Synergism of cytotoxic effects of vinorelbine and paclitaxel in vitro

A novel design of microfluidic platform for metronomic combinatorial chemotherapy drug screening based on 3D tumor spheroid model

For treating cancer at various stages, chemotherapy drugs administered in combination provide better treatment results with lower side effects compared to single-drug therapy. However, finding the potential drug combinations has been challenging due to the large numbers of possible combinations from approved drugs and the failure of in vitro 2D well plate-based cancer models. 3D spheroid-based high-throughput microfluidic platforms recapitulate some of the important features of native tumor tissue and offer a promising alternative to evaluate the combinatory effects of the drugs. This study develops a novel polydimethylsiloxane (PDMS) based microfluidic design with a dynamic environment and strategically placed U-shaped wells for testing all seven possible combinations (three single-drug treatments, three pairwise combinations, treatment with all three drugs) of three chemotherapy drugs (Paclitaxel, Vinorelbine, and Etoposide) on lung tumor spheroids. The design of U-shaped wells has been validated with computational results. Firstly, we test all combinations of drugs on the conventional well plate in static conditions with 3D tumor spheroids. Based on static drug testing results, we show a proof-of-concept by testing the most effective drug combination on the microfluidic device in a dynamic environment. The concentration of the drugs used in combination falls below the maximum tolerated dose (MTD) of the individual drugs, towards low dose metronomic (LDM) chemotherapy. LDM combinatorial chemotherapy identified in this study can potentially lower toxicity and provide better treatment results in cancer patients. The device can be further used to culture patient-specific tumor spheroids and identify synergistic drug combinations for personalized medicine.

Enhanced accumulation of curcumin and temozolomide loaded magnetic nanoparticles executes profound cytotoxic effect in glioblastoma spheroid model

Glioblastomas (GBMs) are highly lethal primary brain tumours. Treatment of these malignant gliomas remains ineffective as these are extremely resistant to chemotherapeutic applications. Furthermore, combination therapy for cancer treatment is becoming more popular because it generates synergistic anticancer effects, by reducing individual drug-related toxicity and associated side effects. Currently, magnetic nanoparticles (MNPs) based drug delivery system has attracted much more attention owing to its intrinsic magnetic properties and drug loading capacity. In the present study, MNPs based drug delivery approach for co-delivering of potent chemotherapeutic drugs such as Curcumin (herbal drug) and Temozolomide (DNA methylating agent) has been implemented. The dual drug loaded MNPs formulations were evaluated in two-dimensional (2-D) monolayer culture and three-dimensional (3-D) tumour spheroid culture of T-98G cells for understanding the therapeutic discrepancy. The dual drug loaded MNPs formulations demonstrated higher cytotoxic effect than single drug loaded MNPs formulations as compared to their corresponding native drugs in 2-D and 3-D culture. The combination index (CI) analysis revealed synergistic mode of action of dual drug loaded MNPs formulations, which was further confirmed by cell death induction assay mediated by acridine orange (AO)/propidium iodide (PI) staining, illustrating higher efficacy of the formulation towards GBM therapy.

The Key to Unlocking the Chemotherapeutic Potential of PPARγ Ligands: Having the Right Combination

Despite extensive preclinical evidence that peroxisome proliferator-activated receptor (PPAR)γ activation protects against tumourigenesis, results from a few clinical trials using PPARγ ligands as monotherapy show modest success. In spite of this, several groups reported exciting results with therapeutic regimens that combine PPARγ ligands with other compounds: chemotherapeutic agents, retinoid x receptor (RXR)α agonists, statins, or cell-to-cell signaling molecules in preclinical cancer models and human trials. Here we have compiled an extensive review, consolidating the existing literature, which overwhelmingly supports a beneficial effect of treating with PPARγ ligands in combination with existing chemotherapies versus their monotherapy in cancer. There are many examples in which combination therapy resulted in synergistic/additive effects on apoptosis, differentiation, and the ability to reduce cell growth and tumour burden. There are also studies that indicate that PPARγ ligand pretreatment overcomes resistance and reduces toxicities. Several mechanisms are explored to explain these protective effects. This paper highlights each of these studies that, collectively, make a very strong case for the use of PPARγ ligands in combination with other agents in the treatment and management of several cancers.

