Pharmacokinetics and metabolism of docetaxel administered as a 1-h intravenous infusion

Utility of Physiologically Based Pharmacokinetic Modeling to Investigate the Impact of Physiological Changes of Pregnancy and Cancer on Oncology Drug Pharmacokinetics

BACKGROUND

The treatment of cancer during pregnancy remains challenging with knowledge gaps in drug dosage, safety, and efficacy due to the under-representation of this population in clinical trials. Our aim was to investigate physiological changes reported in both pregnancy and cancer populations into a PBPK modeling framework that allows for a more accurate estimation of PK changes in pregnant patients with cancer.

METHODS

Paclitaxel and docetaxel were selected to validate a population model using clinical data from pregnant patients with cancer. The validated population model was subsequently used to predict the PK of acalabrutinib in pregnant patients with cancer.

RESULTS

The Simcyp pregnancy population model reasonably predicted the PK of docetaxel in pregnant patients with cancer, while a modified model that included a 2.5-fold increase in CYP2C8 abundance, consistent with the increased expression during pregnancy, was needed to reasonably predict the PK of paclitaxel in pregnant patients with cancer. Changes in protein binding levels of patients with cancer had a minimal impact on the predicted clearance of paclitaxel and docetaxel. PBPK modeling predicted approximately 60% lower AUC and Cmax for acalabrutinib in pregnant versus non-pregnant patients with cancer.

CONCLUSIONS

Our results suggest that PBPK modeling is a promising approach to investigate the effects of pregnancy and cancer on the PK of oncology drugs and potentially inform dosing for pregnant patients with cancer. Further evaluation and refinement of the population model are needed for pregnant patients with cancer with additional compounds and clinical PK data.

A Phase I Dose Escalation Study of Once-Weekly Oral Administration of Docetaxel as ModraDoc001 Capsule or ModraDoc006 Tablet in Combination with Ritonavir

PURPOSE

Oral bioavailability of docetaxel is poor. Absorption could be improved by development of pharmaceutical formulations based on docetaxel solid dispersions, denoted ModraDoc001 capsule and ModraDoc006 tablet (both 10 mg) and coadministration of ritonavir, an inhibitor of CYP3A4 and P-glycoprotein. In this study, the safety, MTD, recommended phase II dose (RP2D), pharmacokinetics, and preliminary antitumor activity of oral docetaxel combined with ritonavir in a once-weekly continuous schedule was investigated.

PATIENTS AND METHODS

Patients with metastatic solid tumors were included. Dose escalation was performed using a classical 3+3 design. Pharmacokinetic sampling was performed for up to 48 hours after drug administration. Safety was evaluated using CTCAE v3.0. Antitumor activity was assessed according to RECIST v1.0.

RESULTS

Sixty-seven patients were treated at weekly docetaxel dosages ranging from 30 to 80 mg in combination with 100- or 200-mg ritonavir. Most common toxicities were nausea, vomiting, diarrhea and fatigue, mostly of grade 1-2 severity. No hypersensitivity reactions were observed. The area under the plasma concentration-time curve (AUC_0-48) of docetaxel at the RP2D of once-weekly 60-mg ModraDoc001 capsule with 100-mg ritonavir was 1,000 ± 687 ng/mL/hour and for once-weekly 60-mg ModraDoc006 tablet with 100-mg ritonavir, the AUC_0-48 was 1,790 ± 819 ng/mL/hour. Nine partial responses were reported as best response to treatment.

CONCLUSIONS

Oral administration of once-weekly docetaxel as ModraDoc001 capsule or ModraDoc006 tablet in combination with ritonavir is feasible. The RP2D for both formulations is 60-mg ModraDoc with 100-mg ritonavir. Antitumor activity is considered promising.

Chemotherapy-induced oral mucositis is associated with detrimental bacterial dysbiosis

BACKGROUND

Gastrointestinal mucosal injury (mucositis), commonly affecting the oral cavity, is a clinically significant yet incompletely understood complication of cancer chemotherapy. Although antineoplastic cytotoxicity constitutes the primary injury trigger, the interaction of oral microbial commensals with mucosal tissues could modify the response. It is not clear, however, whether chemotherapy and its associated treatments affect oral microbial communities disrupting the homeostatic balance between resident microorganisms and the adjacent mucosa and if such alterations are associated with mucositis. To gain knowledge on the pathophysiology of oral mucositis, 49 subjects receiving 5-fluorouracil (5-FU) or doxorubicin-based chemotherapy were evaluated longitudinally during one cycle, assessing clinical outcomes, bacterial and fungal oral microbiome changes, and epithelial transcriptome responses. As a control for microbiome stability, 30 non-cancer subjects were longitudinally assessed. Through complementary in vitro assays, we also evaluated the antibacterial potential of 5-FU on oral microorganisms and the interaction of commensals with oral epithelial tissues.

RESULTS

Oral mucositis severity was associated with 5-FU, increased salivary flow, and higher oral granulocyte counts. The oral bacteriome was disrupted during chemotherapy and while antibiotic and acid inhibitor intake contributed to these changes, bacteriome disruptions were also correlated with antineoplastics and independently and strongly associated with oral mucositis severity. Mucositis-associated bacteriome shifts included depletion of common health-associated commensals from the genera Streptococcus, Actinomyces, Gemella, Granulicatella, and Veillonella and enrichment of Gram-negative bacteria such as Fusobacterium nucleatum and Prevotella oris. Shifts could not be explained by a direct antibacterial effect of 5-FU, but rather resembled the inflammation-associated dysbiotic shifts seen in other oral conditions. Epithelial transcriptional responses during chemotherapy included upregulation of genes involved in innate immunity and apoptosis. Using a multilayer epithelial construct, we show mucositis-associated dysbiotic shifts may contribute to aggravate mucosal damage since the mucositis-depleted Streptococcus salivarius was tolerated as a commensal, while the mucositis-enriched F. nucleatum displayed pro-inflammatory and pro-apoptotic capacity.

CONCLUSIONS

Altogether, our work reveals that chemotherapy-induced oral mucositis is associated with bacterial dysbiosis and demonstrates the potential for dysbiotic shifts to aggravate antineoplastic-induced epithelial injury. These findings suggest that control of oral bacterial dysbiosis could represent a novel preventive approach to ameliorate oral mucositis.

Re-exploring immune-related side effects of docetaxel in an observational study: Blood hypereosinophilia

Docetaxel is a major anticancer drug that can induce hypersensitivity reactions leading to deleterious treatment interruptions. Blood hypereosinophilia could be a biological sign, potentially lethal, of delayed visceral hypersensitivity reactions. We hypothesized this biological event is probably underreported. In this prospective observational study, we followed up 149 patients treated with docetaxel monotherapy for breast or lung cancer. For each patient, blood eosinophil counts were recorded during docetaxel treatment and up to 3 months after the end of docetaxel treatment. For all patients, blood eosinophil counts significantly increased under docetaxel chemotherapy (P < 0.01). Seven percent had persistent eosinophilia after the end of treatment. Four patients had blood eosinophil counts over 1000/mm³ with severe cardiac, cutaneous and digestive toxicities, and docetaxel imputability was confirmed using drug-imputability scales. For two of these four patients, tissue biopsies were performed during the time of hypereosinophilia and of severe toxicities. Specific immunostainings and electron microscopy found numerous degranulating mast cells and eosinophils. Our study demonstrated that eosinophilia is frequent under docetaxel and could lead to severe complications, implicating eosinophils and mast cells, and possibly IgE. One way of treating hypersensitivity reactions could be by targeting IgEs with omalizumab, an anti-IgE monoclonal antibody approved for the treatment of severe allergic asthma, and successfully used in food and poison-induced anaphylactic reactions.

