Polymorphisms and clinical outcome in recurrent ovarian cancer treated with cyclophosphamide and bevacizumab

PURPOSE

This study was designed to evaluate the associations between angiogenesis gene polymorphisms and clinical outcome in ovarian cancer patients treated with low-dose cyclophosphamide and bevacizumab.

EXPERIMENTAL DESIGN

Seventy recurrent/metastatic epithelial ovarian cancer patients were enrolled in a phase II clinical trial. Genomic DNA was available from 53 blood samples. Polymorphisms were analyzed using the PCR-RFLP protocol. A 5' end 33P gammaATP-labeled PCR protocol was used to analyze dinucleotide repeats.

RESULTS

Patients genotyped A/A or A/T for the IL-8 T-251A gene polymorphism had a statistically significant lower response rate (19%; 0%) than those homozygous T/T (50%; P = 0.006, Fisher's exact test). Patients carrying a minimum one C allele (C/C; C/T) of the CXCR2 C+785T polymorphism showed a median progression-free survival (PFS) of 7.4 months compared with the PFS of 3.7 months for those homozygous T/T (P = 0.026, log-rank test). Patients with the VEGF C+936T polymorphism C/T genotype had a longer median PFS of 11.8 months, compared with those with the C/C and T/T genotype, which had median PFS of 5.5 months and 3.2 months, respectively (P = 0.061, log-rank test). Patients carrying both AM 3'end alleles < 14 CA repeats had the shortest median PFS of 3.4 months; patients with at least one allele > 14 repeats or both alleles > 14 repeats showed a median PFS of 6.4 months and 7.2 months, respectively (P = 0.008, log-rank test).

CONCLUSION

Our data suggest that the IL-8 A-251T polymorphism may be a molecular predictor of response to bevacizumab-based chemotherapy. The CXCR2 C+785T, VEGF C+936T single nucleotide polymorphisms and the AM 3' dinucleotide repeat polymorphisms may be molecular markers for PFS in ovarian cancer patients.

Metronomic chemotherapy

Toxic effects and chemoresistance are major hurdles in chemotherapy and to avoid these problems caused by traditional chemotherapeutic regimens, a new modality of drug administration called “metronomic chemotherapy” has emerged. Such regimen involves the frequent administration of conventional chemotherapeutic agents at very low doses to target activated endothelial cells in tumors, the advantages of which include minimal adverse effects and a rare chance of developing acquired drug resistance. Previously it was thought that they act by targeting angiogenesis, but recently additional mechanisms have been discovered which has established metronomic chemotherapy as a type of multi-targeted therapy. The knowledge gained from the preclinical studies of metronomic chemotherapy, along with clinical experience, will help to design better therapeutic protocols against cancer. Detailed pharmacogenomic and pharmacoproteomic studies on tumor endothelial cells and large multi-centered clinical trials, integrating bio-marker analyzes, are needed to investigate and validate the best treatment combinations for each tumor type and patient population.

Metronomic cyclophosphamide eradicates large implanted GL261 gliomas by activating antitumor Cd8+ T-cell responses and immune memory

Cancer chemotherapy using cytotoxic drugs can induce immunogenic tumor cell death; however, dosing regimens and schedules that enable single-agent chemotherapy to induce adaptive immune-dependent ablation of large, established tumors with activation of long-term immune memory have not been identified. Here, we investigate this issue in a syngeneic, implanted GL261 glioma model in immune-competent mice given cyclophosphamide on a 6-day repeating metronomic schedule. Two cycles of metronomic cyclophosphamide treatment induced sustained upregulation of tumor-associated CD8⁺ cytotoxic T lymphocyte (CTL) cells, natural killer (NK) cells, macrophages, and other immune cells. Expression of CTL- and NK–cell-shared effectors peaked on Day 6, and then declined by Day 9 after the second cyclophosphamide injection and correlated inversely with the expression of the regulatory T cell (Treg) marker Foxp3. Sustained tumor regression leading to tumor ablation was achieved after several cyclophosphamide treatment cycles. Tumor ablation required CD8⁺ T cells, as shown by immunodepletion studies, and was associated with immunity to re-challenge with GL261 glioma cells, but not B16-F10 melanoma or Lewis lung carcinoma cells. Rejection of GL261 tumor re-challenge was associated with elevated CTLs in blood and increased CTL infiltration in tumors, consistent with the induction of long-term, specific CD8⁺ T-cell anti-GL261 tumor memory. Co-depletion of CD8⁺ T cells and NK cells did not inhibit tumor regression beyond CD8⁺ T-cell depletion alone, suggesting that the metronomic cyclophosphamide-activated NK cells function via CD8a⁺ T cells. Taken together, these findings provide proof-of-concept that single-agent chemotherapy delivered on an optimized metronomic schedule can eradicate large, established tumors and induce long-term immune memory.

