Vincristine revisited

Variegated clonality and rapid emergence of new molecular lesions in xenografts of acute lymphoblastic leukemia are associated with drug resistance

The use of genome-wide copy-number analysis and massive parallel sequencing has revolutionized the understanding of the clonal architecture of pediatric acute lymphoblastic leukemia (ALL) by demonstrating that this disease is composed of highly variable clonal ancestries following the rules of Darwinian selection. The current study aimed to analyze the molecular composition of childhood ALL biopsies and patient-derived xenografts with particular emphasis on mechanisms associated with acquired chemoresistance. Genomic DNA from seven primary pediatric ALL patient samples, 29 serially passaged xenografts, and six in vivo selected chemoresistant xenografts were analyzed with 250K single-nucleotide polymorphism arrays. Copy-number analysis of non-drug-selected xenografts confirmed a highly variable molecular pattern of variegated subclones. Whereas primary patient samples from initial diagnosis displayed a mean of 5.7 copy-number alterations per sample, serially passaged xenografts contained a mean of 8.2 and chemoresistant xenografts a mean of 10.5 copy-number alterations per sample, respectively. Resistance to cytarabine was explained by a new homozygous deletion of the DCK gene, whereas methotrexate resistance was associated with monoallelic deletion of FPGS and mutation of the remaining allele. This study demonstrates that selecting for chemoresistance in xenografted human ALL cells can reveal novel mechanisms associated with drug resistance.

Clinical pharmacokinetics and effects of vincristine sulfate in dogs with transmissible venereal tumor (TVT)

This study was conducted to evaluate the pharmacokinetic characteristics of vincristine and their correlation with its clinical effects in dogs with transmissible venereal tumor (TVT). Dogs with TVT were intravenously administered vincristine sulfate at a dose of 0.7 mg/m(2) of body surface area. Blood samples were collected starting from 5 min to 48 hr after drug administration. The plasma concentration of vincristine was determined using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The pharmacokinetic parameters of vincristine were characterized using a two-compartmental pharmacokinetic model. The volume of distribution, distribution half-life, elimination half-life and plasma clearance were 0.660 ± 0.210 l/kg, 21.5 ± 6.90 min, 47.6 ± 14.2 min and 0.010 ± 0.001 l/min/kg, respectively. Tumor regression was determined at weekly interval by a physical examination and histopathological analysis. In our study, three to eight administrations of vincristine at a dose of 0.7 mg/m(2) were able to induce a complete tumor regression without any evidence of gross lesion of disease. Therefore, this investigation provides the pharmacokinetic characteristics of vincristine in dogs with TVT, which may be used as an integration tool to gain a better understanding of the disposition properties of the drug and the correlation of these properties with the drug's clinical effects. In addition, we validated the LC-MS/MS method and found that it is suitable for the pharmacokinetic study of vincristine in dog plasma.

Nanotube interactions with microtubules: implications for cancer medicine

Carbon nanotubes (CNTs) and microtubules are both hollow nanofibers and have similar dimensions; they both self-assemble and form bundles. These common features prompt their association into biosynthetic polymers in vitro and in vivo. Unlike CNTs, microtubules are highly dynamic protein polymers essential for cell proliferation and migration. Interaction between these filaments inside live cells leads to microtubule dysfunction, mitotic arrest and cell death. Thus, CNTs behave as spindle poisons, same as taxanes, vinca alkaloids or epotilones. Recent findings support the idea that CNTs represent a ground-breaking type of synthetic microtubule-stabilizing agents that could play a pivotal role in future cancer treatments in combination to traditional antineoplastic drugs. Here we review the potential use of CNTs in cancer medicine.

Low dose tubulin-binding drugs rescue peroxisome trafficking deficit in patient-derived stem cells in Hereditary Spastic Paraplegia

Hereditary Spastic Paraplegia (HSP) is a genetically heterogeneous group of disorders, diagnosed by progressive gait disturbances with muscle weakness and spasticity, for which there are no treatments targeted at the underlying pathophysiology. Mutations in spastin are a common cause of HSP. Spastin is a microtubule-severing protein whose mutation in mouse causes defective axonal transport. In human patient-derived olfactory neurosphere-derived (ONS) cells, spastin mutations lead to lower levels of acetylated α-tubulin, a marker of stabilised microtubules, and to slower speed of peroxisome trafficking. Here we screened multiple concentrations of four tubulin-binding drugs for their ability to rescue levels of acetylated α-tubulin in patient-derived ONS cells. Drug doses that restored acetylated α-tubulin to levels in control-derived ONS cells were then selected for their ability to rescue peroxisome trafficking deficits. Automated microscopic screening identified very low doses of the four drugs (0.5 nM taxol, 0.5 nM vinblastine, 2 nM epothilone D, 10 µM noscapine) that rescued acetylated α-tubulin in patient-derived ONS cells. These same doses rescued peroxisome trafficking deficits, restoring peroxisome speeds to untreated control cell levels. These results demonstrate a novel approach for drug screening based on high throughput automated microscopy for acetylated α-tubulin followed by functional validation of microtubule-based peroxisome transport. From a clinical perspective, all the drugs tested are used clinically, but at much higher doses. Importantly, epothilone D and noscapine can enter the central nervous system, making them potential candidates for future clinical trials.

Effects of anticancer drug docetaxel on the structure and function of the rabbit olfactory mucosa

Docetaxel (DCT) is an anticancer drug which acts by disrupting microtubule dynamics in the highly mitotic cancer cells. Thus, this drug has a potential to affect function and organization of tissues exhibiting high cellular turnover. We investigated, in the rabbit, the effects of a single human equivalent dose (6.26 mg/kg, i.v.) of DCT on the olfactory mucosa (OM) through light and electron microscopy, morphometry, Ki-67 immunostaining, TUNEL assay and the buried food test for olfactory sensitivity. On post-exposure days (PED) 5 and 10, there was disarrangement of the normal cell layering in the olfactory epithelium (OE), apoptotic death of cells of the OE, Bowman's glands and axon bundles, and the presence (including on PED 3) of blood vessels in the bundle cores. A decrease in bundle diameters, olfactory cell densities and cilia numbers, which was most significant on PED 10 (49.3%, 63.4% and 50%, respectively), was also evident. Surprisingly by PED 15, the OM regained normal morphology. Furthermore, olfactory sensitivity decreased progressively until PED 10 when olfaction was markedly impaired, and with recovery from the impairment by PED 15. These observations show that DCT transiently alters the structure and function of the OM suggesting a high regenerative potential for this tissue.

