A rapid and sensitive liquid chromatography/tandem mass spectrometry method for determination of docetaxel in human plasma

Simultaneous estimation of Paclitaxel and Erlotinib in plasma by liquid chromatography/(+) electrospray tandem mass spectrometry: Application in formulation development and pharmacokinetics

The bio-analytical method was developed and validated for simultaneous detection and quantification of paclitaxel (PAC) and erlotinib (ERL) in plasma samples. The sample preparation process was accomplished by liquid -liquid extraction technique. The dried and reconstituted samples were subjected to chromatography on Discovery -C18 (50 × 4.6 × 5µm) column and a mobile phase, composed of a mixture of 0.1% formic acid in water: acetonitrile (70:30, v/v), in isocratic mode at a flow rate of 0.6 mL/min. Liquid chromatography coupled to tandem mass spectrometry detection in positive ion mode was selected to provide optimal selectivity and sensitivity. The mass transitions of erlotinib, erlotinib13C6, Paclitaxel and docetaxel were m/z 394.5→278.4, m/z 400.4→284.5, m/z 876.6→308.4 and m/z 830.0→304.0 respectively. The linearity in the calibration curves were obtained in the concentration range of 3.6 -1006.7 ng/ml (r ≥ 0.99) for erlotinib and 5.3 -1500.0 ng/mL for paclitaxel with a LLOQ (lower limit of quantification) of 3.6 and 5.3ng/ml respectively. The run time was achieved in 2.5 minutes only, for all the analytes.

A stabilized retro-inverso peptide ligand of transferrin receptor for enhanced liposome-based hepatocellular carcinoma-targeted drug delivery

The application of tumor targeting ligands to the treatment of cancer holds promise for improving efficacy and reducing toxicity. ^LT7 (_L(HAIYPRH)) peptide, a phage display-selected peptide, exhibited high binding affinity to transferrin receptor (TfR) overexpressed on tumor cells. However, its in vivo tumor targeting efficiency was impaired due to enzymatic degradation in blood circulation. To improve the stability and targeting ability, a retro-inverso analogue of ^LT7 peptide, named ^DT7 peptide (_D(HRPYIAH)), was designed for targeted therapy of hepatocellular carcinoma. The result of computer simulation predicted that ^DT7 bound to TfR protein more efficiently than ^LT7, and this prediction was confirmed experimentally by surface plasmon resonance (SPR). Ex vivo stability experiment demonstrated that ^DT7 possessed stronger ability against proteolysis than ^LT7 in fresh mouse serum. We further prepared ^DT7-, ^LT7-, and transferrin (Tf)-modified liposomes (^DT7-LIP, ^LT7-LIP, and Tf-LIP, respectively). ^DT7-LIP showed a significantly stronger in vitro targeting ability than ^LT7-LIP and Tf-LIP under normal condition and simulated biological condition. In addition, the in vitro antitumor effect of DTX-loaded ^DT7-LIP was markedly enhanced in comparison to DTX-loaded ^LT7-LIP and DTX-loaded Tf-LIP. In vivo imaging indicated that ^DT7-LIP had better tumor accumulation than ^LT7-LIP and Tf-LIP. For in vivo antitumor studies, the tumor growth rate of mice treated with DTX-loaded ^DT7-LIP was significantly inhibited compared to that in mice treated with DTX-loaded ^LT7-LIP and DTX-loaded Tf-LIP. Overall, this study verified the potential of the stable ^DT7 peptide in improving the efficacy of docetaxel in the treatment of hepatocellular carcinoma. STATEMENT OF SIGNIFICANCE: A phage display library-selected ^LT7 (_L(HAIYPRH)) peptide exhibited high affinity to transferrin receptor (TfR). However, its bioactivity was impaired in vivo as L-peptides are susceptible to degradation by proteolytic enzymes. Here, we designed a retro-inverso peptide ^DT7(_D(HRPYIAH)) and demonstrated its increased serum stability and higher binding affinity to TfR. A stabilized targeted drug delivery system was further constructed by modified ^DT7 peptide on the surface of liposomes. The data indicated that ^DT7 peptide-modified liposomes exhibited higher targeting ability in vitro and in vivo. More importantly, ^DT7-modified liposomes demonstrated positive preclinical significance in enhancing the therapeutic effects against hepatocellular carcinoma.