Predictable and tunable half-life extension of therapeutic agents by controlled chemical release from macromolecular conjugates

Conjugation to macromolecular carriers is a proven strategy for improving the pharmacokinetics of drugs, with many stable polyethylene glycol conjugates having reached the market. Stable conjugates suffer several limitations: loss of drug potency due to conjugation, confining the drug to the extracellular space, and the requirement for a circulating conjugate. Current research is directed toward overcoming such limitations through releasable conjugates in which the drug is covalently linked to the carrier through a cleavable linker. Satisfactory linkers that provide predictable cleavage rates tunable over a wide time range that are useful for both circulating and noncirculating conjugates are not yet available. We describe such conjugation linkers on the basis of a nonenzymatic β-elimination reaction with preprogrammed, highly tunable cleavage rates. A set of modular linkers is described that bears a succinimidyl carbonate group for attachment to an amine-containing drug or prodrug, an azido group for conjugation to the carrier, and a tunable modulator that controls the rate of β-eliminative cleavage. The linkers provide predictable, tunable release rates of ligands from macromolecular conjugates both in vitro and in vivo, with half-lives spanning from a range of hours to >1 y at physiological pH. A circulating PEG conjugate achieved a 56-fold half-life extension of the 39-aa peptide exenatide in rats, and a noncirculating s.c. hydrogel conjugate achieved a 150-fold extension. Using slow-cleaving linkers, the latter may provide a generic format for once-a-month dosage forms of potent drugs. The releasable linkers provide additional benefits that include lowering C(max) and pharmacokinetic coordination of drug combinations.

Phase II study of metronomic chemotherapy with bevacizumab for recurrent glioblastoma after progression on bevacizumab therapy

We evaluated the efficacy of metronomic etoposide or temozolomide administered with bevacizumab among recurrent glioblastoma (GBM) patients who progressed on prior bevacizumab therapy in a phase 2, open-label, two-arm trial. Twenty-three patients received bevacizumab (10 mg/kg) every 2 weeks with either oral etoposide (50 mg/m2) daily for 21 consecutive days each month or daily temozolomide (50 mg/m2). The primary endpoint was 6-month progression-free survival (PFS-6) and secondary endpoints included safety and overall survival. Both the etoposide and temozolomide arms of the study closed at the interim analysis due to lack of adequate anti-tumor activity. No radiographic responses were observed. Although 12 patients (52%) achieved stable disease, PFS-6 was 4.4% and the median PFS was 7.3 weeks. The only grade 4 adverse event was reversible neutropenia. Grade 3 toxicities included fatigue (n = 2) and infection (n = 1). Metronomic etoposide or temozolomide is ineffective when administered with bevacizumab among recurrent GBM patients who have progressed on prior bevacizumab therapy. Alternative treatment strategies remain critically needed for this indication.

Metronomic chemotherapy following the maximum tolerated dose is an effective anti-tumour therapy affecting angiogenesis, tumour dissemination and cancer stem cells

In this article, the effectiveness of a multi-targeted chemo-switch (C-S) schedule that combines metronomic chemotherapy (MET) after treatment with the maximum tolerated dose (MTD) is reported. This schedule was tested with gemcitabine in two distinct human pancreatic adenocarcinoma orthotopic models and with cyclophosphamide in an orthotopic ovarian cancer model. In both models, the C-S schedule had the most favourable effect, achieving at least 80% tumour growth inhibition without increased toxicity. Moreover, in the pancreatic cancer model, although peritoneal metastases were observed in control and MTD groups, no dissemination was observed in the MET and C-S groups. C-S treatment caused a decrease in angiogenesis, and its effect on tumour growth was similar to that produced by the MTD followed by anti-angiogenic DC101 treatment. C-S treatment combined an increase in thrombospondin-1 expression with a decrease in the number of CD133+ cancer cells and triple-positive CD133+/CD44+/CD24+ cancer stem cells (CSCs). These findings confirm that the C-S schedule is a challenging clinical strategy with demonstrable inhibitory effects on tumour dissemination, angiogenesis and CSCs.