SWOG S0215: a phase II study of docetaxel and vinorelbine plus filgrastim with weekly trastuzumab for HER2-positive, stage IV breast cancer

SWOG trial S0102 showed significant activity of the combination of docetaxel and vinorelbine in HER2-negative metastatic breast cancer (MBC). For HER2-positive patients, additional benefit may occur with the addition of trastuzumab due to its synergy with docetaxel and vinorelbine. Patients with HER2-positive MBC, but without prior chemotherapy for MBC or adjuvant taxane, were eligible. Docetaxel (60 mg/m²) was given intravenously on Day 1, vinorelbine (27.5 mg/m²) intravenously on Days 8 and 15, and filgrastim (5 µg/kg) on Days 2-21 of a 21-day cycle. In addition, patients received weekly infusions of trastuzumab (2 mg/kg) after an initial bolus of 4 mg/kg. The primary outcome was 1 year overall survival (OS), with secondary outcomes of progression-free survival (PFS), response rate, and toxicity. Due to slow accrual (February 2003-December 2006), enrollment was stopped after 76 of 90 planned patients. There have been 32 deaths and 51 progressions among the 74 eligible patients who received treatment. The estimated 1 year OS was 93% (95% CI 84-97%) with a median of 48 months. One-year PFS was 70% (95% CI 58-79%) with a median of 20 months. Response rate for measurable disease was 84%. No deaths were attributed to treatment. Grade 4 toxicities were reported for 19% with neutropenia the most common (15%). The most common grade 3 toxicities (33%) were leucopenia (14%) and fatigue (10%). The combination of trastuzumab, docetaxel, and vinorelbine is effective as first-line chemotherapy in HER2-positive MBC with minimal toxicity. One-year survival estimates are among the highest reported in this population.

Paclitaxel and gemcitabine versus paclitaxel and vinorelbine in patients with advanced non-small-cell lung cancer. A phase III study of the Hellenic Cooperative Oncology Group (HeCOG)

BACKGROUND

Paclitaxel (Taxol) and vinorelbine have shown synergism of cytotoxic effects in vitro and clinical activity in phase I and II studies. This combination was compared prospectively with the paclitaxel/gemcitabine regimen in non-operable non-small-cell lung cancer.

PATIENTS AND METHODS

Chemotherapy-naive patients, stage IIIbwet and IV with performance status (0-1), were randomized to receive paclitaxel 200 mg/m(2) on day 1 plus gemcitabine 1 gm/m(2) (group A) on days 1 and 8 every 3 weeks or paclitaxel 80 mg/m(2) plus vinorelbine 22.5 mg/m(2) (group B) on days 1, 8 and 15 every 4 weeks.

RESULTS

A total of 398 out of 415 patients were eligible for analysis on intent-to-treat basis (group A: 196, group B: 202). Progression-free survival (PFS) was 5.0 months [95% confidence interval (CI) 4.3-5.6] and 4.4 months (95% CI 3.7-5.2) for groups A and B respectively (P=0.365). Median survival was 11.1 months (95% CI 9.2-13.0) and 8.6 months (95% CI 7.0-10.2) for groups A and B respectively (P = 0.147). Grade 3/4 neutropenia and leukopenia were worse in group B (P<0.001, in both cases). Febrile neutropenia and severe infections were more prominent (P<0.001, P=0.029 respectively) in group B.

CONCLUSION

Although response rate, PFS and survival were non-different in both groups, toxicity was significantly worse in group B and therefore further investigation of P-Vin is of no value.

Phase I/II Trial of Paclitaxel and Vinorelbine in Advanced Non-Small Cell Lung Cancer

Chemotherapeutic combination regimens for advanced non-small cell lung cancer traditionally have been based on platin compounds. However, a mechanistic rationale could lead to effective non-platin combinations. Paclitaxel and vinorelbine are antimicrotubule agents with different mechanisms of action, both of which have single agent activity against non-small cell lung cancer. A Phase I/II trial of paclitaxel Day 1 and vinorelbine Days 1-3 every 21 days was, therefore, performed for patients with Stage IIIB or Stage IV non-small cell lung cancer who had not previously received chemotherapy for metastatic disease. In the Phase I investigation, up to 4 patients were treated at each dose level. The maximum tolerated dose level was found to be paclitaxel 150 mg/m2 IV Day 1 and vinorelbine 16 mg/m2 IV Days 1-3, with dose-limiting toxicities of fatigue, myalgia, and mucositis at higher doses. This dose level was then expanded with an additional 15 patients. Of the 23 patients treated for up to 10 cycles at or near the maximum tolerated dose level (19 patients with paclitaxel 150 mg/m2 IV Day 1 and vinorelbine 16 mg/m2 Days 1-3, and 4 patients with paclitaxel 150 mg/m2 IV Day 1 and vinorelbine 13 mg/m2 Days 1-3), 7 patients achieved partial response and 5 patients achieved minor response. Fatigue, myalgia, peripheral neuropathy, and transient leukopenia were the most common cumulative toxicities seen. The non-platin chemotherapy doublet of paclitaxel and vinorelbine given on this convenient 3-day schedule is worthy of further investigation in the treatment of non-small cell lung cancer.

