Superior in vivo experimental antitumour activity of vinflunine, relative to vinorelbine, in a panel of human tumour xenografts

Vinca alkaloids as a potential cancer therapeutics: recent update and future challenges

Vinca alkaloids including vincristine, vinblastine, vindesine, and vinflunine are chemotherapeutic compounds commonly used to treat various cancers. Vinca alkaloids are one of the first microtubule-targeting agents to be produced and certified for the treatment of hematological and lymphatic neoplasms. Microtubule targeting agents like vincristine and vinblastine work by disrupting microtubule dynamics, causing mitotic arrest and cell death. The key issues facing vinca alkaloids applications include establishing an environment-friendly production technique based on microorganisms, as well as increasing bioavailability without causing harm to patient's health. The low yield of these vinca alkaloids from the plant and the difficulty of meeting their huge colossal demand around the globe prompted researchers to create a variety of approaches. Endophytes could thus be selected to produce beneficial secondary metabolites required for the biosynthesis of vinca alkaloids. This review covers the significant aspects of these vital drugs, from their discovery to the present day, in a concise manner. In addition, we emphasize the major hurdles that must be overcome in the coming years to improve vinca alkaloid's effectiveness.

Better characterization of vinflunine pharmacokinetics variability and exposure/toxicity relationship to improve its use: Analyses from 18 trials

AIMS

Vinflunine is a novel tubulin-targeted inhibitor indicated as a single agent for the treatment of bladder cancers after failure of prior platinum-based therapy. Its pharmacokinetics (PK) and pharmacodynamics (PD) have been independently characterized through several phase I and phase II studies. However, no global pharmacometric analysis had been conducted as yet.

METHODS

Vinflunine concentrations and safety data from 18 phase I and phase II studies were used to conduct population PK and PK/PD analysis, using Nonmem. A four-compartment model was used to describe vinflunine PK and several covariates were tested to explain interindividual variability. In terms of PK/PD relationship, a semiphysiological population PK/PD model was applied to describe time course of absolute neutrophil counts (ANC) after vinflunine administration and logistic regression models were used to test the relationship between vinflunine exposure and toxicities.

RESULTS

Vinflunine clearance is explained by creatinine clearance, body surface area and combination with PEGylated doxorubicin, leading to a decrease from 28.2 to 25.3% of the interindividual variability. When vinflunine dose is decreased, simulations of ANC time course (via a semiphysiological model) after vinflunine administration show a risk of neutropenia grade 3-4 at cycle 2 always lower than when dose is delayed. As an example, for moderate renal impaired patients, the risk is 42.1% when vinflunine is dosed at 320 mg m-2 once every 4 weeks vs. 23.3% for 280 mg m-2 once every 3 weeks.

CONCLUSIONS

We propose for the first time a global comprehensive clinical pharmacological analysis for intravenous vinflunine that may help drive dose adjustment.

High expression of class III β-tubulin has no impact on functional cancer cell growth inhibition of a series of key vinblastine analogs

Clinical association studies have implicated high expression of class III β-tubulin as a predictive factor for lower response rates and reduced overall survival in patients receiving tubulin binding drugs, most notably the taxanes. Because of the implications, we examined a series of key vinblastine analogs that emerged from our studies in functional cell growth inhibition assays for their sensitivity to high expression of class III β-tubulin (human non-small cell lung cancer cell line A549 vs taxol-resistant A549-T24). Unlike taxol, vinblastine and a set of key analogs 3-10 did not exhibit any loss in sensitivity toward A549-T24. The results suggest that vinblastine and related analogs are not likely prone to resistance derived from high expression of class III β-tubulin unlike the taxanes. Most significant are the results with 4-6, a subset of 20' amide vinblastine analogs. They match or exceed the potency of vinblastine and they display more potent activity against taxol-resistant A549-T24 than even wild type A549 cells (1.2-2-fold), complementing our prior observations that they also display no sensitivity to overexpression of Pgp (HCT116/VM46 vs HCT116) and are not subject to resistance derived from Pgp efflux.