Targeted anti-vascular therapies for ovarian cancer: current evidence

Ovarian cancer presents at advanced stage in around 75% of women, and despite improvements in treatments such as chemotherapy, the 5-year survival from the disease in women diagnosed between 1996 and 1999 in England and Wales was only 36%. Over 80% of patients with advanced ovarian cancer will relapse and despite a good chance of remission from further chemotherapy, they will usually die from their disease. Sequential treatment strategies are employed to maximise quality and length of life but patients eventually become resistant to cytotoxic agents. The expansion in understanding of the molecular biology that characterises cancer cells has led to the rapid development of new agents to target important pathways but the heterogeneity of ovarian cancer biology means that there is no predominant defect. This review attempts to discuss progress to date in tackling a more general target applicable to ovary cancer-angiogenesis.

Metronomic Chemotherapy

Simple Summary

The present article reviews the state of the art of metronomic chemotherapy use to treat the principal types of cancers, namely breast, non-small cell lung cancer and colorectal ones, and of the most recent progresses in understanding the underlying mechanisms of action. Areas of novelty, in terms of new regimens, new types of cancer suitable for Metronomic chemotherapy (mCHT) and the overview of current ongoing trials, along with a critical review of them, are also provided.

Abstract

Metronomic chemotherapy treatment (mCHT) refers to the chronic administration of low doses chemotherapy that can sustain prolonged, and active plasma levels of drugs, producing favorable tolerability and it is a new promising therapeutic approach in solid and in hematologic tumors. mCHT has not only a direct effect on tumor cells, but also an action on cell microenvironment, by inhibiting tumor angiogenesis, or promoting immune response and for these reasons can be considered a multi-target therapy itself. Here we review the state of the art of mCHT use in some classical tumour types, such as breast and no small cell lung cancer (NSCLC), see what is new regarding most recent data in different cancer types, such as glioblastoma (GBL) and acute myeloid leukemia (AML), and new drugs with potential metronomic administration. Finally, a look at the strategic use of mCHT in the context of health emergencies, or in low –and middle-income countries (LMICs), where access to adequate healthcare is often not easy, is mandatory, as we always need to bear in in mind that equity in care must be a compulsory part of our medical work and research.

A Combination of Immune Checkpoint Inhibition with Metronomic Chemotherapy as a Way of Targeting Therapy-Resistant Cancer Cells

Therapeutic resistance remains a major obstacle in treating many cancers, particularly in advanced stages. It is likely that cytotoxic lymphocytes (CTLs) have the potential to eliminate therapy-resistant cancer cells. However, their effectiveness may be limited either by the immunosuppressive tumor microenvironment, or by immune cell death induced by cytotoxic treatments. High-frequency low-dose (also known as metronomic) chemotherapy can help improve the activity of CTLs by providing sufficient stimulation for cytotoxic immune cells without excessive depletion. Additionally, therapy-induced removal of tumor cells that compete for shared nutrients may also facilitate tumor infiltration by CTLs, further improving prognosis. Metronomic chemotherapy can also decrease the number of immunosuppressive cells in the tumor microenvironment, including regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs). Immune checkpoint inhibition can further augment anti-tumor immune responses by maintaining T cells in an activated state. Combining immune checkpoint inhibition with metronomic administration of chemotherapeutic drugs may create a synergistic effect that augments anti-tumor immune responses and clears metabolic competition. This would allow immune-mediated elimination of therapy-resistant cancer cells, an effect that may be unattainable by using either therapeutic modality alone.