A Review on Liquid Chromatography-Tandem Mass Spectrometry Methods for Rapid Quantification of Oncology Drugs

In the last decade, the tremendous improvement in the sensitivity and also affordability of liquid chromatography-tandem mass spectrometry (LC-MS/MS) has revolutionized its application in pharmaceutical analysis, resulting in widespread employment of LC-MS/MS in determining pharmaceutical compounds, including anticancer drugs in pharmaceutical research and also industries. Currently, LC-MS/MS has been widely used to quantify small molecule oncology drugs in various biological matrices to support preclinical and clinical pharmacokinetic studies in R&D of oncology drugs. This mini-review article will describe the state-of-the-art LC-MS/MS and its application in rapid quantification of small molecule anticancer drugs. In addition, efforts have also been made in this review to address several key aspects in the development of rapid LC-MS/MS methods, including sample preparation, chromatographic separation, and matrix effect evaluation.

Pharmacokinetic properties of wogonin and its herb-drug interactions with docetaxel in rats with mammary tumors

Docetaxel, frequently used for the treatment of breast cancer, is mainly metabolized via hepatic cytochrome P450 (CYP) 3A in humans and is also a substrate of P-glycoprotein (P-gp). Wogonin has been shown to be able to modulate the activities of CYPs and P-gp, and it could serve as an adjuvant chemotherapeutic agent. However, the impacts of co-administration of wogonin and docetaxel on their pharmacokinetics have not been studied because of a lack of an analytical method for their simultaneous measurement. In the present study, we established an HPLC-MS/MS method for simultaneous measurement of wogonin and docetaxel in rat plasma, and it was then utilized to explore the pharmacokinetics of wogonin and the herb-drug interactions between wogonin and docetaxel after their combined administration in rats with mammary tumors. The rats received 10, 20 and 40 mg/kg wogonin via oral administration, with or without docetaxel intravenously administered at 10 mg/kg, and the plasma concentrations of wogonin and docetaxel were measured using the established and validated HPLC-MS/MS method. The Cmax and AUC0-t of wogonin were proportionally increased in the dose range from 10 to 40 mg/kg, suggesting a linear pharmacokinetics of wogonin. Moreover, the Cmax and AUC0-t of docetaxel and the AUC0-t of wogonin were increased after co-administration (p < 0.05), indicating increased in vivo exposures of both wogonin and docetaxel, which might lead to an increase in not only therapeutic but also toxic effects. Thus the alterations of pharmacokinetics should be taken into consideration when wogonin and docetaxel are co-administered.

Mass spectrometry in the pharmacokinetic studies of anticancer natural products

In the history of medicine, nature has represented the main source of medical products. Indeed, the therapeutic use of plants certainly goes back to the Sumerian and Hippocrates and nowadays nature still represents the major source for new drugs discovery. Moreover, in the cancer treatment, drugs are either natural compounds or have been developed from naturally occurring parent compounds firstly isolated from plants and microbes from terrestrial and marine environment. A critical element of an anticancer drug is represented by its severe toxicities and, after administration, the drug concentrations have to remain in an appropriate range to be effective. Anyway, the drug dosage defined during the clinical studies could be inappropriate for an individual patient due to differences in drug absorption, metabolism and excretion. For this reason, personalized medicine, based on therapeutic drug monitoring (TDM), represents one of most important challenges in cancer therapy. Mass spectrometry sensitivity, specificity and fastness lead to elect this technique as the Golden Standard for pharmacokinetics and drug metabolism studies therefore for TDM. This review focuses on the mass spectrometry-based methods developed for pharmacokinetic quantification in human plasma of anticancer drugs derived from natural sources and already used in clinical practice. Particular emphasis was placed both on the pre-analytical and analytical steps, such as: sample preparation procedures, sample size required by the analysis and the limit of quantification of drugs and metabolites to give some insights on the clinical practice applicability. © 2015 Wiley Periodicals, Inc. Mass Spec Rev. 36:213-251, 2017.