Vinorelbine Potently Induces Placental Cell Death, Does Not Harm Fertility and is a Potential Treatment for Ectopic Pregnancy

Ectopic pregnancies complicate 1–2 pregnancies and are a leading cause of maternal death. An effective oral drug therapy that replaces surgery might make its treatment safer, cheaper, simpler and therefore more widely accessible. The only current medical treatment offered to women is intramuscular methotrexate, but this only reliably resolves smaller ectopic pregnancies. As such, many ectopic pregnancies require surgical excision. We show that vinorelbine, an orally available chemotherapeutic agent, potently induced placental cell death but did not harm fertility in mice. Vinorelbine was 100–1000 times more potent than methotrexate in inducing placental cell death in vitro, and more potent than combination methotrexate and gefitinib (another proposed treatment for ectopic pregnancy being evaluated in phase III trials). Mechanistically, it caused microtubule condensation, blocked mitosis and activated the apoptosis cascade in placental cells. Vinorelbine was more efficacious than methotrexate ± gefitinib in reducing the volume of placental cell tumors xenografted subcutaneously in SCID mice. Mice exposed to vinorelbine and allowed to breed, following a four week washout period, displayed normal fertility, however long-term fertility was not assessed. Human Fallopian tubes treated with vinorelbine did not exhibit up-regulation of apoptosis molecules. Our findings show that placental cells appear sensitive to vinorelbine and it has potential as a tablet-only approach to treat ectopic pregnancy.

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We have identified vinorelbine, a well tolerated chemotherapeutic, as a potential therapeutic for ectopic pregnancy.

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Vinorelbine potently reduced placental cell viability in-vitro and in-vivo and proved more efficacious than the current medical therapeutic.

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Vinorelbine did not impact upon subsequent fertility in a mouse breeding model.

Ectopic pregnancy occurs when a conceptus implants outside of the womb. They are life threating and are a leading cause of maternal death in early pregnancy. Currently, the large majority of ectopic pregnancies are removed surgical, partly owing to the limited efficacy of the only available medical therapeutic, methotrexate. Here, we have identified a potential new medical therapeutic for ectopic pregnancy, vinorelbine. Vinorelbine, which is orally available chemotherapeutic, reduced placental cell viability both in-vitro and in-vivo and did not impact upon mice fertility in a breeding model. As such, vinorelbine may be an efficacious treatment for ectopic pregnancy and further human studies into its application are warranted.

A Zn(OTf)2 catalyzed Ugi-type reaction of 3-(2-isocyanoethyl)indoles with indole-derived ketimines: rapid access to hexacyclic spiroindolines

A Zn(OTf)₂ catalyzed Ugi-type reaction of 3-(2-isocyanoethyl)indoles and indole-derived ketimines was developed for the synthesis of hexacyclic spiroindolines featuring three stereocenters including two quaternary stereocenters.

Natural Compounds as Modulators of Cell Cycle Arrest: Application for Anticancer Chemotherapies

Natural compounds from various plants, microorganisms and marine species play an important role in the discovery novel components that can be successfully used in numerous biomedical applications, including anticancer therapeutics. Since uncontrolled and rapid cell division is a hallmark of cancer, unraveling the molecular mechanisms underlying mitosis is key to understanding how various natural compounds might function as inhibitors of cell cycle progression. A number of natural compounds that inhibit the cell cycle arrest have proven effective for killing cancer cells in vitro, in vivo and in clinical settings. Significant advances that have been recently made in the understanding of molecular mechanisms underlying the cell cycle regulation using the chemotherapeutic agents is of great importance for improving the efficacy of targeted therapeutics and overcoming resistance to anticancer drugs, especially of natural origin, which inhibit the activities of cyclins and cyclin-dependent kinases, as well as other proteins and enzymes involved in proper regulation of cell cycle leading to controlled cell proliferation.

Vinflunine for the treatment of non-small cell lung cancer

INTRODUCTION

Vinflunine belongs to the class of vinca alkaloids and acts by disrupting the microtubule dynamics during cell cycle; this agent is currently available for previously treated advanced transitional cell carcinoma in Europe. The aim of this invited review is to evaluate the potential role of vinflunine for the treatment of non-small cell lung cancer (NSCLC). Areas covered: The potential role of vinflunine in NSCLC is discussed on the basis of the available data, including full papers and meeting abstracts. Relevant preclinical studies describing the pharmacological properties of vinflunine are also included. The review also summarizes clinical studies, including phase I trials involving NSCLC among other tumors as well as phase II/III trials specifically addressing this malignancy. Additionally, the safety profile and the current regulatory status of vinflunine is discussed. Expert opinion: Vinflunine is active as single agent and as part of platinum-based combinations in NSCLC. It results non-inferior to docetaxel in a randomized phase III trial including previously treated NSCLC patients; additionally, its safety profile is generally considered manageable. Ultimately, further studies are needed to confirm the role of vinflunine in NSCLC, in consideration of the evolving evidence regarding targeted therapies and immune check-point inhibitors.