Fluvastatin enhancement of trastuzumab and classical cytotoxic agents in defined breast cancer cell lines in vitro

The combination of anticancer drugs used in the clinic has been based upon empiricism, and the potential permutations of currently available drugs overwhelm the clinical trials system. Recently, investigators have suggested that the combination of a blockade of vital signal transduction pathways in combination with more standard therapy might enhance anticancer effect. Using a panel of breast cancer cell lines and isobologram median effect analysis, a method of determining synergism or antagonism of drugs, we have investigated in vitro potentially clinically useful combinations of agents with the human cell lines MCF7/wt, MCF7/adr, BT474, and SK-BR-3 grown in log phase. Results were confirmed by curve shift analysis. Cells were exposed to the agent(s) for 72 h and then analyzed for cytotoxicity using a MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyl-tetrazolium bromide) assay. Fluvastatin, an inhibitor of prenylation with excellent tolerability in man, was chosen to disrupt signal transduction pathways and thus potentially enhance the effect of more traditional anticancer agents. Anticancer agents tested were cytotoxics used in the treatment of breast cancer, trastuzumab, and rapamycin as an inhibitor of the AKT pathway. Fluvastatin combined with trastuzumab demonstrates global synergy of cytotoxic effect that is confirmed by apoptosis assay. These effects could only be partially reversed by adding farnesol or geranylgeraniol to restore prenylation. Epirubicin is also synergistic with fluvastatin in three of the four cell lines. Rapamycin, an inhibitor of MTOR, was synergistic with fluvastatin in two of the four cell lines and antagonistic in two other cell lines. The combination of fluvastatin or another inhibitor of prenylation and trastuzumab may be attractive for clinical development as the effect of trastuzumab in Her2/neu positive breast tumors is incomplete as a single agent.

Identification of potentially useful combinations of epidermal growth factor receptor tyrosine kinase antagonists with conventional cytotoxic agents using median effect analysis

Targeted therapy for breast carcinoma has achieved a major advance with the use of trastuzumab in Her2/neu-positive tumors. The epidermal growth factor receptor superfamily thus becomes an attractive target for therapeutic agents. As the epidermal growth factor receptor tyrosine kinase family has a conformational binding site, which allows small molecules to interfere with its function, we have explored the effects of a dual kinase (epidermal growth factor receptor-1 and epidermal growth factor receptor-2) inhibitor (GW282974X) with a variety of cytotoxic agents looking for synergistic effects in vitro. Using a median effect model in four breast cancer cell lines in vitro, cytotoxic agents commonly used in treatment of human malignant disease were combined with trastuzumab or one of two epidermal growth factor receptor tyrosine kinase inhibitors in a 72-h culture and then analyzed for cytotoxic effect by 3-[26]-2,5-diphenyl-tetrazolium bromide assay. Combination index values within one standard deviation of unity were considered additive, less than unity as synergistic and more than unity as antagonistic. Synergistic results were confirmed by curve shift analysis and by an enzyme-linked immunosorbent assay measuring apoptosis by cytoplasmic histone-associated DNA fragments. Quantitative real-time polymerase chain reaction analysis was used to measure the expression of three of the critical enzymes in 5'-deoxy-5-fluorouridine metabolism and activity: thymidine phosphorylase, dihydropyrimidine dehydrogenase and thymidine synthase. 5'-Deoxy-5-fluorouridine with GW282974X demonstrated global synergy, both in high and low expressing epidermal growth factor receptor breast cancer cell lines. These results were confirmed by apoptosis assay and cell counts. RNA quantification following treatment with the dual kinase inhibitor suggested reduction in thymidine synthase levels to be a potential mechanism of synergy. The triplet of trastuzumab, GW282974X and 5'-deoxy-5-fluorouridine, and the triplet of GW282974X, epirubicin and 5'-deoxy-5-fluorouridine were highly synergistic in low expression cells (MCF7/wt) and high expression cells (MCF7/adr). These experiments suggest further studies of the dual kinase inhibitor with selected cytotoxics such as 5'-deoxy-5-fluorouridine are warranted.