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.

Metabolism and excretion of novel pulmonary-targeting docetaxel liposome in rabbits

Our study aims to determine the metabolism and excretion of novel pulmonary-targeting docetaxel liposome (DTX-LP) using the in vitro and in vivo animal experimental models. The metabolism and excretion of DTX-LP and intravenous DTX (DTX-IN) in New Zealand rabbits were determined with ultraperformance liquid chromatography tandem mass spectrometry. We found DTX-LP and DTX-IN were similarly degraded in vitro by liver homogenates and microsomes, but not metabolized by lung homogenates. Ultra-performance liquid chromatography tandem mass spectrometry identified two shared DTX metabolites. The unconfirmed metabolite M _un differed structurally from all DTX metabolites identified to date. DTX-LP likewise had a similar in vivo metabolism to DTX-IN. Conversely, DTX-LP showed significantly diminished excretion in rabbit feces or urine, approximately halving the cumulative excretion rates compared to DTX-IN. Liposomal delivery of DTX did not alter the in vitro or in vivo drug metabolism. Delayed excretion of pulmonary-targeting DTX-LP may greatly enhance the therapeutic efficacy and reduce the systemic toxicity in the chemotherapy of non-small cell lung cancer. The identification of M _un may further suggest an alternative species-specific metabolic pathway.

Pharmacokinetics, dynamics and toxicity of docetaxel: Why the Japanese dose differs from the Western dose

Docetaxel (Taxotere®) has been one of the most important chemotherapeutic drugs for cancer treatment since 1996. Although a large number of clinical studies have been conducted in various cancer fields, there is a discrepancy in the standard dose between Japan and Western countries. This article reviews the pharmacokinetic, pharmacodynamic and toxicological profiles of docetaxel, and explains why there exists an ethnic difference in dose, and further discusses which direction we should go forward to solve this problem. The original recommended dose was 100 mg/m² every 3 weeks in US and European populations, while a Japanese phase I study suggested the recommended dose as 60 mg/m² every 3 weeks. A prospective population pharmacokinetic analysis of docetaxel conducted in both the USA/Europe and Japan, indicated an absence of ethnic difference in the pharmacokinetics. Both analyses demonstrated that docetaxel clearance is related to α1-acid glycoprotein level, hepatic function, age and body surface area. The relationship was observed between increasing docetaxel dose and increased tumor response rates across the dose range of 60 to 100 mg/m². The area under the serum concentration time curve (AUC) of docetaxel at the first cycle was significantly related to time to progression. Hematological toxicities were well correlated with the AUC of docetaxel, and severe hematological toxicities were more frequently observed in Japanese patients treated with 60 mg/m², compared to the US/European patients treated with 75–100 mg/m² dose. The Japanese population seems more susceptible to the toxicity of docetaxel. A docetaxel dose of 75 mg/m² is now standard not only in global trials but also in recent Japanese trials. Although the optimal dose of docetaxel is still unclear, we need to continue to seek the appropriate dose of docetaxel depending on patient status and the goals of chemotherapy.

Cytochrome P450 in Cancer Susceptibility and Treatment

Cytochrome 450 (CYP450) designates a group of enzymes abundant in smooth endoplasmic reticulum of hepatocytes and epithelial cells of small intestines. The main function of CYP450 is oxidative catalysis of various endogenous and exogenous substances. CYP450 are implicated in phase I metabolism of 80% of drugs currently in use, including anticancer drugs. They are also involved in synthesis of various hormones and influence hormone-related cancers. CYP450 genes are highly polymorphic and their variants play an important role in cancer risk and treatment. Association studies and meta-analyses have been performed to decipher the role of CYP450 polymorphisms in cancer susceptibility. Cancer treatment involves multimodal therapies and evaluation of CYP450 polymorphisms is necessary for pharmacogenetic assessment of anticancer therapy outcomes. In addition, CYP450 inhibitors are being evaluated for improved pharmacokinetics and oral formulation of several anticancer drugs.

Synergistic simvastatin and metformin combination chemotherapy for osseous metastatic castration-resistant prostate cancer

Docetaxel chemotherapy remains a standard of care for metastatic castration-resistant prostate cancer (CRPC). Docetaxel modestly increases survival, yet results in frequent occurrence of side effects and resistant disease. An alternate chemotherapy with greater efficacy and minimal side effects is needed. Acquisition of metabolic aberrations promoting increased survival and metastasis in CRPC cells includes constitutive activation of Akt, loss of adenosine monophosphate-activated protein kinase (AMPK) activity due to Ser-485/491 phosphorylation, and overexpression of 3-hydroxy-3-methylglutaryl-Coenzyme A reductase (HMG-CoAR). We report that combination of simvastatin and metformin, within pharmacologic dose range (500 nmol/L to 4 μmol/L simvastatin and 250 μmol/L to 2 mmol/L metformin), significantly and synergistically reduces C4-2B3/B4 CRPC cell viability and metastatic properties, with minimal adverse effects on normal prostate epithelial cells. Combination of simvastatin and metformin decreased Akt Ser-473 and Thr-308 phosphorylation and AMPKα Ser-485/491 phosphorylation; increased Thr-172 phosphorylation and AMPKα activity, as assessed by increased Ser-79 and Ser-872 phosphorylation of acetyl-CoA carboxylase and HMG-CoAR, respectively; decreased HMG-CoAR activity; and reduced total cellular cholesterol and its synthesis in both cell lines. Studies of C4-2B4 orthotopic NCr-nu/nu mice further demonstrated that combination of simvastatin and metformin (3.5-7.0 μg/g body weight simvastatin and 175-350 μg/g body weight metformin) daily by oral gavage over a 9-week period significantly inhibited primary ventral prostate tumor formation, cachexia, bone metastasis, and biochemical failure more effectively than 24 μg/g body weight docetaxel intraperitoneally injected every 3 weeks, 7.0 μg/g/day simvastatin, or 350 μg/g/day metformin treatment alone, with significantly less toxicity and mortality than docetaxel, establishing combination of simvastatin and metformin as a promising chemotherapeutic alternative for metastatic CRPC.

Oral delivery of paclitaxel nanocrystal (PNC) with a dual Pgp-CYP3A4 inhibitor: preparation, characterization and antitumor activity

Several molecular inheritances have severely restrained the peroral delivery of taxanes. The main objective of the present investigation was to develop a paclitaxel (PTX) formulation which can circumvent the hurdles of its extremely poor solubility and permeability, Pgp efflux and high pre-systemic metabolism. Positively charged PTX nanocrystals of 209 nm were prepared by sonoprecipitation with high pressure homogenization technique, wherein an arginine based surfactant was explored as a stabilizer. The BET surface area analysis revealed that the surface area of PNC was 8.53 m(2)/gm, reflecting significant rise in surface area with nanonization of PTX. The DSC and XRD pattern suggested that the PTX is in the form of the most stable dihydrate crystal. The PNC showed very rapid dissolution profile compared to plain PTX in both sinks and non-sink conditions. Clarithromycin (CLM) was evaluated as a better alternative to cyclosporin A in improving PTX permeability. The PNC-CLM showed remarkable enhancement of 453% in relative bioavailability along with maintaining the therapeutic concentration of PTX for 8h. Efficacy data in B16 F10 melanoma tumor bearing mice showed substantial reduction in tumor volume and improvement in percentage survival compared to the control group.

