Vincristine pharmacokinetics and response to vincristine monotherapy in an up-front window study of the Dutch Childhood Leukaemia Study Group (DCLSG)

Simultaneous quantification and pharmacokinetics of vincristine and its major metabolite M1 in Chinese pediatric ALL patients by LC-MS/MS

Vincristine (VCR) is a vital component in numerous treatment regimens for pediatric blood cancer. VCR-induced peripheral neuropathy (VIPN) represents a type of VCR toxicity influenced by multiple factors, including age, race, genetic traits, dosage, interactions, and administration regimen. However, the dose-response relationship of VIPN remains elusive. VCR is primarily metabolized by cytochrome P450 (CYP) 3 A to generate the major metabolite M1. To date, there is a lack of literature documenting the pharmacokinetics (PK) characteristics of VCR and M1 in Chinese children within a 96 h timeframe. To address the gap, a developed LC-MS/MS method was successfully employed in the PK study of VCR and M1 in Chinese pediatric acute lymphoblastic leukemia (ALL) patients. M1 was obtained through in vitro metabolism experiments, and mixed plasma samples of M1 and VCR were prepared. Plasma samples were pre-processed using the solid-phase extraction (SPE) technique. Samples were loaded into ProElut C18 Cartridges, washed with 5% methanol aqueous solution, and eluted with methanol. The eluent was concentrated and reconstituted for liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The standard calibration curves for VCR and M1 were 0.1-50 ng/mL and 0.05-5 ng/mL, respectively, with linear coefficients exceeding 0.99. Accuracy and precision of quality control (QC) samples fell within 115%. The analytical approach satisfied the quantitative demands for VCR and M1 in plasma samples within 96 h. VCR was metabolized to M1 at a relatively constant proportion (5.37%-18.06%) of VCR in vivo. No significant differences were observed in PK parameters of VCR in Chinese children compared to other countries and races. Further investigation is required to identify the key factors influencing VIPN in Chinese children.

A sensitive liquid chromatographic-mass spectrometry method for the quantification of vincristine in whole blood collected with volumetric absorptive microsampling

Vincristine is a well-established cytotoxic drug. In paediatric populations blood collection via venipuncture is not always feasible. Volumetric absorptive microsampling (VAMS) is a less invasive method for blood collection. Furthermore, VAMS lacks the haematocrit effect on the recovery known with dried blood spots. Therefore, a liquid chromatography tandem-mass spectrometry method was developed and validated for the quantification of vincristine in whole blood collected with VAMS devices. Sample preparation consisted of solid-liquid extraction with 0.2% formic acid in water and acetonitrile. The final extract was injected on a C18 column (2.0 ×50 mm, 5 µm). Gradient elution was used and quantification was accomplished with a triple quadruple mass spectrometer operating in the positive mode. The validated concentration range was from 1 to 50 ng/mL with an intra- and inter-accuracy and precision of ± 10.3% and ≤ 7.3%, respectively. This method was able to successfully quantify vincristine concentrations in whole blood collected with VAMS from paediatric oncology patients. Vincristine concentrations in whole blood were non-linearly associated with plasma concentrations, which could be described with a saturable binding equilibrium model.

Proactive therapeutic drug monitoring of vincristine in pediatric and adult cancer patients: current supporting evidence and future efforts

Vincristine (VCR), an effective antitumor drug, has been utilized in several polytherapy regimens for acute lymphoblastic leukemia, neuroblastoma and rhabdomyosarcoma. However, clinical evidence shows that the metabolism of VCR varies greatly among patients. The traditional based body surface area (BSA) administration method is prone to insufficient exposure to VCR or severe VCR-induced peripheral neurotoxicity (VIPN). Therefore, reliable strategies are urgently needed to improve efficacy and reduce VIPN. Due to the unpredictable pharmacokinetic changes of VCR, therapeutic drug monitoring (TDM) may help to ensure its efficacy and to manage VIPN. At present, there is a lot of supporting evidence for the suitability of applying TDM to VCR therapy. Based on the consensus guidelines drafted by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology (IATDMCT), this review aimed to summarize various available data to evaluate the potential utility of VCR TDM for cancer patients. Of note, valuable evidence has accumulated on pharmacokinetics variability, pharmacodynamics, drug exposure-clinical response relationship, biomarkers for VIPN prediction, and assays for VCR monitoring. However, there are still many relevant clinical pharmacological questions that cannot yet be answered merely based on insufficient evidence. Currently, we cannot recommend a therapeutic exposure range and cannot yet provide a dose-adaptation strategy for clinicians and patients. In areas where the evidence is not yet sufficient, more research is needed in the future. The precision medicine of VCR cannot rely on TDM alone and needs to consider the clinical, environmental, genetic background and patient-specific factors as a whole.