Potent efficacy of metronomic topotecan and pazopanib combination therapy in preclinical models of primary or late stage metastatic triple-negative breast cancer

Metronomic chemotherapy has shown promising activity in numerous preclinical studies and also some phase II clinical studies involving various tumor types, and is currently undergoing phase III trial evaluation. Triple-negative breast cancer (TNBC) is an aggressive histological subtype with limited treatment options and very poor prognosis following progression after standard chemotherapeutic regimens. Herein, we evaluated the potential therapeutic impact and molecular mechanisms of topotecan administered in a continuous low-dose metronomic (LDM) manner, alone or in concurrent combination with pazopanib, an antiangiogenic tyrosine kinase inhibitor (TKI), in a triple-negative, primary and metastatic breast cancer orthotopic model; potential molecular mechanisms of efficacy were also studied, especially the impact of hypoxic conditions. The combination of metronomic topotecan and pazopanib significantly enhanced antitumor activity compared to monotherapy with either drug and prolonged survival, even in the advanced metastatic survival setting, with a marked decrease in tumor vascularity, proliferative index, and the induction of apoptosis. Significant changes in tumor angiogenesis, cancer cell proliferation, apoptosis, HIF1α levels, HIF-1 target genes and ABCG2 were found both in vitro and in tumor tissue. Notably, the pazopanib and metronomic topotecan combination treatment inhibited expression of HIF1α and ABCG2 genes in cells grown under hypoxic conditions, and this was associated with an increased intracellular concentration of the active form of topotecan. Our results suggest a potential novel therapeutic option for the treatment of metastatic triple-negative breast cancer patients.

Targeted therapy with propranolol and metronomic chemotherapy combination: sustained complete response of a relapsing metastatic angiosarcoma

We report here a case of a 69-year-old woman with a relapsing metastatic angiosarcoma treated with a combination of metronomic chemotherapy and propranolol. The beta blockers were added since the tumour was positive for betaadrenergic receptor. A complete response was quickly obtained and lasted for 20 months.

With this case, the combination of metronomic chemotherapy and propranolol in angiosarcoma warrants additional studies and illustrates the potential of metronomics to generate innovative yet inexpensive targeted therapies for both high-income and low-/middle-income countries.

A randomized study of KRAS-guided maintenance therapy with bevacizumab, erlotinib or metronomic capecitabine after first-line induction treatment of metastatic colorectal cancer: the Nordic ACT2 trial

BACKGROUND

Maintenance treatment (mt) with bevacizumab (bev) ± erlotinib (erlo) has modest effect after induction chemotherapy in metastatic colorectal cancer (mCRC). We hypothesized the efficacy of erlo to be dependent on KRAS mutational status and investigated this by exploring mt strategies with bev ± erlo and low-dose capecitabine (cap).

PATIENTS AND METHODS

Included patients had mCRC scheduled for first-line therapy, Eastern Cooperative Oncology Group (ECOG) 0-1 and no major comorbidities. Treatment with XELOX/FOLFOX or XELIRI/FOLFIRI + bev was given for 18 weeks. After induction, patients without progression were eligible for randomization to mt; KRAS wild-type (wt) patients were randomized to bev ± erlo (arms wt-BE, N = 36 versus wt-B, N = 35), KRAS mutated (mut) patients were randomized to bev or metronomic cap (arms mut-B, N = 34 versus mut-C, N = 33). Primary end point was progression-free survival (PFS) rate (PFSr) at 3 months after start of mt. A pooled analysis of KRAS wt patients from the previous ACT study was performed.

RESULTS

We included 233 patients. Median age was 64 years, 62% male, 68% ECOG 0, 52% with primary tumor in situ. A total of 138 patients started mt after randomization. PFSr was 64.7% versus 63.6% in wt-B versus wt-BE, P = 1.000; and 75% versus 66.7% in mut-B versus mut-C, P = 0.579, with no significant difference in median PFS and overall survival (OS). In the pooled cohort, median PFS was 3.7 months in wt-B (N = 64) and 5.7 months in wt-BE (N = 62) (hazard ratios 1.03, 95% confidence interval 0.70-1.50, P = 0.867). The frequency of any grade 3/4 toxicities during mt was: 28%/58%/18%/15% (wt-B/wt-BE/mut-B/mut-C).

CONCLUSIONS

Addition of erlo to bev as mt in KRAS wt mCRC did not significantly improve PFS or OS, but it did increase toxicity. KRAS status does not seem to influence the outcome of treatment with erlotinib. Metronomic cap warrants further investigation in mt strategies, given our explorative results.

CLINICALTRIALSGOV

NCT01229813.

