Pharmacokinetics of vinorelbine in patients with liver metastases

Triggered release from thermosensitive liposomes improves tumor targeting of vinorelbine

Triggered drug delivery strategies have been shown to enhance drug accumulation at target diseased sites in comparison to administration of free drug. In particular, many studies have demonstrated improved targetability of chemotherapeutics when delivered via thermosensitive liposomes. However, most studies continue to focus on encapsulating doxorubicin while many other drugs would benefit from this targeted and localized delivery approach. The proposed study explores the therapeutic potential of a thermosensitive liposome formulation of the commonly used chemotherapy drug vinorelbine in combination with mild hyperthermia (39-43 °C) in a murine model of rhabdomyosarcoma. Rhabdomyosarcoma, the most common soft tissue sarcoma in children, is largely treated using conventional chemotherapy which is associated with significant adverse long-term sequelae. In this study, mild hyperthermia was pursued as a non-invasive, non-toxic means to improve the efficacy and safety profiles of vinorelbine. Thorough assessment of the pharmacokinetics, biodistribution, efficacy and toxicity of vinorelbine administered in the thermosensitive liposome formulation was compared to administration in a traditional, non-thermosensitive liposome formulation. This study shows the potential of an advanced formulation technology in combination with mild hyperthermia as a means to target an untargeted therapeutic agent and result in a significant improvement in its therapeutic index.

A Phase I Comparative Pharmacokinetic and Safety Study of Two Intravenous Formulations of Vinorelbine in Patients With Advanced Non-Small Cell Lung Cancer

Purpose: The aim of this study was to compare the pharmacokinetics and safety between two vinorelbine formulations [a new oil-in-water emulsion formulation (ANX) versus a previously marketed solution formulation (Navelbine)] in Chinese patients with advanced non-small cell lung cancer (NSCLC).

Method: This was a single-center, randomized, open-label study. Eligible patients aged 18–70 years who had histologically or cytologically confirmed NSCLC were enrolled. In cycle 1, the patients alternatively received the two formulations (30 mg/m², given as a 10-min infusion) with a 7-day interval. Samples for pharmacokinetic analysis were taken during cycle 1. For all subsequent 21-day cycles (maximum four cycles), ANX was administered on days 1 and day 8. Bioequivalence analysis was performed on C_max, AUC_last, and AUC_inf. The safety profiles and anti-tumor effects were also determined.

Results: From March 2013 to January 2015, 24 patients were enrolled and 20 were eligible for pharmacokinetic evaluation. The 20 subjects in the pharmacokinetic analysis set had a median age of 61 years (range, 37–70 years), and 15 patients were male (75%). Mean vinorelbine C_max values for ANX and Navelbine were 1,317.40 and 1,446.30 ng/mL, respectively. Corresponding AUC_last values were 797.08 and 924.26 ng·h/mL, respectively. AUC_inf values were 830.14 and 957.16 ng·h/mL, respectively. Treatment ratios of the geometric means were 90.00% (90% CI, 83.22–99.07%) for C_max, 86.92% (90% CI, 80.91–93.37%) for AUC_last, and 87.44% (90% CI, 82.08–93.16%) for AUC_inf. These results met the required 80–125% bioequivalence criteria. The most frequently reported adverse events after vinorelbine administration were neutropenia, leucopenia, neutropenic fever, and constipation.

Conclusion: At therapeutic dosage levels, pharmacokinetic behavior and safety profiles were similar for both formulations. Chinese National Registry Code: ChiCTR-IPR-15005856.

A Pilot Study of Vinorelbine Safety and Pharmacokinetics in Patients with Varying Degrees of Liver Dysfunction

Vinorelbine tartrate is a semi‐synthetic vinca alkaloid and an inhibitor of microtubule polymerization with demonstrated antitumor properties across a spectrum of cancers. The pharmacokinetics of vinorelbine may be altered in individuals with liver dysfunction, considering that hepatic metabolism serves as the predominant route of drug elimination. This article reports the pharmacokinetics and safety of vinorelbine in patients with varying degrees of hepatic impairment, including dosing recommendations in this population.

Background.

Vinorelbine has demonstrated anticancer activity and is primarily metabolized in the liver. This single‐institution, phase I pilot study describes the safety and pharmacokinetics of vinorelbine in patients with varying degrees of hepatic impairment.

Materials and Methods.

Patients with treatment‐refractory solid tumors were enrolled into treatment arms based on vinorelbine dose (weekly infusions of 7.5–30 mg/m²) and liver function (normal liver function, mild, moderate, or severe liver dysfunction). Vinorelbine pharmacokinetics were evaluated to describe its relationship with liver function. Indocyanine green (ICG) clearance was assessed for correlation with pharmacokinetics.

Results.

Forty‐seven patients were enrolled, and a total of 108 grade 3–4 treatment‐related adverse events (AEs) occurred. Of these, grade 3–4 myelosuppression was the most common (34.3%). Thirty‐three (30.6%), 22 (20.4%), and 9 (8.3%) grade 3–4 AEs were observed in the vinorelbine 20 mg/m²/severe, 15 mg/m²/moderate, and 7.5 mg/m²/severe liver dysfunction groups, respectively, with the majority being nonhematologic toxicities. ICG clearance decreased as liver function worsened. Vinorelbine pharmacokinetics were not correlated with ICG elimination or the degree of liver dysfunction.

Conclusion.