Kidney protein profiling of Wilms' tumor patients by analysis of formalin-fixed paraffin-embedded tissue samples

Wilms' tumor (nephroblastoma, WT) is the most frequent renal cancer in children. However, molecular details leading to WT have not been characterized sufficiently yet. Proteomic studies might provide new insights but are hampered by limited availability of fresh frozen tissue specimen. Therefore, we tested formalin-fixed paraffin-embedded (FFPE) tissue sections routinely collected for pathological inspection for their use in in-depth-proteomic analyses of WT samples in comparison to fresh frozen specimen. The overlap of the proteins identified was over 65%. Thus we used FFPE material from 7 patients for tandem mass spectrometry based comparison of the proteomes of WT and healthy renal tissues. We detected 262 proteins, which were differentially expressed in tumor compared to healthy renal tissue. The majority of these proteins displayed lower levels in the tumor tissue and only 30% higher levels. For selected candidates data were confirmed by immunohistochemical staining. Correlation analysis of blastemal proportions in WT and protein intensities revealed candidates for tumor stratification.

CONCLUSION

This proof of principle proteomic study of FFPE tissue sections from WT patients demonstrates that these archived tissues constitute a valuable resource for larger in-depth proteomic studies to identify markers to follow chemotherapy efficiency or for stratification of tumor subtypes.

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.

Targeting microtubules by natural agents for cancer therapy

Natural compounds that target microtubules and disrupt the normal function of the mitotic spindle have proven to be one of the best classes of cancer chemotherapeutic drugs available in clinics to date. There is increasing evidence showing that even minor alteration of microtubule dynamics can engage the spindle checkpoint, arresting cell-cycle progression at mitosis and subsequently leading to cell death. Our improved understanding of tumor biology and our continued appreciation for what the microtubule targeting agents (MTAs) can do have helped pave the way for a new era in the treatment of cancer. The effectiveness of these agents for cancer therapy has been impaired, however, by various side effects and drug resistance. Several new MTAs have shown potent activity against the proliferation of various cancer cells, including resistance to the existing MTAs. Sustained investigation of the mechanisms of action of MTAs, development and discovery of new drugs, and exploring new treatment strategies that reduce side effects and circumvent drug resistance could provide more effective therapeutic options for patients with cancer. This review focuses on the successful cancer chemotherapy from natural compounds in clinical settings and the challenges that may abort their usefulness.

Assessment of gross motor skills and phenotype profile in children 9-11 years of age in survivors of acute lymphoblastic leukemia

BACKGROUND

The purpose of this study was to evaluate the usefulness of a new gross motor skill test battery in acute lymphoblastic leukemia (ALL) children who have been off therapy for at least 1 year and to assess its discriminatory power (discriminant analysis) from healthy children.

PROCEDURE

Twenty children (10 males and 10 females) 9-11 years of age (median age = 10.6 years) were assessed by the UQAC-UQAM test battery and then compared to recent provincial norms. This pilot study was also an opportunity to validate this test battery as a reliable tool for clinical or research purposes in the area of chronic or disabling diseases in children. Eleven motor skill variables grouped into five factors have been measured (speed, agility, balance, coordination, and reaction time).

RESULTS

Scores from 10 of the 11 motor skill tests showed significant differences when compared to the control group (P ≤ 0.05). Nearly 50% of patients obtained an average score below the 15th percentile. Furthermore, stepwise discriminant analysis allowed classifying successfully 88.4% of children in the correct group (ALL or Control). The normal development of GMS among children affected by ALL appears to have been compromised. The UQAC-UQAM test battery seems to be sensitive enough to quantify with precision the extent of the motor impairment in these children.

CONCLUSION

The UQAC-UQAM test battery appears to be a useful tool to evaluate the extent to which ALL survivors are affected. Early motor intervention should be considered for those patients even during the treatment periods.

High-dose vincristine sulfate liposome injection (Marqibo) Is not associated with clinically meaningful hematologic toxicity

BACKGROUND

Vincristine sulfate liposome injection (VSLI) facilitates vincristine dose intensification and densification, is active in untreated and relapsed lymphoma, and has been approved in the United States for relapsed and refractory acute lymphoblastic leukemia. Cancer- and concomitant chemotherapy-related anemia, neutropenia, and thrombocytopenia in patients with hematologic malignancy have complicated the evaluation of hematologic toxicity related to new drugs.

PATIENTS AND METHODS

We assessed the hematologic toxicity of VSLI 2.25 mg/m(2) administered every 14 (cohort 1) or 7 (cohort 2) days in 54 patients with metastatic uveal melanoma, a cancer not known to involve the bone marrow.

RESULTS

Cohort 2 received a greater median number of VSLI doses (6 vs. 4) within a shorter median period (5.7 vs. 8.7 weeks), resulting in a larger median cumulative exposure (22.6 vs. 17.7 mg) and near doubling of the median dose density (2.2 vs. 4.0 mg/wk) compared with cohort 1. Despite greater VSLI exposure and dose density, cohort 2 had a lower median decrease from baseline in the neutrophil count and a greater increase from baseline in the platelet count compared with cohort 1. Hematologic adverse events (AEs) were uncommon and mostly grade 1 or 2 in severity. No grade 4 hematologic AEs developed.

CONCLUSION

VSLI at its approved dose resulted in a low incidence of clinically meaningful hematologic toxicity. A near doubling of the median dose density did not have an identifiable effect on the reported incidence and severity of hematologic AEs. VSLI could be well suited for use combined with myelosuppresive drugs and for patients unable to tolerate peripheral blood cytopenia.

Vincristine sulfate liposomal injection for acute lymphoblastic leukemia

Vincristine (VCR) is one of the most extensively used cytotoxic compounds in hemato-oncology. VCR is particularly important for the treatment of acute lymphoblastic leukemia (ALL), a disease that accounts for approximately one-third of all childhood cancer diagnoses. VCR's full therapeutic potential has been limited by dose-limiting neurotoxicity, classically resulting in autonomic and peripheral sensory-motor neuropathy. In the last decade, however, the discovery that liposomal encapsulation of chemotherapeutics can modulate the pharmacokinetic characteristics of a compound has stimulated much interest in liposomal VCR (vincristine sulfate liposomal injection [VSLI]) formulations for the treatment of ALL and other hematological malignancies. Promising data from recent clinical trials investigating VSLI in adults with ALL resulted in US Food and Drug Administration approval for use in patients with Philadelphia chromosome (t[9;22]/BCR-ABL1) (Ph)-negative (Ph-) disease. Additional clinical trials of VSLI in adults and children with both Ph-positive (Ph+) and Ph- ALL are ongoing. Here we review the preclinical and clinical experience to date with VSLI for ALL.