Metronomic oral vinorelbine in advanced breast cancer and non-small-cell lung cancer: current status and future development

Metronomic chemotherapy (mCT), a frequent administration of low-dose chemotherapy, allows prolonged treatment duration and minimizes the toxicity of standard-dose chemotherapy. mCT has multiple actions against cancer cells including inhibition of angiogenesis and modulation of the immune system. A number of studies lend support to the clinical efficacy of mCT in advanced breast cancer and non-small-cell lung cancer. However, further evidence is necessary to describe the optimal use of mCT and to identify suitable patients. Oral vinorelbine has emerged as a promising metronomic treatment in patients with metastatic breast cancer and non-small-cell lung cancer and is the only orally available microtubule-targeting agent. This paper reviews current evidence on metronomic oral vinorelbine, discusses its management and defines a suitable patient profile on the basis of a workshop of Italian experts.

Combination antiangiogenic therapy in advanced breast cancer: a phase 1 trial of vandetanib, a VEGFR inhibitor, and metronomic chemotherapy, with correlative platelet proteomics

This phase 1 study evaluated the safety and tolerability of antiangiogenic therapy using vandetanib and metronomic cyclophosphamide and methotrexate in metastatic breast cancer. Eligible patients had metastatic breast cancer with 0-4 prior chemotherapy regimens. All received cyclophosphamide 50 mg daily, methotrexate 2.5 mg days 1-2 weekly, and vandetanib daily in 3 dose-escalation cohorts: 100 mg (C1), 200 mg (C2), and 300 mg (C3). The primary endpoint was safety and tolerability; secondary endpoints included response rate and evaluation of platelet-associated proteins. Twenty three patients were treated and evaluable for toxicity. Common mild toxicities included nausea, vomiting, LFTs abnormalities, fatigue, and rash. Three episodes of dose-limiting toxicity occurred in C3. In all cohorts, 1/3 of patients required vandetanib dose reduction, and 22 % ended therapy for toxicity. Of the 20 response-evaluable patients, 10 % demonstrated partial response and 15 % stable disease ≥24 weeks. Proteomic analyses demonstrated changes in platelet content of angiogenesis regulators, including vascular endothelial growth factor and platelet factor 4, with exposure to therapy. This regimen was tolerable at a maximum vandetanib dose of 200 mg; modest clinical activity was observed in this heavily pretreated population. Changes in the platelet proteome may serve as pharmacodynamic markers of angiogenesis inhibition. Metronomic chemotherapy is an attractive partner with biologics and deserves further study in metastatic breast cancer.

Repurposing Drugs in Oncology (ReDO)-mebendazole as an anti-cancer agent

Mebendazole, a well-known anti-helminthic drug in wide clinical use, has anti-cancer properties that have been elucidated in a broad range of pre-clinical studies across a number of different cancer types. Significantly, there are also two case reports of anti-cancer activity in humans. The data are summarised and discussed in relation to suggested mechanisms of action. Based on the evidence presented, it is proposed that mebendazole would synergise with a range of other drugs, including existing chemotherapeutics, and that further exploration of the potential of mebendazole as an anti-cancer therapeutic is warranted. A number of possible combinations with other drugs are discussed in the Appendix.

Nanometronomic treatment of 4T1 breast cancer with nanocaged doxorubicin prevents drug resistance and circumvents cardiotoxicity

Chemotherapeutic treatment of breast cancer is based on maximum tolerated dose (MTD) approach. However, advanced stage tumors are not effectively eradicated by MTD owing to suboptimal drug targeting, onset of therapeutic resistance and neoangiogenesis. In contrast, "metronomic" chemotherapy is based on frequent drug administrations at lower doses, resulting in neovascularization inhibition and induction of tumor dormancy. Here we show the potential of H-ferritin (HFn)-mediated targeted nanodelivery of metronomic doxorubicin (DOX) in the setting of a highly aggressive and metastatic 4T1 breast cancer mouse model with DOX-inducible expression of chemoresistance. We find that HFn-DOX administered at repeated doses of 1.24 mg kg-1 strongly improves the antitumor potential of DOX chemotherapy arresting the tumor progression. We find that such a potent antitumor effect is attributable to multiple nanodrug actions beyond cell killing, including inhibition of tumor angiogenesis and avoidance of chemoresistance. Multiparametric assessment of heart tissues, including histology, ultrastructural analysis of tissue morphology, and measurement of markers of reactive oxygen species and hepatic/renal conditions, provided evidence that metronomic HFn-DOX allowed us to overcome cardiotoxicity. Our results suggest that HFn-DOX has tremendous potential for the development of "nanometronomic" chemotherapy toward safe and tailored oncological treatments.

