Antiangiogenic drugs in ovarian cancer

Phase II trial of combretastatin A4 phosphate, carboplatin, and paclitaxel in patients with platinum-resistant ovarian cancer

BACKGROUND

A previous dose-escalation trial of the vascular disrupting agent combretastatin A4 phosphate (CA4P) given before carboplatin, paclitaxel, or both showed responses in 7 of 18 patients with relapsed ovarian cancer.

PATIENTS AND METHODS

Patients with ovarian cancer that had relapsed and who could start trial therapy within 6 months of their last platinum chemotherapy were given CA4P 63 mg/m(2) minimum 18 h before paclitaxel 175 mg/m(2) and carboplatin AUC (area under the concentration curve) 5, repeated every 3 weeks.

RESULTS

Five of the first 18 patients' disease responded, so the study was extended and closed after 44 patients were recruited. Grade ≥2 toxic effects were neutropenia in 75% and thrombocytopenia in 9% of patients (weekly blood counts), tumour pain, fatigue, and neuropathy, with one patient with rapidly reversible ataxia. Hypertension (23% of patients) was controlled by glyceryl trinitrate or prophylactic amlodipine. The response rate by RECIST was 13.5% and by Gynecologic Cancer InterGroup CA 125 criteria 34%.

CONCLUSIONS

The addition of CA4P to paclitaxel and carboplatin is well tolerated and appears to produce a higher response rate in this patient population than if the chemotherapy was given without CA4P. A planned randomised trial will test this hypothesis.

Bevacizumab in the treatment of ovarian cancer

Despite advances in surgical cytoreduction and cytotoxic chemotherapy, ovarian cancer continues to be the leading cause of death in women with gynecologic malignancy. Our understanding of the treatment of ovarian cancer was revolutionized with the discovery of platinum- and taxane-based adjuvant chemotherapy regimens. Since that time however, overall survival has been stable. Given the above, an emphasis has been placed on exploring alternative therapeutics. Recent research efforts have improved our understanding of the molecular biology of ovarian cancer and novel targeted treatment strategies have emerged. The most studied of these agents has been the monoclonal anti-vascular endothelial growth factor antibody bevacizumab. The purpose of this review is to discuss management issues related to the treatment of ovarian cancer, with a focus on the utilization of bevacizumab, summarizing applicable clinical trials, its potential benefits, and reported adverse events.

MicroRNA 376c enhances ovarian cancer cell survival by targeting activin receptor-like kinase 7: implications for chemoresistance

MicroRNAs (miRNAs) are small noncoding RNAs that have important roles in gene regulation. We have previously reported that activin receptor-like kinase 7 (ALK7) and its ligand, Nodal, induce apoptosis in human epithelial ovarian cancer cells. In this study, we examined the regulation of ALK7 by miRNAs and demonstrate that miR-376c targets ALK7. Ectopic expression of miR-376c significantly increased cell proliferation and survival, enhanced spheroid formation and blocked Nodal-induced apoptosis. Interestingly, overexpression of miR-376c blocked cisplatin-induced cell death, whereas anti-miR-376c enhanced the effect of cisplatin. These effects of miR-376c were partially compensated by the overexpression of ALK7. Moreover, in serous carcinoma samples taken from ovarian cancer patients who responded well to chemotherapy, strong ALK7 staining and low miR-376c expression was detected. By contrast, ALK7 expression was weak and miR-376c levels were high in samples from patients who responded poorly to chemotherapy. Finally, treatment with cisplatin led to an increase in expression of mRNA encoding Nodal and ALK7 but a decrease in miR-376c levels. Taken together, these results demonstrate that the Nodal-ALK7 pathway is involved in cisplatin-induced cell death in ovarian cancer cells and that miR-376c enhances proliferation, survival and chemoresistance by targeting, at least in part, ALK7.

Overview of anti-angiogenic agents in development for ovarian cancer

OBJECTIVE

To review the rationale for targeting the vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and fibroblast growth factor (FGF) pathways for anti-angiogenic therapy in patients with ovarian cancer and to summarize the currently available data with agents that block these pathways.

METHODS

Relevant papers and studies were identified by searches conducted on Medline using the terms angiogenesis, ovarian cancer, VEGF, PDGF, FGF, receptor, kinase, and inhibitor alone or in combination as well as by searches by drug name and by review of abstracts presented at recent oncology meetings.

