A comprehensive evaluation of a bioanalytical technique for Encorafenib and Cetuximab combination Cancer therapy by LC-MS/MS and their pharmacokinetics in plasma.

The FDA authorized Encorafenib on April 8, 2020, taken along with cetuximab to treat patients (adults) with advanced metastatic colo-rectal cancers, who have a mutation of BRAF-V600E and have previously undergone therapy. No documented techniques for the simultaneous quantitation of Encorafenib and Cetuximab using LC-MS/MS was available, so a reliable, fast, and unique method was developed and validated. Method development involved optimizing chromatographic and mass spectrometric conditions to achieve high sensitivity and specificity. The method was validated per FDA guidelines, evaluating parameters such as linearity, precision, accuracy, recovery, and stability under various conditions. Mass ion pairs were tracked using multiple reaction monitoring (MRM) in positive polarity mode and the precursor to daughter ion transition m/z values for Encorafenib, Cetuximab(peptide), and Tofacitinib (internal reference) are 540.15 → 369.85, 643.34 → 653.31, and 313.17 → 221.05, respectively. The calibration curves demonstrated excellent linearity over 3.75-150 ng/mL ranges for Encorafenib and 0.25-10 ng/mL for Cetuximab. The MS2 system offers a significant advantage with its ability to specifically target ions of interest. The technique was effectively employed to quantitate the levels of analytes, key pharmacokinetic parameters were assessed in rats following single-dose administration. Encorafenib exhibited a Cmax of 72.543 ng/mL, Tmax of 2 h, and T1/2 of 20 h, whereas Cetuximab showed a Cmax of 4.982 ng/mL, Tmax of 1 h, and T1/2 of 10 h. Stability studies confirmed the analytes' robustness under various conditions. These findings highlight the method's utility for accurate monitoring of pharmacokinetic parameters, essential for therapeutic drug monitoring in biological samples. It tracks drug levels drugs from administration to several hours post-dose at set intervals, enabling the evaluation of metabolism, excretion, and protein binding, which aid in the creation of treatment plans. It also facilitates routine monitoring of selected medications in clinical trials.