Evaluating the Impacts of CYP3A4*1B and CYP3A5*3 Variations on Pharmacokinetic Behavior and Clinical Outcomes in Multiple Myeloma Patients With Autologous Stem Cell Transplant.

Abstract

There exists considerably large interpatient variability in pharmacokinetic exposure of high dose melphalan in multiple myeloma patients with hematopoietic stem-cell transplantation. In this study, we aimed to evaluate the potential impacts of CYP3A4*1B (rs2940574) and CYP3A5*3 (rs776746) variations on pharmacokinetic properties of melphalan and clinical outcomes in multiple myeloma (MM) patients. Genotypes of CYP3A4*1B (rs2940574) and CYP3A5*3 (rs776746) were determined by validated gene-specific real-time PCR (RT-PCR) assays using DNA samples from 108 MM patients; plasma concentrations of melphalan at different time points were quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). CYP3A4*1B/*1B and CYP3A5*3/*3 carriers appeared to have a short median progression-free survival time and a higher maximum melphalan plasma concentration than non-carriers [792 vs. over 950 days, p=0.08; 9.91 (2.67, 34.03) vs. 8.66 (4.46, 17.61) mg/l, p=0.039]. CYP3A4*1B/*1B and CYP3A5*3/*3 variations might influence melphalan therapy in MM patients through yet-to-be-identified mechanisms.