Population pharmacokinetic model development and exposure-response analysis of vincristine in patients with malignant lymphoma

PURPOSE

Vincristine (VCR) is a key drug for treating various malignancies. However, few data are available on the pharmacokinetics of VCR, especially in adult patients. The objective of this study was to clarify the population pharmacokinetics and exposure-response relationships of VCR in adult malignant lymphoma patients.

METHODS

Blood samples were collected from patients who were administered R-CHOP-like regimens, and the VCR plasma concentration was determined using liquid chromatography-mass spectrometry. Using NONMEM software, population pharmacokinetic parameters were estimated, and covariates were evaluated. The relationships between the individual parameters and adverse events or therapeutic effects were also investigated.

RESULTS

Plasma concentrations were measured in 30 patients. In the final population pharmacokinetics model, body surface area and age were incorporated into clearance as significant covariates. The inter-individual variations in clearance and volume of distribution in the central and third compartments were 17.0, 26.6, and 66.3%, respectively, and the residual variability in the plasma concentration was 23.8%. Although the variability observed in the volume of distribution was large, good predictability was obtained in the individual estimation. The severity of anemia and peripheral neuropathy was correlated with clearance and peak concentration, respectively (adjusted P = 0.040 and 0.024, respectively). In diffuse large B cell lymphoma patients, those with higher area under the curve and dose experienced longer progression-free survival (P = 0.023 and 0.013, respectively).

CONCLUSION

The population pharmacokinetics of VCR were evaluated in adult malignant lymphoma patients. VCR pharmacokinetic data could explain in part the adverse events and prognosis of these patients.

Intracellular vincristine levels in lymphoblasts affect treatment outcome in childhood B-lymphoblastic leukaemia: Ma-Spore ALL 2010 study

AIMS

Vincristine (VCR) is a key drug in the successful multidrug chemotherapy for childhood acute lymphoblastic leukaemia (ALL). However, it remains unclear how VCR pharmacokinetics affects its antileukaemic efficacy. The objective of this study is to explore the VCR pharmacokinetic parameters and intracellular VCR levels in an up-front window of Ma-Spore ALL 2010 (MS2010) study.

METHODS

We randomised 429 children with newly diagnosed ALL to 15-minute vs 3-hour infusion for the first dose of VCR to study if prolonging the first dose of VCR infusion improved response. In a subgroup of 115 B-ALL and 20 T-ALL patients, we performed VCR plasma (n = 135 patients) and intracellular (n = 66 patients) pharmacokinetic studies. The correlations between pharmacokinetic parameters and intracellular VCR levels with early treatment response, final outcome and ABCB1 genotypes were analysed.

RESULTS

There was no significant difference between 15-minute and 3-hour infusion schedules in median Day 8 peripheral or bone marrow blast response. Plasma VCR pharmacokinetic parameters did not predict outcome. However, in B-ALL, Day 33 minimal residual disease (MRD) negative patients and patients in continuous complete remission had significantly higher median intracellular VCR_24h levels (P = .03 and P = .04, respectively). The median VCR_24h intracellular levels were similar among the common genetic subtypes of ALL (P = .4). Patients homozygous for wild-type ABCB1 2677GG had significantly higher median intracellular VCR_24h (P = .04) than 2677TT.

CONCLUSION

We showed that in childhood B-ALL, the intracellular VCR_24h levels in lymphoblasts affected treatment outcomes. The intracellular VCR_24h level was independent of leukaemia subtype but dependent on host ABCB1 G2677T genotype.