RESULTS

The VEGF pathway is considered to be the key driver of angiogenesis, but the PDGF and FGF pathways also play important roles and may contribute to resistance to VEGF-specific blockade. Each pathway may also promote tumorigenesis; tumor cell overexpression of these growth factors and their receptors have been detected in ovarian tumor specimens, suggesting that autocrine loops may lead to tumor growth and progression. Selective inhibitors of the VEGF pathway (e.g., bevacizumab and VEGF Trap) as well as VEGF/PDGF pathway inhibitors (e.g., sorafenib and sunitinib) and VEGF/PDGF/FGF pathway inhibitors (e.g., cediranib, pazopanib, and BIBF 1120) have shown single-agent activity in women with ovarian cancer in phase II trials. Response rates of up to 21% have been reported with several agents in patients with recurrent ovarian cancer. Phase III trials with many anti-angiogenic agents in the treatment of ovarian cancer are currently ongoing.

CONCLUSIONS

Anti-angiogenic agents may provide an improvement in the treatment of patients with recurrent ovarian cancer and may be useful when incorporated into first-line platinum/taxane therapy. It remains to be determined whether multitargeted agents will offer greater clinical benefit than specific VEGF pathway inhibitors.

Vascular endothelial growth factor as an anti-angiogenic target for cancer therapy

New blood vessel formation (angiogenesis) is fundamental to tumor growth, invasion, and metastatic dissemination. The vascular endothelial growth factor (VEGF) signaling pathway plays pivotal roles in regulating tumor angiogenesis. VEGF as a therapeutic target has been validated in various types of human cancers. Different agents including antibodies, aptamers, peptides, and small molecules have been extensively investigated to block VEGF and its pro-angiogenic functions. Some of these agents have been approved by FDA and some are currently in clinical trials. Combination therapies are also being pursued for better tumor control. By providing comprehensive real-time information, molecular imaging of VEGF pathway may accelerate the drug development process. Moreover, the imaging will be of great help for patient stratification and therapeutic effect monitoring, which will promote effective personalized molecular cancer therapy. This review summarizes the current status of tumor therapeutic agents targeting to VEGF and the applications of VEGF related molecular imaging.

Vascular endothelial growth factor gene polymorphisms and ovarian cancer survival

OBJECTIVES

We sought to evaluate the effect of polymorphisms in the VEGF (Vascular Endothelial Growth Factor) gene on overall survival in ovarian cancer patients.

METHODS

A sample of 319 women diagnosed with primary invasive epithelial ovarian cancer in Australia between 1985 and 1997, recruited as incident cases, were genotyped for four VEGF single nucleotide polymorphisms (three tagSNPs and one functional SNP) using the Sequenom MassARRAY platform. A SNP found to be associated with ovarian cancer survival in this sample set was then evaluated in two independent datasets in an attempt to replicate the association.

RESULTS

VEGF tagSNPs rs3025033 and rs2146323 were not associated with ovarian cancer survival in the Australian sample. Ovarian cancer patients homozygous for tagSNP rs833068 or the functional SNP rs2010963 displayed significantly shortened overall survival in the Australian sample (HR 2.09, 95% CI 1.16-3.78), an effect most apparent in the first 5years after diagnosis. This association was not replicated in two independent datasets.

CONCLUSIONS

Findings from this study provide no evidence that rs3025033 and rs2146323 VEGF polymorphisms are associated with ovarian cancer survival. Although homozygous carriers of the tagSNP rs833068 experienced significantly worse survival in our Australian dataset, we were unable to replicate this in two independent datasets.

Identification of a metalloprotease-chemokine signaling system in the ovarian cancer microenvironment: implications for antiangiogenic therapy