Effective treatment of advanced human melanoma metastasis in immunodeficient mice using combination metronomic chemotherapy regimens

PURPOSE

The development of effective therapeutic approaches for treatment of metastatic melanoma remains an immense challenge. Present therapies offer minimal benefit. Although dacarbazine chemotherapy remains the standard therapy, it mediates only low response rates, usually of short duration, even when combined with other chemotherapeutic agents. Thus, new therapeutic strategies are urgently needed.

EXPERIMENTAL DESIGN

Using a newly developed preclinical model, we evaluated the efficacy of various doublet metronomic combination chemotherapy against established advanced melanoma metastasis and compared these with the standard maximum tolerated dose dacarbazine (alone or in combination with chemotherapeutic agents or vascular endothelial growth factor receptor-blocking antibody).

RESULTS

Whereas maximum tolerated dose dacarbazine therapy did not cause significant improvement in median survival, a doublet combination of low-dose metronomic vinblastine and low-dose metronomic cyclophosphamide induced a significant increase in survival with only minimal toxicity. Furthermore, we show that the incorporation of the low-dose metronomic vinblastine/low-dose metronomic cyclophosphamide combination with a low-dose metronomic dacarbazine regimen also results in a significant increase in survival, but not when combined with maximum tolerated dose dacarbazine therapy. We also show that a combination of metronomic vinblastine therapy and a vascular endothelial growth factor receptor 2-blocking antibody (DC101) results in significant control of metastatic disease and that the combination of low-dose metronomic vinblastine/DC101 and low-dose metronomic dacarbazine induced a significant improvement in median survival.

CONCLUSIONS

The effective control of advanced metastatic melanoma achieved by these metronomic-based chemotherapeutic approaches warrants clinical consideration of this treatment concept, given the recent results of a number of metronomic-based chemotherapy clinical trials.

Addition of rapamycin and hydroxychloroquine to metronomic chemotherapy as a second line treatment results in high salvage rates for refractory metastatic solid tumors: a pilot safety and effectiveness analysis in a small patient cohort

BACKGROUND

Autophagy is an important oncotarget that can be modulated during anti-cancer therapy. Enhancing autophagy using chemotherapy and rapamycin (Rapa) treatment and then inhibiting it using hydroxychloroquine (HCQ) could synergistically improve therapy outcome in cancer patients. It is still unclear whether addition of Rapa and HCQ to chemotherapy could be used for reversing drug resistance.

PATIENTS AND METHODS

Twenty-five stage IV cancer patients were identified. They had no clinical response to first-line metronomic chemotherapy; the patients were salvaged by adding an autophagy inducer (Rapa, 2 mg/day) and an autophagosome inhibitor (HCQ, 400 mg/day) to their current metronomic chemotherapy for at least 3 months. Patients included 4 prostate, 4 bladder, 4 lung, 4 breast, 2 colon, and 3 head and neck cancer patients as well as 4 sarcoma patients.

RESULTS

Chemotherapy was administered for a total of 137 months. The median duration of chemotherapy cycles per patient was 4 months (95% confidence interval, 3–7 months). The overall response rate to this treatment was of 40%, with an 84% disease control rate. The most frequent and clinically significant toxicities were myelotoxicities. Grade ≥3 leucopenia occurred in 6 patients (24%), grade ≥3 thrombocytopenia in 8 (32%), and anemia in 3 (12%). None of them developed febrile neutropenia. Non-hematologic toxicities were fatigue (total 32%, with 1 patient developing grade 3 fatigue), diarrhea (total 20%, 1 patient developed grade 3 fatigue), reversible grade 3 cardiotoxicity (1 patient), and grade V liver toxicity from hepatitis B reactivation (1 patient).

CONCLUSION

Our results of Rapa, HCQ and chemotherapy triplet combination suggest autophagy is a promising oncotarget and warrants further investigation in phase II studies.