Open-label, randomized, single-dose, crossover study to evaluate the pharmacokinetics and safety differences between two docetaxel products, CKD-810 and Taxotere injection, in patients with advanced solid cancer

PURPOSE

The aim of this study was to compare CKD-810 (test docetaxel) with Taxotere(®) (reference docetaxel) in terms of pharmacokinetics and safety for patients with advanced or metastatic carcinoma.

METHODS

A randomized, open-label, two-way crossover study was conducted in eligible patients. Patients received with reference or test drugs of 75 mg/m(2) docetaxel by intravenous infusion for 60 min in the first period and the alternative drug in the second period with a washout of 3 weeks. Plasma concentrations of docetaxel were determined by validated high-performance liquid chromatography coupled to tandem mass spectrometry detection. Pharmacokinetic parameters, including the maximum plasma concentration (C(max)) and the area under the concentration-time curve (AUC), were determined by non-compartmental analysis.

RESULTS

A total of 44 patients were included in the study, 21 patients received test drug and 23 received reference drug for the first cycle. The C(max) of docetaxel was 2,658.77 ng/mL for test drug and 2,827.60 ng/mL for reference drug, and two drugs showed no difference with a statistical significance. Time to reach C(max) (T(max)) of CKD-810 (0.94 h) versus reference docetaxel (0.97 h) was also not significantly different. Other pharmacokinetic parameters including the plasma AUC, elimination half-life, and total body clearance exhibited similar values without a significant difference. The most common grade 3 or 4 toxicity was neutropenia (CKD-810 19.5 or 29.3 %; reference docetaxel 14.6 or 41.5 %). Febrile neutropenia was experienced by only one patient in each group. Two patients died of progression of disease during the study.

CONCLUSION

Docetaxel anhydrous CKD-810 use with patients suffering advanced or metastatic solid malignancies was equivalent to reference docetaxel in terms of pharmacokinetic parameters and safety profile. Additionally, the test and reference drug met the regulatory criteria for pharmacokinetic equivalence.

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

RATIONALE

During drug development accurate quantification of metabolites in biological samples using mass spectrometry is often hampered by the lack of metabolites of chemically pure quality. However, quantification of metabolites can be useful for assessment and interpretation of (pre)clinical data. We now describe an approach to quantify docetaxel metabolites in human plasma by liquid chromatography/tandem mass spectrometry (LC/MS/MS) using docetaxel calibration standards.

METHODS

Metabolites (M1/M3, M2 and M4) were generated using microsomal incubations. Retention times of docetaxel and its metabolites were assessed using an LC/UV assay and peak identification was performed by LC/MS(n). Samples containing isolated metabolites from human faeces were quantified by LC/UV and used as references for spiking human plasma samples. LC/MS/MS was applied to sensitively quantify docetaxel and its metabolites in human plasma using docetaxel calibration standards in a range of 0.25-500 ng/mL.

RESULTS

Because ionisation of docetaxel and its metabolites differed, correction factors were established to quantify the metabolites using docetaxel calibration samples. During method validation, accuracy and precision of the metabolites were within ±7.7% and ≤17.6%, respectively, and within ±14.3% and ≤10.1%, respectively, for docetaxel. Metabolites were found to be unstable in human plasma at ambient temperature. After storage up to 1 year at -20 °C, recovered metabolite concentrations were within ±25%.

CONCLUSIONS

Development and validation of an LC/MS/MS assay for the quantification of docetaxel and its metabolites M1/M3, M2 and M4 using docetaxel calibration standards is described. The same approach may be used for quantification of metabolites of other drugs by LC/MS/MS when chemically pure reference substances are unavailable.

Differential drug responses of circulating tumor cells within patient blood

Personalized medicine holds great promise for cancer treatment, with the potential to address challenges associated with drug sensitivity and interpatient variability. Circulating tumor cells (CTC) can be useful for screening cancer drugs as they may reflect the severity and heterogeneity of primary tumors. Here we present a platform for rapidly evaluating individualized drug susceptibility. Treatment efficacy is evaluated directly in blood, employing a relevant environment for drug administration, and assessed by comparison of CTC counts in treated and control samples. Multiple drugs at varying concentrations are evaluated simultaneously to predict an appropriate therapy for individual patients.

Toward prediction of efficacy of chemotherapy: a proof of concept study in lung cancer patients using [¹¹C]docetaxel and positron emission tomography

PURPOSE

Pharmacokinetics of docetaxel can be measured in vivo using positron emission tomography (PET) and a microdose of radiolabeled docetaxel ([(11)C]docetaxel). The objective of this study was to investigate whether a [(11)C]docetaxel PET microdosing study could predict tumor uptake of therapeutic doses of docetaxel.

EXPERIMENTAL DESIGN

Docetaxel-naïve lung cancer patients underwent 2 [(11)C]docetaxel PET scans; one after bolus injection of [(11)C]docetaxel and another during combined infusion of [(11)C]docetaxel and a therapeutic dose of docetaxel (75 mg·m(-2)). Compartmental and spectral analyses were used to quantify [(11)C]docetaxel tumor kinetics. [(11)C]docetaxel PET measurements were used to estimate the area under the curve (AUC) of docetaxel in tumors. Tumor response was evaluated using computed tomography scans.

RESULTS

Net rates of influx (Ki) of [(11)C]docetaxel in tumors were comparable during microdosing and therapeutic scans. [(11)C]docetaxel AUCTumor during the therapeutic scan could be predicted reliably using an impulse response function derived from the microdosing scan together with the plasma curve of [(11)C]docetaxel during the therapeutic scan. At 90 minutes, the accumulated amount of docetaxel in tumors was less than 1% of the total infused dose of docetaxel. [(11)C]docetaxel Ki derived from the microdosing scan correlated with AUCTumor of docetaxel (Spearman ρ = 0.715; P = 0.004) during the therapeutic scan and with tumor response to docetaxel therapy (Spearman ρ = -0.800; P = 0.010).

CONCLUSIONS

Microdosing data of [(11)C]docetaxel PET can be used to predict tumor uptake of docetaxel during chemotherapy. The present study provides a framework for investigating the PET microdosing concept for radiolabeled anticancer drugs in patients.

Qualitative structure-metabolism relationships in the hydrolysis of carbamates

The aims of this review were 1) to compile a large number of reliable literature data on the metabolic hydrolysis of medicinal carbamates and 2) to extract from such data a qualitative relation between molecular structure and lability to metabolic hydrolysis. The compounds were classified according to the nature of their substituents (R³OCONR¹R²), and a metabolic lability score was calculated for each class. A trend emerged, such that the metabolic lability of carbamates decreased (i.e., their metabolic stability increased), in the following series: Aryl-OCO-NHAlkyl >> Alkyl-OCO-NHAlkyl ~ Alkyl-OCO-N(Alkyl)₂ ≥ Alkyl-OCO-N(endocyclic) ≥ Aryl-OCO-N(Alkyl)₂ ~ Aryl-OCO-N(endocyclic) ≥ Alkyl-OCO-NHAryl ~ Alkyl-OCO-NHAcyl >> Alkyl-OCO-NH₂ > Cyclic carbamates. This trend should prove useful in the design of carbamates as drugs or prodrugs.