Population Pharmacokinetics of Vincristine Related to Infusion Duration and Peripheral Neuropathy in Pediatric Oncology Patients

Vincristine (VCR) is frequently used in pediatric oncology and can be administered intravenously through push injections or 1 h infusions. The effects of administration duration on population pharmacokinetics (PK) are unknown. We described PK differences related to administration duration and the relation between PK and VCR-induced peripheral neuropathy (VIPN). PK was assessed in 1-5 occasions (1-8 samples in 24 h per occasion). Samples were analyzed using high-performance liquid chromatography/tandem mass spectrometry. Population PK of VCR and its relationship with administration duration was determined using a non-linear mixed effect. We estimated individual post-hoc parameters: area under the concentration time curve (AUC) and maximum concentration (C_max) in the plasma and peripheral compartment. VIPN was assessed using Common Terminology Criteria for Adverse Events (CTCAE) and the pediatric-modified total neuropathy score (ped-mTNS). Overall, 70 PK assessments in 35 children were evaluated. The population estimated that the intercompartmental clearance (IC-Cl), volume of the peripheral compartment (V₂), and C_max were significantly higher in the push group. Furthermore, higher IC-Cl was significantly correlated with VIPN development. Administration of VCR by push led to increased IC-Cl, V₂, and C_max, but were similar to AUC, compared to 1 h infusions. Administration of VCR by 1 h infusions led to similar or higher exposure of VCR without increasing VIPN.

Doxorubicin induces cytotoxicity and miR-132 expression in granulosa cells

Doxorubicin (DOX) is one of the most commonly used drugs for the treatment of childhood cancers, including leukemia and lymphomas. Despite the high survival rate, female leukemia survivors are at higher risk of ovarian failure and infertility later in life. Treatment with chemotherapeutic drugs like DOX is associated with damage in ovarian follicles, but the affectation grade of granulosa cells remains unclear. To assess and avoid the possible side-effects of DOX, early biomarkers of ovarian injury and chemotherapy-induced ovarian toxicity should be identified. MicroRNAs (miRNAs) have emerged in recent years as a promising new class of biomarkers for drug-induced tissue toxicity. In this study, the effects of DOX on cell viability, steroidogenesis, and miRNA expression were studied in primary granulosa cells (GCs) and in two cellular models (COV434 and KGN cells). We report that compared to other chemotherapeutic drugs, DOX treatment is more detrimental to granulosa cells as observed by decrease of cell viability. Treatment with DOX changes the expression of the aromatase gene (CYP19A1) and the secretion of 17β-estradiol (E2) in a cell-specific manner. miR-132-3p is dose-dependently increased by DOX in all cellular models. In absence of DOX, miR-132-3p overexpression in COV434 cells has no effect on E2 secretion or CYP19A1 expression. Altogether, these findings contribute to understanding the hormonal disbalance caused by DOX in human ovarian cells and suggest miR-132 as a putative sensor to predict DOX-induced ovarian toxicity.

A review of current induction strategies and emerging prognostic factors in the management of children and adolescents with acute lymphoblastic leukemia

INTRODUCTION

Acute lymphoblastic leukemia is the most frequent hematologic malignancy in children. Almost 95% of children potentially achieve a complete remission after the induction treatment, but over the last years, new insights in the genomic disease profile and in minimal residual disease detection techniques have led to an improvement in the prognostic stratification, identifying selected patients' subgroups with peculiar therapeutic needs.

AREAS COVERED

According to a comprehensive search of peer-review literature performed in Pubmed, in this review we summarize the recent evidences on the induction treatment strategies comprised in the children acute lymphoblastic leukemia scenario, focusing on the role of key drugs such as corticosteroids and asparaginase and discussing the crucial significance of the genomic characterization at baseline which may drive the proper induction treatment choice.

EXPERT OPINION

Current induction strategies already produce durable remissions in a significant proportion of standard-risk children with acute lymphoblastic leukemia. A broader knowledge of the biologic features related to acute lymphoblastic leukemia subtypes with worse prognosis, and an optimization of targeted drugs now available, might lead to the achievement of long-term molecular remissions in this setting.

Vincristine Sulfate Liposomes Injection (VSLI, Marqibo®): Results From a Phase I Study in Children, Adolescents, and Young Adults With Refractory Solid Tumors or Leukemias

BACKGROUND

Vincristine sulfate liposome injection (VSLI; Marqibo®) is an encapsulated preparation of standard vincristine in sphingomyelin/cholesterol liposomes. Clinical trials in adults have demonstrated safety, tolerability, and activity, leading to Food and Drug Administration (FDA) approval for adults with relapsed acute lymphoblastic leukemia (ALL). Pediatric experience with VSLI is limited.

