Motesanib, or open-label bevacizumab, in combination with paclitaxel, as first-line treatment for HER2-negative locally recurrent or metastatic breast cancer: a phase 2, randomised, double-blind, placebo-controlled study

Targeting angiogenesis in metastatic breast cancer

Angiogenesis has become an important target in the treatment of several solid tumors, including breast cancer. As monotherapy, antiangiogenic agents have demonstrated limited activity in metastatic breast cancer (MBC); therefore, they have generally been developed for use in combination with chemotherapies. Thus far, the experience with antiangiogenic agents for MBC has been mixed. The results from one study assessing addition of the monoclonal antibody bevacizumab to paclitaxel led to approval of bevacizumab for MBC. However, the modest improvement of progression-free survival rates in subsequent MBC studies has led to reappraisal of bevacizumab. Phase III studies have not produced evidence supporting use of the multikinase inhibitor sunitinib alone or in combination with MBC chemotherapy. Experience with sorafenib in a phase IIb program indicates potential when used in select combinations, particularly with capecitabine; however, phase III confirmatory data are needed. Although antiangiogenic therapies combined with chemotherapy have increased progression-free survival rates for patients with MBC, increases in overall survival times have not been observed. Some studies have tried to combine antiangiogenic agents such as bevacizumab and sunitinib or sorafenib, but that approach has been limited because of toxicity concerns. Sequential use of antiangiogenic agents with differing mechanisms of action may be an effective approach. Despite setbacks, angiogenesis will likely remain an important target of treatment for selected patients with MBC.

Vascular-endothelial-growth-factor (VEGF) targeting therapies for endocrine refractory or resistant metastatic breast cancer

BACKGROUND

Vascular-endothelial-growth-factor (VEGF) is a key mediator of angiogenesis. VEGF-targeting therapies have shown significant benefits and been successfully integrated in routine clinical practice for other types of cancer, such as metastatic colorectal cancer. By contrast, individual trial results in metastatic breast cancer (MBC) are highly variable and their value is controversial.

OBJECTIVES

To evaluate the benefits (in progression-free survival (PFS) and overall survival (OS)) and harms (toxicity) of VEGF-targeting therapies in patients with hormone-refractory or hormone-receptor negative metastatic breast cancer.

SEARCH METHODS

Searches of CENTRAL, MEDLINE, EMBASE, the Cochrane Breast Cancer Group's Specialised Register, registers of ongoing trials and proceedings of conferences were conducted in January and September 2011, starting in 2000. Reference lists were scanned and members of the Cochrane Breast Cancer Group, experts and manufacturers of relevant drug were contacted to obtain further information. No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials (RCTs) to evaluate treatment benefit and non-randomised studies in the routine oncology practice setting to evaluate treatment harms.

DATA COLLECTION AND ANALYSIS

We performed data collection and analysis according to the published protocol. Individual patient data was sought but not provided. Therefore, the meta-analysis had to be based on published data. Summary statistics for the primary endpoint (PFS) were hazard ratios (HRs).

MAIN RESULTS

We identified seven RCTs, one register, and five ongoing trials from a total of 347 references. The published trials for VEGF-targeting drugs in MBC were limited to bevacizumab. Four trials, including a total of 2886 patients, were available for the comparison of first-line chemotherapy, with versus without bevacizumab. PFS (HR 0.67; 95% confidence interval (CI) 0.61 to 0.73) and response rate were significantly better for patients treated with bevacizumab, with moderate heterogeneity regarding the magnitude of the effect on PFS. For second-line chemotherapy, a smaller, but still significant benefit in terms of PFS could be demonstrated for patients treated with bevacizumab (HR 0.85; 95% CI 0.73 to 0.98), as well as a benefit in tumour response. However, OS did not differ significantly, neither in first- (HR 0.93; 95% CI 0.84 to 1.04), nor second-line therapy (HR 0.98; 95% CI 0.83 to 1.16). Quality of life (QoL) was evaluated in four trials but results were published for only two of these with no relevant impact. Subgroup analysis stated a significant greater benefit for patients with previous (taxane) chemotherapy and patients with hormone-receptor negative status. Regarding toxicity, data from RCTs and registry data were consistent and in line with the known toxicity profile of bevacizumab. While significantly higher rates of adverse events (AEs) grade III/IV (odds ratio (OR) 1.77; 95% CI 1.44 to 2.18) and serious adverse events (SAEs) (OR 1.41; 95% CI 1.13 to 1.75) were observed in patients treated with bevacizumab, rates of treatment-related deaths were lower in patients treated with bevacizumab (OR 0.60; 95% CI 0.36 to 0.99).