For patients with severe liver dysfunction (bilirubin >3.0 mg/dL), vinorelbine doses ≥7.5 mg/m² are poorly tolerated. The high incidence of grade 3–4 AEs with 15 mg/m² vinorelbine in moderate liver dysfunction (bilirubin 1.5–3.0 mg/dL) raises concerns for its safety in this population. Vinorelbine pharmacokinetics are not affected by liver dysfunction; however, levels of the active metabolite 4‐O‐deacetylvinorelbine were not measured and may be higher in patients with liver dysfunction if its elimination is impacted by liver impairment to a greater degree than the parent drug.

Implications for Practice.

Vinorelbine remains widely prescribed in advanced malignancies and is under development in immunotherapy combinations. Given vinorelbine is primarily hepatically metabolized, understanding its safety and pharmacokinetics in liver dysfunction remains paramount. In this phase I pilot study, weekly vinorelbine at doses ≥7.5 mg/m² is poorly tolerated in those with severe liver dysfunction. Furthermore, a high incidence of grade 3–4 toxicities was observed with vinorelbine at 15 mg/m² in those with moderate liver dysfunction. Vinorelbine pharmacokinetics do not appear affected by degree of liver dysfunction. Further evaluation of levels of the free drug and active metabolites in relationship to liver function are warranted.

Pharmacologic Considerations in the Disposition of Antibodies and Antibody-Drug Conjugates in Preclinical Models and in Patients

The rapid advancement in the development of therapeutic proteins, including monoclonal antibodies (mAbs) and antibody-drug conjugates (ADCs), has created a novel mechanism to selectively deliver highly potent cytotoxic agents in the treatment of cancer. These agents provide numerous benefits compared to traditional small molecule drugs, though their clinical use still requires optimization. The pharmacology of mAbs/ADCs is complex and because ADCs are comprised of multiple components, individual agent characteristics and patient variables can affect their disposition. To further improve the clinical use and rational development of these agents, it is imperative to comprehend the complex mechanisms employed by antibody-based agents in traversing numerous biological barriers and how agent/patient factors affect tumor delivery, toxicities, efficacy, and ultimately, biodistribution. This review provides an updated summary of factors known to affect the disposition of mAbs/ADCs in development and in clinical use, as well as how these factors should be considered in the selection and design of preclinical studies of ADC agents in development.

Pharmacokinetics of Chemotherapy in the Older Patient

Background

The number of individuals aged 65 years and older is growing rapidly, and the majority of cancers are diagnosed in this age group. Age-related changes in physiology can affect chemotherapy pharmacokinetics and pharmacodynamics in older patients.

Methods

We review the literature regarding the impact of age on the pharmacokinetics of commonly used chemotherapy drugs and discuss age-related changes in physiology and pharmacology that can affect chemotherapy tolerance in older patients.

Results

The data on age-related changes in chemotherapy pharmacokinetics are conflicting. While a few studies report age-related differences in chemotherapy pharmacokinetics, most found no significant difference or subtle differences in pharmacokinetics with aging. A difference in pharmacodynamics was commonly seen, however, with older patients at increased risk of myelosuppression and toxicity from age-related decline in organ function. The majority of these studies were performed in a small cohort of patients, thus limiting the generalizability of these results.

Conclusions

Additional studies are needed to address the pharmacokinetics and pharmacodynamics of cancer therapies in the older patient. Multicenter pharmacokinetic studies of adequate sample size, which include a thorough evaluation of physiologic factors and geriatric assessment parameters, would provide further insight into the factors affecting treatment tolerance. These studies would also help to guide appropriate chemotherapy dosing and interventions in order to maximize efficacy and minimize toxicity in the older patient.

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.

Cancer and liver cirrhosis: implications on prognosis and management

Liver cirrhosis, the end-stage of every chronic liver disease, is not only the major risk factor for the development of hepatocellular carcinoma but also a limiting factor for anticancer therapy of liver and non-hepatic malignancies. Liver cirrhosis may limit surgical and interventional approaches to cancer treatment, influence pharmacokinetics of anticancer drugs, increase side effects of chemotherapy, render patients susceptible for hepatotoxicity, and ultimately result in a competitive risk for morbidity and mortality. In this review, we provide a concise overview about the impact of liver cirrhosis on the management and prognosis of patients with primary liver cancer or non-hepatic malignancies.

The effects of nanoparticle drug loading on the pharmacokinetics of anticancer agents

Major advances in carrier-mediated agents, which include nanoparticles, nanosomes and conjugates, have revolutionized drug delivery capabilities over the past decade. While providing numerous advantages, such as greater solubility, duration of exposure and delivery to the site of action over their small-molecule counterparts, there is substantial variability in systemic clearance and distribution, tumor delivery and pharmacologic effects (efficacy and toxicity) of these agents. This review provides an overview of factors that affect the pharmacokinetics and pharmacodynamics of carrier-mediated agents in preclinical models and patients.

Formulation and physiologic factors affecting the pharmacology of carrier-mediated anticancer agents

INTRODUCTION

Major advances in carrier-mediated agents (CMAs), which include nanoparticles and conjugates, have revolutionized drug delivery capabilities over the past decade. While providing numerous advantages such as increased exposure duration, greater solubility and delivery to tumor sites over their small molecule counterparts, there is substantial variability in how individual CMA formulations affect the pharmacology, pharmacokinetics and pharmacodynamics (efficacy and toxicity) of these agents.

