Estimation of zorifertinib metabolic stability in human liver microsomes using LC-MS/MS

Zorifertinib (AZD-3759; ZFB) is a novel, potent, oral, small molecule used to treat non-small cell lung cancer. ZFB is an epidermal growth factor receptor inhibitor that is capable of crossing blood-brain barrier. The in silico metabolic software used for ZFB metabolic stability prediction was the StarDrop software package (WhichP450 module). An LC-MS/MS analytical method (fast and accurate) was established for ZFB quantification in human liver microsomes (HLMs) in order to estimate its metabolic stability. ZFB and encorafenib (ENF) (internal standard; IS) were separated through the use of an isocratic mobile phase system with a C₈ stationary phase column. The LC-MS/MS method for ZFB exhibited linearity in the range of 5 ng/mL to 500 ng/mL in HLMs matrix with a linear regression equation: y = 0.2438x - 0.341 (R² = 0.9992). The limit of quantification (LOQ) was 3.78 ng/mL confirming the LC-MS/MS method sensitivity. The inter- and intraday accuracy and precision were less than 9.56% confirming the reproducibility of the LC-MS/MS method. The intrinsic clearance and in vitro half-life of ZFB were 32.5 µL/min/mg and 21.33 min, respectively. ZFB exhibited a moderate extraction ratio that revealed good bioavailability. Literature review demonstrated that the developed analytical method is the first developed LC-MS/MS method for determining ZFB metabolic stability.