CYP3A4*22 genotype and systemic exposure affect (Taxol) paclitaxel-induced neurotoxicity

Abstract

Purpose: Paclitaxel is used for the treatment of several solid tumors and displays a high inter- individual variation in exposure and toxicity. Neurotoxicity is one of the most prominent side-effects of paclitaxel. This study explores potential predictive pharmacokinetic and pharmacogenetic determinants for the onset and severity of neurotoxicity.  

Experimental Design: In an exploratory cohort of patients (n=261) treated with paclitaxel, neurotoxicity incidence and severity, pharmacokinetic parameters and pharmacogenetic variants were determined. ....... Genetic variants of paclitaxel pharmacokinetics tested were CYP3A4*22, CYP2C8*3, CYP2C8*4, and ABCB1 3435 C>T. The association between CYP3A4*22 and neurotoxicity observed in the exploratory cohort was validated in an independent patient cohort (n=239).  

Results: Exposure to paclitaxel (logAUC) was correlated with severity of neurotoxicity (P <0.00001). Female CYP3A4*22 carriers were at increased risk of developing neurotoxicity (P = 0.043) in the exploratory cohort. CYP3A4*22 carrier status itself was not associated with pharmacokinetic parameters (CL, AUC, Cmax, or T>0.05) of paclitaxel in males or females. Other genetic variants displayed no association with neurotoxicity. In the subsequent independent validation cohort, CYP3A4*22 carriers were at risk of developing grade 3 neurotoxicity (odds ratio = 19.1; P = 0.001).  

Conclusions: Paclitaxel exposure showed a relationship with the severity of paclitaxel-induced neurotoxicity. In this study, female CYP3A4*22 carriers had increased risk of developing severe neurotoxicity during paclitaxel therapy. These observations may guide future individualization of paclitaxel treatment.