How to manage intravenous vinflunine in cancer patients with renal impairment: results of a pharmacokinetic and tolerability phase I study

AIMS

Vinflunine (VFL) ditartrate, a novel tubulin-targeted inhibitor, is registered for the treatment of patients with advanced or metastatic urothelial transitional cell carcinoma. This phase I study assessed the effect of renal impairment on the pharmacokinetics and tolerability of VFL.

METHODS

VFL was infused in patients with advanced/metastatic solid tumours once every 3 weeks with anticipated dose reduction on the first cycle stratified according to the creatinine clearance (CLcr ) values. Pharmacokinetic data were collected on the first two cycles in renally impaired patients (CLcr ≤ 60 ml min(-1) ) and were compared with a control cohort of patients (CLcr > 60 ml min(-1) ).

RESULTS

Thirty-three patients (46-86 years) were treated, 13 in group 1 (40 ml min(-1) ≤ CLcr ≤ 60 ml min(-1) ) and 20 in group 2 (20 ml min(-1) ≤ CLcr < 40 ml min(-1) ). The renal dysfunction induced a mean decrease in VFL clearance of 12% in group 1 and 28% in group 2, compared with the control group. The anticipated dose reduction given in renally impaired patients (i.e. 280 mg m(-2) and 250 mg m(-2) in groups 1 and 2, respectively) yielded similar drug exposure to control patients. The tolerance profile of VFL in patients with renal dysfunction was similar to that observed in patients with CLcr > 60 ml min(-1) .

CONCLUSION

In conclusion, the recommended doses of intravenous VFL administered once every 3 weeks in cancer patients with renal impairment are 280 mg m(-2) when CLcr is between 40 and 60 ml min(-1) and 250 mg m(-2) when CLcr is between 20 and <40 ml min(-1) .

Second-line systemic therapy for metastatic urothelial carcinoma of the bladder

While platinum-based combination chemotherapy leads to high response rates in patients with advanced urothelial cancer of the bladder, most patients will ultimately progress and optimal treatment in the second-line setting still needs to be determined. Advanced age, poor performance status, comorbidities and rapidly progressive disease have rendered accrual into trials difficult. Vinflunine is the only cytotoxic agent to demonstrate survival benefit in a randomized Phase III setting, but its response rate is disappointing and it has not been compared with other currently used agents such as taxanes. Recent years have seen a better definition of prognostic and predictive factors in patients with relapsed urothelial cancer. In addition, several trials have investigated novel biological agents to target chemoresistant disease. This review provides an update on the current systemic management of advanced urothelial cancer on progression following first-line chemotherapy, and discusses emerging data from recent Phase II/III trials.

Nonplatinum therapy in advanced bladder cancer

Carcinoma of the bladder is the second most prevalent genitourinary malignancy and the fifth most common solid malignancy in the USA. Combination chemotherapy is used in most patients with advanced disease. Traditionally, on the basis of favorable response rates and survival data, cisplatin-based regimens have been the preferred chemotherapy for patients with metastatic bladder cancer. However, the toxicity profile of cisplatin precludes its use in a significant subset of patients with advanced bladder cancer. Conversely, noncisplatin-containing regimens have been shown to have a more favorable toxicity profile and to have activity in advanced bladder cancer. Here, various nonplatinum chemotherapy regimens for advanced disease are reviewed.

Monotherapy with intravenous vinflunine in patients with advanced or metastatic urothelial cancer after failure of a platinum-containing regimen: a retrospective analysis of German routine data

OBJECTIVE

The objective of this retrospective study was to investigate the efficacy and safety of vinflunine monotherapy and the utility of second-line prognostic factors in patients with advanced or metastatic urothelial cancer relapsing/progressing during or after a prior platinum-containing regimen under daily routine clinical conditions in Germany.

METHODS

The selection was based on the marketing authorization indication and recommendations as well as on the evaluation of second-line prognostic factors issued from prior pivotal trials.