PROCEDURE

This single center, phase I dose escalation study examined the safety, toxicity, maximum tolerated dose, and pharmacokinetics of VSLI administered weekly to pediatric patients age <21 years with relapsed or chemotherapy-refractory solid tumors or leukemia.

RESULTS

Twenty-one subjects were treated in total. Median age was 13.3 years (range 2-19). Fourteen subjects completed one 28-day cycle of therapy and five subjects completed more than one cycle. No subject experienced dose-limiting toxicity (DLT) at the first dose level (1.75 mg/m(2) /dose, dose range: 2-3.7 mg). At the second dose level (2.25 mg/m(2) /dose, dose range: 1.3-4.5 mg), one subject had transient dose-limiting grade 4 transaminase elevation, and this dose level was expanded with no additional DLT observed. The second dose level then opened to an expansion phase to evaluate activity in ALL. Clinical activity included minimal residual disease negative complete remission in one subject with ALL and stable disease in nine subjects. Clearance of total vincristine was found to be approximately 100-fold lower in comparison to published data using standard vincristine.

CONCLUSIONS

Children tolerate 2.25 mg/m(2) /dose of weekly VSLI (the adult FDA-approved dose) with evidence for clinical activity without dose-limiting neurotoxicity. Future plans include studying VSLI as substitution for standard vincristine with combination chemotherapy in children with ALL.

Pharmacokinetic evaluation of vincristine for the treatment of lymphoid malignancies

INTRODUCTION

Vincristine is a key agent for the treatment of acute lymphoblastic leukemia (ALL) and other lymphoid malignancies. The strong antineoplastic activity of vincristine has been limited by its pharmacological characteristics.

AREAS COVERED

This paper reviews the role of vincristine in the treatment of lymphoid malignancies. This review summarizes its efficacy and toxicity, and focuses on the pharmacokinetic features of vincristine that affect clinical outcomes.

EXPERT OPINION

As a single agent, vincristine is associated with brief and incomplete responses, but in combination with other agents, vincristine has dramatically improved the outcomes of lymphoid malignancies such as ALL. Vincristine is a key drug of hyper-fractionated cyclophosphamide, vincristine, doxorubicin and dexamethasone, an intensive chemotherapeutic regimen for the treatment of ALL, and of cyclophosphamid, adriamycin, vincristine and prednisone, which has been used extensively in the treatment of patients with aggressive or indolent lymphomas and Richter syndrome. The strong antileukemic activity of vincristine has been limited by its variable and unpredictable pharmacological characteristics, narrow therapeutic index and neurotoxicity profile. These characteristics prompted the development of liposomal vincristine, which has optimized its clinical application. Liposomal vincristine has promising antileukemic activity, and it is approved by the FDA as a single agent for the treatment of relapsed/refractory Philadelphia chromosome-negative ALL.

Vincristine chemotherapy trials and pharmacokinetics in tasmanian devils with tasmanian devil facial tumor disease

Tasmanian Devil Facial Tumor Disease (DFTD) is a transmissible cancer threatening to cause the extinction of Tasmanian Devils in the wild. The aim of this study was to determine the susceptibility of the DFTD to vincristine. Escalating dosage rates of vincristine (0.05 to 0.136 mg/kg) were given to Tasmanian devils in the early stages of DFTD (n = 8). None of these dosage rates impacted the outcome of the disease. A dosage rate of 0.105 mg/kg, a rate significantly higher than that given in humans or domestic animals, was found to the highest dosage rate that could be administered safely. Signs of toxicity included anorexia, vomiting, diarrhea and neutropenia. Pharmacokinetic studies showed that, as with other species, there was a rapid drop in blood concentration following a rapid intravenous infusion with a high volume of distribution (1.96 L/kg) and a relatively long elimination half life (11 h). Plasma clearance (1.8 ml/min/kg) was slower in the Tasmanian devil than in humans, suggesting that pharmacodynamics and not pharmacokinetics explain the Tasmanian devil's ability to tolerate high dosage rates of vincristine. While providing base-line data for the use of vincristine in Tasmanian devils and possibly other marsupials with vincristine susceptible cancers, these findings strongly suggest that vincristine will not be effective in the treatment of DFTD.