Therapeutic drug monitoring for the individualization of docetaxel dosing: a randomized pharmacokinetic study

PURPOSE

Docetaxel pharmacokinetic (PK) parameters, notably clearance and exposure (AUC), are characterized by large interindividual variability. The purpose of this study was to evaluate the effect of PK-guided [area under the plasma concentration versus time curve (AUC) targeted], individualized docetaxel dosing on interindividual variability in exposure.

EXPERIMENTAL DESIGN

A limited sampling strategy in combination with a validated population PK model, Bayesian analysis, and a predefined target AUC was used. Fifteen patients were treated for at least 2 courses with body surface area-based docetaxel and 15 with at least 1 course of PK-guided docetaxel dosing.

RESULTS

Interindividual variability (SD of ln AUC) was decreased by 35% (N = 15) after 1 PK-guided course; when all courses were evaluated, variability was decreased by 39% (P = 0.055). PK-guided dosing also decreased the interindividual variability of percentage decrease in white blood cell and absolute neutrophil counts by approximately 50%.

CONCLUSIONS

Further research is required to determine whether the decrease in PK variability can contribute to a reduction in interindividual variability in efficacy and toxicity.

Biodistribution and radiation dosimetry of 11C-labelled docetaxel in cancer patients

PURPOSE

Docetaxel is an important chemotherapeutic agent used for the treatment of several cancer types. As radiolabelled anticancer agents provide a potential means for personalized treatment planning, docetaxel was labelled with the positron emitter (11)C. Non-invasive measurements of [(11)C]docetaxel uptake in organs and tumours may provide additional information on pharmacokinetics and pharmacodynamics of the drug docetaxel. The purpose of the present study was to determine the biodistribution and radiation absorbed dose of [(11)C]docetaxel in humans.

METHODS

Biodistribution of [(11)C]docetaxel was measured in seven patients (five men and two women) with solid tumours using PET/CT. Venous blood samples were collected to measure activity in blood and plasma. Regions of interest (ROI) for various source organs were defined on PET (high [(11)C]docetaxel uptake) or CT (low [(11)C]docetaxel uptake). ROI data were used to generate time-activity curves and to calculate percentage injected dose and residence times. Radiation absorbed doses were calculated according to the MIRD method using OLINDA/EXM 1.0 software.

RESULTS

Gall bladder and liver demonstrated high [(11)C]docetaxel uptake, whilst uptake in brain and normal lung was low. The percentage injected dose at 1 h in the liver was 47 +/- 9%. [(11)C]docetaxel was rapidly cleared from plasma and no radiolabelled metabolites were detected. [(11)C]docetaxel uptake in tumours was moderate and highly variable between tumours.

CONCLUSION

The effective dose of [(11)C]docetaxel was 4.7 microSv/MBq. As uptake in normal lung is low, [(11)C]docetaxel may be a promising tracer for tumours in the thoracic region.

Hemorrhagic cystitis in a patient receiving docetaxel for prostate cancer

A case is reported in which docetaxel was used to treat a patient with hormone refractory metastatic prostate cancer. The treatment was terminated at the third course of docetaxel following the development of hemorrhagic cystitis. This reaction was unexpected, as it is not a known reaction to docetaxel. Hemorrhagic cystitis has been associated with cyclophosphamide, where the metabolite acrolein has been implicated. The mechanism of this reaction from docetaxel is not yet known.

Bortezomib/docetaxel combination therapy in patients with anthracycline-pretreated advanced/metastatic breast cancer: a phase I/II dose-escalation study

The aim of this study was to determine the dose-limiting toxicities (DLTs) and maximum tolerated dose (MTD) of bortezomib plus docetaxel in patients with anthracycline-pretreated advanced/metastatic breast cancer. Forty-eight patients received up to eight 21-day cycles of docetaxel (60-100 mg m(-2) on day 1) plus bortezomib (1.0-1.5 mg m(-2) on days 1, 4, 8, and 11). Pharmacodynamic and pharmacokinetic analyses were performed in a subset of patients. Five patients experienced DLTs: grade 3 bone pain (n=1) and febrile neutropenia (n=4). The MTD was bortezomib 1.5 mg m(-2) plus docetaxel 75 mg m(-2). All 48 patients were assessable for safety and efficacy. The most common adverse events were diarrhoea, nausea, alopecia, asthenia, and vomiting. The most common grade 3/4 toxicities were neutropenia (44%), and febrile neutropenia and diarrhoea (each 19%). Overall patient response rate was 29%. Median time to progression was 5.4 months. In patients with confirmed response, median time to response was 1.3 months and median duration of response was 3.2 months. At the MTD, response rate was 38%. Pharmacokinetic characteristics of bortezomib/docetaxel were comparable with single-agent data. Addition of docetaxel appeared not to affect bortezomib inhibition of 20S proteasome activity. Mean alpha-1 acid glycoprotein concentrations increased from baseline at nearly all time points across different bortezomib dose levels. Bortezomib plus docetaxel is an active combination for anthracycline-pretreated advanced/metastatic breast cancer. The safety profile is manageable and consistent with the side effects of the individual agents.

Gemcitabine and docetaxel in metastatic sarcoma: past, present, and future

Objective. In the era of oral molecular kinase inhibitors, cytotoxic chemotherapy agents are somewhat overlooked, but remain the backbone of treatment for most cancers. Patients with non-gastrointestinal stromal tumor sarcomas, such as leiomyosarcoma, liposarcoma, and undifferentiated high-grade pleomorphic sarcoma (formerly called malignant fibrous histiocytoma), have received doxorubicin and ifosfamide as the backbone of their treatment for over 15 years or more. The goal of this article is to review the data that have led to the use of gemcitabine and docetaxel as a useful combination for patients with metastatic sarcomas, and to comment on possible synergy of the combination. Methods and results. The literature regarding the use of gemcitabine, docetaxel, or both, is reviewed, with emphasis on patients with metastatic sarcoma. Results. Activity of gemcitabine and docetaxel is observed in leiomyosarcoma and undifferentiated high-grade pleomorphic sarcoma. There is apparent schedule dependence of the combination in other cancers; it is unclear if schedule matters in patients with sarcomas. The dose and schedule of gemcitabine and docetaxel examined in phase II studies are probably too high for routine practice. Conclusions. The combination of gemcitabine and docetaxel is an effective option for patients with metastatic sarcoma, increasing the armamentarium for the practicing oncologist in treating this heterogeneous group of diseases. Given the low response rate to docetaxel as a single agent, it is likely that there is true clinical synergy of the combination. Disclosure of potential conflicts of interest is found at the end of this article.

A phase I study of docetaxel with ketoconazole modulation in patients with advanced cancers

PURPOSE

The aims were to determine the maximum tolerable dose (MTD) of docetaxel with CYP3A inhibition by ketoconazole, and to correlate the pharmacokinetics of docetaxel with midazolam phenotyping of CYP3A activity.

METHODS

Forty-one patients with refractory metastatic cancers were treated with an escalating dose of intravenous docetaxel once in every 3 week of 10 mg/m(2), concurrently with oral ketoconazole 200 mg twice daily for 3 days starting 2 days before the administration of docetaxel. Midazolam phenotyping test with ketoconazole modulation was performed before the first cycle of docetaxel. Docetaxel and midazolam pharmacokinetics were compared to our previous study of docetaxel treatment without ketoconazole modulation.