Dose modifications in Asian cancer patients with hepatic dysfunction receiving weekly docetaxel: A prospective pharmacokinetic and safety study

Hepatic dysfunction may modify the safety profile and pharmacokinetics of docetaxel in cancer patients, but no validated guideline exists to guide dose modification necessitated by this uncommon comorbidity. We carried out the first prospective study of a personalized dosage regimen for cancer patients with liver dysfunction treated with docetaxel. Weekly dosages were stratified by hepatic dysfunction classification as such: Category 1, normal; Category 2, mild – alkaline phosphatase, aspartate aminotransferase, and/or alanine aminotransferase ≤5× upper limit of normal (ULN), and total bilirubin within normal range; and Category 3, moderate – any alkaline phosphatase, and aspartate aminotransferase or alanine aminotransferase ≤5–10× ULN, and/or total bilirubin ≤1–1.5× ULN. Category 1, 2 and 3 patients received starting dosages of 40, 30, and 20 mg/m² docetaxel, respectively. Pharmacokinetics were evaluated on day 1 and 8 of the first treatment cycle, and entered into a multilevel model to delineate interindividual and interoccasion variability. Adverse event evaluation was carried out weekly for two treatment cycles. We found that docetaxel clearance was significantly different between patient categories (P < 0.001). Median clearance was 22.8, 16.4, and 11.3 L/h/m² in Categories 1, 2, and 3, respectively, representing 28% and 50% reduced clearance in mild and moderate liver dysfunction patients, respectively. However, docetaxel exposure (area under the concentration–time curve) and docetaxel‐induced neutropenia (nadir and the maximum percentage decrease in neutrophil count) were not significantly different between categories. Median area under the concentration–time curve was 1.74, 1.83, and 1.77 mg·h/L in Categories 1, 2, and 3, respectively. The most common Grade 3/4 toxicity was neutropenia (30.0%). An unplanned comparison with the Child–Pugh and National Cancer Institute Organ Dysfunction Working Group grouping systems suggests that the proposed classification system appears to more effectively discriminate patients by docetaxel clearance and dose requirements. (ClinicalTrials.gov registration no. NCT00703378).

Quantification of taxanes in biological matrices: a review of bioanalytical assays and recommendations for development of new assays

Since the isolation of paclitaxel and its approval for the treatment of breast cancer, various taxanes and taxane formulations have been developed. To date, almost 100 bioanalytical assays have been published with the method development and optimization often extensively discussed by the authors. This Review presents an overview of assays published between January 1970 and September 2013 that described method development and validation of assays used to quantify taxanes in biological matrices such as plasma, urine, feces and tissue samples. For liquid chromatography assays, sample pretreatment, chromatographic separation and assay performance are compared. Since this Review discusses the limitations of previously developed liquid chromatography assays and gives recommendations for future assay development, it can be used as a reference for future development of liquid chromatography assays for the quantification of taxanes in various biological matrices to support preclinical and clinical studies.

ABCB1 polymorphism as prognostic factor in breast cancer patients treated with docetaxel and doxorubicin neoadjuvant chemotherapy

Expression of the adenosine triphosphate-binding cassette B1 (ABCB1) transporter and P-glycoprotein are associated with resistance to anticancer drugs. The purpose of this study was to investigate the role of single nucleotide polymorphism in the ABCB1 and CYP3A genes in breast cancer patients who were treated with neoadjuvant chemotherapy. Stage II/III breast cancer patients were treated with three cycles of neoadjuvant, after which the patients received curative surgery and adjuvant chemotherapy. The polymorphisms of ABCB1 and CYP3A were genotyped. The correlation of polymorphism of ABCB1, CYP3A, and clinical outcomes was analyzed. Among the 216 patients, ABCB1 3435TT genotype had a longer overall survival (OS). than CC/CT. Multivariate analyses demonstrated that good PS, invasive ductal carcinoma, non-triple negative phenotype and initial operable stage were significantly associated with a lower death risk. ABCB1 3435TT genotype had a higher AUC than CC/CT for docetaxel. These higher AUCs in the C3435TT was associated with increased toxicities of neutropenia and diarrhea. This study showed that the genetic polymorphism of ABCB1 C3435T might be associated with a longer OS. Our results also suggest that the prediction of docetaxel toxicity might be possible for C3435T polymorphism. This study results provides valuable information on individualized therapy according to genotypes.