AUTHORS' CONCLUSIONS

The overall patient benefit from adding bevacizumab to first- and second-line chemotherapy in metastatic breast cancer can at best be considered as modest. It is dependent on the type of chemotherapy used and limited to a prolongation of PFS and response rates in both first- and second-line therapy, both surrogate parameters. In contrast, bevacizumab has no significant impact on the patient-related secondary outcomes of OS or QoL, which indicate a direct patient benefit. For this reason, the clinical value of bevacizumab for metastatic breast cancer remains controversial.

The evolving landscape of protein kinases in breast cancer: clinical implications

Dysfunction of protein kinases has been associated with the development of the various molecular subtypes of breast cancer. The best example is the known role of HER2 in the tumorigenesis of a proportion of breast tumors. In this article, we review the state of the art knowledge on protein kinases involved in breast cancer. Special attention is given to those that are potentially druggable and those for which targeted agents are currently under clinical evaluation. Options for targeted drug combinations will be discussed, as well as the optimal way to integrate new kinase inhibitors in the clinical armamentarium to fight breast cancer. We will review recent results from clinical studies with agents targeting different kinases involved in the pathophysiology of breast cancer. In addition, we will evaluate the clinical development of kinase inhibitors to identify areas of knowledge that could be explored in future preclinical and clinical studies.

Effect of angiogenesis inhibitor bevacizumab on survival in patients with cancer: a meta-analysis of the published literature

Bevacizumab is a recombinant humanized monoclonal antibody against vascular endothelial growth factor which has been used in conjunction with other anti-cancer agents in the treatment of patients with many cancers. It remains controversial whether bevacizumab can prolong survival in cancer patients. This meta-analysis was therefore performed to evaluate effect of bevacizumab on survival in cancer patients. PubMed, EMBASE, and Web of Science databases were searched for English-language studies of randomized controlled trials comparing bevacizumab with control therapy published through February 8, 2012. Progression-free survival, overall survival, and one-year survival rate were analyzed using random- or fixed-effects model. Thirty one assessable randomized controlled trials were identified. A significant improvement in progression-free survival in cancer patients was attributable to bevacizumab compared with control therapy (hazard ratio, 0.72; 95% confidence interval, 0.68 to 0.76; p<0.001). Overall survival was also significantly longer in patients were treated with bevacizumab (hazard ratio, 0.87; 95% confidence interval, 0.83 to 0.91; p<0.001). The significant benefit in one-year survival rate was further seen in cancer patients receiving bevacizumab (odds ratio, 1.30; 95% confidence interval, 1.20 to 1.41; p<0.001). Current evidences showed that bevacizumab prolong progression-free survival and overall survival, and increase one-year survival rate in cancer patients as compared with control therapy.