The ORCA2 transcription factor plays a key role in regulation of the terpenoid indole alkaloid pathway

BACKGROUND

The terpenoid indole alkaloid (TIA) pathway leads to the production of pharmaceutically important drugs, such as the anticancer compounds vinblastine and vincristine. Unfortunately, these drugs are produced in trace amounts, causing them to be very costly. To increase production of these drugs, an improved understanding of the TIA regulatory pathway is needed. Towards this end, transgenic Catharanthus roseus hairy roots that overexpress the ORCA2 TIA transcriptional activator were generated and characterized.

RESULTS

Transcriptional profiling experiments revealed that overexpression of ORCA2 results in altered expression of key genes from the indole and terpenoid pathways, which produce precursors for the TIA pathway, and from the TIA pathway itself. In addition, metabolite-profiling experiments revealed that overexpression of ORCA2 significantly affects the levels of several TIA metabolites. ORCA2 overexpression also causes significant increases in transcript levels of several TIA regulators, including TIA transcriptional repressors.

CONCLUSIONS

Results presented here indicate that ORCA2 plays a critical role in regulation of TIA metabolism. ORCA2 regulates expression of key genes from both feeder pathways, as well as the genes (STR and SGD) encoding the enzymes that catalyze the first two steps in TIA biosynthesis. ORCA2 may play an especially important role in regulation of the downstream branches of the TIA pathway, as it regulates four out of five genes characterized from this part of the pathway. Regulation of TIA transcriptional repressors by ORCA2 may provide a mechanism whereby increases in TIA metabolite levels in response to external stimuli are transient and limited in magnitude.

Protective effect of augmenter of liver regeneration on vincristine-induced cell death in Jurkat T leukemia cells

Augmenter of liver regeneration (ALR) is a crucial factor in the process of proliferation of hepatocytes. Recently, it has been demonstrated that ALR plays an important role of anti-apoptosis in several cell lines, but the biological effects of ALR in acute T lymphoblastic leukemia have remained unclear. In this study, we investigated the effect of ALR on Jurkat T leukemia cell growth and survival. We found that ALR was up-regulated in Jurkat cells and could reduce the sensitivity of Jurkat cells to vincristine, but had a minimal effect on proliferation of Jurkat cells. Results from analysis of flow cytometry showed ALR attenuated apoptotic cells and inhibited G2/M-arrest in vincristine-treated Jurkat cells. Following incubation with ALR, an increase in pro-caspase8, pro-caspase3, pro-PARP and Bcl-2 levels was observed in vincristine-treated Jurkat cells. In summary, the results of this study demonstrate that ALR protects Jurkat T leukemia cells from vincristine-induced cell death via regulation of apoptotic signaling pathways and cell cycle.

Pharmacokinetics and pharmacodynamics of vincristine sulfate liposome injection (VSLI) in adults with acute lymphoblastic leukemia

Vincristine sulfate liposome injection (VSLI,) is a sphingomyelin and cholesterol nanoparticle formulation of vincristine sulfate (VCR) that was designed to overcome the dosing and pharmacokinetic limitations of standard VCR. In contrast to the rapid CL and wide tissue distribution of non-liposomal VCR, VSLI circulates in plasma for a prolonged period of time, with a slow CL of 345 mL/h and relatively small Vd of 3,570 mL. This facilitates enhanced and prolonged tumor-tissue delivery of VCR. The maximum tolerated dose of VSLI, 2.25 mg/m(2) once per week without a dose cap, enables individual and cumulative VCR exposure unachievable with non-liposomal VCR at its labeled dose of 1.4 mg/m(2) . VSLI is associated with a dose-dependent peripheral neurotoxicity albeit at doses that are two to three times that of standard VCR. VCR dose intensification with VSLI correlated with an increased probability of overall response and a strong trend towards increased complete response in adults with relapsed and/or refractory acute lymphoblastic leukemia. Overall, VSLI improves the therapeutic index by facilitating increased dose intensification while maintaining a predictable and manageable safety profile.

Nanosolvated microtubule-modulating chemotherapeutics: a case-to-case study

About 10% of the drugs in the preclinical stage are poorly soluble, 40% of the drugs in the pipeline have poor solubility, and even 60% of drugs coming directly from synthesis have aqueous solubility below 0.1 mg/ml. Out of the research around, 40% of lipophilic drug candidates fail to reach the market despite having potential pharmacodynamic activities. Microtubule-modulating chemotherapeutics is an important class of cancer chemotherapy. Most chemotherapeutics that belong to this category are plant-derived active constituents, such as vincristine, vinblastine, colchicine, docetaxel, paclitaxel, and noscapinoids. The pKa of a drug considerably affects its solubility in physiological fluids and consequently bioavailability. It usually ranges from 5 to 12 for microtubule-modulating drugs. Hence, the solubility of these drugs in physiological fluids is considerably affected by a change in pH. However, because of unpredictable parameters involved in poor solubility and the low oral bioavailability of these chemotherapeutics during the early phases of drug development, they often have an unusual pharmacokinetic profile. This makes the development process of novel chemotherapeutics slow, inefficient, patient-unfriendly, and very costly, emphasizing a need for more rational approaches on the basis of preclinical concepts. Nanosolvation is a process of increasing the polarity of a hydrophobic molecule either by solvation or cavitization in a hydrophilic macrocycle. The present review therefore focuses on the techniques applied in nanosolvation of microtubule-modulating chemotherapeutics to enhance solubility and bioavailability. The methodologies described will be highly beneficial for anticancer researchers to follow a trend of rational drug development.

Mechanism of the interaction of plant alkaloid vincristine with DNA and chromatin: spectroscopic study

Chromatin has been successfully used as a tool for the study of genome function in cancers. Vincristine as a vinca alkaloid anticancer drug exerts its action by binding to tubulins. In this study the effect of vincristine on DNA and chromatin was investigated employing various spectroscopy techniques as well as thermal denaturation, equilibrium dialysis and DNA-cellulose affinity. The results showed that the binding of vincristine to DNA and chromatin reduced absorbance at both 260 and 210 nm with different extent. Chromopheres of chromatin quenched with the drug and fluorescence emission intensity decreased in a dose-dependent manner. Chromatin exhibited higher emission intensity changes compared to DNA. Upon addition of vincristine, Tm of DNA and chromatin exhibited hypochromicity without any shift in Tm. The binding of the drug induced structural changes in both positive and negative extremes of circular dichroism spectra and exhibited a cooperative binding pattern as illustrated by a positive slope observed in low r values of the binding isotherm. Vincristine showed higher binding affinity to double stranded DNA compared to single stranded one. The results suggest that vincristine binds with higher affinity to chromatin compared to DNA. The interaction is through intercalation along with binding to phosphate sugar backbone and histone proteins play fundamental role in this process. The binding of the drug to chromatin opens a new insight into vincristine action in the cell nucleus.