Zoledronic acid (Zometa) enhances the cytotoxic effect of gemcitabine and fluvastatin: in vitro isobologram studies with conventional and nonconventional cytotoxic agents

OBJECTIVES

To identify synergistic combinations of clinically available agents with zoledronic acid which would enhance antitumor activity as measured by median effect isobologram analysis and apoptosis assays in vitro.

METHODS

The interaction of zoledronic acid as a doublet with either carboplatin, cisplatin, 5'DFUR, docetaxel, epirubicin, fluvastatin, gemcitabine, imatinib, paclitaxel, trastuzumab, or vinorelbine was studied in a 72-hour in vitro system using defined human cancer cell lines grown as a monolayer in exponential phase. Drug effect on growth was measured by a standard MTT assay. Median effect isobologram analysis was applied to the results to determine the presence of synergism, additive effects, or antagonism of drug combinations. Synergistic combinations were also assayed by a cytoplasmic histone-associated DNA fragmentation apoptosis assay to verify that the effect was not cytostatic.

RESULTS

Zoledronic acid with gemcitabine demonstrated global cytotoxic synergy across 7 of 8 cell lines. Clinically achievable concentrations of fluvastatin with zoledronic acid also demonstrated synergy in 7 of 8 cell lines. All the breast cancer cell lines were sensitive. Zoledronic acid and epirubicin were antagonistic in all 4 breast cell lines studied.

CONCLUSIONS

Combinations of zoledronic acid with either gemcitabine or fluvastatin may have a therapeutic role in treatment of bone metastasis of selected malignancies.

Altered tubulin dynamics, localization and post-translational modifications in sodium arsenite resistant Leishmania donovani in response to paclitaxel, trifluralin and a combination of both and induction of apoptosis-like cell death

In this study the anti-leishmanial activity and anti-microtubule effects of paclitaxel, trifluralin and a combination of paclitaxel and trifluralin have been tested in a wild type and sodium arsenite-resistant strain of Leishmania donovani. Both paclitaxel and trifluralin have been shown to be effective in limiting parasite growth. Specific alterations in morphology, tubulin polymerization dynamics, post-translational modifications and cellular distribution of the tubulins have been confirmed to be a part of the intracellular anti-microtubule-events that occur in arsenite-resistant L. donovani in response to these agents, ultimately leading to death of the parasite. DNA analyses of the drug-treated wild type and arsenite-resistant strains revealed an apoptosis-like death in response to paclitaxel and the combination but not to trifluralin. Data provide valuable information for further development of chemotherapeutic strategies based on anti-microtubule agents against drug resistant Leishmania parasites.

Late Phase II Clinical Study of Vinorelbine Monotherapy in Advanced or Recurrent Breast Cancer Previously Treated with Anthracyclines and Taxanes

BACKGROUND

At present, it is one of the most important issues for the treatment of breast cancer to develop the standard therapy for patients previously treated with anthracyclines and taxanes. With the objective of determining the usefulness of vinorelbine monotherapy in patients with advanced or recurrent breast cancer after standard therapy, we evaluated the efficacy and safety of vinorelbine in patients previously treated with anthracyclines and taxanes.

METHODS

Vinorelbine was administered at a dose level of 25 mg/m(2) intravenously on days 1 and 8 of a 3 week cycle. Patients were given three or more cycles in the absence of tumor progression. A maximum of nine cycles were administered.

RESULTS

The response rate in 50 evaluable patients was 20.0% (10 out of 50; 95% confidence interval, 10.0-33.7%). Responders plus those who had minor response (MR) or no change (NC) accounted for 58.0% [10 partial responses (PRs) + one MR + 18 NCs out of 50]. The Kaplan-Meier estimate (50% point) of time to progression (TTP) was 115.0 days. The response rate in the visceral organs was 17.3% (nine PRs out of 52). The major toxicity was myelosuppression, which was reversible and did not require discontinuation of treatment.

CONCLUSION

The results of this study show that vinorelbine monotherapy is useful in patients with advanced or recurrent breast cancer previously exposed to both anthracyclines and taxanes.