Vincristine pharmacodynamics and pharmacogenetics in children with cancer: a limited-sampling, population modelling approach

BACKGROUND

Vincristine is a key component of many childhood cancer treatment regimens. Pharmacodynamic parameters such as clinical efficacy and toxicity may be influenced by polymorphisms of CYP3A.

AIM

The aim of this study was to document CYP3A5 genotype, vincristine pharmacokinetics (PK) and neurotoxicity profile for 50 children with cancer and determine whether, in a population of Australian children, the CYP3A5 genotype influenced the pharmacodynamics of vincristine as reflected by peripheral neurotoxicity.

METHODS

Blood for PK analysis was collected after any single dose of vincristine and assayed using high performance liquid chromatography with tandem mass spectrometry detection. CYP3A5*3 and CYP3A5*6 genotype was determined using gel-electrophoresis or automated microfluidic electrophoresis. Neurotoxicity was determined by physical examination.

RESULTS

The median age of children sampled was 6.5 years (range 1-16.25). Half the patients received concurrent corticosteroids for acute lymphoblastic leukaemia. Six patients (12%) had experienced grade 3 or 4 neurotoxicity. The median clearance, area under the curve and Cmax of vincristine was 482 mL/min/m(2) (range 132-698), 49.7 mcg/L.h (16.5-143.1) and 3.5 mcg/L (1.0-31.2), respectively. In contrast to prediction, all but three children were homozygous for wild-type CYP3A5*3. No CYP3A5*6 polymorphisms were identified.

CONCLUSIONS

No correlation was identified between vincristine clearance, vincristine neurotoxicity, age, sex or concomitant steroid therapy. The limited sampling methodology proved acceptable to patients and families and would be suitable for larger scale studies including a wider range of genotypic variants and more detailed prospective evaluation of neurotoxicity.

Do pharmacokinetic polymorphisms explain treatment failure in high-risk patients with neuroblastoma?

PURPOSE

Neuroblastoma is the most common extracranial solid tumour in childhood. It accounts for 15% of all paediatric oncology deaths. In the last few decades, improvement in treatment outcome for high-risk patients has not occurred, with an overall survival rate <30-40%. Many reasons may account for such a low survival rate. The aim of this review is to evaluate whether pharmacogenetic factors can explain treatment failure in neuroblastoma.

METHODS

A literature search based on PubMed's database Medical Subject Headings (MeSH) was performed to retrieve all pertinent publications on current treatment options and new classes of drugs under investigation. One hundred and fifty-eight articles wer reviewed, and relevant data were extracted and summarised.

RESULTS AND CONCLUSIONS

Few of the large number of polymorphisms identified thus far showed an effect on pharmacokinetics that could be considered clinically relevant. Despite their clinical relevance, none of the single nucleotide polymorphisms (SNPs) investigated can explain treatment failure. These findings seem to reflect the clinical context in which anti-tumour drugs are used, i.e. in combination with multimodal therapy. In addition, many pharmacogenetic studies did not assess (differences in) drug exposure, which could contribute to explaining pharmacogenetic associations. Furthermore, it remains unclear whether the significant activity of new drugs on different neuroblastoma cell lines translates into clinical efficacy, irrespective of resistance or myelocytomatosis viral related oncogene, neuroblastoma derived (MYCN) amplification. Elucidation of the clinical role of pharmacogenetic factors in the treatment of neuroblastoma demands an integrated pharmacokinetic-pharmacodynamic approach to the analysis of treatment response data.

Long-term results of Dutch Childhood Oncology Group studies for children with acute lymphoblastic leukemia from 1984 to 2004

The Dutch Childhood Oncology Group (DCOG) has used two treatment strategies for children with acute lymphoblastic leukemia (ALL) based on Pinkel's St Jude Total Therapy or the Berlin-Frankfurt-Münster (BFM) backbone. In four successive protocols, 1734 children were treated. Studies ALL-6 and ALL-9 followed the Total Therapy approach; cranial irradiation was replaced by medium-dose methotrexate infusions and prolonged triple intrathecal therapy; dexamethasone was used instead of prednisone. Studies ALL-7 and ALL-8 had a BFM backbone, including more intensive remission induction, early reinduction and maintenance therapy without vincristine and prednisone pulses. The 5-year event-free survival and overall survival increased from 65.4 to 80.6% (P<0.001) and from 78.7 to 86.4% (P=0.07) in ALL-7 and ALL-9, respectively. In ALL-7 and ALL-8 National Cancer Institute (NCI) high-risk criteria, male gender, T-lineage ALL and high white blood cells (WBCs) predict poor outcome. In ALL-9 NCI criteria, gender, WBC >100 x 109/l, and T-lineage ALL have prognostic impact. We conclude that the chemotherapy-only approach in children with ALL in Total Therapy-based strategies and BFM-backbone treatment does not jeopardize survival and preserves cognitive functioning. This experience is implemented in the current DCOG-ALL-10 study using a BFM backbone and minimal residual disease-based stratification.