RESULTS

Neutropenia was the dose-limiting toxicity. The maximum tolerated dose was 70 mg with mean AUC at 70 mg similar to 75 mg/m(2) of docetaxel without ketoconazole. The plasma clearances of docetaxel and midazolam were reduced by 1.7- and 6-fold, respectively. The variability of midazolam AUC was reduced from 157 to 67%, but variability of docetaxel clearance was not reduced by CYP3A inhibition. Docetaxel clearance correlated with renal function and maximum concentration of ketoconazole, but not midazolam clearance or other variables of hepatic function.

CONCLUSION

Fixed dosing was found to be feasible, without increased variability of clearance or neutrophil toxicity compared to BSA-based dosing. With ketoconazole modulation, docetaxel clearance correlated with renal function but not CYP3A phenotype.

A phase I study of flavopiridol and docetaxel

BACKGROUND

Flavopiridol is a cyclin dependent kinase inhibitor. Preclinical models suggest a sequence dependent synergy between flavopiridol and taxanes. The primary objective of this study was to determine the maximum tolerated dose (MTD) of flavopiridol and docetaxel and the influence of flavopiridol on the pharmacokinetics of docetaxel.

METHODS

The major eligibility criteria included: a diagnosis of non-hematologic cancer with no conventional effective therapy, normal organ function, and ECOG performance status of 0-2. Patients were treated with docetaxel followed 24 h later by flavopiridol given via continuous intravenous infusion over a 24-h period. The starting doses of docetaxel and flavopiridol were 60 and 60 mg/m2, respectively. Cycles were repeated every 21 days. All patients received diarrhea prophylaxis consisting of bismuth subsalicylate.

RESULTS

Ten patients (M:F 4:6; median age 56 years) were treated. The median number of cycles per patient was 2 (range 1-6). Two of the three patients on dose level 1 developed dose-limiting toxicities consisting of neutropenia and fever. Seven patients were subsequently enrolled on dose level -1 (docetaxel 60 mg/m2, flavopiridol 50 mg/m2). One episode of grade 3 diarrhea was reported at dose level -1.

CONCLUSIONS

Neutropenia complicated by infection was the major dose-limiting toxicity. The recommended doses of flavopiridol and docetaxel for phase II trials are 50 and 60 mg/m2 every three weeks, respectively.

Medicinal Cannabis Does Not Influence the Clinical Pharmacokinetics of Irinotecan and Docetaxel

OBJECTIVE

To date, data regarding the potential of cannabinoids to modulate cytochrome P450 isozyme 3A (CYP3A) activity are contradictory. Recently, a standardized medicinal cannabis product was introduced in The Netherlands. We anticipated an increased use of medicinal cannabis concurrent with anticancer drugs, and undertook a drug-interaction study to evaluate the effect of concomitant medicinal cannabis on the pharmacokinetics of irinotecan and docetaxel, both subject to CYP3A-mediated biotransformation.

PATIENTS AND METHODS

Twenty-four cancer patients were treated with i.v. irinotecan (600 mg, n = 12) or docetaxel (180 mg, n = 12), followed 3 weeks later by the same drugs concomitant with medicinal cannabis (200 ml herbal tea, 1 g/l) for 15 consecutive days, starting 12 days before the second treatment. Blood samples were obtained up to 55 hours after dosing and analyzed for irinotecan and its metabolites (SN-38, SN-38G), respectively, or docetaxel. Pharmacokinetic analyses were performed during both treatments. Results are reported as the mean ratio (95% confidence interval [CI]) of the observed pharmacokinetic parameters with and without concomitant medicinal cannabis.

RESULTS

Medicinal cannabis administration did not significantly influence exposure to and clearance of irinotecan (1.04; CI, 0.96-1.11 and 0.97; CI, 0.90-1.05, respectively) or docetaxel (1.11; CI, 0.94-1.28 and 0.95; CI, 0.82-1.08, respectively).

CONCLUSION

Coadministration of medicinal cannabis, as herbal tea, in cancer patients treated with irinotecan or docetaxel does not significantly influence the plasma pharmacokinetics of these drugs. The evaluated variety of medicinal cannabis can be administered concomitantly with both anticancer agents without dose adjustments.

Phase I and pharmacokinetic study of docetaxel, irinotecan, and celecoxib in patients with advanced non-small cell lung cancer

PURPOSE

We studied the toxicities, potential pharmacokinetic interactions, and preliminary antitumor activity of the combination of docetaxel and irinotecan with celecoxib, a selective cyclooxygenase-2 inhibitor.

PATIENTS AND METHODS

Eligible patients had advanced non-small lung cancer (NSCLC) with measurable disease, good performance status, and adequate end organ function. Docetaxel and irinotecan were administered intravenously on days 1 and 8, every 21 days, and their doses were escalated on successive patient cohorts at three dose levels: 30/50, 30/60, and 35/60 (doses in mg/m2). Celecoxib was administered at a starting dose of 400 mg orally twice daily without interruption, beginning on day 2 of cycle 1. Pharmacokinetic studies were performed on day 1 of cycle 1 and day 1 of cycle 2.

RESULTS

Seventeen patients with advanced NSCLC were enrolled and collectively received 78 cycles of therapy. Diarrhea was the most common toxicity; it was noted in 13 patients (76%). Dose-limiting toxicities occurred at dose level 1 (myocardial infarction in a patient with multiple coronary artery disease risk factors) and dose level 3 (grade 4 neutropenia with fatal urosepsis). Other major toxicities were: grade 3 neutropenia (2 patients); grade 3/4 diarrhea (3/1); grade 3 nausea (2); grade 2 rash (1); and grade 3 pneumonitis (1). The maximum tolerated dose was at dose level 3, i.e., docetaxel 35 mg/m2 and irinotecan 60 mg/m2 on days 1 and 8, plus celecoxib 400 mg twice daily, repeated every 21 days. Five of 15 evaluable patients achieved an objective response. The pharmacokinetics of docetaxel were not altered by celecoxib. However, we observed an 18% increase in the average elimination clearance of irinotecan coincident with the addition of celecoxib.

CONCLUSIONS

The addition of celecoxib to docetaxel and irinotecan was generally well tolerated but unpredictable fatal toxicity occurred. Diarrhea was the most common toxicity. Antitumor activity was promising. The alteration of irinotecan pharmacokinetic parameters observed may not be clinically relevant.

Vinorelbine/docetaxel combination treatment of metastatic breast cancer: a phase I study

PURPOSE

The aim of this study was to investigate the combination of vinorelbine (VRL) alternating intravenous (i.v.) and oral in combination with docetaxel (DCT) as first-line chemotherapy of patients with metastatic breast cancer.

PATIENTS AND METHODS

Tested doses were 60 or 70 mg m(-2) given on day 1 for DCT, 20 to 25 mg m(-2) for i.v. VRL on day 1, 60 mg m(-2) on day 8 or day 15 for oral VRL. Day 1 was administered every 3 weeks. Three to six patients were treated per dose level.