Combined quantification of paclitaxel, docetaxel and ritonavir in human feces and urine using LC-MS/MS

A combined assay for the determination of paclitaxel, docetaxel and ritonavir in human feces and urine is described. The drugs were extracted from 200 μL urine or 50 mg feces followed by high-performance liquid chromatography analysis coupled with positive ionization electrospray tandem mass spectrometry. The validation program included calibration model, accuracy and precision, carry-over, dilution test, specificity and selectivity, matrix effect, recovery and stability. Acceptance criteria were according to US Food and Drug Administration guidelines on bioanalytical method validation. The validated range was 0.5-500 ng/mL for paclitaxel and docetaxel, 2-2000 ng/mL for ritonavir in urine, 2-2000 ng/mg for paclitaxel and docetaxel, and 8-8000 ng/mg for ritonavir in feces. Inter-assay accuracy and precision were tested for all analytes at four concentration levels and were within 8.5% and <10.2%, respectively, in both matrices. Recovery at three concentration levels was between 77 and 94% in feces samples and between 69 and 85% in urine samples. Method development, including feces homogenization and spiking blank urine samples, are discussed. We demonstrated that each of the applied drugs could be quantified successfully in urine and feces using the described assay. The method was successfully applied for quantification of the analytes in feces and urine samples of patients.

A sensitive and specific liquid chromatography-tandem mass spectrometric method for determination of belinostat in plasma from liver cancer patients

A novel, sensitive and reliable liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the determination of belinostat (PXD101) in human plasma. Oxamflatin was used as the internal standard. Liquid-liquid extraction of the plasma sample was performed using tert-butyl methyl ether as the organic solvent. Chromatographic separation was achieved on a BDS Hypersil C18 column (2.1 mm x1 00 mm, 5 microm) using gradient elution mode using 0.05% formic acid in water and 0.05% formic acid in acetonitrile as solvents A and B, respectively, 60/40. The run time was 6 min. The mass spectrometer was operated under a positive electrospray ionization condition and a multiple reaction monitoring mode. An excellent linear calibration was achieved in the range of 0.5-1000 ng/mL. An average recovery of belinostat for four quality controls was 72.6% and the recovery of the internal standard at 1000 ng/mL was 67.8%. The intra-day and inter-day precisions for belinostat were <or=8.0 and <or=10.3%, respectively, and their accuracy ranged from 100.2 to 106.7%. No significant matrix effect was identified. In analysis of patient samples, belinostat glucuronide was identified and baseline separated from belinostat. This well-validated assay has been applied for quantification of belinostat in plasma samples within 24h after the start of infusion for Asian hepatocellular carcinoma patients in a dose escalation study.

Highly selective and sensitive assay for paclitaxel accumulation by tumor cells based on selective solid phase extraction and micro-flow liquid chromatography coupled to mass spectrometry

The taxanes are among the most important cancer chemotherapy drugs approved for clinical use in the last two decades. Paclitaxel is used as first-line therapy for a variety of cancers, and numerous drug delivery approaches are under investigation to enhance its selectivity and effectiveness against tumors. One strategy is to produce sustained, low drug levels within the tumor to enhance apoptosis and inhibit angiogenesis. The interest in altering drug concentration/time exposure profiles to improve therapeutic outcomes creates the necessity to quantify low concentrations of paclitaxel in cells or tissues. Here, a selective solid phase extraction (SPE) method, coupled with a capillary liquid chromatography-tandem mass spectrometry (microLC-MS/MS) method, was developed to quantify low, therapeutically relevant concentrations of paclitaxel that could not be analyzed using conventional LC-MS/MS. Under optimized SPE wash and elution conditions, paclitaxel was selectively extracted from biological samples, and most matrix components were removed. A 150 x 0.5 mm ID ODS capillary column was used for microLC separation and the flow rate was 12 microL min(-1). Sample extracts were focused at the front of the microLC column and then eluted with a gradient. The lower limits of detection and quantification were 5 and 20 pg mL(-1), respectively, permitting quantification of paclitaxel in small tissue samples or in cultured cells exposed to low drug concentrations. The quantitative linear range was 20-20 000 pg mL(-1). The ability to quantify these low concentrations of paclitaxel provides an important tool to study the concentration-dependent pharmacological effects of this important drug.

