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CYP3A4*22 genotype and systemic exposure affect paclitaxel-induced neurotoxicity.

ABSTRACT: PURPOSE:Paclitaxel is used for the treatment of several solid tumors and displays a high interindividual 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. Paclitaxel plasma concentrations were measured by high-performance liquid chromatography or liquid chromatography/tandem mass spectrometry, and individual pharmacokinetic parameters were estimated from previously developed population pharmacokinetic models by nonlinear mixed effects modeling. 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 (OR = 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.

SUBMITTER: de Graan AJ

PROVIDER: S-EPMC3686845 | biostudies-literature | 2013 Jun

REPOSITORIES: biostudies-literature

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CYP3A4*22 genotype and systemic exposure affect paclitaxel-induced neurotoxicity.

de Graan Anne-Joy M AJ Elens Laure L Sprowl Jason A JA Sparreboom Alex A Friberg Lena E LE van der Holt Bronno B de Raaf Pleun J PJ de Bruijn Peter P Engels Frederike K FK Eskens Ferry A L M FA Wiemer Erik A C EA Verweij Jaap J Mathijssen Ron H J RH van Schaik Ron H N RH

Clinical cancer research : an official journal of the American Association for Cancer Research 20130502 12

<h4>Purpose</h4>Paclitaxel is used for the treatment of several solid tumors and displays a high interindividual 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.<h4>Experimental design</h4>In an exploratory cohort of patients (n = 261) treated with paclitaxel, neurotoxicity incidence, and severity, pharmac ...[more]

PMID: 23640974

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Project description:Drug toxicity is a hurdle to drug development and to clinical translation of basic research. Antiepileptic drugs such as carbamazepine (CBZ) and selective serotonin reuptake inhibitors such as sertraline (SRT) are commonly co-prescribed to patients with epilepsy and comorbid depression. Because SRT may interfere with cytochrome P450 (CYP) enzyme activity and CYPs have been implicated in the conversion of CBZ to reactive cytotoxic metabolites, we investigated in vitro models to determine whether SRT affects the neurotoxic potential of CBZ and the mechanisms involved.Human fetal brain-derived dopaminergic neurons, human brain microvascular endothelial cells (HBMECs), and embryonic kidney (HEK) cells were used to evaluate cytotoxicity of CBZ and SRT individually and in combination. Nitrite and glutathione (GSH) levels were measured with drug exposure. To validate the role of CYP3A4 in causing neurotoxicity, drug metabolism was compared to cell death in HEK CYP3A4 overexpressed and cells pretreated with the CYP3A4 inhibitor ketoconazole.In all cellular systems tested, exposure to CBZ (127 ?M) or SRT (5 ?M) alone caused negligible cytotoxicity. By contrast CBZ, tested at a much lower concentration (17 ?M) in combination with SRT (5 ?M), produced prominent cytotoxicity within 15 min exposure. In neurons and HBMECs, cytotoxicity was associated with increased nitrite levels, suggesting involvement of free radicals as a pathogenetic mechanism. Pretreatment of HBMECs with reduced GSH or with the GSH precursor N-acetyl-L-cysteine prevented cytotoxic response. In HEK cells, the cytotoxic response to the CBZ + SRT combination correlated with the rate of CBZ biotransformation and production of 2-hydroxy CBZ, further suggesting a causative role of reactive metabolites. In the same system, cytotoxicity was potentiated by overexpression of CYP3A4, and prevented by CYP3A4 inhibitor.These results demonstrate an unexpected neurotoxic interaction between CBZ and SRT, apparently related to increased CYP3A4-mediated production of reactive CBZ metabolites. The potential clinical implications of these findings are discussed.

Project description:BackgroundPaclitaxel treatment produces significant peripheral neuropathy, but the time course of neuropathy development and outcomes are unclear. Dose reduction is the only strategy to prevent neurotoxicity, however, the impact of dose-reduction on neuropathy outcomes remains unknown. This study aimed to prospectively evaluated neuropathy development from weekly paclitaxel treatment and evaluate the impact of dose-reduction on post-treatment neuropathy outcomes.Patients and methodsBreast cancer patients receiving paclitaxel (80mg/m2 ) weekly for 12-weeks were prospectively assessed using patient reported (Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity; FACTGOG-Ntx), clinical (Total Neuropathy Score clinical version; TNSc) and neurophysiological measures up to 12-months post completion. The impact of dose-reduction on post-treatment (3.6 ± 0.1 months) clinical and patient reported outcomes was evaluated in 105 weekly paclitaxel-treated patients.ResultsSignificant neuropathy was present by 6-weeks across patient-reported, clinical, and objective neurophysiological assessments, increasing in prevalence and severity over the treatment course. Limited recovery occurred, with significant neuropathy being maintained up to 12 months (p < .05). Patients who received dose reduction had worse patient reported (FACT-GOG-Ntx: 40.2 ± .1.4) and clinical neuropathy outcomes (TNSc: 4.3 ± 0.4) compared to those who received the full dose (FACT-GOG-Ntx: 45.9 ± 0.9; TNSc: 3.3 ± 0.3, p < .05). Patients who ceased treatment early demonstrated the worse deficits (TNSc: 5.0 ± 0.6; FACT-GOG-Ntx: 37.3 ± 2.7) compared to those who received the complete dose (TNSc: 3.5 ± 0.3; FACT-GOG-Ntx: 45.3 ± 0.9, p < .05).ConclusionWeekly paclitaxel produces symptomatic and objective neuropathy early in the treatment course which can persist. Dose reduction does not necessarily lead to more favorable neuropathy outcomes, with individual risk factors likely important in addition to cumulative dose.Implications for practiceWeekly paclitaxel schedules are extensively used in breast cancer. Patients may develop symptomatic and objective neuropathy early in the treatment course, with these individuals requiring closer monitoring. Furthermore, neuropathy is a long-term sequela that may impact quality of life and require appropriate supportive services. Results suggest that dose reduction does not necessarily lead to better neuropathy outcomes. Understanding schedule-specific toxicity and risk factors for neuropathy will be critical to determining individualized treatment strategies and improving quality of life in breast cancer survivors.

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CYP3A4*22 genotype and systemic exposure affect paclitaxel-induced neurotoxicity.

Publications

CYP3A4*22 genotype and systemic exposure affect paclitaxel-induced neurotoxicity.

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