RESULTS

The median age of the 30 treated patients was 60 years. Four patients were non evaluable for the maximum tolerated dose (MTD) and were replaced. Reported dose-limiting toxicities were 11 omissions of oral VRL for neutropenia, two cases of febrile neutropenia and two grade 4 neutropenia >or=7 days. Dose levels using DCT doses >60 mg m(-2) and/or i.v. VRL doses >20 mg m(-2) met the criteria for MTD. Most frequent toxicities were febrile neutropenia in seven patients and neutropenic infection in four patients (one fatal). Therefore, the recommended schedule was established at i.v. VRL 20 mg m(-2) with DCT 60 mg m(-2) on day 1 and oral VRL 60 mg m(-2) given on day 15 every 3 weeks. At this recommended schedule, only one of six patients experienced febrile neutropenia. Among 22 patients evaluable for tumour response, 2 complete and 10 partial responses were reported. Pharmacokinetics of combined VRL and DCT demonstrated the absence of mutual interaction.

CONCLUSIONS

This phase I study established the recommended doses and schedules of the combination alternating i.v. and oral VRL with DCT, this recommended regimen being further explored in a phase II study.

Docetaxel-associated epiphora

Docetaxel is a semisynthetic taxane indicated for the treatment of advanced breast, prostate, and non-small cell lung cancers; it is also used for the treatment of various other solid tumors. The standard intermittent dosage of docetaxel is 60-100 mg/m2 every 3 weeks. At this dose and schedule, myelosuppression is common and neutropenia is usually the dose-limiting toxicity. Weekly administration of docetaxel 20-42 mg/m2 is being tested in the treatment of advanced solid tumors in order to improve patient tolerance by reducing the interval dose and to maintain therapeutic efficacy by increasing overall dose intensity. Asthenia and peripheral neuropathy can limit continued administration of weekly docetaxel. Epiphora (excess tearing due to narrowing or blockage of the lacrimal outflow passages) is associated with repeated weekly administration of docetaxel. This adverse effect can interfere with activities of daily life and negatively affect quality of life. Epiphora may be an underreported adverse effect of treatment because of underrecognition by clinicians and patient embarrassment with respect to seemingly uncontrolled tearing. The use of weekly docetaxel administration is expanding; therefore, patients should be educated to recognize and report signs and symptoms of epiphora. It is important for clinicians participating in the care of patients undergoing treatment with docetaxel to monitor for excess tearing and signs of eye irritation to ensure timely management of treatment-related epiphora.

Phase I and Pharmacokinetic Study of the Dolastatin 10 Analogue TZT-1027, Given on Days 1 and 8 of a 3-Week Cycle in Patients with Advanced Solid Tumors

PURPOSE

TZT-1027 [N(2)-(N,N-dimethyl-l-valyl)-N-[(1S,2R)-2-methoxy-4-[(2S)-2-[(1R,2R)-1-methoxy-2-methyl-3-oxo-3-[(2-phenylethyl)]amino]propyl]-1-pyrrolidinyl]-1-[(S)-1-methylpropyl]-4-oxobutyl]-N-methyl-l-valinamide] is a cytotoxic dolastatin 10 derivative inhibiting microtubule assembly through the binding to tubulins. The objectives of this phase I study was to assess the dose-limiting toxicities (DLT), to determine the maximum tolerated dose, and to study the pharmacokinetics of TZT-1027 when given i.v. over 60 minutes on days 1 and 8 every 3 weeks to patients with advanced solid tumors.

EXPERIMENTAL DESIGN

Patients were treated with escalating doses of TZT-1027 at doses ranging from 1.35 to 2.7 mg/m(2). For pharmacokinetic analysis, plasma sampling was done during the first and second course and assayed using a validated high-performance liquid chromatographic assay with mass spectrometric detection.

RESULTS

Seventeen patients received a total of >70 courses. The stopping dose was reached at 2.7 mg/m(2), with neutropenia and infusion arm pain as DLT. Neutropenia was not complicated by fever. Over all dose levels, eight patients experienced pain in the infusion arm 1 to 2 days after administration of the drug, which seemed ameliorated by adding additional flushing after drug administration. Other side effects included nausea, vomiting, diarrhea, and fatigue. One partial response lasting >54 weeks was observed in an extensively pretreated patient with metastatic liposarcoma. The pharmacokinetics of TZT-1027 suggested linearity over the dose ranges. No correlation between body surface area and absolute CL of TZT-1027 was established, vindicating that a flat dosing regimen might be used in the future. A correlation was observed between the percentage decrease in neutrophil count and the AUC of TZT-1027.

CONCLUSIONS

In this study, the DLT of TZT-1027 was neutropenia and infusion arm pain. The recommended dose for phase II studies of TZT-1027 is 2.4 mg/m(2) given i.v. over 60 minutes, on days 1 and 8 every 21 days. Phase II studies have recently started.

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.

Liver metastases from breast cancer: management of patients with significant liver dysfunction

The liver is a common site of metastases in breast cancer. Although the development of liver metastases has long been associated with a poor prognosis in this disease, this dogma has been challenged by more recent data, perhaps reflecting some treatment and other technological advances achieved in the last decade. Nevertheless, the specific population of breast cancer patients presenting with liver disease and associated liver dysfunction remain poorly studied. These women still seem to have a poor prognosis as compared to other patients with liver metastases. This is further complicated by the fact that the most active cytotoxic agents in breast cancer have significant hepatic metabolism and/or biliary excretion. Unfortunately, since these patients have been most of the time excluded from clinical trials, there are currently no clear recommendations for the management of such dramatic presentations. With some exceptions, recommendations for dose adjustments have also been largely empirical. In this paper, we review the optimal doses of cytotoxics used in this clinical situation and provide some tips on the management of these patients, based on the limited data currently available in the literature.

Comparison of pharmacokinetics and pharmacodynamics of docetaxel and Cisplatin in elderly and non-elderly patients: why is toxicity increased in elderly patients?

PURPOSE

Following phase I studies of docetaxel and cisplatin in patients with non-small-cell lung cancer, the recommended doses of docetaxel were different for elderly (> or = 75 years) and non-elderly (< 75 years) patients. To elucidate the mechanism of the difference, the pharmacokinetics of docetaxel and cisplatin were investigated in two phase II studies separately conducted in elderly and non-elderly patients.

PATIENTS AND METHODS

Twenty-seven elderly and 25 non-elderly patients were treated with three weekly administrations of docetaxel and cisplatin every 4 weeks. Doses of docetaxel were 20 and 35 mg/m(2) for elderly and non-elderly patients, respectively. All patients received 25 mg/m(2) of cisplatin. The pharmacokinetics and pharmacodynamics of docetaxel and cisplatin were compared in elderly and non-elderly patients.

RESULTS

There were no differences in pharmacokinetics of docetaxel or cisplatin between elderly versus non-elderly patients with regard to clearance and volume of distribution. In the pharmacodynamic analysis, neutropenia was positively correlated with the area under the concentration-time curve for docetaxel but not for cisplatin. In evaluating the relationship between neutropenia and the area under the concentration-time curve of docetaxel, elderly patients experienced greater neutropenia than those predicted by a pharmacodynamic model developed in non-elderly patients; the residual for prediction of the percent change in neutrophil count was -11.2% (95% CI, -21.8 to -0.5%).

CONCLUSION

The pharmacokinetics of docetaxel and unchanged cisplatin were not different between elderly and non-elderly patients. The elderly patients were more sensitive to docetaxel exposure than the non-elderly patients, resulting in the different recommended doses for the phase II studies.