A novel submicron emulsion system loaded with vincristine-oleic acid ion-pair complex with improved anticancer effect: in vitro and in vivo studies

Background

Vincristine (VCR), which is a widely used antineoplastic drug, was integrated with a submicron-emulsion drug-delivery system to enhance the anticancer effect.

Methods

After the formation of a VCR-oleic acid ion-pair complex (VCR-OA), the VCR-OA-loaded submicron emulsion (VCR-OA-SME), prepared by classical high-pressure homogenization, was characterized and its in vitro anticancer effects were evaluated.

Results

The submicron-emulsion formulation exhibited a homogeneous round shape. The mean particle size, zeta potential, and encapsulation efficiency were 157.6 ± 12.6 nm, −26.5 ± 5.0 mV and 78.64% ± 3.44%, respectively. An in vitro release study of the VCR-OA-SME revealed that 12.4% of the VCR was released within the first 2 hours (initial burst-release phase) and the rest of the drug was detected in the subsequent sustained-release phase. Compared with VCR solution, the pharmacokinetic study of VCR-OA-SME showed relatively longer mean residence time (mean residence time [0–∞] increased from 187.19 to 227.56 minutes), higher maximum concentration (from 252.13 ng/mL to 533.34 ng/mL), and greater area under the curve (area under the curve [0–∞] from 11,417.77 μg/L/minute to 17,164.34 μg/L/minute. Moreover, the VCR-OA-SME exhibited higher cytotoxicity (P < 0.05) on tumor cells by inducing cell arrest in the G2/M phase or even apoptosis (P < 0.05).

Conclusion

The VCR-OA-SME formulation in our study displayed great potential for an anticancer effect for VCR.

Marqibo® (vincristine sulfate liposome injection) improves the pharmacokinetics and pharmacodynamics of vincristine

Vincristine (VCR) is a mainstay of treatment of hematologic malignancies and solid tumors due to its well-defined mechanism of action, demonstrated anticancer activity and its ability to be combined with other agents. VCR is an M-phase cell cycle-specific anticancer drug with activity that is concentration and exposure duration dependent. The pharmacokinetic profile of standard VCR is described by a bi-exponential elimination pattern with a very fast initial distribution half-life followed by a longer elimination half-life. VCR also has a large volume of distribution, suggesting diffuse distribution and tissue binding. These properties may limit optimal drug exposure and delivery to target tissues as well as clinical utility as a single agent or as an effective component of multi-agent regimens. Vincristine sulfate liposome injection (VSLI), Marqibo^®, is a sphingomyelin and cholesterol-based nanoparticle formulation of VCR that was designed to overcome the dosing and pharmacokinetic limitations of standard VCR. VSLI was developed to increase the circulation time, optimize delivery to target tissues and facilitate dose intensification without increasing toxicity. In xenograft studies in mice, VSLI had a higher maximum tolerated dose, superior antitumor activity and delivered higher amounts of active drug to target tissues compared to standard VCR. VSLI recently received accelerated FDA approval for use in adults with advanced, relapsed and refractory Philadelphia chromosome-negative ALL and is in development for untreated adult ALL, pediatric ALL and untreated aggressive NHL. Here, we summarize the nonclinical data for VSLI that support its continued clinical development and recent approval for use in adult ALL.

Azithromycin synergistically enhances anti-proliferative activity of vincristine in cervical and gastric cancer cells

In this study, the anti-proliferative and anticancer activity of azithromycin (AZM) was examined. In the presence of AZM, cell growth was inhibited more effectively in Hela and SGC-7901 cancer cells, relative to transformed BHK-21 cells. The respective 50% inhibition of cell growth (IC₅₀) values for Hela, SGC-7901 and BHK-21 were 15.66, 26.05 and 91.00 µg/mL at 72 h post incubation, indicative of a selective cytotoxicity against cancer cells. Cell apoptosis analysis using Hoechst nuclear staining and annexin V-FITC binding assay further demonstrated that AZM was capable of inducing apoptosis in both cancer cells and transformed cells. The apoptosis induced by AZM was partly through a caspase-dependent mechanism with an up-regulation of apoptotic protein cleavage PARP and caspase-3 products, as well as a down-regulation of anti-apoptotic proteins, Mcl-1, bcl-2 and bcl-X1. More importantly, a combination of AZM and a low dose of the common anti-cancer chemotherapeutic agent vincristine (VCR), produced a selectively synergistic effect on apoptosis of Hela and SGC-7901 cells, but not BHK-21 cells. In the presence of 12.50 μg/mL of VCR, the respective IC₅₀ values of Hela, SGC-7901 and BHK-21 cells to AZM were reduced to 9.47 µg/mL, 8.43 µg/mL and 40.15 µg/mL at 72 h after the incubation, suggesting that the cytotoxicity of AZM had a selective anti-cancer effect on cancer over transformed cells in vitro. These results imply that AZM may be a potential anticancer agent for use in chemotherapy regimens, and it may minimize side effects via reduction of dosage and enhancing the effectiveness common chemotherapeutic drugs.

The dichloromethane extract of the ethnomedicinal plant Neurolaena lobata inhibits NPM/ALK expression which is causal for anaplastic large cell lymphomagenesis

The present study investigates extracts of Neuolaena lobata, an anti-protozoan ethnomedicinal plant of the Maya, regarding its anti-neoplastic properties. Firstly, extracts of increasing polarity were tested in HL-60 cells analyzing inhibition of cell proliferation and apoptosis induction. Secondly, the most active extract was further tested in anaplastic large cell lymphoma (ALCL) cell lines of human and mouse origin. The dichloromethane extract inhibited proliferation of HL-60, human and mouse ALCL cells with an IC50 of ~2.5, 3.7 and 2.4 µg/ml, respectively and arrested cells in the G2/M phase. The extract induced the checkpoint kinases Chk1 and Chk2 and perturbed the orchestrated expression of the Cdc25 family of cell cycle phosphatases which was paralleled by the activation of p53, p21 and downregulation of c-Myc. Importantly, the expression of NPM/ALK and its effector JunB were drastically decreased, which correlated with the activation of caspase 3. Subsequently also platelet derived growth factor receptor β was downregulated, which was recently shown to be transcriptionally controlled by JunB synergizing with ALK in ALCL development. We show that a traditional healing plant extract downregulates various oncogenes, induces tumor suppressors, inhibits cell proliferation and triggers apoptosis of malignant cells. The discovery of the 'Active Principle(s)' is warranted.

