Level of evidence for therapeutic drug monitoring of taxanes

Development, validation, and application of an UPLC-MS/MS method for vancomycin, norvancomycin, methotrexate, paclitaxel, and imatinib analysis in human plasma

Background

Vancomycin, norvancomycin, methotrexate, paclitaxel, and imatinib are five commonly used drugs which are all recommended to therapeutic drug monitoring in clinical settings. However, the blood concentration monitoring of these drugs and the interpretations of the test results are limited to some extent due to the differences of testing instruments and testing methods.

Methods

We established an ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) method for simultaneous quantification of vancomycin, norvancomycin, methotrexate, paclitaxel, and imatinib in human plasma. The method was validated according to the guideline for bioanalytical method validation and applied in clinical therapy.

Results

The calibration ranges of vancomycin, norvancomycin, methotrexate, paclitaxel, and imatinib were 0.5–100 μg/mL, 0.5–100 μg/mL, 5–1000 ng/mL, 10–2000 ng/mL, and 5–500 ng/mL, respectively. Inaccuracy and imprecision of every drug were less than 15%. The internal standard normalized recovery rates of vancomycin and norvancomycin were about 45%, while which of methotrexate, paclitaxel, and imatinib were almost 100%. No obvious carryover effect was observed. Samples were stable for at least 24 h in the automatic sampler, 72 h at 4°C, and 1 week in −80°C. There were no differences of concentrations between plasma and serum for the five drugs. Moreover, there were positive correlations between methotrexate and vancomycin concentrations and creatinine, as well as positive correlation between imatinib concentration and age of the patient.

Conclusions

The UPLC-MS/MS method was competent for the simultaneous monitoring of vancomycin, norvancomycin, methotrexate, paclitaxel, and imatinib because of its short analysis time, high specificity, and accuracy.

Pharmacokinetics and Toxicities of Oral Docetaxel Formulations Co-Administered with Ritonavir in Phase I Trials

Introduction

Docetaxel is widely used as intravenous (IV) chemotherapy. Oral docetaxel is co-administered with the cytochrome P450 3A4 and P-glycoprotein inhibitor ritonavir to increase oral bioavailability. This research explores the relationship between the pharmacokinetics (PK) and toxicity of this novel oral chemotherapy.

Methods

The patients in two phase I trials were treated with different oral docetaxel formulations in combination with ritonavir in different dose levels, ranging from 20 to 80 mg docetaxel with 100 to 200 mg ritonavir a day. The patients were categorized based on the absence or occurrence of severe treatment-related toxicity (grade ≥3 or any grade leading to treatment alterations). The docetaxel area under the plasma concentration–time curve (AUC) and maximum plasma concentration (C_max) were associated with toxicity.

Results

Thirty-four out of 138 patients experienced severe toxicity, most frequently observed as mucositis, fatigue, diarrhea, nausea and vomiting. The severe toxicity group had a significantly higher docetaxel AUC (2231 ± 1405 vs 1011 ± 830 ng/mL*h, p<0.0001) and C_max (218 ± 178 vs 119 ± 77 ng/mL, p<0.0001) as compared to the patients without severe toxicity. When extrapolated from IV PK data, the patients without severe toxicity had a similar cumulative docetaxel AUC as with standard 3-weekly IV docetaxel, while the C_max was up to 10-fold lower with oral docetaxel and ritonavir.

Conclusion

Severe toxicity was observed in 25% of the patients treated with oral docetaxel and ritonavir. This toxicity seems related to the PK, as the docetaxel AUC_0-inf and C_max were up to twofold higher in the severe toxicity group as compared to the non-severe toxicity group. Future randomized trials will provide a further evaluation of the toxicity and efficacy of the new weekly oral docetaxel and ritonavir regimen in comparison to standard IV docetaxel.