Metronomic vinorelbine: Anti-angiogenic activity in vitro in normoxic and severe hypoxic conditions, and severe hypoxia-induced resistance to its anti-proliferative effect with reversal by Akt inhibition

Metronomic chemotherapy is the protracted, dense administration of low sub-toxic doses of chemotherapy, to inhibit tumor angiogenesis. Vinorelbine is an orally bioavailable vinca alkaloid shown to be useable for metronomic administration. In clinical trials, metronomic vinorelbine has been demonstrated to generate sustainable antitumor efficacy at low nanomolar (nM) concentrations with negligible toxicity. We sought to determine whether the clinically relevant metronomic concentration of vinorelbine is anti-angiogenic in vitro and whether hypoxia, often induced by anti-angiogenic therapy, modifies its effectiveness. We found that the metronomic concentration of 10 nM vinorelbine inhibited human umbilical vein endothelial cell (HUVEC) proliferation, migration, tube formation and sprouting. Severe hypoxia, did not affect the inhibitory effect of metronomic vinorelbine on migration, tube formation and sprouting. However, severe hypoxia reduced its anti-proliferative effect by decreasing its ability to induce G2/M block as it shifted the cell population to the G1 phase and decreased the fraction of the cells in the DNA synthesis S phase. Furthermore, the pro-apoptotic effects of 10 nM vinorelbine were also decreased. Metronomic vinorelbine decreased the Bcl-2/Bax ratio in normoxia whereas the ratio was reduced in severe hypoxia but unaltered by vinorelbine treatment. Akt signals to an anti-apoptotic pathway and we demonstrated that the Akt inhibitor V reversed the protective effect of severe hypoxia. Thus, we provide evidence for the anti-angiogenic basis of metronomic vinorelbine and we show that severe hypoxia mediates resistance to its anti-proliferative effect on endothelial cells. Akt warrants further investigation as a potential target to circumvent this hypoxic resistance.

Cellular and molecular effects of metronomic vinorelbine and 4-O-deacetylvinorelbine on human umbilical vein endothelial cells

Metronomic oral vinorelbine (VRL; Navelbine) was shown in clinical trials to yield sustainable antitumor activity possibly through antiangiogenic mechanisms. We investigated the effects of protracted low-dose VRL on human umbilical vein endothelial cells, compared with a conventional chemotherapy model. Human umbilical vein endothelial cell cultures were treated with different concentrations of VRL (0.001 nmol/l to 1 mmol/l) for 4, 24 and 96 h. The effects of different drug concentrations on cell growth, cell cycle, apoptosis and expression of the angiogenesis-modulating genes interleukin-8, cyclooxygenase-2, CD36 and peroxisome proliferator-activated receptor γ were assessed using the metronomic or conventional chemotherapy model. Apoptosis and cell-cycle effects were assessed by flow cytometry. Gene expression was measured at the transcript level by quantitative reverse transcriptase-PCR, protein expression by immunoblotting and levels of proteins secreted in the cell medium by enzyme-linked immunosorbent assay. Activation of the nuclear factor-κB pathway was investigated by immunoblot analysis of cytosolic and nuclear protein extracts. The half-maximal inhibitory concentrations (IC50) of VRL at 96 h were four orders lower compared with those after a 24-h exposure (1.23 nmol/l vs. 32 mmol/l for VRL). Drug concentrations at high nanomolar levels and above, which are relevant to conventional pulsatile dosing of VRL, induced a dose-dependent and nuclear factor-κB-related increase in proangiogenic interleukin-8 and cyclooxygenase-2 and a decrease in the thrombospondin-1 receptor CD36 and peroxisome proliferator-activated receptor γ at mRNA and protein levels. In contrast, the opposite was evident with protracted picomolar to low nanomolar concentrations (metronomic dosing). Our data provide experimental support for metronomic VRL by showing that a protracted low dose outperforms pulsed high-dose administration in inducing antiangiogenic effects in proliferating human endothelial cells.