Mechanisms of vincristine-induced neurotoxicity: Possible reversal by erythropoietin

Vincristine (VCR) is a potent anticancer drug, but neurotoxicity is one of its most important dose-limiting toxicities. In this study, we investigated the neurotoxic effect of VCR, the possible mechanisms and the role of erythropoietin (EPO) in the protection against VCR-induced neurotoxicity in a rat model. The neurotoxicity of VCR and protective effect of EPO were examined using the tail flick test and by recording electrophysiological characteristics in isolated sciatic nerve. To elucidate the underlying mechanisms, mRNA expression of N-methyl-D-aspartate (NMDA) receptor, an index of glutamate excitotoxicity, and calcitonin gene-related peptide (CGRP), an important regulator of vascular tone, were measured in both spinal cord and sciatic nerves using an RT-PCR method. After intraperitoneal injection at a dose of 150 μg/kg three times weekly for five consecutive weeks, VCR significantly decreased the latency of tail withdrawal reflex, the amplitude of maximum compound action potential (MCAP) and chronaxie, and prolonged the duration of action potential (AP) and relative refractory period (RRP), but it had no effect on conduction velocity. VCR increased NMDA receptor expression and decreased CGRP expression. Forty μg/kg of EPO improved all VCR-induced changes, except chronaxie, while a higher dose of 80 μg/kg reversed all parameters and its effect was more prominent on tail flick test latency and NMDA receptor expression. These results suggested that VCR might cause increased nerve excitability and induce a state of glutamate excitotoxicity through enhancing NMDA receptor expression and diminishing CGRP expression, thus resulting in axonal degeneration. EPO had an obvious neuroprotective effect probably through decreasing NMDA receptor expression and increasing CGRP expression both centrally and peripherally.

Pharmacokinetic characteristics of vincristine sulfate liposomes in patients with advanced solid tumors

AIM

To evaluate the single- and multiple-dose pharmacokinetics of vincristine sulfate liposomes (VSLI) in patients with advanced solid tumors.

METHODS

In single-dose pharmacokinetic study, 16 patients were administered VSLI (1.5, 2.0, or 2.3 mg·m(-2)) through intravenous infusion. Another 6 patients receiving vincristine sulfate (VCR, 2.0 mg) were taken as the control. In multiple-dose pharmacokinetic study, 12 patients were administered VSLI (1.5 or 1.8 mg·m(-2)) through intravenous infusion weekly for 4 consecutive weeks. The plasma concentration of VSLI was determined using the liquid chromatography-tandem mass spectrometry (LC-MS/MS) method.

RESULTS

After intravenous infusion of the single dose of VSLI, the plasma concentrations were characterized by bi-exponential decline curves. No statistically significant differences were observed between the main pharmacokinetic parameters in the 3 dose groups. Compared with the patients receiving VCR, the patients treated with VSLI displayed an increase in the area under the plasma concentration vs time curve (AUC), and a decrease in plasma clearance rates. On the 4th cycle in the multiple-dose study, the plasma concentration of VCR in all subjects prior to the weekly administration was below the lower limit of quantification (LLOQ). The calculated pharmacokinetic parameters from the subjects in the multiple- and single-dose (1.5 mg·m(-2)) groups had no significant differences. Although the administration of liposomal VCR may significantly elevate the plasma concentration of VCR, VSLI-associated adverse events were similar to those associated with conventional VCR.

CONCLUSION

VSLI exhibits a lower clearance and a higher AUC compared with conventional VCR. No accumulation was observed in patients exposed to VSLI for 4 consecutive weeks. VSLI was generally tolerated in the subjects. The phase II dose of VSLI may be recommended as 4 doses of 1.5 mg·m(-2) for treatment of patients with advanced solid tumors.

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.

Adverse interactions between antifungal azoles and vincristine: review and analysis of cases

Triazole and imidazole antifungal agents inhibit metabolism of vincristine, leading to excess vinca alkaloid exposure and severe neurotoxicity. Recent reports of debilitating interactions between vincristine and itraconazole, as well as posaconazole, voriconazole and ketoconazole underscore the need to improve medical awareness of this adverse combination. We, therefore, undertook a comprehensive analysis of reports of adverse drug interactions (ADIs) with the combination of vincristine and azole antifungal agents, established a new classification, and provided a detailed summary of these toxicities. In patients who had sufficient data for analysis, 47 individuals were identified who had an ADI with the combination of vincristine and antifungal azoles. Median age was 8 years (1.3-68 years) with 33(70%) having a diagnosis of acute lymphoblastic leukaemia. Median time to ADI with vincristine was 9.5 days with itraconazole, 13.5 days posaconazole and 30 days voriconazole. The median number of vincristine doses preceding the ADI was 2 doses with itraconazole, 3 doses posaconazole and 2 doses voriconazole. The most common severe ADIs included gastrointestinal toxicity, peripheral neuropathy, hyponatremia/SIADH, autonomic neuropathy and seizures. Recovery from these ADIs occurred in 80.6% of patients. We recommend using alternative antifungal agents if possible in patients receiving vincristine to avoid this serious and potentially life-threatening drug interaction.

Effect of azole antifungal therapy on vincristine toxicity in childhood acute lymphoblastic leukaemia

BACKGROUND

Vincristine is one of the cornerstones of the treatment of children with acute lymphoblastic leukaemia (ALL). Constipation, and peripheral and central neurotoxicities are the most common side effects. A comparative study exploring vincristine toxicity in individual patients receiving vincristine with and without azoles, however, is lacking.

METHODS

In total, 20 paediatric patients with de novo ALL were included. In each patient, vincristine toxicity in the period with and without azole co-medication was retrospectively graded according to the US National Cancer Institute toxicity scale. Statistical analysis was performed using the Wilcoxon signed rank test and McNemar's test.

RESULTS

Patients receiving vincristine in combination with azole treatment experienced significantly more constipation and peripheral neurotoxicity (P = 0.001 and P < 0.001, respectively). Vincristine-induced CNS toxicity was only seen in patients (30%) receiving vincristine in combination with azole treatment.

CONCLUSIONS

Vincristine toxicity is significantly enhanced when combined with azole treatment and can even be life threatening. Therefore, we advise avoidance of the combination of azole and vincristine treatments in patients with ALL.

Increased risk of vincristine neurotoxicity associated with low CYP3A5 expression genotype in children with acute lymphoblastic leukemia

BACKGROUND

This study evaluates the relationship between cytochrome P450 (CYP) 3A5 genotype and vincristine-induced peripheral neuropathy (VIPN) in children with precursor B cell acute lymphoblastic leukemia (preB ALL). We have shown in vitro that vincristine is metabolized significantly more efficiently by CYP3A5 than by CYP3A4. We also found that vincristine neurotoxicity is less common in African-Americans (70% express CYP3A5) than in Caucasians. We test the hypothesis that CYP3A5 expressers experience less vincristine neuropathy than do CYP3A5 non-expressers.