Paclitaxel, vinorelbine and 5-fluorouracil in breast cancer patients pretreated with adjuvant anthracyclines

We investigated the activity and toxicity of a combination of vinorelbine (VNB), paclitaxel (PTX) and 5-fluorouracil (5-FU) continuous infusion administered as first-line chemotherapy in metastatic breast cancer patients pretreated with adjuvant anthracyclines. A total of 61 patients received a regimen consisting of VNB 25 mg m⁻² on days 1 and 15, PTX 60 mg m⁻² on days 1, 8 and 15 and continuous infusion of 5-FU at 200 mg m⁻² every day. Cycles were repeated every 28 days. Disease response was evaluated by both RECIST and World Health Organization (WHO) criteria. Objective responses were recorded in 39 of 61 patients (64.0%) assessed by WHO and in 36 of 50 patients (72.0%) assessable by RECIST criteria. Complete remission occurred in 15 (24.6%) and 14 patients (28.0%), respectively. The median time to progression and overall survival of entire population was 10.6 and 27.3 months, respectively, and median duration of complete response was 14.8 months. The dose-limiting toxicity was myelosuppression (leucopenia grade 3/4 in 52.5% of patients). Grade 3/4 nonhaematologic toxicities included mucositis/diarrhoea in 13.1%, skin in 3.3% and cardiac in 1.6% of patients. Grade 2/3 neurotoxicity was observed in five patients (7.2%). The VNB, PTX and 5-FU continuous infusion combination regimen was active and manageable. Complete responses were frequent and durable.

Studies of synergistic and antagonistic combinations of conventional cytotoxic agents with the multiple eicosanoid pathway modulator LY 293111

The arachidonic acid metabolic pathway is currently under active investigation as a promoter of malignancy and several molecules have been synthesized to block either the cyclooxygenase or lipoxygenase branches. LY 293111 is an oral agent known to be a leukotriene B4 antagonist, a 5-lipoxygenase inhibitor and a peroxisome proliferator-activated receptor (PPAR)-gamma agonist with cytotoxic properties in cell lines. We have studied this agent with classical chemotherapeutic agents in a 72-h culture with cell lines using median-effect analysis as a measure of antagonism or synergy. LY 293111 displays global synergy with the active metabolite of irinotecan, SN-38, in the majority of cell lines, synergistic to additive effects with gemcitabine in bladder cancer cell lines, and synergism with 5'-DFUR (the active metabolite of capecitabine) in two breast cancer and one sarcoma cell line. These effects occur at clinically attainable concentrations. The addition of a proteosome inhibitor to the LY 293111 and SN-38 combination markedly enhanced the cytotoxic effects in the sarcoma cell line. As the toxicity of LY 293111 in man is not hematological, this agent may have a role in combination therapy of selected malignancies.

Laulimalide and paclitaxel: a comparison of their effects on tubulin assembly and their synergistic action when present simultaneously

Previous work has shown that laulimalide, a sponge-derived natural product, resembles paclitaxel in enhancing tubulin assembly and in its effects on cellular microtubules. The two compounds, however, seem to have distinct binding sites on tubulin polymer. Nearly equimolar amounts of tubulin, laulimalide, and paclitaxel are recovered from microtubules formed with both drugs. In the present study, we searched for differences between laulimalide and paclitaxel in their interactions with tubulin polymer. Laulimalide was compared with paclitaxel and epothilone A, a natural product that competes with paclitaxel in binding to microtubules, for assembly properties at different temperatures and for effects of GTP and microtubule-associated proteins on assembly. Although minor differences were observed among the three drugs, their overall effects were highly similar, except that aberrant assembly products were observed more frequently with paclitaxel and that the polymers formed with laulimalide and epothilone A were more stable at 0 degrees C. The most dramatic difference observed between laulimalide and epothilone A was that only laulimalide was able to enhance assembly synergistically with paclitaxel, as would be predicted if the two drugs bound at different sites in polymer. Because stoichiometric amounts of laulimalide and paclitaxel can cause extensive tubulin assembly, maximum synergy was observed at lower temperatures under reaction conditions in which each drug alone is relatively inactive. Laulimalide-induced assembly, like paclitaxel-induced assembly, was inhibited by drugs that inhibit tubulin assembly by binding at either the colchicine- or vinblastine-binding site. When radiolabeled GTP is present in a reaction mixture with either laulimalide or paclitaxel, nucleotide hydrolysis occurs with incorporation of radiolabeled GDP into polymer.

Phase II Study of Paclitaxel Combined With Vinorelbine in Patients With Advanced Breast Cancer

Paclitaxel and vinorelbine are two drugs active against breast cancer. A phase II study was initiated with the aim of assessing the efficacy and feasibility of the combination. Twenty-six patients presenting with advanced breast cancer with a taxane- and vinorelbine-free line of chemotherapy were included and treated with vinorelbine (20 mg/m2 on D1, D15), followed by paclitaxel (175 mg/m2 on D1), every 3 weeks. A 48% (95% CI: 35-61) response rate was obtained in the 23 patients evaluable for response. Vinorelbine was administered on D15, as scheduled, in 72% of cycles. The main toxicity observed was grade III to IV neutropenia in 73% of patients. Febrile neutropenia was reported in three patients. Disease-free survival was 118 days, and overall median survival was 361 days. This combination of paclitaxel and vinorelbine is feasible and effective in patients with early relapse or previously treated with first-line chemotherapy for metastatic disease.

