Quantifying plasma dacarbazine levels in advanced melanoma patients: a liquid chromatography-tandem mass spectrometry...

The aim of this study was to develop a robust liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying dacarbazine levels in the plasma of advanced melanoma patients, followed by an assessment of its analytical capabilities. The research encompassed the design of a high-performance liquid chromatography (HPLC) system, with the quantitative analysis performed using the multiple reaction monitoring (MRM) techniques and specific ion transition: 181.0 > 152.5 for dacarbazine and 187.1 > 158.6 for the internal standard (IS), dacarbazine-D6. The validation of the method involved an evaluation of parameters including linearity, detection limit, precision, and accuracy. Notably, the linear range extended from 10 to 1,000 µg/L for dacarbazine, and the method exhibited a detection limit of 10 µg/L. The method's precision, indicated by within-run and between-run coefficients of variation (CV), both being ≤4.2% and ≤8.3%, respectively. Furthermore, the accuracy of measurements, ranging from 86.1% to 99.4%, underscored the method's reliability. In clinical application, the dacarbazine levels of healthy control (n = 20) were 0.6 ± 0.02 μg/L; 770.9 ± 203.2 μg/mL in early-stage-melanoma patients (n = 22), and 588.7 ± 153.2 μg/mL in advanced melanoma patients (n = 25). The results serve as clinical evidence showing that long-term dacarbazine treatment affects the metabolism of dacarbazine.