AREAS COVERED

CMA formulations are complex in nature compared to their small molecule counterparts and consist of multiple components and variables that can affect the pharmacological profile. This review provides an overview of factors that affect the pharmacologic profiles observed in CMA-formulated chemotherapy, primarily in liposomal formulations, that are currently in preclinical or early clinical development.

EXPERT OPINION

Despite the numerous advantages that CMA formulations provide, their clinical use is still in its infancy. It is critical that we understand the mechanisms and effects of CMAs in navigating biological barriers and how these factors affect their biodistribution and delivery to tumors. Future studies are warranted to better understand the complex pharmacology and interaction between CMA carriers and biological systems, such as the mononuclear phagocyte system and tumor microenvironment.

Population pharmacokinetics of pegylated liposomal CKD-602 (S-CKD602) in patients with advanced malignancies

S-CKD602 is a pegylated long-circulating liposomal formulation of CKD-602, a potent topoisomerase I inhibitor. A population pharmacokinetic (PK) model for encapsulated and released CKD-602 following administration of S-CKD602 was developed to assess factors that may influence S-CKD602 PK. Plasma samples from 45 patients with solid tumors were collected in a phase 1 study. S-CKD602 was administered as a 1-hour intravenous infusion with doses ranging from 0.1 to 2.5 mg/m(2) . Plasma concentrations of encapsulated and released CKD-602 were used to develop a population PK model using NONMEM. PK of encapsulated CKD-602 was described by a 1-compartment model with nonlinear clearance, and PK of released CKD-602 was described by a 2-compartment model with linear clearance for all patients. Covariate analysis revealed that tumor in the liver was a significant covariate for clearance of encapsulated CKD-602 and that age significantly influenced the release rate of CKD-602 from S-CKD602. Maximum elimination rate in patients with liver tumor is 1.5-fold higher compared with patients without liver tumor. Release rate of CKD-602 from S-CKD602 in patients less than 60 years old was 2.7-fold higher compared with patients 60 years old or older. These observations have potential implications in the optimal dosing of liposomal agents.

Hepatotoxicity Secondary to Chemotherapy

The difficult problem faced by multiple generation of practicing physicians is determining the cause of abnormal liver function tests in cancer patients on chemotherapy. Hepatotoxicity from chemotherapy occurs frequently from an unpredictable or idiosyncratic reaction. Despite remarkable advances in our understanding of the mechanisms of action, pharmacodynamics, and interrelationships between the liver and chemotherapy, the underlying etiology of hepatic toxicity for various agents remains unexplained. Here, we present a concise review of the broad differential diagnosis for abnormal liver function tests (LFTs) in oncology patients.

Genomic signatures for predicting survival and adjuvant chemotherapy benefit in patients with non-small-cell lung cancer

Background

Improved methods are needed for predicting prognosis and the benefit of delivering adjuvant chemotherapy (ACT) in patients with non-small-cell lung cancer (NSCLC).

Methods

A novel prognostic algorithm was identified using genomic profiles from 332 stage I-III adenocarcinomas and independently validated on a separate series of 264 patients with stage I-II tumors, compiled from five previous studies. The prognostic algorithm was used to interrogate genomic data from a series of patients treated with adjuvant chemotherapy. Those genes associated with outcome in the adjuvant treatment setting, independent to prognosis were used to train an algorithm able to classify a patient as either a responder or non-responder to ACT. The performance of this signature was independently validated on a separate series of genomic profiles from patients enrolled in a randomized controlled trial of cisplatin/vinorelbine vs. observation alone (JBR.10).

Results

NSCLC patients exhibiting the high-risk, poor-prognosis form of the 160-gene prognosis signature experienced a 2.80-times higher rate of 5-year disease specific death (log rank P < 0.0001) compared to those with the low-risk, good prognosis profile, adjusted for covariates. The prognosis signature was found to especially accurate at identifying early stage patients at risk of disease specific death within 24 months of diagnosis when compared to traditional methods of outcome prediction.

Separately, NSCLC patients with the 37-gene ACT-response signature (n = 70, 64 %), benefited significantly from cisplatin/vinorelbine (adjusted HR: 0.23, P = 0.0032). For those patients predicted to be responders, receiving this form of ACT conferred a 25 % improvement in the probability of 5-year-survival, compared to observation alone and adjusted for covariates. Conversely, in those patients predicted to be non-responders, ACT was observed to offer no significant survival benefit (adjusted HR: 0.55, P = 0.32).

The two gene signatures overlap by one gene only SPSB3, which interacts with the oncogene MET. In this study, higher levels of SPSB3 which were associated with favorable prognosis and benefit from ACT.

Conclusions

These complimentary prognostic and predictive gene signatures may assist physicians in their management and treatment of patients with early stage lung cancer.

Interpatient pharmacokinetic and pharmacodynamic variability of carrier-mediated anticancer agents

Major advances in the field of carrier-mediated agents (CMAs) have revolutionized drug delivery capabilities over the past decade. While providing numerous advantages over their small-molecule counterparts (solubility,duration of exposure, and delivery to the site of action are higher), these agents display substantial variability in systemic clearance (CL) and distribution, tumor delivery, and pharmacologic effects. This review provides an overview of factors that affect the pharmacokinetics (PK) and pharmacodynamics (PD) of CMAs in preclinical models and patients.