RESULTS

Eight centers across Germany provided a total of 21 patient records. Demographic and clinical characteristics were similar to the data previously reported in pivotal trials. Complete and partial response to vinflunine treatment was observed in 1 (4.8%) and 3 (14.3%) patients, respectively, resulting in an overall response rate of 19.1%. The disease control rate reached 47.7%. The median progression-free survival amounted to 4.4 months (95% CI 2.6-6.6), with a median overall survival of 6.2 months (95% CI 3.9-10.7). The observed toxicity profile was manageable and consistent with prior clinical trials: leukopenia (33.3%), neutropenia (9.5%), anemia (9.5%) and hyperglycemia (4.8%). The reported satisfaction rate with the treatment was 90.5 and 61.9% among patients and physicians, respectively.

CONCLUSIONS

This retrospective study confirms that the clinical outcomes obtained from routine medical practice in Germany with vinflunine in the treatment of advanced/metastatic urothelial cancer are in line with the data observed in prior clinical trials.

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.

Vinflunine: a new vision that may translate into antiangiogenic and antimetastatic activity

Microtubules and tubulin are major dynamic and structural cellular components that play a key role in several cell functions, including division, signalling and intracellular trafficking. Normal epithelial cells have a highly structured, rigid cytoskeletal network that is compatible with cell motility. Thus, tubulin and microtubules are compelling cellular targets for chemotherapy. In fact, among anticancer agents, those that target microtubules constitute one of the most effective classes of chemotherapeutics in cancer. The list of compounds that target either tubulin or microtubules is extensive and consists of chemically unique compounds that bind to the tubulin dimers and destabilize microtubules (Vinca alkaloids) and those that bind to the microtubule polymer and stabilize microtubules (taxanes). Tumour-induced angiogenesis, the formation of new capillaries from existing blood vessels, and epithelial-mesenchymal transition are two steps that are critical for both tumour growth and metastatic spread. Three possible mechanisms of action are described with vinflunine, the new-generation Vinca alkaloid to arrive in clinical practice are as follows: it acts against tubulin and microtubules, disrupts newly formed blood vessels and seems to be able to reduce the metastatic process as shown in preclinical studies. These findings support the hypothesis that vinflunine, by blocking microtubule functions that contribute to cell shape, polarization, migration and other processes, might be responsible not only for tumour-cytostatic but also for specific antiangiogenic or antiepithelial-mesenchymal transition effects.

Current chemotherapeutic strategies against bladder cancer

Urothelial cancer is a chemotherapy-sensitive malignancy, with the regimen of methotrexate, vinblastine, doxorubicin, and cisplatin (M-VAC) until recently considered to be the first choice for chemotherapy. Poor survival and substantial toxicity associated with M-VAC have led to investigations into alternative chemotherapy strategies, and the combination of gemcitabine and cisplatin (GC) may be promising. In addition, combination chemotherapy of taxanes along with gemcitabine and/or platinum-based agents is also considered to provide clinical benefits as second-line chemotherapy following M-VAC or GC therapy. In the near future, results of trials using molecular target therapies may bring improved outcomes for patients with bladder cancer.

Vinflunine in the treatment of advanced bladder cancer

Accounting for 14,000 deaths in the USA last year, research informs us that advanced bladder cancer is a lethal disease with a median survival that has remained a little over 1 year for the past two decades. For the majority of patients with metastatic disease, chemotherapy with cisplatin-based combinations is the standard first-line treatment. Although initial response rates are high, disease progression is common, creating a growing number of patients in need of effective second-line chemotherapy. For this population, no standard of care currently exists. Salvage chemotherapy is associated with low response rates and studies exploring potential clinical benefit over supportive care alone are limited to nonrandomized Phase II trials. Vinflunine, a novel anti-mitotic drug from the Vinca alkaloid class, is the first and only agent that has been compared with supportive care in the second-line setting. In Europe, vinflunine is approved as a treatment option for patients with advanced urothelial cancer who have failed a prior platinum-containing regimen. To date, in the USA, there is no FDA-approved second-line chemotherapy for patients with metastatic bladder cancer and treatment continues to emphasize patient enrollment into a clinical trial.

Novel cytotoxic backbones and targeted therapies: recent data and ongoing clinical trials

Novel therapies are emerging for treatment of patients with localized or advanced breast cancer. Targeted therapies such as trastuzumab, lapatinib, and bevacizumab have demonstrated significant clinical benefit in the metastatic setting, and trastuzumab has also improved patient outcome as adjuvant therapy in HER2+ breast cancer. Novel chemotherapies are also being developed to improve drug delivery, enhance efficacy, or decrease drug toxicity. These novel cytotoxic agents are being combined with established targeted therapies and are showing early promise for the treatment of patients with advanced breast cancer. Finally, new targeted therapies have shown clinical benefit, either as single agents or in combination with established targeted therapy or chemotherapy.