Current approaches to the management of Her2-negative metastatic breast cancer

While metastatic breast cancer (MBC) remains incurable, a vast array of active therapeutic agents has provided the opportunity for long-term disease control while maintaining quality of life and physical function. Optimal management of MBC balances a multitude of factors, including a woman's performance status, social support, symptoms, disease burden, prior therapies, and surrogates for tumor biology. Choosing the most appropriate initial therapy and subsequent sequence of treatments demands flexibility as goals and patient preferences may change. Knowledge of the estrogen receptor (ER), progesterone receptor (PR), and Her2 receptor status of the metastatic tumor has become critical to determining the optimal treatment strategy in the metastatic setting as targeted therapeutic approaches are developed. Patients with ER⁺ or PR⁺ breast cancer or both have a wide array of hormonal therapy options that can forestall the use of cytotoxic therapies, although rapidly progressive phenotypes and the emergence of resistance may ultimately lead to the need for chemotherapy in this setting. So-called 'triple-negative' breast cancer - lacking ER, PR, and Her2 overexpression - remains a major challenge. These tumors have an aggressive phenotype, and clear targets for therapy have not yet been established. Chemotherapy remains the mainstay of treatment in this group, but biologically based clinical trials of new agents are critical to developing a more effective set of therapies for this patient population.

Bevacizumab in the treatment of metastatic breast cancer: friend or foe?

Metastatic breast cancer (MBC) is a major cause of death among women worldwide. Progress has been made in treating MBC with the advent of anti-estrogen therapies, potent cytotoxic agents, and monoclonal antibodies. Bevacizumab is a monoclonal antibody against circulating vascular endothelial growth factor (VEGF), which was approved in 2008 by the US Food and Drug Administration (FDA), for first-line treatment of HER-2 negative MBC in combination with paclitaxel. The FDA then reversed this decision in December 2010 by recommending removal of the MBC indication from bevacizumab, citing primarily safety concerns, and that these risks did not outweigh the ability of bevacizumab to significantly prolong progression-free survival. This decision was unexpected in the oncology community and remains controversial. This review looks at all available phase 3 data with bevacizumab in the MBC setting to determine whether the data support this decision by the FDA, and discusses the future of bevacizumab in breast cancer.

Controlling angiogenesis in breast cancer: a systematic review of anti-angiogenic trials

PURPOSE

Angiogenesis is critical for tumor growth and a promising therapeutic target. This review will summarize and analyze data from clinical trials of anti-angiogenic agents in the treatment of breast cancer (BC).

DESIGN

A systematic search of PubMed and conference databases was performed to identify reports of randomized clinical trials investigating specific anti-angiogenic agents in the treatment of BC.

RESULTS AND DISCUSSION

Phase III trials in advanced BC have demonstrated a reduction in the risk of disease progression (22-52%), improved response rates and net improvements in progression-free survival of 1.2 to 5.5 months, but no significant improvements in overall survival with the addition of bevacizumab to chemotherapy. Results of phase III trials in early breast cancer have been inconsistent. Bevacizumab-containing regimens have also been associated with higher overall adverse event rates compared to chemotherapy alone. Phase III trials of the tyrosine kinase inhibitor sunitinib were negative, while randomized phase II trials of sorafenib and pazopanib have improved some outcomes when combined with chemotherapy or targeted therapy compared to controls. In addition to expected vascular class safety signals, tyrosine kinase inhibitors show "off-target" side effects. Ongoing clinical trials evaluating combinatorial strategies based on biological synergies and translational studies identifying biological predictors of response will be crucial to establish meaningful clinical benefits in selected BC populations.

CONCLUSION

Most trials of anti-angiogenic agents in BC have reported improved response rate and progression-free survival but no increase in overall survival compared to chemotherapy alone. Optimizing the therapeutic indices of these agents is a focus of ongoing research and will be critical to their future development.

Novel targets for VEGF-independent anti-angiogenic drugs

INTRODUCTION

In the last decades, the active research in the field of tumor angiogenesis led to the development of a class of agents providing an effective inhibition of neovessels formation through the blockade of VEGF-related pathways. More recently, the identification of several non-VEGF factors such as PDGF, FGF, HGF, angiopoietins, ALK1/endoglin, endothelis and ephrins involved in tumor angiogenesis have emphasized the need to develop agents targeting multiple pro-angiogenic pathways.