Potentiating cancer vaccine efficacy in liver cancer

Hepatocellular carcinoma (HCC) is the most common liver malignancy with a poor prognosis and an overall 5-year survival rate of approximately 5-6%. This is due because standard of care treatment options are limited and none of them shows a sufficient efficacy. HCC is an "inflammation-induced cancer" and preliminary preclinical and clinical data suggest that immunotherapeutic approaches may be a good alternative candidate for the treatment of HCC patients improving the dismal prognosis associated with this cancer. However, recent findings strongly suggest that an optimal immunotherapy in HCC requires the combination of an immune activator with immune modulators, aiming at compensating the strong liver immune suppressive microenvironment. One of the most promising strategy could be represented by the combination of a cancer vaccine with immunomodulatory drugs, such as chemotherapy and checkpoint inhibitors. Very limited examples of such combinatorial strategies have been evaluated in HCC to date, because HCC easily develops resistance to standard chemotherapy, which is also poorly tolerated by patients with liver cirrhosis. The present review describes the most update knowledge in this field.

Combining low-dose or metronomic chemotherapy with anticancer vaccines: A therapeutic opportunity for lymphomas

Therapeutic vaccination is regarded as a promising strategy against multiple hematological malignancies including lymphoma. However, this approach alone possesses limited potential for the treatment of established tumors. As several anticancer regimens relies on the combination of multiple drugs, it is reasonable to predict that also cancer vaccination will be most effective in the context of multimodal approaches. In particular, low-dose or metronomic chemotherapy could be coupled to anticancer vaccines to improve the efficacy of this immunotherapeutic interventions. This review summarizes recent findings in support of the use of anticancer vaccines combined with low-dose or metronomic chemotherapy for the treatment and management of lymphoid malignancies.

Novel metronomic chemotherapy and cancer vaccine combinatorial strategy for hepatocellular carcinoma in a mouse model

Hepatocellular carcinoma (HCC) is the most frequent primary liver cancer and represents the third and the fifth leading cause of cancer-related death worldwide in men and women, respectively. Hepatitis B virus (HBV) and hepatitis C virus (HCV) chronic infections account for pathogenesis of more than 80 % of primary HCC. HCC prognosis greatly varies according to stage at beginning of treatment, but the overall 5-year survival rate is approximately 5-6 %. Given the limited number of effective therapeutic strategies available, immunotherapies and therapeutic cancer vaccines may help in improving the clinical outcome for HCC patients. However, the few clinical trials conducted to date have shown contrasting results, indicating the need for improvements. In the present study, a novel combinatorial strategy, based on metronomic chemotherapy plus vaccine, is evaluated in a mouse model. The chemotherapy is a multi-drug cocktail including taxanes and alkylating agents, which is administered in a metronomic-like fashion. The vaccine is a multi-peptide cocktail including HCV as well as universal tumor antigen TERT epitopes. The combinatorial strategy designed and evaluated in the present study induces an enhanced specific T cell response, when compared to vaccine alone, which correlates to a reduced Treg frequency. Such results are highly promising and may pave way to relevant improvements in immunotherapeutic strategies for HCC and beyond.

Therapeutic efficacy of metronomic chemotherapy with cyclophosphamide and doxorubicin on murine mammary adenocarcinomas

BACKGROUND

Metronomic chemotherapy (MCT) refers to the chronic and equally spaced administration of low doses of different chemotherapy drugs, without extended rest periods. Herein, we investigated the therapeutic efficacy of metronomic cyclophosphamide (Cy) combined with doxorubicin (Dox) in two mouse mammary adenocarcinoma models.

MATERIALS AND METHODS

Mice were s.c. challenged with M-234p or M-406 mammary tumors, and when the tumors reached ∼150 mm(3), they were treated with: (I) no treatment (controls); (II) Cy in the drinking water (30 mg/kg body weight/day); (III) Dox (0.5 mg/kg body weight i.p. three times/week); (IV) treated as (II) + (III). Mice challenged i.v. with M-234p or M-406 tumor cells received, on day 3, the same treatments.

RESULTS

We found that MCT with Cy plus Dox inhibited tumor growth, decreased lung metastases, and increased the median survival time, while having low toxic effect. Combined MCT was more effective than each monotherapy causing decrease in VEGF serum concentration and tumor proliferation rate plus increase in tumor apoptosis.

CONCLUSION(S)

The therapeutic benefits of combined MCT with Cy and Dox on mammary adenocarcinomas together with its low toxic effect profile suggest the possibility of future translation into the clinic.