Vinflunine: review of a new vinca alkaloid and its potential role in oncology

Objective: To review the pharmacology, pharmacokinetics, in vitro and in vivo efficacy, and safety profile of vinflunine in the treatment of various solid tumors.

Data sources: A literature search was conducted using keywords included vinflunine, vinca alkaloid, Javlor, and solid tumor in PubMed/MEDLINE (1950—January 2009) and International Pharmaceutical Abstracts (1950—January 2009). Study selection and data extraction: Published studies, posters, and meeting abstracts evaluating the in vitro and in vivo efficacy of vinflunine were reviewed.

Data synthesis: Vinflunine is the newest member of the vinca alkaloid family. It has the weakest affinity to tubulins, but is shown to have unique receptor-independent antiangiogenesis, and antimetastasis properties. After administration, it is distributed extensively into tissues, metabolized via the CYP3A4 system, and eventually excreted in urine and feces. Phase II/III trials reported activities of vinflunine in advanced stage nonsmall-cell lung cancer, metastatic breast cancer, metastatic renal cell carcinoma, transitional cell carcinomas of the urothelium, small-cell lung cancer, and malignant pleural mesothelioma as monotherapy and in combination with other chemotherapy agents. More ongoing trials are evaluating its use in other solid tumors and in combination regimens. The most common adverse events in these trials were hematological (anemia and neutropenia), constipation, fatigue, abdominal pain, and myalgia.

Conclusions: Vinflunine is a new vinca alkaloid for the treatment of advanced staged solid tumors. Available data showed promising activities in various malignancies. Further studies are needed to further define vinflunine’s role in oncology.

Single agent vinflunine in the salvage treatment of patients with castration-resistant prostate cancer: a phase II trial of the Sarah Cannon research consortium

Patients with metastatic prostate cancer resistant to hormones and docetaxel were treated with vinflunine (320 mg/m(2) every 21 days), a new vinca alkaloid with improved preclinical activity. Only 1 of 36 patients (3%) had partial response; the median progression-free survival (PFS) was 2.1 months. Treatment was well tolerated, with myelosuppression as the only frequent toxicity. Vinflunine has a low level of activity in the treatment of refractory metastatic prostate cancer, and should not be further developed for this indication.

Vinflunine in platinum-pretreated patients with locally advanced or metastatic urothelial carcinoma: results of a large phase 2 study

BACKGROUND

The activity and safety of vinflunine was evaluated in patients with locally advanced or metastatic urothelial carcinoma (UC) who developed disease progression within 12 months of platinum-containing chemotherapy.

METHODS

Patients with UC were eligible if they received a prior platinum-based regimen in the neoadjuvant/adjuvant setting or as first-line treatment for advanced/metastatic disease and had developed disease progression within 12 months. Vinflunine was administered intravenously every 3 weeks. Patients with Karnofsky performance status of 80 or 90, impaired renal function, prior pelvic irradiation, or age>or=75 years received an initial dose of 280 mg/m2, which was escalated to 320 mg/m2 in Cycle 2 if well tolerated. All other patients received an initial dose of 320 mg/m2. The primary endpoint was response rate defined by an independent response review committee (IRRC).

RESULTS

Per the IRRC, 22 patients achieved a partial response, with a response rate of 15% (95% confidence interval, 9%-21%) with a median duration of response of 6.0 months. Sixty-four (42%) patients had stable disease. The median progression-free survival was 2.8 months, and the median overall survival was 8.2 months. Myelosuppression was the most frequent adverse event, with grade 3 of 4 (adverse events were evaluated according to the National Cancer Institute Common Toxicity Criteria [version 2.0] guidelines) neutropenia reported in 58% of the patients. Grade 3 of 4 febrile neutropenia occurred in 10 (7%) patients. Nonhematologic treatment-related events (grade 3 of 4) were generally manageable and included constipation (17%), asthenia/fatigue (13%), ileus (5%), and abdominal pain (5%). No cumulative toxicity was observed.

CONCLUSIONS

Vinflunine demonstrates moderate activity in patients with platinum-pretreated UC. Toxicity is manageable and noncumulative.