PROCEDURE

This study of pharmacogenetics of vincristine neuropathy in children with preB ALL was completed at Indiana University Simon Cancer Center. Whole blood for DNA extraction and genotyping was collected as well as plasma from a single time-point for analysis of vincristine and primary metabolite (M1) concentrations. Vincristine neuropathy was captured via chart review and graded per the National Cancer Institute Common Terminology Criteria for Adverse Events, version 3.0.

RESULTS

Eighty-nine percent of CYP3A5 expressers experienced neurotoxicity versus 100% of non-expressers (P = 0.03). The proportion of treatment months with neurotoxicity was significantly different between the expressers and non-expressers (16% vs. 27%, P = 0.0007). Limited pharmacokinetic data suggest different rates of vincristine metabolism between CYP3A5 genotype groups with higher primary metabolite (M1) plasma concentrations (P = 0.0004) and lower metabolic ratios ([vincristine]/[M1]) (P = 0.036) in the CYP3A5 expressers compared to the CYP3A5 non-expressers. M1 concentration was also inversely related to severity of neuropathy (P = 0.0316).

CONCLUSIONS

In children with preB ALL, CYP3A5 expressers experience less VIPN, produce more M1, and have lower metabolic ratios compared to CYP3A5 non-expressers.

Development of pegylated liposomal vincristine using novel sulfobutyl ether cyclodextrin gradient: is improved drug retention sufficient to surpass DSPE-PEG-induced drug leakage?

The purpose of this study is to develop novel stable PEGylated liposome vincristine formulations with optimal antitumor efficacy. Vincristine could interact with negatively charged distearoylphosphatidylethanolamine-polyethylene glycol (DSPE-PEG), leading to rapid drug release from vesicles. To improve drug retention, vincristine was loaded into vesicles using sulfobutyl ether cyclodextrin (sbe-CD) as trapping agent. Despite that, vincristine could not form a precipitate with sbe-CD; the aggregation status of vincristine/sbe-CD inside vesicles must be complicated because drug retention was considerably improved in vivo. Theoretical consideration revealed that the release constant K equals to pA(m)k(1)k(2)/([H(+)](i)[sbe(-)](i)V(i) ), which can be used to expound why increasing drug/lipid ratio induced decreased vincristine circulation half-life. The stabilization effect afforded by sbe-CD was sufficient to surpass DSPE-PEG-induced drug leakage, so PEGylated liposomal vincristine formulations with prolonged circulation half-life (t(1/2): from 43.6 to 70.0 h) could be achieved, of which the formulation pLV-c-2.9-3 exhibited optimal antitumor effects and reduced toxicity. The strategy might be used to load other vinca alkaloids into PEGylated liposomes and improve their retention inside vesicles.

Molecular docking and pharmacogenomics of vinca alkaloids and their monomeric precursors, vindoline and catharanthine

Vinblastine and vincristine are dimeric indole alkaloids derived from Catharanthus roseus (formerly: Vinca rosea). Their monomeric precursor molecules are vindoline and catharanthine. While vinblastine and vincristine are well-known mitotic spindle poisons, not much is known about vindoline and catharanthine. Vindoline and catharanthine showed weak cytotoxicity, while vinblastine, vincristine, and the semisynthetic vindesine and vinorelbine revealed high cytotoxicity towards cancer cells. This may reflect a general biological principle of poisonous plants. Highly toxic compounds are not only active towards predators, but also towards plant tissues. Hence, plants need mechanisms to protect themselves from their own poisons. One evolutionary strategy to solve this problem is to generate less toxic precursors, which are dimerized to toxic end products when needed. As shown by in silico molecular docking and biochemical approaches, vinblastine, vincristine and vinorelbine bound with high affinity to α/β-tubulin and inhibited tubulin polymerization, whereas the effects of vindoline and catharanthine were weak. Similarly, vinblastine produced high fractions of mono- and multipolar mitotic spindles, while vindoline and catharanthine did only weakly affect bipolar mitotic spindle formation. Here, we show that vinblastine contributes to cell death by interference with spindle polarity. P-glycoprotein-overexpressing multidrug-resistant CEM/VCR1000 cells were highly resistant towards vincristine and cross-resistant to vinblastine, vindesine, and vinorelbine, but not or only weakly cross-resistant to vindoline and catharanthine. In addition to tubulin as primary target, microarray-based mRNA signatures of responsiveness of these compounds have been identified by COMPARE and signaling pathway profiling.

Cancer chemotherapy: an annotated history

Treating cancer with drugs is an ancient art, but it is from discoveries made during and after the Second World War that real clinical success with cancer chemotherapy has occurred. Human and veterinary cancer chemotherapy have coevolved in the context of fascinating historical, political, and scientific events created by equally fascinating individuals.

DNA interaction studies of an anticancer plant alkaloid, vincristine, using Fourier transform infrared spectroscopy

The binding of vincristine with DNA has been investigated using Fourier transform infrared spectroscopy. Various changes in the double helical structure of DNA after addition of vincristine have been examined. It is evident from Fourier transform infrared results that vincristine-DNA interaction occurs through guanine and cytosine base pairs. External binding of vincristine with phosphate backbone of the DNA is also observed. Vincristine perturbs guanine band at 1714 cm(-1), cytosine band at 1488 cm(-1), and the phosphate vibrations at 1225 and 1086 cm(-1). The UV-visible spectra of vincristine-DNA complex show hypochromic and bathochromic shifts, indicating the intercalation of vincristine into the double helical structure of DNA. Both intercalative and external binding modes are observed for vincristine binding with DNA, with an estimated binding constant K = 1.0 × 10(3) M(-1).

Influence of blood-brain barrier efflux pumps on the distribution of vincristine in brain and brain tumors

Vincristine (VCR) is efficacious in some but not all brain cancers and an established substrate of Pgp and Mrp1. However, the extent to which such transporters affect the VCR penetration through the blood-brain barrier (BBB) is poorly understood. To evaluate the role of Pgp and Mrp1 in VCR CNS distribution, VCR concentrations were analyzed under steady-state conditions in normal brain, brain tumor, and bone marrow in wild-type (WT), Mrp1 ko (mrp1-/-), Pgp ko (mdr1a-/-:mdr1b-/-), and TKO (mdr1a-/-:mdr1b-/-:mrp1-/-) mice. VCR normal brain partition coefficients (i.e. tissue/plasma VCR concentrations) in TKO mice were greater than those in WT mice at both targeted 10 and 50 ng/mL plasma VCR concentrations, and ranged from 1.3- to 3.6-fold. VCR brain tumor partition coefficients in Mrp1 mice were greater than WT mice at both doses, being 1.5- and 2.4-fold higher at low and high doses, respectively. TKO mice also showed elevated VCR brain tumor penetration with a brain tumor partition coefficient of 1.9-fold greater than that in WT mice at the high-dose level. The bone marrow partition coefficient in Mrp1 ko mice was 1.65-fold greater than that in WT mice. Within strain comparisons revealed that VCR brain tumor concentrations were significantly greater than normal brain in all strains, ranging from 9- to 40-fold. These findings indicate that disruption of the BBB caused the largest enhancement in VCR tumor concentrations, yet the absence of Mrp1 on the brain tumor vasculature could enhance the penetration compared with that in normal brain.