Oral bioavailability of docetaxel in combination with OC144-093 (ONT-093)

OBJECTIVE

Docetaxel given orally as monotherapy results in low bioavailability of <10%. Previous studies have indicated that the intestinal efflux pump P-glycoprotein (P-gp) prevents uptake from the gut resulting in low systemic exposure to docetaxel. The purpose of this study was to determine the degree of enhancement of the oral uptake of docetaxel on combination with orally administered OC144-093, a potent P-gp inhibitor. Furthermore, the safety of combined treatment was determined and whether known functional genetic polymorphisms of the MDR1 gene could be associated with variability in docetaxel pharmacokinetics was also investigated.

PATIENTS AND METHODS

A proof of concept study was carried out in 12 patients with advanced solid tumors. Patients were randomized to receive one course of 100 mg oral docetaxel combined with 500 mg OC144-093 followed 2 weeks later by a second i.v. course of docetaxel at a flat dose of 100 mg, without OC144-093, or vice versa. This was followed by standard i.v. docetaxel treatment if indicated.

RESULTS

The apparent relative oral bioavailability of docetaxel was 26+/-8%. Orally administered docetaxel combined with oral OC144-093 resulted in a Cmax of 415+/-255 ng ml(-1), an AUC0-infinity of 844+/-753 ng h ml(-1) and kel of 0.810+/-0.296 h(-1). These values differed significantly from those following i.v. administration of docetaxel, with a Cmax of 2124+/-1054 ng ml(-1), an AUC0-infinity of 2571+/-1598 ng h ml(-1) and a kel of 1.318+/-0.785 h(-1) (P=0.003, P=0.006, P=0.016). The study medication was well tolerated and most of the adverse events possibly or probably related to OC144-093 and docetaxel were of CTC grade 1 and 2. One patient had a homozygous 3435T/T mutation, which is associated with low intestinal P-gp expression, and two other patients had a homozygous mutation on exon 21.

CONCLUSION

The relative apparent bioavailability of 26% was most likely caused by a significant effect of OC144-093 on the oral uptake of docetaxel. Large intrapatient and interpatient (pharmacokinetic) variation was found after oral as well as after i.v. administration of docetaxel. Higher plasma levels were observed after 100 mg i.v. docetaxel than after 100 mg oral docetaxel plus 500 mg oral OC144-093. The safety of the oral combination was good. More patients should be evaluated to determine the effect of P-gp single nucleotide polymorphisms on oral pharmacokinetic values of docetaxel.

Immunomodulatory effects of docetaxel on human lymphocytes

Docetaxel is an antineoplastic taxoid that interferes with microtubule polymerization dynamics and is used clinically to treat advanced cancers. Because microtubules play significant roles in T lymphocyte activation and function we characterized the in vitro immunomodulatory properties of docetaxel. Effects of docetaxel on lectin-induced peripheral blood mononuclear cell (PBMC) proliferation were measured by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay and proliferating cell nuclear antigen (PCNA) staining. In addition, apoptosis was measured by annexin V staining and cell activation by determination of CD25 and CD71 cell surface expression. Intracellular calcium kinetics in lectin-activated Jurkat T lymphocytes exposed to docetaxel were investigated. Th1 cytokine production was assessed in T lymphocytes by intracellular cytokine staining. Docetaxel significantly inhibited PBMC proliferation and promoted apoptosis of lectin-activated PBMCs. Docetaxel significantly decreased expression of CD71 but not that of CD25. Docetaxel altered intracellular calcium homeostasis but did not affect Th1 cytokine production in T lymphocytes. In conclusion we demonstrate that docetaxel, although exerting significant antiproliferative effects on lymphocytes and promoting activation-induced apoptosis does affect only partially lymphocyte activation and function and does not affect Th1 cytokine production. These results suggest maintenance of lymphocyte functions important for host tumor surveillance and suggest that this compound may have a role in the treatment of cancer arising organ transplant recipients.

Docetaxel, Carboplatin and Concomitant Radiotherapy for Unresectable Squamous Cell Carcinoma of the Head and Neck

Concomitant chemoradiotherapy is the most effective treatment of unresectable head and neck cancer. Docetaxel and carboplatin are two active drugs that potentiate radiotherapy. Thirty patients (median age = 56 years; median Eastern Cooperative Oncology Group performance status = 1) received radiotherapy (70 Gy, 2 Gy/d, 5 d/wk) concurrent with carboplatin AUC 0.3 to 0.5 on day 1-5, weeks 1, 3, 5, 7, and docetaxel 15 to 25 mg/m2 on day 4 of weeks 2, 4, and 6. Site of unresectable squamous cell carcinoma was as follows: oropharynx, 41%; hypopharynx, 27%; oral cavity, 16%; and larynx, 16%. Stage was III in 13% and IV in 87%. In 11 patients, pharmacokinetic parameters were evaluated. Acute G4 toxicity was as follows: neutropenia, 20%; mucositis, 33%. We had the following acute G3 toxicities: mucositis, 40%; neutropenia, 37%; dermatitis, 23%; and anemia, 13%. The maximum tolerated dosage was area under the curve 0.5 for carboplatin and 20 mg/m2 for docetaxel. Median radiotherapy dose was 69 Gy, and 175 out of 210 courses (83%) were administered. At the end of the treatment, we had 20 complete responses (CR) (67%), 9 partial responses (30%), and 1 no change (3%). After radial neck dissection, 2 patients achieved a CR (overall CR = 73%). After a median follow-up of 2.5 years, we had a 3-year local progression-free survival of 85%, failure-free survival of 69%, and overall survival of 60%. A significant increase of Cmax of carboplatin concentration was noted at the beginning of weeks 3, 5, and 7. Total plasma platinum raises during each course of 5 days of carboplatin without reaching a steady state. Carboplatin, docetaxel, and concomitant conventional radiotherapy is a feasible and effective treatment of unresectable head and neck cancer. The concurrent administration of two drugs does not alter pharmacokinetic drug behavior compared with single-agent data.

Pharmacology of cytotoxic agents: a helpful tool for building dose adjustment guidelines in the elderly

Aging is associated with multidimensional changes, including alterations in physiological functions, co-morbidities and poly-medications. These changes may lead to modifications in the absorption, distribution, metabolism and excretion of drugs. The lack of a scientific basis for optimal drug dosing in the elderly is a major problem. The development and validation of guidelines are therefore essential to improve treatment administration and monitoring in elderly patients. Even though it has been widely demonstrated that standard therapies used in adults may be of great benefit in the elderly, there may be a higher incidence of toxicity. This could be avoided by using dosage individualization based on a sound knowledge of the physiological factors implicated in the pharmacokinetic (PK) characteristics of the drugs administered and in their observed pharmacodynamic (PD) effects in each patient. The so-called "population modeling" approach renders such studies feasible by allowing the analysis of PK-PD relationships from sparse observational data.

Improvement of oral drug treatment by temporary inhibition of drug transporters and/or cytochrome P450 in the gastrointestinal tract and liver: an overview

The oral bioavailability of many cytotoxic drugs is low and/or highly variable. This can be caused by high affinity for drug transporters and activity of metabolic enzymes in the gastrointestinal tract and liver. In this review, we will describe the main involved drug transporters and metabolic enzymes and discuss novel methods to improve oral treatment of affected substrate drugs. Results of preclinical and clinical phase I and II studies will be discussed in which affected substrate drugs, such as paclitaxel, docetaxel, and topotecan, are given orally in combination with an inhibitor of drug transport or drug metabolism. Future randomized studies will, hopefully, confirm that this strategy for oral treatment is at least as equally effective and safe as standard intravenous administration of these drugs.

