Determination of GDC-0980 (apitolisib), a small molecule dual phosphatidylinositide 3-kinase/mammalian target of rapamycin inhibitor in dog plasma by LC-MS/MS to support a GLP toxicology study.

An LC-MS/MS method for the determination of GDC-0980 (apitolisib) concentrations in dog plasma has been developed and validated for the first time to support pre-clinical drug development. Following protein precipitation with acetonitrile, the resulting samples were analyzed using reverse-phase chromatography on a Metasil AQ column. The mass analysis was performed on a triple quadruple mass spectrometer coupled with an electrospray interface in positive ionization mode. The selected reaction monitoring transitions monitored were m/z 499.3 → 341.1 for GDC-0980 and m/z 507.3 → 341.1 for IS. The method was validated over the calibration curve range 0.250-250 ng/mL with linear regression and 1/x(2) weighting. Relative standard deviation (RSD) ranged from 0.0 to 10.9% and accuracy ranged from 93.4 to 113.6% of nominal. Stable-labeled internal standard GDC-0980-d8 was used to minimize matrix effects. This assay was used for the measurement of GDC-0980 dog plasma concentrations to determine toxicokinetic parameters after oral administration of GDC-0980 (0.03, 0.1 and 0.3 mg/kg) to beagle dogs in a GLP toxicology study. Peak concentration ranged from 3.23 to 84.9 ng/mL. GDC-0980 was rapidly absorbed with a mean time to peak concentration ranging from 1.3 to 2.4 h. Mean area under the concentration-time curve from 0 to 24 hours ranged from 54.4 to 542 ng h/mL.

Validation and application of a liquid chromatography-tandem mass spectrometric method for the determination of GDC-0879 and its metabolite in dog plasma using solid phase extraction.

A liquid-chromatographic-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the determination of GDC-0879 and its ketone metabolite (M1) in dog plasma to support preclinical toxicokinetic evaluation. The method consisted of solid phase extraction for sample preparation and LC-MS/MS analysis in positive ion mode using electrospray ionization for analysis. D(4)-GDC-0879 and (13)C(2)-D(2)-M1 were used as internal standards. A quadratic regression (weighted 1/concentration(2)) was used to fit calibration curves over the concentration range of 1-1000 ng/ml for both GDC-0879 and M1. The accuracy (%bias) at the lower limit of quantitation (LLOQ) was 12.0% and 2.0% for GDC-0879 and M1, respectively. The precision (%CV) for samples at the LLOQ was 11.3% and 2.6% for GDC-0879 and M1, respectively. For quality control samples at 3.00, 400 and 800 ng/ml, the between run %CV was ≤3.9% for GDC-0879 and ≤2.4% for M1. Between run %bias ranged from 4.6 to 12.0% for GDC-0879 and from -0.8 to 2.7% for M1. GDC-0879 and M1 were stable in dog plasma for at least 44 days at -70 °C.