novel insulin lispro formulation developed to more closely match physiological insulin secretion and improve postprandial glucose control. This study compared the pharmacokinetic profile and glucodynamic response of URLi when administered subcutaneously into the abdomen, upper arm, or thigh. An intravenous (IV) bolus administration was included to determine the absolute bioavailability at each injection site. METHODS: In this Phase I, randomized, open-label, 4-period, crossover study, healthy subjects received a single dose of 15 U URLi subcutaneously into the abdomen, upper arm, or thigh, or by intravenous injection. Serum insulin lispro concentrations and glucodynamic response during a 10-hour euglycemic clamp procedure were assessed after URLi administration. FINDINGS: Total insulin lispro exposure was similar for the abdomen, upper arm, and thigh, and absolute bioavailability was ∼65% at each subcutaneous (SC) injection site. Total and peak insulin action were similar across these SC injection sites. The onset of appearance was <1 minute, and the time to early half-maximal drug concentration occurred at ∼10 minutes across these three SC injection sites. Onset of insulin action occurred at ∼22 minutes, and the early insulin action (for the first hour) was also similar across these SC injection sites. URLi was well tolerated after single SC injections and IV bolus administration. IMPLICATIONS: The pharmacokinetic and glucodynamic profiles of URLi were similar after a single SC dose into the abdomen, upper arm, or thigh. The rate of insulin lispro absorption and early insulin action were maintained regardless of the SC injection site. The current study supports SC injection of URLi into the abdomen, upper arm, and thigh. CLINICALTRIALS: gov identifier: NCT03232983.

Serum Lipid and Protein Changes in Healthy Dyslipidemic Subjects Given a Selective Inhibitor of p70 S6 Kinase-1.

The safety, pharmacokinetic, and pharmacodynamic effects of LY2584702, a selective inhibitor for p70 S6 serine/threonine protein kinase-1, were evaluated in healthy dyslipidemic volunteers. LY2584702 was tolerated well as a monotherapy and dose-dependently reduced low-density lipoprotein cholesterol and triglycerides by up to 60% and 50%, respectively, without significantly changing high-density lipoprotein cholesterol levels in plasma. LY2584702 also dose-dependently decreased factor V activity. Alanine aminotransferase elevations were noted in 2 subjects when LY2584702 was given with atorvastatin. We suspect that the formation of 4-aminopyrazolo[3,4-d]pyrimidine (4-APP) during metabolism may have contributed to some of the adverse effects of LY2584702, and the contribution of 4-APP to the pharmacology merits further investigation. Although clinical investigation of LY2584702 has been terminated because of hepatotoxicity risk, we suggest that a selective inhibitor of p70 S6 serine/threonine protein kinase-1 with a larger margin of safety and without the possibility of being metabolized to 4-APP may be useful in the treatment of dyslipidemia.