Abstract:

Drugs used to treat hematologic malignancies often exhibit narrow therapeutic windows， significant inter-individual variability， and high risks of drug-drug interactions， necessitating therapeutic drug monitoring （TDM） for individualized dosing. For patients requiring concomitant antifungal therapy due to infections arising from severe chemotherapy-induced myelosuppression， TDM can optimize plasma concentrations of both antineoplastic and antifungal agents. This concurrent optimization ensures anti-tumor efficacy while effectively mitigating the risk of invasive fungal infections， positioning TDM as a critical component of personalized management in hematologic malignancies. This study established and validated a rapid ultra-high performance liquid chromatography-tandem mass spectrometry （UHPLC-MS/MS） method for the simultaneous quantification of the antineoplastic agents selinexor （SEL） and venetoclax （VEN）， along with the antifungal agents voriconazole （VOR） and posaconazole （POSA） in human plasma. Chromatographic separation was achieved using a Kinetex^® XB-C18 column （50 mm × 3.0 mm， 2.6 µm） with a mobile phase consisting of methanol and 10 mmol/L ammonium acetate containing 0.1% formic acid， delivered at a flow rate of 0.5 mL/min under gradient elution conditions. The injection volume was 2 μL， and the total run time was 4.0 min. Detection employed an electrospray ionization source operating in positive ion mode with multiple reaction monitoring （MRM）. Following optimization of mass spectrometric parameters， the method underwent comprehensive validation. Calibration curves demonstrated excellent linearity （r>0.994） over the ranges of 0.04-1.48 μg/mL for SEL， 0.15-5.50 μg/mL for VEN， 0.29-11.77 μg/mL for VOR， and 0.15-6.05 μg/mL for POSA. Intra-day and inter-day precisions （RSDs） were ≤7.1% at all concentration levels. Extraction recoveries were ≥85.3%， demonstrating efficient and consistent sample processing. Method accuracy， determined by the percentage deviation of measured concentrations from nominal values， fell within the acceptable range of 87.4% to 109.0% across all QC levels， confirming the method’s trueness. The practical utility of the validated UHPLC-MS/MS method was demonstrated through its application to clinical specimens. We collected and analyzed 81 clinical samples from 30 patients with acute myeloid leukemia treated with the combination of SEL and VEN. Measured plasma concentrations of SEL in these patients ranged from 0.049 μg/mL to 0.646 μg/mL. Notably， significant inter-individual variability in the peak plasma concentration （C_max） of SEL was observed within the same treatment cycle for approximately 30% of the patient cohort. This study offers evidence-based support for personalized precision therapy in this patient population， which exhibits substantial inter-individual variability and complex drug-drug interactions in clinical practice.

Key words: ultra-high performance liquid chromatography-tandem mass spectrometry （UHPLC-MS/MS）, selinexor, venetoclax, triazole antifungal agent, therapeutic drug monitoring