Pharmacokinetics and safety of Marqibo (vincristine sulfate liposomes injection) in cancer patients with impaired liver function

Marqibo (vincristine sulfate liposome injection, VSLI) is a novel liposomal formulation of vincristine sulfate (VCR) being developed for the systemic treatment of cancer. This study evaluated the pharmacokinetics (PK) of Marqibo in subjects with melanoma and impaired hepatic function. Calculated PK parameters were similar in subjects with impaired liver function compared with those in subjects with adequate liver function. Subjects with impaired liver function universally had a monoexponential total plasma VCR concentration versus time decline, whereas two thirds of subjects with adequate liver function had a biexponential decline profile. Because one third of subjects with normal hepatic function demonstrated monoexponential disposition, lack of biexponential disposition in the hepatically impaired subjects cannot be clearly attributed to liver impairment. VSLI was generally well tolerated in all subjects.

Mild to moderate liver dysfunction does not require dose reduction of oral or intravenous vinorelbine: results of a pharmacokinetic study

We studied the pharmacokinetic profile of weekly oral and intravenous vinorelbine in cancer patients with various degrees of hepatic function, and assessed an intra-patient comparison of the pharmacokinetics of i.v. versus oral vinorelbine. In this open-label study, patients were randomised to receive an initial dose of vinorelbine at day 1 by either i.v. or the oral route followed by a second dose on day 8 via the alternative route. A total of 16 patients were included, 12 patients received the planned two administrations. Toxicities were similar for all cohorts and were mainly of haematological and gastrointestinal origin. Pharmacokinetic analysis of both routes did not reveal any differences between cohort I and II. Based on these findings in patients with mild to moderate liver dysfunction no dose modifications of vinorelbine have to be taken into consideration.

Part II: Liver function in oncology: towards safer chemotherapy use

The liver is fundamentally important in drug metabolism. In oncology, the astute clinician must not only understand the meaning and limitations of commonly ordered liver biochemical tests, but also be aware of which anticancer agents might induce liver dysfunction, and of the strategies for appropriate dosing of patients with pre-existing liver dysfunction. In part I of our Review, we highlighted both the importance and inadequacies of identifying serum biochemical liver abnormalities in oncology; we also discussed a lack of routine formal investigation of liver function. We summarised chemotherapy-related hepatotoxicity and other causes of liver toxic effects in patients with cancer. Here in part II, we discuss trials that have specifically assessed chemotherapy dosing strategies in the setting of overt biochemical liver dysfunction and we note their recommendations. Furthermore, we review other assessments of liver metabolic and excretory function, particularly in the setting of chemotherapy drug handling. We discuss the potential use of these metabolic probes in practice.

Combined Chemotherapy with Mitomycin C, Folinic Acid, and 5-Fluorouracil (MiFoFU) as Salvage Treatment for Patients with Liver Metastases from Breast Cancer - a Retrospective Analysis

BACKGROUND: The aim of this study was to analyze the activity and tolerability of a combined chemotherapy with mitomycin C, folinic acid, and 5-fluorouracil (MiFoFU) in patients with hepatic metastases from breast cancer, and in particular in patients with impaired liver function. PATIENTS AND METHODS: We retrospectively studied the charts of 44 patients who were treated with a MiFoFU combination therapy because of progressive metastatic breast cancer. Predominant site of metastases was the liver. Primary endpoints were response and time to progression (TTP); secondary endpoints were overall survival (OS) and tolerability. RESULTS: Median age prior to treatment was 59 years. A median of 6 treatment cycles were administered per patient. Clinical benefit rate amounted to 64%. A mean TTP of 9 months and a mean OS of 14 months were found. Main clinical signs of nonhematological toxicity were stomatitis, nausea, and diarrhea. Grade III/IV hematotoxicity was seen in only 9 patients. 16 patients showed clinical signs of liver dysfunction. A clinical benefit could be achieved in 8 of these patients. CONCLUSION: MiFoFU combination chemotherapy is a well-tolerated treatment alternative in the palliative therapy of patients with liver metastases from breast cancer. Particularly in patients with hepatic dysfunction, this regimen seems to represent a helpful treatment option.

Commentary: Oncologic drugs in patients with organ dysfunction: a summary

There are few prospective data regarding the pharmacokinetics and clinical toxicity of commonly used chemotherapeutics in cancer patients with organ dysfunction. Although increasing numbers of studies are investigating newer chemotherapeutics in patients with liver or kidney dysfunction, most guidelines for dosing, especially for established agents, remain empiric. This review describes the available data (both prospective and case study) evaluating the impact of renal and hepatic dysfunction on toxicity and dosing of commonly used chemotherapeutics and provides a practical summary for their use in this setting.

International Society of Geriatric Oncology Chemotherapy Taskforce: evaluation of chemotherapy in older patients--an analysis of the medical literature

The elderly comprise the majority of patients with cancer and are the recipients of the greatest amount of chemotherapy. Unfortunately, there is a lack of data to make evidence-based decisions with regard to chemotherapy. This is due to the minimal participation of older patients in clinical trials and that trials have not systematically evaluated chemotherapy. This article reviews the available information with regard to chemotherapy and aging provided by a task force of the International Society of Geriatric Oncology (SIOG). Due to the lack of prospective data, the conclusions and recommendations made are a consensus of the participants. Extrapolation of data from younger to older patients is necessary, particularly to those patients older than 80 years, for which data is almost entirely lacking. The classes of drugs reviewed include alkylators, antimetabolites, anthracyclines, taxanes, camptothecins, and epipodophyllotoxins. Clinical trials need to incorporate an analysis of chemotherapy in terms of the pharmacokinetic and pharmacodynamic effects of aging. In addition, data already accumulated need to be reanalyzed by age to aid in the management of the older cancer patient.