A Phase 1 Dose-Escalation Study of Low-Dose Metronomic Treatment With Novel Oral Paclitaxel Formulations in Combination With Ritonavir in Patients With Advanced Solid Tumors

ModraPac001 (MP1) and ModraPac005 (MP5) are novel oral paclitaxel formulations that are coadministered with the cytochrome P450 3A4 inhibitor ritonavir (r), enabling daily low-dose metronomic (LDM) treatment. The primary aim of this study was to determine the safety, pharmacokinetics and maximum tolerated dose (MTD) of MP1/r and MP5/r. The second aim was to establish the recommended phase 2 dose (RP2D) as LDM treatment. This was an open-label phase 1 trial. Patients with advanced solid tumors were enrolled according to a classical 3+3 design. After initial employment of the MP1 capsule, the MP5 tablet was introduced. Safety was assessed using the Common Terminology Criteria for Adverse Events version 4.02. Pharmacokinetic sampling was performed on days 1, 2, 8, and 22 for determination of paclitaxel and ritonavir plasma concentrations. In this study, 37 patients were treated with up to twice-daily 30-mg paclitaxel combined with twice-daily 100-mg ritonavir (MP5/r 30-30/100-100) in 9 dose levels. Dose-limiting toxicities were nausea, (febrile) neutropenia, dehydration and vomiting. At the MTD/RP2D of MP5/r 20-20/100-100, the maximum paclitaxel plasma concentration and area under the concentration-time curve until 24 hours were 34.6 ng/mL (coefficient of variation, 79%) and 255 ng • h/mL (coefficient of variation, 62%), respectively. Stable disease was observed as best response in 15 of 31 evaluable patients. Based on these results, LDM therapy with oral paclitaxel coadministrated with ritonavir was considered feasible and safe. The MTD and RP2D were determined as MP5/r 20-20/100-100. Further clinical development of MP5/r as an LDM concept, including potential combination treatment, is warranted.

CETSA-based target engagement of taxanes as biomarkers for efficacy and resistance

The use of taxanes has for decades been crucial for treatment of several cancers. A major limitation of these therapies is inherent or acquired drug resistance. A key to improved outcome of taxane-based therapies is to develop tools to predict and monitor drug efficacy and resistance in the clinical setting allowing for treatment and dose stratification for individual patients. To assess treatment efficacy up to the level of drug target engagement, we have established several formats of tubulin-specific Cellular Thermal Shift Assays (CETSAs). This technique was evaluated in breast and prostate cancer models and in a cohort of breast cancer patients. Here we show that taxanes induce significant CETSA shifts in cell lines as well as in animal models including patient-derived xenograft (PDX) models. Furthermore, isothermal dose response CETSA measurements allowed for drugs to be rapidly ranked according to their reported potency. Using multidrug resistant cancer cell lines and taxane-resistant PDX models we demonstrate that CETSA can identify taxane resistance up to the level of target engagement. An imaging-based CETSA format was also established, which in principle allows for taxane target engagement to be accessed in specific cell types in complex cell mixtures. Using a highly sensitive implementation of CETSA, we measured target engagement in fine needle aspirates from breast cancer patients, revealing a range of different sensitivities. Together, our data support that CETSA is a robust tool for assessing taxane target engagement in preclinical models and clinical material and therefore should be evaluated as a prognostic tool during taxane-based therapies.

The effect of diabetes mellitus on pharmacokinetics, pharmacodynamics and adverse drug reactions of anticancer drugs

Diabetes mellitus (DM) and cancer are global problems carrying huge human, social, and economic impact. Type 2 diabetes (T2DM) is associated with an increased risk for a number of cancers, including breast, pancreatic, and liver cancer. Moreover, adverse drug reactions are higher in paitents with cancer with T2DM compared to cancer patients without T2DM. Cellular mechanisms of hyperglycemia and chemotherapy efficacy may be different depending upon the particular cancer type and the condition of the patient. This review evaluates the effect of DM on the pharmacokinetic, pharmacodynamic, and adverse drug reactions of commonly used anticancer drugs such as cisplatin, methotrexate, paclitaxel, doxorubicin, and adriamycin in both clinical and animal models. A literature search was conducted in scientific databases including Web of Science, PubMed, Scopus, and Google Scholar including the relevant keywords. The results of the effectiveness of anticancer therapies in patients with DM are, however, inconsistent because DM can negatively impact multiple diverse entities including nerves and vascular structures, insulin-like growth factor 1, the function of the innate immune system, drug pharmacokinetics, the expression levels of hepatic CYP₄₅₀ , Mdr _1b and enzymes that then lead to drug toxicity. However, in a few circumstances, DM led to attenuation of the toxicity of anticancer drugs secondary to attenuation of the energy-dependent renal uptake process. Overall, the impact of DM on patients with cancer is variable because of the diverse types of cancers and the spectrum of anticancer drugs. With respect to the evidence for cancer involvement in DM pathophysiology and the response to anticancer treatment in patients with DM, many questions still remain and further clinical trials are needed.