Ovarian cancer is a lethal gynecologic malignancy that may benefit from new therapies that block key paracrine pathways involved in tumor-stromal interactions and tumor vascularity. It was recently shown that matrix metalloprotease-1 (MMP1) activation of the G protein-coupled receptor protease-activated receptor-1 (PAR1) is an important stimulator of angiogenesis and metastasis in peritoneal mouse models of ovarian cancer. In the present study, we tested the hypothesis that MMP1-PAR1 promotes angiogenesis through its paracrine control of angiogenic chemokine receptors. We found that MMP1-PAR1 activation induces the secretion of several angiogenic factors from ovarian carcinoma cells, most prominently interleukin (IL)-8, growth-regulated oncogene-alpha (GRO-alpha), and monocyte chemoattractant protein-1. The secreted IL-8 and GRO-alpha acts on endothelial CXCR1/2 receptors in a paracrine manner to cause robust endothelial cell proliferation, tube formation, and migration. A cell-penetrating pepducin, X1/2pal-i3, which targets the conserved third intracellular loop of both CXCR1 and CXCR2 receptors, significantly inhibited endothelial cell proliferation, tube formation, angiogenesis, and ovarian tumor growth in mice. Matrigel plugs mixed with MMP1-stimulated, OVCAR-4-conditioned media showed a dramatic 33-fold increase in blood vessel formation in mice. The X1/2pal-i3 pepducin completely inhibited MMP1-dependent angiogenesis compared with a negative control pepducin or vehicle. Conversely, a vascular endothelial growth factor-directed antibody, Avastin, suppressed angiogenesis in mice but, as expected, was unable to inhibit IL-8 and GRO-alpha-dependent endothelial tube formation in vitro. These studies identify a critical MMP1-PAR1-CXCR1/2 paracrine pathway that might be therapeutically targeted for ovarian cancer treatment.

Expression pattern of the class I homeobox genes in ovarian carcinoma

OBJECTIVE

Although some sporadic reports reveal the link between the homeobox (HOX) genes and ovarian carcinoma, there is no comprehensive analysis of the expression pattern of the class I homeobox genes in ovarian carcinoma that determines the candidate genes involved in ovarian carcinogenesis.

METHODS

The different patterns of expression of 36 HOX genes were analyzed, including 4 ovarian cancer cell lines and 4 normal ovarian tissues. Using a reverse transcription-polymerase chain reaction (RT-PCR) and quantification analysis, the specific gene that showed a significantly higher expression in ovarian cancer cell lines than in normal ovaries was selected, and western blot analysis was performed adding 7 ovarian cancer tissue specimens. Finally, immunohistochemical and immunocytochemical analyses were performed to compare the pattern of expression of the specific HOX gene between ovarian cancer tissue and normal ovaries.

RESULTS

Among 36 genes, 11 genes had a different level of mRNA expression between the cancer cell lines and the normal ovarian tissues. Of the 11 genes, only HOXB4 had a significantly higher level of expression in ovarian cancer cell lines than in normal ovaries (p=0.029). Based on western blot, immunohistochemical, and immunocytochemical analyses, HOXB4 was expressed exclusively in the ovarian cancer cell lines or cancer tissue specimens, but not in the normal ovaries.

CONCLUSION

We suggest HOXB4 may be a novel candidate gene involved in ovarian carcinogenesis.

The role of dysregulated glucose metabolism in epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is the most lethal gynecologic cancer and also one of the most poorly understood. Other health issues that are affecting women with increasing frequency are obesity and diabetes, which are associated with dysglycemia and increased blood glucose. The Warburg Effect describes the ability of fast-growing cancer cells to preferentially metabolize glucose via anaerobic glycolysis rather than oxidative phosphorylation. Recent epidemiological studies have suggested a role for hyperglycemia in the pathogenesis of a number of cancers. If hyperglycemia contributes to tumour growth and progression, then it is intuitive that antihyperglycemic drugs may also have an important antitumour role. Preliminary reports suggest that these drugs not only reduce available plasma glucose, but also have direct effects on cancer cell viability through modification of molecular energy-sensing pathways. This review investigates the effect that hyperglycemia may have on EOC and the potential of antihyperglycemic drugs as therapeutic adjuncts.

Angiogenesis and ovarian cancer

Ovarian carcinoma is the most important cause of gynaecological cancer-related mortality in Western societies. The age at diagnosis, extent of disease (as expressed by FIGO state), success of primary surgery and the histopathological features of the tumour are important prognostic markers. The majority of patients with ovarian cancer present with advanced disease (FIGO stage III/IV) and in this group of patients the median survival is only three years. New treatment approaches are therefore required to improve outcome in this disease. Angiogenesis, the development of a neovascular blood supply, is a critical step in the propagation of malignant tumour growth and metastasis and represents a promising target. This review will focus on angiogenesis, VEGF biology and the potential value of angiogenic factors with prognostic value in ovarian cancer.