Paclitaxel, Cisplatin, and Vinorelbine Combination Chemotherapy in Metastatic Non–Small-Cell Lung Cancer

Vinorelbine-cisplatin combination chemotherapy is a standard approach for the treatment of advanced non-small-cell lung cancer (NSCLC). The addition of paclitaxel as a third therapeutic agent seems promising. The aim of the present study was to evaluate the activity and toxicity of this new regimen. Forty-six nonselected and chemotherapy-naive patients with stage IV NSCLC and an Eastern Cooperative Oncology Group performance status of 0 to 2 were treated every 4 weeks with paclitaxel (135 mg/m2 given iv in 3 hours) and cisplatin (120 mg/m2 given iv in 6 hours) on day 1 and vinorelbine (30 mg/m2 given iv in 30 minutes) on days 1 and 15. All patients were evaluated for toxicity and response according to the intent-to-treat principle. An objective response was observed in 39% of the patients (95% CI: 25% to 55%). World Health Organization grade III to IV neutropenia, thrombocytopenia, and anemia occurred in 43%, 2%, and 17%, respectively. There was one treatment-related death. Nonhematologic toxicities were mild, mainly grade III nausea and vomiting in 20% of the patients. After a median follow-up period of 54 months, the median progression-free survival was 14.3 weeks and the median overall survival was 31.3 weeks. This three-drug chemotherapy combination is feasible, well tolerated, and shows activity in metastatic NSCLC.

Effect of nitric oxide on cytotoxicity of Taxol: enhanced Taxol transcellular permeability

The present studies were aimed at testing the hypothesis that nitric oxide (NO) may enhance Taxol-induced cytotoxicity in carcinoma cells by increasing influx of Taxol into intracellular compartments. Prostate carcinoma cells (PC-3, LNCaP) and neuroblastoma cells (SKNDZ, CHP212) were used to investigate both transmembrane permeability and cytotoxicity of Taxol in the presence and absence of S-nitrosocaptopril (CapNO), a nitric oxide donating compound. The order of permeability rate of Taxol across the four cell lines was SKNDZ>LNCaP>PC-3>CHP212. Pretreatment of the cell lines with CapNO (100 microM) enhanced permeability of Taxol across prostate PC-3 and LNCaP cells, but not neuroblastoma SKNDZ and CHP212 cells. Taxol inhibited cell growth at nanomolar levels with IC(50)s of 0.21, 17.4, 96.4 and 842.9 nM corresponding to SKNDZ, PC-3, LNCaP and CHP212 cells, respectively. However, CapNO inhibited proliferation of the four cell lines at millimolar levels with IC(50)s ranging from 0.3 to 1.1 mM. Enhancing effect of CapNO (100 microM) on Taxol cytotoxicity were found in PC-3 and LNCaP cells, but not in SKNDZ and CHP212. The findings suggest that the cytotoxic potency of Taxol is mainly dependent upon the cell membrane permeabilization to Taxol, and the enhancing effect of CapNO on Taxol-induced cytotoxicity is primarily mediated via the increased influx of Taxol by NO into intracellular compartments, while NO-induced cytotoxicity cannot be excluded.

Unique induction of p21(WAF1/CIP1)expression by vinorelbine in androgen-independent prostate cancer cells

To study the mechanisms of the development of hormone refractory prostate cancer, we established an androgen-independent (AI) prostate cancer cell line derived from hormone-dependent (AD) LNCaP cells. Our previous studies have demonstrated that AI cells are deficient in expression of p21(WAFl/CIP1) (p21) due to overexpressed AR and are resistant to apoptosis. In this study, the induction of p53 and p21 expression by vinorelbine (Navelbine) was compared between AD and AI cells in an attempt to understand the difference(s) in apoptotic signalling pathways in these cells. Using a series of deletion of p21 reporter constructs, we found that vinorelbine mediated p21 induction in a p53-dependent manner in AD cells. In contrast, p21 expression restored by vinorelbine in AI cells was found to be through both p53-dependent and-independent pathways. In the absence of two p53 binding sites, Spl-3 and Spl-4 sites, in the promoter of human p21 gene, were found to be required for vinorelbine-mediated p21 activation. No p21 induction was observed by paclitaxel in AI cells. Exposure of AI cells to paciltaxel followed by vinorelbine produced synergism. Our data, thus, provide a basis for the synergistic combination of vinorelbine and paclitaxel for the treatment of advanced prostate cancer.