Total synthesis of vinblastine, vincristine, related natural products, and key structural analogues

Full details of the development of a direct coupling of catharanthine with vindoline to provide vinblastine are described along with key mechanistic and labeling studies. Following an Fe(III)-promoted coupling reaction initiated by generation of a presumed catharanthine radical cation that undergoes a subsequent oxidative fragmentation and diastereoselective coupling with vindoline, addition of the resulting reaction mixture to an Fe(III)-NaBH(4)/air solution leads to oxidation of the C15'-C20' double bond and reduction of the intermediate iminium ion directly providing vinblastine (40-43%) and leurosidine (20-23%), its naturally occurring C20' alcohol isomer. The yield of coupled products, which exclusively possess the natural C16' stereochemistry, approaches or exceeds 80% and the combined yield of the isomeric C20' alcohols is >60%. Preliminary studies of Fe(III)-NaBH(4)/air oxidation reaction illustrate a generalizable trisubstituted olefin scope, identify alternatives to O(2) trap at the oxidized carbon, provide a unique entry into C20' functionalized vinblastines, and afford initial insights into the observed C20' diastereoselectivity. The first disclosure of the use of exo-catharanthine proceeding through Delta(19',20')-anhydrovinblastine in such coupling reactions is also detailed with identical stereochemical consequences. Incorporating either a catharanthine N-methyl group or a vindoline N-formyl group precludes Fe(III)-promoted coupling, whereas the removal of the potentially key C16 methoxy group of vindoline does not adversely impact the coupling efficiency. Extension of these studies provided a total synthesis of vincristine (2) via N-desmethylvinblastine (36, also a natural product), 16-desmethoxyvinblastine (44) and 4-desacetoxy-16-desmethoxyvinblastine (47) both of which we can now suggest are likely natural products produced by C. roseus, desacetylvinblastine (62) and 4-desacetoxyvinblastine (59), as well as a series of key analogues bearing systematic modifications in the vindoline subunit. Their biological evaluation provided additional insights into the key functionality within the vindoline subunit contributing to the activity and sets the foundation on which further, more deep-seated changes in the structures of 1 and 2 will be explored in future studies.

Vinflunine in the treatment of bladder cancer

Vinflunine (VFL) is a third-generation bifluorinated semi-synthetic vinca alkaloid obtained by superacidic chemistry from its parent compound, vinorelbine. As with the other vinca alkaloids, the main antineoplastic effects of VFL arise from its interaction with tubulin, the major component of microtubules in mitotic spindles. In contrast to other vinca alkaloids, VFL shows some distinctive properties in terms of tubulin binding, possibly explaining its superior antitumor activity in vitro and in vivo compared with vinorelbine as well as its excellent safety profile. In transitional cell carcinoma (TCC), two single-agent phase II trials were performed testing VFL in platinum-pretreated patients, showing moderate response rates and promising disease control rates. Therefore, the first phase III trial in modern times for second-line TCC of the urothelium was designed in order to further investigate the activity of VFL. First results were presented at the 2008 ASCO conference. VFL appears to be a possible treatment option for patients with TCC progressing after first-line platinum-containing chemotherapy.

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.

Vinflunine: a new microtubule inhibitor agent

Vinflunine (Javlor) is the first fluorinated microtubule inhibitor belonging to the Vinca alkaloids family. Vinflunine is obtained by semisynthesis using superacidic chemistry to selectively introduce two fluorine atoms at the 20' position of the catharanthine moiety. This compound has been selected for clinical development on the basis of encouraging preclinical activity that warrants study in patients with a wide spectrum of solid tumors. Clinically significant activity has been seen in phase II studies, mainly in the treatment of transitional cell carcinoma of the urothelial tract, non-small cell lung cancer, and carcinoma of the breast. Vinflunine is currently in phase III trial assessment in patients with (second line) transitional cell carcinoma of the urothelium and first-line advanced breast cancer. The efficacy of vinflunine in patients with advanced non-small cell lung cancer previously treated with a platinum-containing regimen was confirmed by a large phase III trial.

Comparative study of the radiosensitizing and cell cycle effects of vinflunine and vinorelbine, in vitro

Background

Vinca alkaloids are an important class of anticancer agents and semisynthetic vinca alkaloids are developed to improve the therapeutic index of this class of drugs. In the present study, a direct comparison was made between vinflunine and vinorelbine regarding their radiosensitising and cell cycle effects.

Methods

Four human tumour cell lines were tested under identical experimental conditions, using equitoxic concentrations of vinflunine and vinorelbine.

Results

Vinflunine and vinorelbine induced a comparable radiosensitising effect (p-value never below 0.01) when cells were incubated for 24 h immediately prior to radiation. Regarding the cell cycle effects, a statistically significant concentration-dependent G2/M block was seen after 24 h incubation with vinorelbine in all tested cell lines. Similar results, with small cell line-related differences, were observed with vinflunine.