Diet-induced obesity alters vincristine pharmacokinetics in blood and tissues of mice

Obesity is associated with poorer outcome from many cancers, including leukemia. One possible contributor to this could be suboptimal chemotherapy dosing in obese patients. We have previously found that vincristine (VCR) is less effective in obese compared to non-obese mice with leukemia, despite weight-based dosing. In the present study, we administered (3)H-VCR to obese and control mice to determine whether obesity would cause suboptimal VCR exposure. Blood VCR concentrations were fitted with a three-compartment model using pharmacokinetic analysis (two-stage PK) in three subsets of VCR concentrations vs. time method. Tissue and blood VCR concentrations were also analyzed using non-compartmental modeling. Blood VCR concentrations showed a triexponential decay and tended to be slightly higher in the obese mice at all time-points. However, the t(1/2,beta) and t(1/2,gamma) were shorter in the obese mice (9.7 min vs. 44.5 min and 60.3h vs. 85.6h, respectively), resulting in a lower AUC(0-infinity) (13,099 ng/m Lh vs. 15,384 ng/mL h). Had the dose of VCR been "capped", as is done in clinical practice, the AUC(0-infinity) would have been 36% lower in the obese mice than the controls. Tissue disposition of VCR revealed a biexponential decay from spleen, liver, and adipose. Interestingly, VCR slowly accumulated in the bone marrow of control mice, but had a slow decay from the marrow in the obese mice. Thus, obesity alters VCR PK, causing a lower overall exposure in circulation and bone marrow. Given the high prevalence of obesity, additional PK studies should be performed in obese subjects to optimize chemotherapy dosing regimens.

Squalene: A natural triterpene for use in disease management and therapy

Squalene is a natural lipid belonging to the terpenoid family and a precursor of cholesterol biosynthesis. It is synthesized in humans and also in a wide array of organisms and substances, from sharks to olives and even bran, among others. Because of its significant dietary benefits, biocompatibility, inertness, and other advantageous properties, squalene is extensively used as an excipient in pharmaceutical formulations for disease management and therapy. In addition, squalene acts as a protective agent and has been shown to decrease chemotherapy-induced side-effects. Moreover, squalene alone exhibits chemopreventive activity. Although it is a weak inhibitor of tumor cell proliferation, it contributes either directly or indirectly to the treatment of cancer due to its potentiation effect. In addition, squalene enhances the immune response to various associated antigens, and it is therefore being investigated for vaccine delivery applications. Since this triterpene is well absorbed orally, it has been used to improve the oral delivery of therapeutic molecules. All of these qualities have rendered squalene a potentially interesting excipient for pharmaceutical applications, especially for the delivery of vaccines, drugs, genes, and other biological substances. This paper is the first review of its kind and offers greater insight into squalene's direct or indirect contribution to disease management and therapy.

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.

Kasabach-Merritt phenomenon: a single centre experience

OBJECTIVE

Kasabach-Merritt phenomenon (KMP) can lead to life-threatening bleeding, and its optimum treatment has not been established. We review the experience of managing KMP in a single institution.

METHODS

A retrospective chart review on all children with KMP treated at the Hospital for Sick Children, Toronto, over an 18 yr period was carried out.

RESULTS

All 15 patients had profound thrombocytopenia and hypofibrinogenemia at presentation, half had bleeding symptoms, and three had cardiac failure. All patients received corticosteroids. Five responded to steroids alone, given for an average of 13 wk, increasing platelets to >20 x 10(9)/L at a mean of 6.2 d and fibrinogen >1 g/dL at 25.6 d. Ten patients received at least one other therapeutic modality in addition to steroids, including vincristine, interferon, anti-platelet agents and pentoxifylline. Five patients received vincristine, for a mean of 6 wk, with two patients responding. Eight patients received interferon, for a mean of 4 months, with two patients responding. Overall, the mean time to increasing platelets >20 x 10(9)/L was 56 d, to >150 x 10(9)/L was 88 d and fibrinogen >1 g/dL 49 d. Ten patients showed a partial response to embolisation, with a mean of 2.8 procedures performed. Thrombotic complications occurred in 7%. Twelve patients remain alive, with relapse in six patients, all treated successfully. One patient died, and two patients have been lost to follow-up.

CONCLUSION

KMP is a rare condition, with significant morbidity and mortality. The therapeutic approach should include a multidisciplinary team and consensus on guidelines.

The effects of UV-B stress on the production of terpenoid indole alkaloids in Catharanthus roseus hairy roots

In nature, plants generate protective secondary metabolites in response to environmental stresses. Such metabolites include terpenoid indole alkaloids (TIAs), which absorb UV-B light and serve putatively to protect the plant from harmful radiation. Catharanthus roseus plants, multiple shoot cultures, and cell suspension cultures exposed to UV-B light show significant increases in the production of TIAs, including precursors to vinblastine and vincristine, which have proven effective in the treatment of leukemia and lymphoma. Here, the effect of UV-B light on C. roseus hairy roots was examined. Analysis of alkaloid concentrations up to 168 h after UV-B exposure shows significant increases in the concentrations of lochnericine and significant decreases in the concentration of hörhammericine over time (ANOVA, P < 0.05). Our results also indicate that increasing UV-B exposure time up to 20 min caused significant increases in lochnericine, serpentine, and ajmalicine and a decrease in hörhammericine (t-test, p < 0.05).

Vincristine sulfate liposomes injection (Marqibo) in heavily pretreated patients with refractory aggressive non-Hodgkin lymphoma: report of the pivotal phase 2 study

BACKGROUND

Marqibo, a sphingosomal/cholesterol encapsulation of vincristine sulfate has targeted, increased, and sustained delivery of vincristine to tumor tissues. A phase 2, open-label, single-arm, and multinational study evaluated the efficacy and tolerability of Marqibo as a single agent in patients with multiply relapsed or refractory aggressive non-Hodgkin lymphoma (NHL).