Ultra-sensitive quantification of paclitaxel using selective solid-phase extraction in conjunction with reversed-phase capillary liquid chromatography/tandem mass spectrometry

The ability to quantify ultra-low concentrations of biologically active compounds in biological matrices is essential for the study of pharmacological/toxicological effects occurring at low doses. Selective solid-phase extraction (SPE) was combined with highly sensitive capillary LC (microLC)-MS/MS analysis to achieve ultra-sensitive quantification of the anti-cancer drug paclitaxel in cancer cells. The optimized SPE selectively extracted paclitaxel and eliminated undesirable matrix compounds, thus enabling a high sample loading volume on the microLC column without compromising chromatographic performance and operational robustness. The validated lower limit of quantification (LOQ) was 5pg/mL, approx. 20-fold more sensitive than published LC-MS/MS methods. The calibration curve was linear over the range of 5-6250pg/mL. Accuracy was 98-109% and the variation (CV%) was 2.3-7.4%. This method was applied successfully to quantify temporal drug accumulation by A121a ovarian cancer cells treated with sub-ng/mL concentrations of paclitaxel.

Clinical pharmacokinetics of docetaxel : recent developments

Docetaxel belongs to the class of taxane antineoplastic agents that act by inducing microtubular stability and disrupting the dynamics of the microtubular network. The drug has shown a broad spectrum of antitumour activity in preclinical models as well as clinically, with responses observed in various disease types, including advanced breast cancer and non-small cell lung cancer. The pharmacokinetics and metabolism of docetaxel are extremely complex and have been the subject of intensive investigation in recent years. Docetaxel is subject to extensive metabolic conversion by the cytochrome P450 (CYP) 3A isoenzymes, which results in several pharmacologically inactive oxidation products. Elimination routes of docetaxel are also dependent on the presence of drug-transporting proteins, notably P-glycoprotein, present on the bile canalicular membrane. The various processes mediating drug elimination, either through metabolic breakdown or excretion, impact substantially on interindividual variability in drug handling. Strategies to individualise docetaxel administration schedules based on phenotypic or genotype-dependent differences in CYP3A expression are underway and may ultimately lead to more selective chemotherapeutic use of this agent.

High sensitivity assays for docetaxel and paclitaxel in plasma using solid-phase extraction and high-performance liquid chromatography with UV detection

Background

The taxanes paclitaxel and docetaxel have traditionally been used in high doses every third week in the treatment of cancer. Lately there has been a trend towards giving weekly low doses to improve the therapeutic index. This article describes the development of high performance liquid chromatographic (HPLC) methods suitable for monitoring taxane levels in patients, focusing on patients receiving low-dose therapy.

Methods

Paclitaxel and docetaxel were extracted from human plasma by solid phase extraction, and detected by absorbance at 227 nm after separation by reversed phase high performance liquid chromatography. The methods were validated and their performance were tested using samples from patients receiving paclitaxel or docetaxel.

Results

The limits of quantitation were 1 nM for docetaxel and 1.2 nM for paclitaxel. For both compounds linearity was confirmed from the limit of quantitation up to 1000 nM in plasma. The recoveries ranged between 92% and 118% for docetaxel and between 76% and 104% for paclitaxel. Accuracy and precision were within international acceptance criteria, that is within ± 15%, except at the limit of quantitation where values within ± 20% are acceptable. Low-dose patients included in an on going clinical trial had a median docetaxel concentration of 2.8 nM at 72 hours post infusion. Patients receiving 100 mg/m² of paclitaxel had a mean paclitaxel concentration of 21 nM 48 hours after the end of infusion.

Conclusion

We have developed an HPLC method using UV detection capable of quantifying 1 nM of docetaxel in plasma samples. The method should be useful for pharmacokinetic determinations at all relevant doses of docetaxel. Using a similar methodology paclitaxel can be quantified down to a concentration of 1.2 nM in plasma with acceptable accuracy and precision. We further demonstrate that the previously reported negative influence of Cremophor EL on assay performance may be overcome by degradation of the detergent by incubation with lipase.

Measurement of paclitaxel and its metabolites in human plasma using liquid chromatography/ion trap mass spectrometry with a sonic spray ionization interface