Vincristine: Can its therapeutic index be enhanced?

Vincristine is one of the most widely used and more effective drugs in paediatric oncology. The dose-limiting toxicity of neuropathy, lack of proven neuroprotective measures and an incomplete understanding of the pharmacokinetics and pharmacogenetics of vincristine have limited its therapeutic potential. Recent advances in the understanding of vincristine pharmacokinetics and pharmacogenetics, and potential methods of preventing neurotoxicity are reviewed which could enable dose escalation and dose individualisation in order to enhance the therapeutic index.

Validated assay for the simultaneous quantification of total vincristine and actinomycin-D concentrations in human EDTA plasma and of vincristine concentrations in human plasma ultrafiltrate by high-performance liquid chromatography coupled with tandem mass spectrometry

A sensitive, specific and efficient high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) assay for the simultaneous determination of total vincristine and actinomycin-D concentrations in human plasma and an assay for the determination of unbound vincristine are presented. Electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and heated electrospray ionization (H-ESI) were tested as ionization interfaces. For reasons of robustness ESI was chosen followed by tandem mass spectrometry (ESI-MS/MS). For the plasma assay a 30 microL aliquot was protein precipitated with acetonitrile/methanol (50:50, v/v) containing the internal standard vinorelbine and 10 microL volumes were injected onto the HPLC system. To determine unbound vincristine, ultrafiltrate was produced from plasma using 30 kDa centrifugal filter units. The plasma ultrafiltrate was mixed with methanol (50:50, v/v), internal standard vinorelbine was added and 20 microL aliquots were injected onto the HPLC system. Separation was achieved on a 50x2.1 mm i.d. Xbridge C18 column using 1 mM ammonium acetate/acetonitrile (30:70, v/v) adjusted to pH 10.5 with ammonia, run in a gradient with methanol at a flow rate of 0.4 mL/min. HPLC run time was 6 min. The assay quantifies in plasma vincristine from 0.25 to 100 ng/mL and actinomycin-D from 0.5 to 250 ng/mL using plasma sample volumes of only 30 microL. Vincristine in plasma ultrafiltrate can be quantified from 1 to 100 ng/mL. Validation results demonstrate that vincristine and actinomycin-D can be accurately and precisely quantified in human plasma and plasma ultrafiltrate with the presented methods. The assays are now in use to support clinical pharmacological studies in children treated with vincristine and actinomycin-D.

Pharmacogenetics influence treatment efficacy in childhood acute lymphoblastic leukemia

Pharmacogenetics covers the genetic variation affecting pharmacokinetics and pharmacodynamics, and their influence on drug-response phenotypes. The genetic variation includes an estimated 15 million single nucleotide polymorphisms (SNPs) and is a key determinator for the interindividual differences in treatment resistance and toxic side effects. As most childhood acute lymphoblastic leukemia treatment protocols include up to 13 different chemotherapeutic agents, the impact of individual SNPs has been difficult to evaluate. So far focus has mainly been on the widely used glucocorticosteroids, methotrexate, and thiopurines, or on metabolic pathways and transport mechanisms that are common to several drugs, such as the glutathione S-transferases. However, beyond the thiopurine methyltransferase polymorphisms, the candidate-gene approach has not established clear associations between polymorphisms and treatment response. In the future, high-throughput, low-cost, genetic platforms will allow screening of hundreds or thousands of targeted SNPs to give a combined gene-dosage effect (=individual SNP risk profile), which may allow pharmacogenetic-based individualization of treatment.