Conclusion

The radiosensitising effects of both semisynthetic vinca alkaloids were comparable (not statistically different) and nearly always cell line-specific and concentration-dependent. The cell cycle effects could be related to the observed radiosensitising effects. Considering the more favourable toxicity profile of vinflunine, this agent might be more promising than vinorelbine for chemoradiation studies in the clinic.

Phase II Study of Vinflunine in Malignant Pleural Mesothelioma

Purpose

Malignant pleural mesothelioma (MPM) is a disease of increasing incidence for which treatment options are limited. This study reports the clinical efficacy data for vinflunine, a novel microtubule inhibitor, in MPM.

Patients and Methods

Patients with a histologically confirmed diagnosis of MPM were eligible for enrollment onto this multicenter phase II trial if they had not received prior chemotherapy or radiotherapy and had measurable lesions by Response Evaluation Criteria in Solid Tumors (RECIST) criteria. Vinflunine 320 mg/m2 by 10-minute intravenous infusion was administered on day 1 of 21-day cycles. Modifications of dose and schedule were made according to National Cancer Institute Common Toxicity Criteria version 2.0. Efficacy was assessed by an external, independent radiologist. The one-sample multiple testing procedure of Fleming was applied at the predetermined recruitment stages of 20 and 40 assessable patients.

Results

Sixty-seven patients were enrolled. Five patients were not assessable for tumor response. The response rate was 13.8% (95% CI, 6.5% to 24.7%). The median survival was 10.8 months (95% CI, 7.8 to 12.0 months). The most common adverse events were anemia, neutropenia, fatigue, constipation, and nausea. Of grade 3 and 4 toxicities, neutropenia and constipation were the most common (45% and 9% of patients, respectively).

Conclusion

Vinflunine can be delivered with high-dose intensity in patients with MPM. The response rate and median survival are encouraging for a single agent. These data suggest that vinflunine should be further evaluated in the management of MPM.

Novel cytotoxic drugs: old challenges, new solutions

The discovery of cytotoxic agents was revolutionary for anticancer therapy in the last century, improving survival rates and the quality of life of patients with different types of tumours. However, the development of agents that combine efficacy, safety and convenience remains a great challenge, due to the narrow therapeutic index of some drugs, the fact that they may damage not only cancer cells, but also normal and healthy tissue and the occurrence of resistance, limiting anticancer efficacy. Novel cytotoxic agents have brought certain advantages over the conventional ones, such as shorter administration time, mechanisms to overcome drug resistance and lower incidence of adverse events. In this review we highlight the development of promising novel cytotoxic drugs that will hopefully offer not only gains in efficacy, but also in safety, tolerability and convenience in the treatment of patients with cancer.

Further mechanistic unravelling of the influence of the cell cycle effects on the radiosensitising mechanism of vinflunine, in vitro

PURPOSE

Vinflunine is an innovative microtubule inhibitor belonging to the vinca alkaloid class that possesses radiosensitising properties, which could lead to promising activity in chemoradiation studies in the clinic.

METHOD

In the current study, different incubation times with vinflunine, immediately before radiation and different time intervals between vinflunine treatment and radiation were investigated, in vitro, using four different human tumour cell lines differing in cell type and p53 status. Results were correlated with the cell cycle distribution at the moment of radiation, in order to elucidate the role of cell cycle perturbations caused by vinflunine on its radiosensitising effect.

RESULTS

Radiosensitisation was observed in all cell lines, and maximal radiosensitisation was both cell line- and schedule-dependent. The cell cycle distributions were cell line-dependent also, and when correlated with the observed radiosensitising effects could explain many (but not all) of the radiosensitising properties of vinflunine.

CONCLUSION

The cell cycle perturbations caused by vinflunine may definitely have an impact on its radiosensitising potential, but other factors must play a role because of some unaccountable differences between cell cycle distribution and the radiosensitising potential.