A quantitative liquid chromatography/ion trap mass spectrometry method for the simultaneous determination of paclitaxel, 6alpha-hydroxypaclitaxel and p-3'-hydroxypaclitaxel in human plasma has been developed and validated. 6alpha-,p-3'-Dihydroxypaclitaxel was also quantified using paclitaxel as a reference and docetaxel as an internal standard. The substances were extracted from 0.500 mL plasma using solid-phase extraction. The elution was performed with acetonitrile and the samples were reconstituted in the mobile phase. Isocratic high-performance liquid chromatography analysis was performed by injecting 50 microL of reconstituted material onto a 100 x 3.00 mm C12 column with a methanol:1% trifluoroacetic acid/ammonium trifluoroacetate in H(2)O 70:30 mobile phase at 350 microL/min. The [M+H](+) ions generated in the sonic spray ionization interface were isolated and fragmented using two serial mass spectrometric methods: one for paclitaxel (transition 854 --> 569 & 551) and the dihydroxymetabolite (transition 886 --> 585 & 567) and one for the hydroxy metabolites (transition 870 --> 585 & 567; transition 870 --> 569 & 551) and docetaxel ([M+Na](+), transition 830 --> 550). Calibration curves were created ranging between 0.5 and 7500 ng/mL for paclitaxel, 0.5 and 750 ng/mL for 6alpha-hydroxypaclitaxel, and 0.5 and 400 ng/mL for p-3'-hydroxypaclitaxel. Adduct ion formation was noted and investigated during method development and controlled by mobile phase optimization. In conclusion, a sensitive method for simultaneous quantification of paclitaxel and its metabolites suitable for analysis in clinical studies was obtained.

Quantitative analysis of docetaxel in human plasma using liquid chromatography coupled with tandem mass spectrometry

An assay for the quantitative determination of docetaxel in human plasma is described. Docetaxel was extracted from the matrix using liquid-liquid extraction with ter-butylmethylether, followed by high-performance liquid chromatographic analysis using an alkaline eluent. Paclitaxel was used as internal standard. Positive ionization electrospray tandem mass spectrometry was performed for selective and sensitive detection. The method was validated according to the FDA guidelines on bioanalytical method validation. The validated range for docetaxel was from 0.25--1000 ng/mL using 200 microL plasma aliquots. The method requires only a limited volume (200 microL) of human plasma and the method can be applied in studies requiring a low lower limit of quantitation of 0.25 ng/mL. The assay was applied successfully in several clinical and pharmacological studies with docetaxel.

Liquid chromatography-mass spectrometry for the quantitative bioanalysis of anticancer drugs

The monitoring of anticancer drugs in biological fluids and tissues is important during both pre-clinical and clinical development and often in routine clinical use. Traditionally, liquid chromatography (LC) in combination with ultraviolet (UV), fluorescence, or electrochemical detection is employed for this purpose. The successful hyphenation of LC and mass spectrometry (MS), however, has dramatically changed this. MS detection provides better sensitivity and selectivity than UV detection and, in addition, is applicable to a significantly larger group of compounds than fluorescence or electrochemical detection. Therefore, LC-MS has now become the method of first choice for the quantitative bioanalysis of many anticancer agents. There are still, however, a lot of new developments to be expected in this area, such as the introduction of more sensitive and robust mass spectrometers, high-throughput analyses, and further optimization of the coupled LC systems. Many articles have appeared in this field in recent years and are reviewed here. We conclude that LC-MS is an extremely powerful tool for the quantitative analysis of anticancer drugs in biological samples.

A molecular model to explain paclitaxel and docetaxel sensitivity changes through adduct formation with primary amines in electrospray ionization mass spectrometry

The objective of this study was to adopt a molecular modeling approach to understand changes in signal intensity due to adduct formation with short-chain alkylamines for two anticancer agents, paclitaxel and docetaxel, during electrospray mass spectrometric analysis. We describe a simple and intuitive modeling procedure using a comparison of hydropathic interaction (HINT) scores to explain differences in responses of amine adducts formed with the two analytes. The responses of paclitaxel and docetaxel were generally enhanced considerably (up to approximately 500% in some instances) on adding the amines. However, for the docetaxel adduct formed with added decylamine in the mobile phase, the response dropped by 32%. A mechanistic understanding for this behavior is proposed, and binding scores calculated from corresponding molecular models were found to be consistent with the trend obtained from mass spectrometric data.

Quantification of docetaxel and its main metabolites in human plasma by liquid chromatography/tandem mass spectrometry

Docetaxel is an antineoplastic agent widely used in therapeutics. The objective of this study was to develop and validate a routine assay, using liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS), for the simultaneous quantification of docetaxel and its main hydroxylated metabolites in human plasma. A structural analogue, paclitaxel, was used as the internal standard. Determination of docetaxel and four metabolites (M1, M2, M3 and M4) was achieved using only 100 microL of plasma. Liquid-liquid extraction was used for sample preparation, with extraction efficiency of at least 90% for all analytes. Detection used positive-mode electrospray ionization in selected reaction monitoring mode. The lower limit of quantification (LLOQ) was 0.5 ng/mL for all analytes. The assay was linear in the calibration curve range 0.5-1000 ng/mL and acceptable precision and accuracy (<15%) were obtained with concentrations above the LLOQ. This method was sufficiently selective and sensitive for quantification of metabolites in plasma from cancer patients receiving docetaxel chemotherapy, and is suitable for routine analyses during pharmacokinetic studies.

