Role of vascular endothelial growth factor inhibitors in the treatment of gynecologic malignancies

This article reviews the history and current status of vascular endothelial growth factor targeted therapy for the most common gynecologic malignancies - epithelial ovarian, endometrial and cervical cancers. The biologic rationale for targeting vascular endothelial growth factor (VEGF) for these disease sites is well-founded, and pre-clinical studies have supported the development of anti-VEGF agents. Their classification, known mechanisms of action, unique toxicities and clinical development are herein explored, the latter including issues related to study design, disease site and disease setting.

Antiangiogenic drugs in ovarian cancer

BACKGROUND

There is a critical need to develop effective new strategies for the management of patients with advanced epithelial ovarian cancer.

OBJECTIVE

The purpose of this manuscript is to discuss the rationale for, and initial clinical results of, attempts to interfere with the process of tumor angiogenesis as a novel treatment paradigm in ovarian cancer.

RESULTS/CONCLUSION

Phase II clinical trial data provide strong support for the suggestion that antiangiogenic agents have the potential to play a major therapeutic role in this difficult malignancy. It is reasonable to acknowledge that the pending results of several ongoing evidence-based randomized Phase III trials that directly explore the clinical utility of this strategy may substantially alter the current standard management approaches in advanced ovarian cancer.

Antiangiogenic drugs in ovarian cancer

Ovarian cancer continues to be a major cause of morbidity and mortality in women. Antiangiogenic treatments have emerged as a promising strategy to treat ovarian cancer. This article reviews the rationale supporting the use of antiangiogenic treatments in ovarian cancer, the clinical development of this group of drugs and the toxicities specific to this modality of treatment.

Development of antiangiogenic agents for ovarian cancer

Epithelial ovarian cancer (EOC) remains a major source of cancer morbidity and mortality, despite advances in surgical and chemotherapeutic management. The molecular pathways that control angiogenesis have been demonstrated to be key to the pathogenesis of EOC, and have been shown to have prognostic significance. Increased understanding of the pathways and molecules involved in angiogenesis has allowed the identification of a number of targets for antiangiogenic therapies and the development of a variety of antiangiogenic drugs. There is now significant preclinical evidence, and a growing body of clinical data, demonstrating promising results with antiangiogenic drugs in the treatment of EOC. Single-agent VEGF inhibitor response rates in pretreated patients of between 15 and 20% have been reported, with much higher response rates when used in combination with chemotherapeutic agents. These benefits, however, must be balanced with the toxicities associated with these drugs, particularly the more serious ones, such as gastrointestinal perforation. The results of ongoing and future randomized clinical trials will confirm if, and how, antiangiogenic therapies should be integrated into the routine management of EOC. However, critical issues, such as the relative importance of combination remission induction regimens and maintenance therapy, remain poorly defined.

Bevacizumab in the treatment of ovarian cancer

Current treatment for epithelial ovarian cancer involves a combination of surgery and chemotherapy with platinum- and taxane-based chemotherapy. With the recent approval of the anti-VEGF antibody bevacizumab by several regulatory bodies in colorectal and non-small-cell lung cancers, interest has developed regarding the potential role of bevacizumab therapy in ovarian cancer. Several case series and Phase II studies indicate that in ovarian cancer bevacizumab is active as a single agent or in combination with other drugs. Currently, ongoing Phase III trials are testing bevacizumab in front-line adjuvant therapy with carboplatin and paclitaxel. Bevacizumab has been generally well tolerated in ovarian cancer patients, but recent reports on increased risk of gastrointestinal perforations have gained attention. Bevacizumab offers a novel therapeutic modality in the treatment of epithelial ovarian cancers.

Antiangiogenic therapy for ovarian cancer

PURPOSE OF REVIEW

To highlight the current antiangiogenic compounds being evaluated as single agents or in association with chemotherapy in the treatment of ovarian cancer, as well as the rationale for their development.

RECENT FINDINGS

Several proangiogenic factors may be potential targets for antiangiogenic therapy in ovarian cancer. Bevacizumab, a monoclonal antibody against vascular endothelial growth factor, has been evaluated as a single agent in two phase II clinical trials and in combination with chemotherapy in three phase II studies, with promising results. This agent is also being evaluated in association with chemotherapy in two phase III clinical trials, both in the treatment and in the maintenance settings. Heparanase inhibitors and inhibitors of platelet-derived growth factor signalling remain as potential agents to be investigated in phase II trials. The development of biomarkers to define appropriate dosing regimens and predict which patients may benefit from antiangiogenic therapies is of great importance.

SUMMARY

Data from preclinical and clinical studies reported in the last 2 years demonstrate the importance of several proangiogenic factors in the prognosis of ovarian cancer, suggesting possible new targets for antiangiogenic therapy. The agents that are currently being investigated in phase II and III clinical trials include bevacizumab, erlotinib, sunitinib, sorafenib and vascular endothelial growth factor Trap, and the results of these trials will have significant implications in the future management of ovarian cancer.

Experience With Bevacizumab in the Management of Epithelial Ovarian Cancer

Müllerian duct adenocarcinomas, in particular epithelial ovarian cancers, continue to represent a major source of female cancer-related morbidity and mortality, despite advances in surgical management and innovations in cytotoxic chemotherapy. Angiogenesis-targeted therapy seems to be appropriate for exploration in these disease processes based on a wealth of evidence from preclinical and molecular epidemiology studies. Bevacizumab is a prototypical agent neutralizing vascular endothelial growth factor (VEGF), a critical angiogenic promoter related to tumor progression, malignant effusions, and prognosis in ovarian cancer. Phase II trials have demonstrated the activity of bevacizumab as a single agent and in combination with other modalities such as low-dose metronomic cyclophosphamide. Historical studies have supported these observations. Unique toxicities have been ascribed to the administration of bevacizumab and other anti-VEGF molecules for patients with this disease and other solid tumors. Although most of these toxicities (such as proteinuria, hypertension, and bleeding) are generally mild, and are either self-limiting or controllable, other adverse effects, though uncommon, may be serious (these include arterial thromboembolism, wound healing complications, and GI perforation or fistulae). Phase III trials are now in progress to determine the role of this drug in primary therapy as an adjunct to platinum-taxane chemotherapy. This article reviews the background and rationale for anti-VEGF therapy of ovarian cancer, summarizes efficacy and safety data from phase II trials and historical studies of bevacizumab in this disease, introduces the implementation of bevacizumab in phase III front-line trials, examines controversial aspects related to anti-VEGF therapy, and proposes future directions regarding bevacizumab and other angiogenic growth factor–targeted therapeutics.