A new high-performance liquid chromatography-tandem mass spectrometry method for the determination of paclitaxel and 6α-hydroxy-paclitaxel in human plasma: Development, validation and application in a clinical pharmacokinetic study

Paclitaxel belongs to the taxanes family and it is used, alone or in multidrug regimens, for the therapy of several solid tumours, such as breast-, lung-, head and neck-, and ovarian cancer. Standard dosing of chemotherapy does not take into account the many inter-patient differences that make drug exposure highly variable, thus leading to the insurgence of severe toxicity. This is particularly true for paclitaxel considering that a relationship between haematological toxicity and plasma exposure was found. Therefore, in order to treat patients with the correct dose of paclitaxel, improving the overall benefit–risk ratio, Therapeutic Drug Monitoring is necessary. In order to quantify paclitaxel and its main metabolite, 6α-hydroxy-paclitaxel, in patients’ plasma, we developed a new, sensitive and specific HPLC–MS/MS method applicable to all paclitaxel dosages used in clinical routine. The developed method used a small volume of plasma sample and is based on quick protein precipitation. The chromatographic separation of the analytes was achieved with a SunFire^™ C18 column (3.5 μM, 92 Å, 2,1 x 150 mm); the mobile phases were 0.1% formic acid/bidistilled water and 0.1% formic acid/acetonitrile. The electrospray ionization source worked in positive ion mode and the mass spectrometer operated in selected reaction monitoring mode. Our bioanalytical method was successfully validated according to the FDA-EMA guidelines on bioanalytical method validation. The calibration curves resulted linear (R² ≥0.9948) over the concentration ranges (1–10000 ng/mL for paclitaxel and 1–1000 ng/mL for 6α-hydroxy-paclitaxel) and were characterized by a good accuracy and precision. The intra- and inter-day precision and accuracy were determined on three quality control concentrations for paclitaxel and 6α-hydroxy-paclitaxel and resulted respectively <9.9% and within 91.1–114.8%. In addition, to further verify the assay reproducibility, we tested this method by re-analysing the incurred samples. This bioanalytical method was employed with success to a genotype-guided phase Ib study of weekly paclitaxel in ovarian cancer patients treated with a wide range of drug’s dosages.

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.

Comparative pharmacokinetic study of paclitaxel and docetaxel in streptozotocin-induced diabetic rats

The pharmacokinetics of paclitaxel and docetaxel were compared in diabetic rats induced by streptozotocin (DMIS rats) and the impact of altered expression of cytochrome P450 3A (Cyp3A) and P-glycoprotein (P-gp) in the diabetic state. The pharmacokinetics of paclitaxel and docetaxel were determined after intravenous (5 mg/kg) and oral (30 and 40 mg/kg, respectively) administration to both groups and the mRNA expression levels of Cyp3A isozymes and Mdr1a and Mdr1b in the liver and small intestine were determined in control and DMIS rats. After intravenous administration, the AUC and clearance of paclitaxel and docetaxel were not significantly different in DMIS vs control rats. After oral administration, the AUC and C(max) of paclitaxel in DMIS rats were significantly greater than those in the control rats, whereas those of docetaxel was not changed significantly. The mRNA expression levels of hepatic Cyp3A1, Cyp3A9 and Mdr1b were significantly increased in DMIS compared with the control rats. In the intestine, Cyp3A62 expression decreased in the DMIS rats compared with the controls. Thus the pharmacokinetic changes of taxanes observed in the DMIS rats were attributed to changes in P-gp and Cyp3A, predominant factors that control the absorption of paclitaxel and docetaxel, respectively. It seemed that there were different susceptibilities to intestinal P-gp and Cyp3A between the two taxanes.