A phase II study of non-platinum based chemotherapy with paclitaxel and vinorelbine in non-small cell lung cancer

INTRODUCTION

Paclitaxel and vinorelbine combination in previous untreated patients with stage IIIb-IV non-small cell lung cancer (NSCLC) as a phase II study.

PATIENTS AND METHODS

Thirty-four patients (4 patients with stage IIIb, 30 patients in stage IV), with median age 66 and performance status 0-1, were administered paclitaxel, 175 mg/m(2) in a 3-h infusion rate on day 1 and vinorelbine, 25 mg/m(2) in a 10-min infusion rate on days 1, and 8 with G-CSF and EPO support.

RESULTS

Among our 33 evaluable patients for toxicity 16 patients (48.4%) presented leukopenia and 15 patients (45.4%) presented anemia despite G-CSF and EPO administration. Two patients (6%) presented Grade III-IV peripheral neuropathy. The overall response rate was 67.7%; 5 patients (16.1%) showed complete response (2 patients stage IIIb) and 16 patients (51.6%) showed partial response (1 patient stage IIIb). The overall median survival time was 10 months (range 3-18 months) and the median disease-free survival was 9 months (range 3-15 months) with an 1-year survival time of 45.1% (14 patients).

CONCLUSION

The results of the combination as 1st line treatment for patients with non-operable NSCLC are promising and should be further investigated.

Synergistic and antagonistic combinations of drugs in human prostate cancer cell lines in vitro

Microtubulin binding agents such as docetaxel have significant preclinical and clinical activity in the treatment of hormone-refractory prostate cancer. We have previously used median-effect analysis to define both synergistic and antagonistic drug combinations which may be of value in management of human disease. These studies extend our findings in defined prostate cancer cell lines. A semi-automated microtiter culture system was used. Docetaxel was combined with 18 other agents, incubated with DU 145, LnCaP or PC 3 prostate cancer cell lines for 72 h and the cells then incubated with MTT to determine cytotoxic effect. Both doublet and triplet combinations were examined. Synergy and antagonism as measured by the combination index were determined for each combination. The non-mutually exclusive criterion was applied. Docetaxel demonstrated cytotoxic additive effects or synergy with -retinoic acid, cyclosporin A and vinorelbine in all three cell lines. Docetaxel combined with either epirubicin or doxorubicin displayed cytotoxic synergistic effects in hormone-refractory DU 145 and PC 3 cell lines. In contrast, drugs which have been combined clinically to treat hormone-refractory prostate cancer, i.e. cisplatin, carboplatin or etoposide, were antagonistic when combined with docetaxel. We conclude that combinations of docetaxel with either -retinoic acid or vinorelbine may offer an enhanced cytotoxic effect in the management of hormone-refractory prostate cancer and need to be evaluated for therapeutic effect. The combination of docetaxel with an anthracycline was also synergistic in the two hormone-refractory cell lines, DU 145 and PC3, thus suggesting a potential role in advanced disease after endocrine failure. Combinations of docetaxel with platinum or etoposide may lead to subadditive effects in treatment.

In vitro search for synergy and antagonism: evaluation of docetaxel combinations in breast cancer cell lines

The use of combination chemotherapy is the accepted standard for most human malignancies but little attention has been paid to drug interactions. A combination of drugs may be synergistic, additive, or antagonistic in cytotoxic activity. This study evaluated combinations of agents with docetaxel, one of the most active agents in human breast cancer, using a median effects model to look at synergy or antagonism in vitro as a potential predictor of clinical outcome. Three human breast cancer cell lines, MCF7/wt, MCF7/adr (multiply drug resistant), and BT474 were grown to confluence, plated into 96 well dishes, and incubated with combinations of drugs for 72h. Cytotoxic effect was measured by the MTT assay. Median effect analysis was used to calculate the combination index (CI) with values less than 1 indicating synergism, 1 additive effects, and greater than 1 antagonism. Potentially useful combinations for clinical study which were identified included docetaxel with vinorelbine, docetaxel with dexrazoxane, docetaxel with cis-retinoic acid, docetaxel with disulfiram and either doxorubicin or epirubicin, and docetaxel with dexrazoxane and epirubicin.