New molecular targets and novel agents in the treatment of advanced urothelial cancer

Standard cytotoxic regimens for metastatic bladder cancer, such as gemcitabine/cisplatin or methotrexate, vinblastine, doxorubicin, and cipslatin (M-VAC), yield impressive overall response rates of 45% to 70%. Despite this, long-term, disease-free, overall survival is rare, and most patients eventually succumb to the disease. Much work has been undertaken evaluating the clinical and molecular factors associated with progressive bladder cancer, and this has, in turn, led to the development of both novel targets and agents. These include standard cytotoxics such as pemetrexed, an antifolate and antimetabolite agent that has demonstrated an overall response rate of 30% in early studies, and small-molecule tyrosine kinase inhibitors such as sunitinib, which will be studied as maintenance therapy for patients who respond to first-line chemotherapy. The evaluation of new targets and new agents in the midst of limited patient, logistical, and financial resources will be one of the more difficult challenges for investigators over the next several years.

CYP3A4 mediated in vitro metabolism of vinflunine in human liver microsomes

AIM

To study the metabolism of vinflunine and the effects of selective cytochrome P-450 (CYP450) inhibitors on the metabolism of vinflunine in human liver microsomes.

METHODS

Individual selective CYP450 inhibitors were used to investigate their effects on the metabolism of vinflunine and the principal CYP450 isoform involved in the formation of metabolites M(1) and M(2) in human liver microsomes.

RESULTS

Vinflunine was rapidly metabolized to 2 metabolites: M(1) and M(2) in human liver microsomes. M(1) and M(2) were tentatively presumed to be the N-oxide metabolite or hydroxylated metabolite and epoxide metabolite of vinflunine, respectively. Ketoconazole uncompetitively inhibited the formation of M(1), and competitively inhibited the formation of M(2), while alpha-naphthoflavone, sulfaphenazole, diethyl dithiocarbamate, tranylcypromine and quinidine had little or no inhibitory effect on the formation of M(1) and M(2).

CONCLUSION

Vinflunine is rapidly metabolized in human liver microsomes, and CYP3A4 is the major human CYP450 involved in the metabolism of vinflunine.

Phase I study of vinflunine administered as a 10-minute infusion on days 1 and 8 every 3 weeks

Vinflunine is a novel vinca alkaloid developed through the selective modification of vinorelbine using super-acidic chemistry. In preclinical testing, vinflunine demonstrated significantly enhanced anti-tumour activity in human tumour xenograft models when compared to its parent compound. A phase I study was conducted to evaluate the safety and toxicity of vinflunine administered as a 10 minute intravenous infusion on days 1 and 8 every three weeks. Sixteen patients with advanced solid tumours were treated. Two of four patients experienced dose limiting toxicities (DLT) at 190 mg/m2 and this was established as the maximum tolerated dose (MTD). At the MTD, the DLT of vinflunine consisted of constipation and neutropenia. Fatigue was notable but not dose limiting. No objective responses were observed. A dose of 170 mg/m2 given on a day 1 and 8 schedule every three weeks would be suitable for future studies.

Vinflunine: a new active drug for second-line treatment of advanced breast cancer. Results of a phase II and pharmacokinetic study in patients progressing after first-line anthracycline/taxane-based chemotherapy

To evaluate the single agent activity, pharmacokinetics and tolerability of the novel tubulin targeted agent vinflunine (VFL) (320 mg m⁻² q 21 days) as second-line chemotherapy in patients with metastatic breast carcinoma (MBC). All patients had disease progression after anthracycline/taxane (A/T) therapy. They could have received a nonanthracycline adjuvant treatment and subsequently received a first-line A/T combination for advanced/metastatic disease; or relapsed >6 months after completion of adjuvant A/T therapy and were subsequently treated with the alternative agent; or relapsed within 6 months from an adjuvant A/T combination. Objective response was documented in 18 of 60 patients enrolled (RR: 30% (95% confidence interval (CI): 18.9–43.2%)). Among the responders, seven patients had relapsed during a period of <3 months from taxane-based regimen yielding a RR of 33.3%. The median duration of response was 4.8 months (95% CI: 4.2–7.2), median progression-free survival was 3.7 months (95% CI: 2.8–4.2) and median overall survival was 14.3 months (95% CI: 9.2–19.6). The most frequent adverse event was neutropenia (grade 3 in 28.3% and grade 4 in 36.7% of patients). No febrile neutropenia was observed. Fatigue (grade 3 in 16.7% of patients) and constipation (grade 3 in 11.7% of patients) were also common; these were non-cumulative and manageable permitting achievement of a good relative dose intensity of 93.5%. Vinflunine is an active agent with acceptable tolerance in the management of MBC patients previously treated with (A/T)-based regimens. These encouraging phase II results warrant further investigation of this novel agent in combination with other active agents in this setting or in earlier stages of disease.