AREAS COVERED

This review aimed at summarizing the role of non-VEGF molecular pathways in targeting tumor angiogenesis. Preclinical and clinical data for investigational agents against non-VEGF targets have been reviewed emphasizing the role of combined inhibition strategies.

EXPERT OPINION

Besides the successful development of drugs providing a specific VEGF blockade, novel agents targeting alternative angiogenesis-related pathways are being tested. Although it seems that the potential clinical usefulness of these novel compounds have been not yet fully investigated, sunitinib, sorafenib, pazopanib and other multikinase inhibitors have certainly displayed encouraging results. A more in-depth clarification of anti-angiogenic agents is still needed, in order to design the best clinical setting and schedule for target-based agents and possibly anticipate potential tools to overcome the emerging issue of anti-angiogenic drug resistance.

Antiangiogenic therapy--evolving view based on clinical trial results

Antiangiogenic therapies that target VEGF or its receptors have become a mainstay of cancer therapy in multiple malignancies. However, the clinical efficacy of these agents is less than originally anticipated and, in most settings, requires the addition of cytotoxic chemotherapy suggesting that, as for other targeted therapies, VEGF inhibitors will require selection of patient subpopulations to achieve maximal clinical benefit. Without the identification and use of predictive biomarkers for VEGF-targeted agents, and other agents that target the vasculature, further improvements in current clinical outcomes are unlikely. Exciting new data presented in 2011 at the ESMO conference showed that retrospective evaluation of plasma concentrations of VEGF-A predicted progression-free survival and/or overall survival benefit from bevacizumab in phase III trials in certain tumour types; prospective evaluation of the assay is required. This endeavour should be followed by further biomarker research, requiring inter-laboratory collaboration and high-quality, adequately powered clinical trials.

Bevacizumab: a review of its use in combination with paclitaxel or capecitabine as first-line therapy for HER2-negative metastatic breast cancer

Bevacizumab (Avastin™) is a humanized monoclonal antibody directed against vascular endothelial growth factor. In patients with human epidermal growth factor receptor type 2 (HER2)-negative metastatic breast cancer, bevacizumab is indicated as first-line therapy in combination with paclitaxel, or in combination with capecitabine when treatment with other chemotherapy options, including taxanes or anthracyclines, is not considered appropriate. This article reviews the efficacy and tolerability of these combination therapies in the first-line treatment of patients with metastatic breast cancer, and summarizes the pharmacological properties of bevacizumab. In randomized, controlled, phase III trials in patients with predominantly HER2-negative metastatic or locally recurrent breast cancer, the addition of bevacizumab to paclitaxel or capecitabine significantly prolonged progression-free survival (PFS; investigator assessment) by a median of 5.9 and 2.9 months, respectively, relative to paclitaxel or capecitabine alone. It also significantly increased the objective response rate, but not overall survival. Independent reviews of data supported the results of the primary analyses of investigator-assessed PFS. However, as the efficacy of bevacizumab in combination with capecitabine appears to be less than that of other available options, it should be used only if treatment with other chemotherapy options are not considered appropriate. The addition of bevacizumab to paclitaxel had no significant adverse effects on health-related quality of life. Efficacy data from two routine clinical practice studies were generally consistent with those from the phase III trials. Bevacizumab had generally acceptable tolerability when administered in combination with paclitaxel or capecitabine as first-line therapy in these studies, and adverse events were consistent with the known tolerability profiles of the individual agents. The most common adverse events associated with bevacizumab combination therapy in phase III trials were sensory neuropathy and grade ≥3 hypertension, occurring more frequently with combination therapy than with chemotherapy alone. Potentially life-threatening events, such as venous thromboembolism, gastrointestinal perforation, arterial thromboembolism, haemorrhage and left ventricular dysfunction, occurred in ≤5% of patients receiving combination therapy in these trials. In conclusion, bevacizumab administered in combination with paclitaxel, or in combination with capecitabine if other chemotherapy regimens are not appropriate, may be considered as an option for the first-line treatment of patients with HER2-negative metastatic breast cancer.