Calmodulin is a selective modulator of estrogen receptors

In the search for differences between ERalpha and ERbeta, we analyzed the interaction of both receptors with calmodulin (CaM) and demonstrated that ERalpha but not ERbeta directly interacts with CaM. Using transiently transfected HeLa cells, we examined the effect of the CaM antagonist N-(6-aminohexyl)-5-chloro-naphthalene sulfonilamide hydrochloride (W7) on the transactivation properties of ERalpha and ERbeta in promoters containing either estrogen response elements or activator protein 1 elements. Transactivation by ERalpha was dose-dependently inhibited by W7, whereas that of ERbeta was not inhibited or even activated at low W7 concentrations. In agreement with these results, transactivation of an estrogen response element containing promoter in MCF-7 cells (which express a high ERalpha/ERbeta ratio) was also inhibited by W7. In contrast, transactivation in T47D cells (which express a low ERalpha/ERbeta ratio) was not affected by this CaM antagonist. The sensitivity of MCF-7 cells to W7 was abolished when cells were transfected with increasing amounts of ERbeta, indicating that the sensitivity to CaM antagonists of estrogen-responsive tissues correlates with a high ERalpha/ERbeta ratio. Finally, substitution of lysine residues 302 and 303 of ERalpha for glycine rendered a mutant ERalpha unable to interact with CaM whose transactivation activity became insensitive to W7. Our results indicate that CaM antagonists are selective modulators of ER able to inhibit ERalpha-mediated activity, whereas ERbeta actions were not affected or even potentiated by W7.

Differential effect of vinorelbine versus paclitaxel on ERK2 kinase activity during apoptosis in MCF-7 cells

The effects of vinorelbine and paclitaxel on the activity of extracellular signal-regulated protein kinase2 (ERK2), a member of MAP kinase, and its role in the induction of bcl-2 phosphorylation and apoptosis were evaluated in MCF-7 cells. We demonstrated that ERK2 was activated rapidly by vinorelbine, and was inhibited by either paclitaxel or estramustine. A 3-fold increase of ERK2 kinase activity was observed within 30 min when MCF-7 cells were treated with 0.1 microM vinorelbine. In contrast, the same treatment with paclitaxel resulted in a significant decrease of ERK2 kinase activity. We also demonstrated that elevated bcl-2 phosphorylation induced by vinorelbine is paralleled by decrease of a complex formation between bcl-2 and bax, cleavage of poly (ADP) ribose polymerase (PARP) protein, activation of caspase-7, and apoptosis. The levels of bcl-2 phosphorylation, bax, and PARP were not significantly affected by 2'-amino-3'-methoxyflavone (PD 98059), an ERK kinase specific inhibitor. Thus, our data suggest that the apoptosis induced by vinorelbine in MCF-7 cells is mediated through the bcl-2 phosphorylation/bax/caspases pathways, and that activation of ERK2 by vinorelbine does not directly lead to the drug-mediated apoptosis. Since decrease of PARP occurred quickly following the treatment of MCF-7 cells with either 0.1 microM of vinorelbine or paclitaxel, this protein may serve as an early indicator of apoptosis induced not only by DNA damaging agents, but also by antimicrotubule drugs.

In vitro effects of dexrazoxane (Zinecard) and classical acute leukemia therapy: time to consider expanded clinical trials?

Anthracyclines have been the backbone of acute leukemia therapy in the adult for many years, but little attention has been paid to the long-term toxicity of these agents in this disease because of the poor survival of this population of patients. Recent studies have examined dose-intensified daunorubicin with dosages as high as 95 mg/m2 daily x 3 in this population with the attendant concerns of both acute and chronic toxicity. We have examined three human leukemia cell lines in vitro, treated with either daunorubicin, mitoxantrone, with or without cytosine arabinoside in the presence of dexrazoxane to determine whether such treatment would be synergistic or antagonistic. AML-193, CRF-SB, and Molt-4 cell lines were grown to confluence, plated into microtiter dishes and incubated for 72 h with varying concentrations of the above drugs. Cytotoxicity was determined by the MTT assay, and synergy or antagonism by median effect analysis. Dexrazoxane demonstrated additive or synergistic cytotoxic effects (CI <1) under most conditions. The triplet of daunorubicin, cytosine arabinoside, and dexrazoxane showed profound synergy in all three cell lines. These effects occurred at clinically achievable levels. If high dosages of anthracyclines are contemplated in this population, these preclinical data suggest that the addition of dexrazoxane to classical therapy is not antagonistic and thus may allow an investigation of the role of dexrazoxane as a cardiac protectant.