Dose adaptation of antineoplastic drugs in patients with liver disease

Dose adaptation for liver disease is important in patients treated with antineoplastic drugs because of the high prevalence of impaired liver function in this population and the dose-dependent, frequently serious adverse effects of these drugs. We classified the antineoplastic drugs marketed in Switzerland at the end of 2004 according to their bioavailability and/or hepatic extraction to predict their kinetic behaviour in patients with decreased liver function. This prediction was compared with kinetic studies carried out with these drugs in patients with liver disease. The studies were identified by a structured, computer-based literature search. Of the 69 drugs identified, 52 had a predominant extrarenal (in most cases hepatic) metabolism and/or excretion. For 49 drugs, hepatic extraction could be calculated and/or bioavailability data were available, allowing classification according to hepatic extraction. For 18 drugs, kinetic studies have been reported in patients with impaired liver function, with the findings generally resulting in quantitative recommendations for adaptation of the dosage. In particular, recommendations are precise for 16 drugs excreted by the bile (e.g. doxorubicin and derivatives and vinca alkaloids). Validation studies comparing such recommendations with kinetics and/or dynamics of antineoplastic drugs in patients with decreased liver function have not been published. We conclude that there are currently not enough data for safe use of cyctostatics in patients with liver disease. Pharmaceutical companies should be urged to provide kinetic data (especially hepatic extraction data) for the classification of such drugs and to conduct kinetic studies for drugs with primarily hepatic metabolism in patients with impaired liver function to allow quantitative advice to be given for dose adaptation.

A phase II study of an oxaliplatin/vinorelbine/5-fluorouracil combination in patients with anthracycline-pretreated and taxane-pretreated metastatic breast cancer

The aim of this phase II study was to evaluate safety and efficacy of an oxaliplatin/vinorelbine/5-fluorouracil (FON) combination in anthracycline and taxane-pretreated metastatic breast cancer patients. The following treatment was given: on day 1 of a 21-day cycle, oxaliplatin 130 mg/m (2-h intravenous infusion); on days 1 and 5, vinorelbine [dose level (DL) 1: 17.5 mg/m; DL2: 22 mg/m]; on days 1-5, continuous infusion 5-fluorouracil (DL1: 600 mg/m/day; DL2: 750 mg/m/day). Forty-seven patients were treated (DL1: 43; DL2: 4). Median age was 54 years; 68% had liver metastases, 53% were taxane refractory/resistant and 38% were anthracycline refractory/resistant. Patients received a median of six treatment cycles. Of 46 eligible patients, 16 had partial response; the overall response rate was 34.8% (95% confidence interval 21.3-50.3%), 11 had stable disease lasting more than 4 months. Median follow-up was 13.0 months, median time to progression 5.7 months and estimated overall survival 18.8 months. DL2 was too toxic with three patients having grade 3-4 toxicity, including one death. At DL1, 26 patients (60%) experienced grade 3-4 neutropenia (six febrile neutropenia) and eight had grade 3 oxaliplatin-specific peripheral neuropathy after a median of 646.4 mg/m oxaliplatin (range 124-1619 mg/m). Oxaliplatin (130 mg/m, day 1)/vinorelbine (17.5 mg/m, days 1,5)/5-fluorouracil (600 mg/m/day, days 1-5) demonstrate encouraging activity and a manageable safety profile in anthracycline- and taxane-pretreated metastatic breast cancer patients.

[Microsomal oxidative metabolism in the liver of rats treated with vinorelbine: evaluation through antipyrine elimination]

BACKGROUND

Determination of the metabolic efficiency of the liver in neoplastic diseases in patients receiving highly toxic drugs is of great practical importance.

METHODS

The effect of vinorelbine on the metabolic efficiency of the liver was evaluated by means of phenazone kinetics in rats. The test was compared with a battery of tests routinely used whenever hepatic dysfunction is suspected.

RESULTS

Vinorelbine was administered to the rats and the pharmacokinetic parameters of antipyrine were compared with those in control rats. A statistically significant prolongation of the elimination half-life, as well as a decrease in the elimination constant and clearance of antipyrine were found in the rats receiving the anticancer drug in comparison with controls (p < 0.01). Statistically significant correlations were found between the elimination half-life of antipyrine and serum albumin values (p < 0.01) and prothrombin time (p < 0.001).

CONCLUSIONS

Determination of antipyrine pharmacokinetics allows early detection of vinorelbine-induced hepatic dysfunction, with a sensitive scale.