Approval Summary

PURPOSE

Docetaxel, a taxane previously approved for the treatment of breast cancer and non-small cell lung cancer, was approved by the United States Food and Drug Administration on May 19, 2004 for use in combination with prednisone for the treatment of metastatic androgen-independent (hormone-refractory) prostate cancer. The purpose of this summary is to review the database supporting this approval.

EXPERIMENTAL DESIGN

In a randomized, global study enrolling 1,006 patients, two schedules of docetaxel were compared with mitoxantrone + prednisone as follows: MTZ q 3w, mitoxantrone 12 mg/m2 every 21 days + prednisone 5 mg twice a day for a total of 10 cycles; TXT q 3w, docetaxel 75 mg/m2 every 21 days + prednisone 5 mg twice a day for a total of 10 cycles; and TXT qw, docetaxel 30 mg/m2 days 1, 8, 15, 22, and 29 every 6 weeks + prednisone 5 mg twice a day for a total of 5 cycles.

RESULTS

There was a statistically significant overall survival advantage shown for the TXT q 3w arm over MTZ q 3w (median survival 18.9 months versus 16.5 months, P = 0.0094). No overall survival advantage was shown for TXT qw compared with MTZ q 3w. The most commonly occurring adverse events included anemia, neutropenia, infection, nausea, sensory neuropathy, fluid retention, alopecia, nail changes, diarrhea, and fatigue.

CONCLUSIONS

This report describes the Food and Drug Administration review supporting this first approval of a combination therapy for hormone-refractory prostate cancer based on demonstration of a survival benefit.

Simple and rapid docetaxel assay in plasma by protein precipitation and high-performance liquid chromatography–tandem mass spectrometry

A simple, rapid and low cost sample preparation method was developed for quantification of docetaxel in mouse plasma by high-performance liquid chromatography/tandem mass spectrometry with paclitaxel as the internal standard. A small volume of plasma (40 microl) and one-step protein precipitation using methanol and acetonitrile (1:1 (v/v)) were used for sample preparation. The calibration curve for docetaxel in mouse plasma was linear over the range 25-2500 nM. The detection limit was 8 nM. The lower limit of quantitation is 25 nM. The intra- and inter-day precisions (CV) of analysis were 9.5 and 9.7% for the low quality control (LQC), 5.5 and 4.9% for the medium quality control (MQC) and 3.9 and 6.3% for the high quality control (HQC), respectively. The accuracy was 102.5% for LQC, 97.9% for MQC and 108.8% for HQC. This assay has now been applied to evaluation of mouse pharmacogenetics and other clinical pharmacology applications.

Simultaneous analysis of docetaxel and the formulation vehicle polysorbate 80 in human plasma by liquid chromatography/tandem mass spectrometry

An analytical procedure for the simultaneous determination of the anticancer agent docetaxel (Taxotere) and its formulation vehicle polysorbate 80 (Tween 80) in human plasma samples is described. Sample pretreatment involved a double liquid-liquid extraction step with a mixture of acetonitrile/n-butyl chloride (1/4, v/v). Separation of the compounds of interest, including the internal standard paclitaxel, was achieved on a reversed-phase Waters X-Terra mass spectrometry (MS) column (50 x 2.1mm internal diameter) packed with a 3.5-microm octadecyl stationary phase, using isocratic elution. Detection of docetaxel and polysorbate 80 was performed using tandem MS detection with electrospray ionization. Validation results indicated that the method is accurate and precise and has lower limits of quantitation of 0.500 nM (approximately 0.4 ng/ml) and 1.00 microg/ml for docetaxel and polysorbate 80, respectively. The method was subsequently used to measure concentrations of docetaxel and polysorbate 80 in plasma samples in support of a project to assess the influence of polysorbate 80 concentrations on the disposition and toxicity profile of docetaxel in cancer patients receiving Taxotere.