Pharmacokinetic study of docetaxel in intraoperative hyperthermic i.p. chemotherapy for ovarian cancer

The purpose of this study was to evaluate the pharmacokinetics and toxicity of docetaxel in continuous hyperthermic perfusion peritoneal chemotherapy (CHPPC) after cytoreductive surgery for peritoneal involvement of gynecological malignancies, mainly ovarian cancer. Eighteen patients, with a mean age of 64 years (range 51-80), underwent cytoreductive surgery and subsequent CHPPC with 75 mg/m2 docetaxel at 41-43 degrees C. One patient was treated twice. In eight cases, peritoneal fluid and blood samples were obtained for pharmacokinetic analysis. Death occurred in two heavily pretreated elderly patients with a high volume i.p. tumor recurrence, probably reflecting poor patient selection (mortality rate 10.5%). Other complications, mainly minor, were recorded after 63% of the procedures. Hematological docetaxel-induced toxicity was limited, while the incidence of wound complications was relatively high and probably caused by the direct exposure of the wound to docetaxel during CHPPC. The maximal i.p. versus plasma concentration ratio ranged from 17 to 95 (average 45), while the i.p. versus systemic exposure ratio varied between 105 and 555 (average 207). We conclude that the use of docetaxel in CHPPC following cytoreductive surgery seems feasible and results in a high i.p. versus systemic exposure ratio. The AUC for the peritoneal cavity is on average 13-27 times higher after i.p. administration of 75 mg/m2 during CHPPC than the AUC achieved in the systemic compartment after i.v. administration of the recommended dose of 100 mg/m2, while docetaxel-induced systemic toxicity is highly limited.

Phase I clinical and pharmacokinetic studies of the taxoid derivative RPR 109881A administered as a 1-hour or a 3-hour infusion in patients with advanced solid tumors

PURPOSE

To define the maximum tolerated dose (MTD), the recommended phase II dose, the optimal infusion duration and pharmacokinetics of the semisynthetic taxoid derivative RPR 109881A, given as a 1-h or 3-h infusion every 3 weeks.

PATIENTS AND METHODS

RPR109881A was administered as a 1-h i.v. infusion to 34 patients (study 1) with oral steroids as pre-medication. In a subsequent study, 29 patients were treated at the recommended dose or at the dose immediately below (study 2); the first 14 patients received RPR 109881A as a 3-h infusion, while the subsequent 15 were randomized to receive the drug as a 1-h or 3-h infusion. The pharmacokinetics of RPR109881A was studied in plasma and urine and for selected patients in some biological fluids (cerebrospinal fluid, pleural effusion, ascitis).

RESULTS

In study 1, the dose was escalated from 15 to 105 mg/m(2), at which dose two of five patients presented dose-limiting toxicities with febrile neutropenia (FN) after the first cycle, thus defining the MTD. The dose of 90 mg/m(2), at which grade 3/4 neutropenia was almost universal with FN in 18%, was recommended for phase II. At 90 mg/m(2) the incidence of diarrhea, fatigue and alopecia were 59, 29 and 70%, respectively. The results of study 2 were comparable to those of study 1, thus recommending the 1-h infusion duration for phase II evaluation. RPR 109881A exhibited a high total body clearance, a large distribution volume and long terminal half-life of 20 h. RPR 109881A was detected in cerebrospinal fluid shortly after the end of 1-h infusion. Three objective responses were observed in non-small-cell lung cancer (NSCLC) patients, including a patient with brain metastases.

CONCLUSIONS

The antitumor activity in NSCLC, the reproducible profile of toxicity and above all the ability to cross the blood-brain barrier make RPR 109881A worthy of further disease-oriented clinical development.

A preliminary pharmacokinetic study of docetaxel, carboplatin and concurrent radiotherapy for regionally advanced squamous cell carcinoma of the head and neck

This work investigates the pharmacokinetics and toxicity resulting from the concomitant use of low dose carboplatin (CBCA)/docetaxel (DTX) plus concurrent radiotherapy in patients with head and neck cancer. The study comprised 11 patients with stage III-IV head and neck cancer. All patients received 2 Gy radiotherapy daily, 5 fractions per week, up to a planned total of 70 Gy over 7 weeks. CBCA (AUC 0.4 mg/ml, min/day) was also administrated as 20 min i.v. infusion, starting 1 day before the first radiotherapy fraction. CBCA was administered for 5 consecutive days every 2 weeks (weeks 1, 3, 5 and 7). DTX 30 mg/m2 (1 h i.v. infusion) was given as a single dose on days 10, 24 and 38. CBCA on day 1 and DTX on day 10 were analysed to determine the concentration-time curves during the first 24 h. CBCA Cmax and Cmin in 2-5 days and on day 15 and 29, as well as total plasma platinum on days 2, 3, 4, 5, 29 and 43 were also assayed. By calculating the non-compartmental pharmacokinetic parameters of the two drugs from the available plasma concentrations we found in the first week values similar to those reported in the literature as single agents. In contrast, during subsequent weeks (weeks 3 and 5), a significant and progressive increase of platinum levels was observed. So, it could be assumed that after 2 weeks of CBCA and DTX treatment a bias in dose calculation occurred because the linear relationship between creatinine clearance (used to calculate the expected AUC through the Calvert formula) and CBCA clearance was no longer observed.

Coadministration of cyclosporine strongly enhances the oral bioavailability of docetaxel

PURPOSE

Oral bioavailability of docetaxel is very low, which is, at least in part, due to its affinity for the intestinal drug efflux pump P-glycoprotein (P-gp). In addition, metabolism of docetaxel by cytochrome P450 (CYP) 3A4 in gut and liver may also contribute. The purpose of this study was to enhance the systemic exposure to oral docetaxel on coadministration of cyclosporine (CsA), an efficacious inhibitor of P-gp and substrate for CYP 3A4.

PATIENTS AND METHODS

A proof-of-concept study was carried out in 14 patients with solid tumors. Patients received one course of oral docetaxel 75 mg/m(2) with or without a single oral dose of CsA 15 mg/kg. CsA preceded oral docetaxel by 30 minutes. During subsequent courses, patients received intravenous (IV) docetaxel 100 mg/m(2).

RESULTS

The mean (+/- SD) area under the concentration-time curve (AUC) in patients who received oral docetaxel 75 mg/m(2) without CsA was 0.37 +/- 0.33 mg.h/L and 2.71 +/- 1.81 mg.h/L for the same oral docetaxel dose with CsA. The mean AUC of IV docetaxel 100 mg/m(2) was 4.41 +/- 2.10 mg.h/L. The absolute bioavailability of oral docetaxel was 8% +/- 6% without and 90% +/- 44% with CsA. The oral combination of docetaxel and CsA was well tolerated.

CONCLUSION

Coadministration of oral CsA strongly enhanced the oral bioavailability of docetaxel. Interpatient variability in the systemic exposure after oral drug administration was of the same order as after IV administration. These data are promising and form the basis for the further development of a clinically useful oral formulation of docetaxel.