Phase II study of an oxaliplatin/vinorelbine combination in patients with anthracycline- and taxane-pre-treated metastatic breast cancer

A phase II study was conducted to evaluate the safety and efficacy of an oxaliplatin (OXA)/vinorelbine (VNB) combination in metastatic breast cancer (MBC) patients pre-treated with anthracyclines and taxanes. Patients received OXA at 130 mg/m (2-h i.v.), day 1, and VNB days 1 and 8 at 24-26 mg/m repeated every 3 weeks. Forty-two patients (median age 54; 64% with liver metastasis, 67% taxane resistant/refractory and 38% anthracycline resistant/refractory) were treated. A median of 4 cycles of treatment was given per patient, with 31% receiving 6 or more. Eleven partial responses and 16 patients with stable disease (five lasting more than 4 months) in 41 eligible patients were seen, for an overall response rate of 26.8% (95% confidence interval 14.2-42.9). Median follow-up was 15.9 months (7.2-30.6), median time to progression was 3.4 months and estimated overall survival was 12.7 months (20 events). Thirty-three patients experienced (National Cancer Institute Common Toxicity Criteria version 2) grade 3-4 neutropenia (one case of febrile neutropenia) and three patients had severe constipation requiring hospitalization. Nine patients developed grade 3 OXA-specific neurotoxicity. There were no treatment-related deaths. We conclude that OXA 130 mg/m (day 1) and VNB 24 mg/m (day 1 and 8) combination given every 3 weeks is effective with a good safety profile in MBC patients previously treated with anthracyclines and taxanes.

Dexamethasone as a probe for vinorelbine clearance

AIM

To assess the value of using dexamethasone as an in vivo probe for predicting vinorelbine clearance (CL).

METHODS

A population approach (implemented with NONMEM) was used to analyse blood vinorelbine pharmacokinetic data from 20 patients who received a 20-min intravenous infusion of vinorelbine (from 20 to 30 mg m(-2)). Selected patient clinical data as well as known functional single CYP3A5 and ABCB1 genotype were also tested as covariates.

RESULTS

The best covariate model (with +/- 95% confidence intervals) was based on dexamethasone plasma clearance (DPC) and alkaline phosphatase (ALP): vinorelbine blood CL (l h(-1)) = 39.8(+/- 4.0) x (DPC/13.2)(0.524(+/-0.322)) x (ALP/137)(-0.198(+/-0.158)). Interindividual variability in vinorelbine CL decreased from 29.7% (model without covariate) to 14.7% when including DPC and ALP. Vinorelbine CL was not correlated with body surface area (BSA) or associated with CYP3A5 and ABCB1 genotype.

CONCLUSIONS

These results indicate that individualization of vinorelbine dose would be improved by using dexamethasone clearance rather than BSA. Dexamethasone merits further evaluation as a probe of CYP3A metabolism.

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.

Pharmacology of anticancer drugs in the elderly population

Modifications to bodily functions and physiology are known to occur with age. These changes can have a considerable impact on the pharmacokinetic processes of absorption, distribution, metabolism and excretion and the pharmacodynamic properties of administered drugs. For many drugs with a high therapeutic index, this will be clinically unimportant, but for anticancer drugs, which usually have a low therapeutic index, these pharmacological changes can lead to dramatic consequences, such as excessive drug concentrations and unacceptable toxicity, or subtherapeutic drug concentrations and ineffective treatment. Despite the increased susceptibility of the elderly to these changes, doses are rarely adapted on the basis of pharmacokinetics and pharmacodynamics, with the exception of changes secondary to altered renal function. Until recently, only a few large prospective randomised trials have provided evidence-based data for dose adaptations in elderly patients. However, with increasing knowledge of the pharmacokinetics of anticancer drugs, advances in the knowledge of pharmacokinetic behaviour with aging, and documented efficacy and toxicity data in the elderly population, it is possible to highlight aspects of prescribing anticancer drugs in the elderly. In general, and for most drugs, age itself is not a contraindication to full-dose chemotherapy. The main limiting factors are comorbidity and poor functional status, which may be present in a significant number of the elderly population. Elderly patients with cancer are part of the daily practice of oncologists, but currently clinicians can often only estimate whether dose modification is advantageous for the elderly. This review attempts to elucidate the factors that can influence the pharmacokinetics of anticancer drugs frequently used in the elderly, and the clinical or biochemical parameters that form the basis for dose adjustments with age.

A limited-sampling strategy to estimate individual pharmacokinetic parameters of vinorelbine in elderly patients with advanced metastatic cancer

The aim of this study was to characterize the population pharmacokinetic of vinorelbine in elderly patients and to propose a limited-sampling strategy to estimate individual pharmacokinetic parameters. Vinorelbine was administered by a 10-min continuous infusion at a dose of 20-30 mg/m2. The population parameters were computed, using a three-compartment model, from an initial group of 27 patients. Twelve additional courses were used for model validation and evaluation of eight different limited-sampling strategies. The inter-individual variability of CL was explained by a linear dependency with age. The population average parameters and the interindividual variabilities (CV%) were: CL=47.1 l/h (31.7%), V=16.6 l (64%), k21=0.776 h-1 (20%), k31=0.0346 h-1 (15.2%), alpha=0.431 h-1 (6.84%) and beta=0.0167 h-1 (25%). Bayesian estimation with three measured levels (end of infusion, and 6 and 48 h) can be selected, because it allows adequate estimation of CL, elimination half-life and vinorelbine concentrations with a non-significant bias. Moreover, the choice of these three sampling times presents practicality advantages for the patient's comfort. Vinorelbine clearance decreasing with age and AUC being a good predictor of several toxicity end points during vinorelbine treatment, the limited-sampling strategy developed in this paper may be clinically relevant.

Population pharmacokinetics model and limited sampling strategy for intravenous vinorelbine derived from phase I clinical trials

AIMS

a) To characterize the pharmacokinetics of intravenous vinorelbine, b) to use a population analysis for the identification of patient covariates that might appreciably influence its disposition and c) to define a limited sampling strategy for further Bayesian estimation of individual pharmacokinetic parameters.