METHODS

Eligible patients had relapsed or refractory de novo or transformed aggressive NHL and prior treatment with at least 2 multiagent chemotherapy regimens. Marqibo was administered at 2 mg/m2, every 2 weeks, for a maximum of 12 cycles or until toxicity or disease progression.

RESULTS

One hundred and nineteen patients were enrolled and treated on trial. Ninety-six had histological confirmed de novo (N=89) or transformed (N=7) aggressive NHL. Median number of cycles was 4 (median dose/cycle 4 mg). Overall response (CR and complete response unconfirmed and PR) was 25% (95% confidence interval [CI], 17, 35), CR and complete response unconfirmed confirmed by external reviewers was 5%. Median overall survival was 6.6 months (Kaplan-Meier estimate, 95% CI, 4.7, 9.8). Grade 3 of 4 neurotoxicity occurred in 32% of patients. All patients had prior neurotoxic agents, and 85% had baseline residual neuropathy symptoms (grades 1-2) from prior treatment.

CONCLUSIONS

Marqibo is an active agent in patients with heavily pretreated aggressive NHL, and tolerated at approximately twice the dose intensity of standard vincristine. Its activity supports further investigation as a substitution for vincristine in combination treatment of lymphoid disorders.

Fulvestrant (ICI 182,780) sensitizes breast cancer cells expressing estrogen receptor alpha to vinblastine and vinorelbine

Cumulative data suggest that some chemotherapeutic agents may be less effective in estrogen receptor alpha positive (ER+) breast tumors than ER negative (ER-) tumors, which has raised a clinically relevant question as to how to reverse this ER-mediated chemoresistance in ER+ breast tumors. This study is to investigate the possible influence of estrogen receptor alpha (ERalpha) on the therapeutic effects of vinblastine and vinorelbine on breast cancer cells and explore whether combination of anti-estrogen agent fulvestrant (ICI 182, 780) may enhance the sensitivity of ERalpha+ cells to these chemotherapeutic agents. Through comparing ER+ with ER- human breast tumor cells or through stable transfection of an ERalpha expression vector into ER negative human breast cancer BCap37 cells, a series of assays were applied to determine the sensitivity of ER+ and ER- breast tumor cells to vinblastine and vinorelbine in the presence or absence of 17-beta-estradiol and/or fulvestrant. 17-beta-Estradiol showed no effect on the sensitivity of ER- MDA-MB-468 and BCap37 cells to the treatment of vincristine or vinblastine, but it significantly reduced the sensitivity of ER+ T47D cells and BCap37 cells expressing ERalpha to the two drugs mentioned. Further analyses show that ERalpha has little effect on vinca alkaloids-induced mitotic arrest, but dramatically affects their ability to induce tumor cell apoptosis. Moreover, through a series of assays, we also demonstrated that the combination of fulvestrant, a selective ER down-regulator, could reverse the resistance of ER+ breast tumor cells to vinca alkaloids and even produce synergistic effects. The findings obtained from this study have provided important evidence that expression and subsequent activation of ERalpha are associated with resistance of breast cancer cells to vinca alkaloids. This study also suggested that the combination of anti-estrogen agents, such as fulvestrant, might be a novel strategy to reverse ER-mediated chemoresistance or sensitize ER+ breast tumors to vinca alkaloids and possibly other chemotherapeutic agents.

Polymorphisms in genes involved in vincristine pharmacokinetics or pharmacodynamics are not related to impaired motor performance in children with leukemia

INTRODUCTION

Impaired motor performance in children who completed treatment for acute lymphoblastic leukemia (ALL) may be related to polymorphisms of the metabolising gene CYP3A5 or vincristine toxicity related genes MDR-1 and MAPT.

METHODS

Motor performance was measured with the Movement Assessment Battery for Children (movement-ABC). DNA, from mononuclear blood cells was genotyped for CYP3A5, MDR-1 and MAPT polymorphisms.

RESULTS

Motor performance was not significantly affected by CYP3A5*3/*3 and CYP3A5*1*3 genotypes, MDR-1 polymorphisms or MAPT haplotype.

CONCLUSION

Our data did not show that CYP3A5, MDR-1 or MAPT polymorphisms are linked to impaired motor performance in children after treatment for ALL.

Vincristine pharmacokinetics in children with Down syndrome

Children with Down syndrome (DS), who represent about 2% of childhood acute lymphoblastic leukemia, have inferior prognosis compared to non-DS children. For vincristine (and many other anticancer agents) pharmacokinetic data are scant or missing, and there is considerable uncertainty about the optimal dosing of drugs to patients with DS. We studied vincristine pharmacokinetics on treatment day one in six children with DS and compared to 92 non-DS children. No differences were found. Thus, we found no rationale for dose reduction of vincristine in DS children from a strictly pharmacokinetic point of view.

Effect of noscapine and vincristine combination on demyelination and cell proliferation in vitro

Peripheral neuropathy is a common, dose-limiting side effect of vincristine, a frontline therapy for acute lymphoblastic leukemia. Combination chemotherapy that reduces the neurotoxicity without compromising the efficacy of vincristine would improve patient outcomes. We performed in vitro studies using a combination of microtubule-binding antimitotics, noscapine and vincristine. In cell cultures containing neurons, astrocytes, and oligodendrocytes, vincristine caused demyelination as shown by transmission electron microscopy. A combination of vincristine and noscapine protected against demyelination. Human acute lymphoblastic and acute myelogenous leukemia cell lines CCRF-CEM and HL-60, respectively, were used to determine the antiproliferative effect of this novel drug combination. Vincristine and noscapine decreased cell proliferation with IC(50) concentrations of 1 nM and 20 microM, respectively. Analysis of dose-effect relationships using isobolograms and combination indices demonstrated that noscapine acts synergistically with vincristine. Thus, noscapine is a promising candidate for use with vincristine to decrease neurotoxicity and enhance antineoplastic effectiveness.

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.

Exploring the mechanisms of action of the novel microtubule inhibitor vinflunine

Microtubules have been identified as a suitable target for anticancer therapy, primarily based on their biological importance in coordinating chromosomal segregation at mitosis. Two main classes of microtubule-targeted agents, the taxanes and vinca alkaloids, suppress the dynamic behavior of spindle microtubules, inducing mitotic arrest and subsequent apoptotic cell death. Clinical activity of taxanes and first-generation vinca alkaloids in the treatment of solid tumors and hematologic malignancies, respectively, has prompted further research for novel analogs with improved clinical efficacy and safety. Such efforts have led to the development of vinflunine, a bifluorinated vinca alkaloid endowed with unique antitumor properties. Highlighted in this review are the key features of vinflunine that lead to effective suppression of microtubule dynamics and induction of cell death in cancer cells.