Metabolic profiles of ribociclib in rat and human liver microsomes using liquid chromatography combined with electrospray ionization high‐resolution mass spectrometry

Development and Validation of a Quantitative LC-MS/MS Method for CDK4/6 Inhibitors Palbociclib, Ribociclib, Abemaciclib, and Abemaciclib-M2 in Human Plasma

BACKGROUND

The cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors, palbociclib, ribociclib, and abemaciclib, are standard-of-care agents for patients with hormone receptor-positive human epidermal growth factor receptor 2-negative metastatic breast cancer. In support of therapeutic drug monitoring and clinical pharmacokinetic studies, a liquid chromatography coupled with tandem mass spectrometry assay for the simultaneous quantitation of CDK4/6 inhibitors and the major active metabolite M2 of abemaciclib in human plasma has been developed.

METHODS

Analytes were extracted from 50 μL of human plasma by precipitating proteins with methanol and then collecting the supernatant. Reversed-phase high-performance liquid chromatography was performed for analyte separation using a biphasic gradient at a flow rate of 0.25-0.5 mL/min. The total run time was 9.5 minutes. The analytes were detected using MS/MS with electrospray ionization operating in positive ion mode.

RESULTS

Validation according to the US Food and Drug Administration's guidance showed that the new assay produced accurate (94.7%-107%) and precise (within-run: 1.2%-8.2%; between-run: 0.6%-7.5%) measurements of all analytes over a concentration range of 5-2000 ng/mL. Overall, analyte recoveries were consistent (mean values: 110%-129%). The analytes were also stable in human plasma and the final extract under various storage conditions. Finally, the clinical applicability of the assay was confirmed by quantitation of all analytes in plasma samples obtained from patients treated with CDK4/6 inhibitors. Reproducibility of the measured analyte concentrations in study samples was confirmed successfully by incurred sample reanalysis.

CONCLUSIONS

A sensitive liquid chromatography coupled with tandem mass spectrometry method to measure CDK4/6 inhibitors was developed and validated according to the Food and Drug Administration criteria. Quantitation of all analytes in clinical plasma samples confirmed that the assay is suitable for therapeutic drug monitoring and clinical pharmacokinetic studies of CDK4/6 inhibitors.

Binimetinib Is a Potent Reversible and Time-Dependent Inhibitor of Cytochrome P450 1A2

Binimetinib is a selective MEK1/2 inhibitor, which is indicative of melanoma. We aimed to investigate the inhibitory effect of binimetinib on cytochrome P450 using human liver microsomes. Binimetinib was demonstrated to display reversible and time-dependent inhibitory effects on human CYP1A2. Binimetinib can inhibit the activity of phenacetin deethylation with IC₅₀ of 5.6 μM. A 30 min preincubation of binimetinib with NADPH-supplemented human liver microsomes raised a significant left IC₅₀ shift (6.5-fold), from 5.69-0.88 μM. The inactivation parameters K_inact and K_I were 0.063 min^-1 and 15.47 μM, and the half-life of inactivation was 11 min. Glutathione (GSH) and catalase/superoxide exhibited minor or no protective effect on binimetinib-induced enzyme inactivation. Trapping experiment by GSH induced a detection of GSH adduct, of which the formation was believed to be through the oxidation of electron-rich 1,4-benzenediamine to reactive 1,4-diiminoquinone species. Cytochrome P450 3A4, 2C9, and 2D6 were involved in the bioactivation of binimetinib. In conclusion, binimetinib was proven to display reversible and time-dependent inhibitory effect on CYP1A2, which may have implications for the toxicity of binimetinib.

Metabolomics approach based on utra-performance liquid chromatography coupled to mass spectrometry with chemometrics methods for high-throughput analysis of metabolite biomarkers to explore the abnormal metabolic pathways associated with myocardial dysfunction

Ultra-performance liquid chromatography/mass spectrometry-based metabolomics can been used for discovery of metabolite biomarkers to explore the metabolic pathway of diseases. Identification of metabolic pathways is key to understanding the pathogenesis and mechanism of disease. Myocardial dysfunction induced by sepsis (SMD) is a severe complication of septic shock and represents major causes of death in intensive care units; however its pathological mechanism is still not clear. In this study, ultrahigh-pressure liquid chromatography with mass spectrometry-based metabolomics with chemometrics anaylsis and multivariate pattern recognition analysis were used to detect urinary metabolic profile changes in a lipopolysaccharide-induced SMD mouse model. Multivariate statistical analysis including principal component analysis and orthogonapartial least squares discriminant analysis for the discrimination of SMD was conducted to identify potential biomarkers. A total of 19 differential metabolites were discovered by high-resolution mass spectrometry-based urinary metabolomics strategy. The altered biochemical pathways based on these metabolites showed that tyrosine metabolism, phenylalanine metabolism, ubiquinone biosynthesis and vitamin B6 metabolism were closely connected to the pathological processes of SMD. Consequently, integrated chemometric analyses of these metabolic pathways are necessary to extract information for the discovery of novel insights into the pathogenesis of disease.