METHODS

All data were collected from 64 patients (99 courses) entered in three different phase I trials that have been previously reported. All patients received vinorelbine as a 20 min infusion with dose levels ranging from 20-45 mg m-2. The population pharmacokinetic model was built in a sequential manner on a subset of two-thirds of the data, starting with a covariate-free model then progressing to a covariate model using the nonlinear-mixed effect methodology. The remaining one-third of the data were used to validate several sparse sampling designs.

RESULTS

A linear three-compartment model characterized vinorelbine blood concentrations (n=1228). Two primary pharmacokinetic parameters (total clearance and volume of distribution) were related to various combinations of covariates. The relationship for total clearance (CLtotal (l h-1)=29.2xBSAx(1-0.0090 Plt)+6.7xWt/Crs) was dependent on the patient's body surface area (BSA), weight (Wt), serum creatinine (Crs) and platelet count before administration (Plt). The optimal limited sampling strategy consisted of a combination of three measured blood concentrations; the first immediately before the end of infusion or 20 min later, the second at either 1 h, 3 h or 6 h and the third at 24 h after drug administration.

CONCLUSIONS

A population pharmacokinetic model and a limited sampling strategy for intravenous vinorelbine have been developed. This is the first population analysis performed on the basis of a large phase I database that has identified clinical covariates influencing the disposition of i.v. vinorelbine. The model can be used to obtain accurate Bayesian estimates of pharmacokinetic parameters in situations where extensive pharmacokinetic sampling is not feasable.

A sequence-dependent combination of docetaxel and vinorelbine: pharmacokinetic interactions

We studied possible pharmacokinetic interactions between docetaxel (DTX) and vinorelbine (VNR) in patients affected by different types of cancer. Patients with metastatic breast cancer or recurrent head and neck cancer received the following schedules: Protocol A: 11 patients were i.v. infused for 1 h with DTX (80 mg/m2) at once, followed by VNR (25 mg/m2) as slow i.v. bolus; Protocol B: VNR (25 mg/m2) as a slow 10 min i.v. bolus was administered to 12 patients, immediately followed by 1 h i.v. infusion of DTX (80 mg/m2). In both schedules, VNR and DTX plasma concentrations versus time were analysed by HPLC obtaining the corresponding non-compartmental pharmacokinetic parameters. VNR appeared pharmacokinetically affected by the sequential administration of DTX, since with protocol B, Cmax and AUC were significantly higher and clearance lower than in protocol A. Moreover, a significant increase in the VNR plasma level was observed in correspondence with the peak plasma level of DTX. By contrast, Cmax, AUC and clearance of DTX did not vary in the two protocols. Also the number of neutrophils at nadir on day 8 of treatment varied significantly in the two schedules. In conclusion we observed altered pharmacokinetic parameters between protocol A (DTX, VNR) and protocol B (VNR/DTX). In particular, patients following protocol B seemed to be exposed to higher VNR plasma concentration and to higher haematological toxicity.

Sensitive determination of vinorelbine and its metabolites in human serum using liquid chromatography-electrospray mass spectrometry

A liquid chromatography-electrospray mass spectrometry method was developed for the quantitation of vinorelbine (VNB) and two metabolites, vinorelbine N-oxide (VNO) and deacetyl vinorelbine (DAV) in human serum. The limits of quantitation (LOQ) reached 0.5 ng/ml for both VNB and VNO and 1 ng/ml for DAV. The method was proved linear in the range of LOQs up to 1000 ng/ml, and extraction recovery was 80% on average for the three compounds. It was applied to the pharmacokinetic monitoring of vinorelbine and, for the first time, to the detection of VNO in the serum of patients suffering from non-small-cell lung cancer.

The MEGX test: a tool for the real-time assessment of hepatic function

The dynamic liver function test based on the hepatic conversion of lidocaine to monoethylglycinexylidide (MEGX) can complement established static liver function tests if prognostic information is of particular interest. Because of its ease of use and rapid turnaround, the MEGX test has found widespread application for realtime assessment of hepatic function in transplantation, critical care medicine, and various experimental models. Lidocaine is metabolized primarily by the liver cytochrome P450 system through sequential oxidative N-dealkylation, the major initial metabolite in humans being MEGX. Because of the relatively high extraction ratio of lidocaine, this liver function test depends not only on hepatic metabolic capacity but also on hepatic blood flow. For the determination of MEGX in serum, an immunoassay based on the fluorescence polarization immunoassay technique high-performance liquid chromatography and gas liquid chromatography methods have been described. Whereas high-performance liquid chromatography and gas liquid chromatography are specific for MEGX, the fluorescence polarization immunoassay also cross-reacts with 3-OH-MEGX. Although this is not a problem in humans, some species, such as the rat, produce significant amounts of this metabolite. The findings of most studies published so far suggest that the MEGX test is a useful tool that can improve our decision-making process with respect to the selection of transplant candidates. Patients with a MEGX 15- or 30-minute test value <10 microg/L have a particularly poor 1-year survival rate. Serial monitoring of liver graft recipients early after transplantation with the MEGX test may initially alert the clinician to a major change in liver function; if used with other tests, such as serum hyaluronic acid concentrations, it may become more discriminatory. In critically ill patients, several studies have shown that an initially rapid decrease in MEGX test values is associated with an enhanced risk for the development of multiple organ dysfunction syndrome and a poor outcome. Further, this decrease appears to be associated with an enhanced systemic inflammatory response. The MEGX test has potential for investigating the pathogenesis of multiple organ dysfunction syndrome with regard to early hepatic functional impairment in critically ill patients after polytrauma or sepsis.