In vitro sensitivity testing of minimally passaged and uncultured gliomas with TRAIL and/or chemotherapy drugs

TRAIL/Apo-2L has shown promise as an anti-glioma drug, based on investigations of TRAIL sensitivity in established glioma cell lines, but it is not known how accurately TRAIL signalling pathways of glioma cells in vivo are reproduced in these cell lines in vitro. To replicate as closely as possible the in vivo behaviour of malignant glioma cells, 17 early passage glioma cell lines and 5 freshly resected gliomas were exposed to TRAIL-based agents and/or chemotherapeutic drugs. Normal human hepatocytes and astrocytes and established glioma cell lines were also tested. Cross-linked TRAIL, but not soluble TRAIL, killed both normal cell types and cells from three tumours. Cells from only one glioma were killed by soluble TRAIL, although only inefficiently. High concentrations of cisplatin were lethal to glioma cells, hepatocytes and astrocytes. Isolated combinations of TRAIL and chemotherapy drugs were more toxic to particular gliomas than normal cells, but no combination was generally selective for glioma cells. This study highlights the widespread resistance of glioma cells to TRAIL-based agents, but suggests that a minority of high-grade glioma patients may benefit from particular combinations of TRAIL and chemotherapy drugs. In vitro sensitivity assays may help identify effective drug combinations for individual glioma patients.

Vincristine pharmacokinetics is related to clinical outcome in children with standard risk acute lymphoblastic leukemia

Vincristine is a key drug in the treatment of childhood and adult acute lymphoblastic leukemia (ALL), and many other childhood malignancies. Despite decades of wide clinical use, no data on the correlation between vincristine pharmacokinetics and long-term clinical outcome have been published. We here report clinical data (median follow-up time 10.5 years, range 7.3-12 years) for 86 children with B-cell precursor ALL, in whom vincristine kinetics were studied on treatment day 1. The median total plasma clearance was 429 and 331 ml/min per m(2) and the area under the plasma concentration-time curve (AUC) was 4.49 and 5.40 mg/l x min in relapse and non-relapse patients, respectively (not significant). In standard risk patients, where treatment depends more heavily on vincristine than in other subgroups, the relative risk (RR) of relapse was significantly increased for patients with clearance values above median (RR 5.2; P = 0.036), or AUC values below median (RR 5.8; P = 0.025). Our data suggest a relationship between the antileukemic effect and the systemic exposure of the drug, which warrants further studies.

Rapid and sensitive analysis of vincristine in human plasma using on-line extraction combined with liquid chromatography/tandem mass spectrometry

A simple and rapid method has been developed and validated for the quantitation of vincristine in human plasma by liquid chromatography/tandem mass spectrometry (LC/MS/MS) with atmospheric pressure chemical ionization using on-line solid-phase extraction. The method uses vinblastine as internal standard and the sample preparation is limited just to a plasma protein precipitation step. Further sample clean-up is carried out on-line through a perfusion column preceding an analytical phenyl LC column, the latter directly connected to the mass spectrometer. Quantitation is performed in multiple reaction monitoring mode using the transitions of m/z 825.3 --> 765.3 and 811.3 --> 751.3 for vincristine and vinblastine respectively. The assay was linear (r2 > or =0.99) in a concentration range from 0.1 to 500 ng/mL. Carry-over, measured on the experimental set-up, was less than 0.04%. Recovery for vincristine and the internal standard was within 90-95%. The intra-day and inter-day assay precision ranged from 1.2% to 6.8% RSD while mean percentage deviation from nominal value ranged from 0.01% to 6.1%. The proposed assay was found suitable for pharmacokinetics investigations and clinical therapeutic drug monitoring especially in pediatric cancer patients.

Recent applications of liquid chromatography-mass spectrometry in natural products bioanalysis

Natural flavonoids, alkaloids, saponins and sesquiterpenoids have been extensively investigated because of their biological and physiological significances, as well as their promising clinical uses. It is necessary to monitor them or their metabolites in biological fluids for both pre-clinical studies and routine clinical uses. The successful hyphenation of LC and MS, which was thought as "the bird wants to marry with fish", has been conducted widely in biological samples analysis. This present paper reviewed the feasibility of LC-MS techniques in the identification and quantification of natural products (flavonoids, alkaloids, saponins and sesquiterpenoids) in biological fluids, dealing with sample preparation, LC techniques, suitability of different MS techniques. Perspective of LC-MS was also discussed to show the potential of this technology. The citations cover the period 2002-2006. We conclude that LC-MS is an extremely powerful tool for the analysis of natural products in biological samples.