Adaptive control methods for the dose individualisation of anticancer agents

Numerous studies have found a clear relationship between systemic exposure and the toxicity or (more rarely) the efficacy of anticancer agents. Moreover, the clearance of most of these drugs differs widely between patients. These findings, combined with the narrow therapeutic index of anticancer drugs, suggest that patient outcome would be improved if doses were individualised to achieve a target systemic exposure. Bayesian maximum a posteriori probability (MAP) forecasting is an efficient and robust method for the optimisation of drug therapy, but its use for anticancer drugs is not yet extensive. The aim of this paper is to review the application of population pharmacokinetics and MAP to anticancer drugs and to evaluate whether and when MAP Bayesian estimation improves the clinical benefit of anticancer chemotherapy. For each drug, the relationships between pharmacokinetic variables [e.g. plasma concentration or the area under the concentration-time curve] and pharmacodynamic effects are described. Secondly, the methodologies employed are considered and, finally, the results are analysed in terms of predictive performance as well as, where possible, the impact on clinical end-points. Some studies were retrospective and intended only to evaluate individual pharmacokinetic parameter values using very few blood samples. Among the prospective trials, a few studied the pharmacokinetic/pharmacodynamic relationships which provided the basis for routine pharmacokinetic monitoring. Others were performed in clinical context where MAP Bayesian estimation was used to determine maximum tolerated systemic exposure (e.g. for carboplatin, topotecan, teniposide) or for pharmacokinetic monitoring (e.g. for methotrexate or platinum compounds). Indeed, its flexibility in blood sampling times makes this technique much more applicable than other limited sampling strategies. These examples demonstrate that individual dose adjustment helps manage toxicity. The performance of pharmacokinetic monitoring is linked to the methodology used at each step of its design and application. Moreover, a limitation to the use of pharmacokinetic monitoring for certain anticancer drugs has been the difficulty in obtaining pharmacokinetic or pharmacodynamic data. Recent progress in analytical methods, as well as the development of noninvasive methods (such as positron emission tomography) for evaluating the effects of chemotherapy, will help to define pharmacokinetic-pharmacodynamic relationships. Bayesian estimation is the strategy of choice for performing pharmacokinetic studies, as well as ensuring that a given patient benefits from the desired systemic exposure. Together, these methods could contribute to improving cancer chemotherapy in terms of patient outcome and survival.

Pharmacokinetics of anticancer agents in patients with impaired liver function

This report reviews published information on the clinical pharmacokinetics of antitumour agents in patients with liver dysfunction, associated with primary liver disease or liver metastases. Information was available for anthracyclines and their related compounds, antimetabolites, cyclophosphamide, vinca alkaloids, taxanes and epipodophyllotoxins. Changes in the pharmacokinetic profile or metabolism in patients with mild or severe hepatobiliary dysfunction are described and the relationships between serum levels, parameters employed for measuring hepatic function and toxic or therapeutic effects are examined. Current knowledge of the pharmacokinetics of antineoplastic agents in liver disease is far from complete, mostly obtained in small numbers of non-homogeneous patients often presenting only moderate liver dysfunction, and empirical guidelines for dose assessment are still largely applied in clinical practice. Because of the complex pathophysiological mechanisms of liver insufficiency in cancer patients, there is still doubt whether endogenous markers are useful. Although caution in treating cancer patients with liver insufficiency is compulsory, for most compounds there seems no need to recommend dose reductions for moderate impairment. However, for the tubulin acting agents, vincristine, vinblastine and possibly for paclitaxel and docetaxel, there is strong evidence that dose adjustment is mandatory in order to avoid excessive neutropenia and neurotoxicity.

Vinorelbine (Navelbine): a third-generation vinca alkaloid

The vinca alkaloids represent one of the oldest classes of antineoplastic agents used in humans with a wide spectrum of activity against both animal and human tumors. These agents are known to inhibit microtubule polymerization. Vinorelbine is a semisynthetic analog that reached clinical trial on the basis of less preclinical evidence of toxicity to neuronal tissue and greater cytotoxic activity in preclinical models than the older compounds of this class. In humans, the clearance of this agent shows a wide variation among subjects with the predominant toxicity being hematological. Significant antitumor activity has been observed in diseases that previously have been shown to respond to vinca alkaloids.

Pharmacokinetics and tolerance of vinorelbine in elderly patients with metastatic breast cancer

25 patients older than 65 years with metastatic breast cancer were treated with vinorelbine 30 mg/m2 i.v. days 1 and 8 every 3 weeks; the pharmacokinetics were studied in 10 of them. Vinorelbine showed a large apparent volume of distribution (mean 23.4 l/kg), a long terminal half-life (mean 26.2 h) and a large systemic clearance rate (mean 1.2 l/kg). These results are similar to those reported in younger patients. No correlation has been found between toxicity, age and drug exposure. We observed 6 partial responses out of 20 evaluable patients despite a relatively low mean dose intensity (67%). Severe neutropenia occurred in 37% of the patients; other side-effects were acceptable. This study does not provide a pharmacokinetic rationale for reducing the dosage of vinorelbine in selected elderly patients.