Antiangiogenic agents in the management of non-small cell lung cancer: Where do we stand now and where are we headed?

Several therapies targeting angiogenesis are currently in development for non-small cell lung cancer (NSCLC). This review discusses results of recent clinical trials evaluating chemotherapy plus antiangiogenic therapy for NSCLC. Bevacizumab, an anti-VEGF antibody, is currently approved for the treatment of advanced NSCLC in combination with carboplatin and paclitaxel. Completed phase III trials evaluating bevacizumab plus chemotherapy have shown prolonged progression-free survival; however, not all trials showed significant improvement in overall survival (OS). Phase III trials of the tyrosine kinase inhibitors (TKIs) vandetanib and sorafenib and the vascular disrupting agent ASA404 also failed to improve OS compared with chemotherapy alone. Clinical trials are ongoing involving several new antiangiogenic therapies, including ramucirumab, aflibercept, cediranib, BIBF 1120, sunitinib, pazopanib, brivanib, ABT-869, axitinib, ABT-751, and NPI-2358; several of these agents have shown promising phase I/II results. Results from recently completed and ongoing phase III trials will determine if these newer antiangiogenic agents will be incorporated into clinical practice.     

Recent advances in the treatment of renal cell carcinoma and the role of targeted therapies

Immunotherapy confers a small but significant overall survival advantage in metastatic renal cell carcinoma (RCC) but only for the minority of patients, i.e. the 20% with good prognostic features. Recent developments in the molecular biology of renal cell carcinoma have identified multiple pathways associated with the development of this cancer. Several strategies have been investigated targeting these pathways, with significant clinical benefits shown in early studies. New agents including the small molecule targeted inhibitors sunitinib, sorafenib and temsirolimus, and the monoclonal antibody bevacizumab have shown anti-tumour activity in randomised clinical trials and have become the standard of care for most patients. Sunitinib and temsirolimus have shown significant improvements in progression-free survival (sunitinib) and overall survival (temsirolimus) in separate phase III studies in the first-line setting when compared with interferon-alpha. Sorafenib has demonstrated prolonged progression-free survival in a phase III study in comparison with placebo in the second-line setting. More recently two phase III studies have compared bevacizumab and interferon-alpha with interferon-alpha alone. Both studies showed a statistically significant improvement in progression-free survival for the combination arm. Additional studies are needed to optimise the use of these agents by identifying those patients who most benefit and elucidating the best way of delivering them, either in combination or as sequential single agents.     

Recent translational research: antiangiogenic therapy for breast cancer – where do we stand?

The central importance of angiogenesis and our understanding of how new blood vessels are formed have led to the development of novel antiangiogenic therapies. Although the number of agents in development has grown exponentially, only one phase III trial in breast cancer has been completed. In that study the addition of bevacizumab to capecitabine did not extend the progression-free survival of patients with refractory disease as compared with capecitabine monotherapy. Early enthusiasm for antiangiogenic therapy must give way to clinical reality. Our challenge now is to exploit better the activity of antiangiogenic agents seen in the early clinical studies.     

Targeting angiogenesis in esophagogastric adenocarcinoma

The possibility of targeting tumor angiogenesis was postulated almost 40 years ago. The vascular endothelial growth factor (VEGF) family and its receptors have since been characterized and extensively studied. VEGF overexpression is a common finding in solid tumors, including esophagogastric cancer, and frequently correlates with poor prognosis. Monoclonal antibodies, soluble receptors, and small-molecule tyrosine kinase inhibitors have been developed to inhibit tumor angiogenesis, and antiangiogenic therapy is now a component of standard treatment for advanced renal cell, hepatocellular, colorectal, breast, and non-small cell lung carcinomas. The small-molecule tyrosine kinase inhibitors sunitinib and sorafenib have been evaluated in phase II studies in esophagogastric cancer but appear to have only modest activity. Similarly, despite promising efficacy signals from phase II studies, the addition of the anti-VEGF-A monoclonal antibody bevacizumab to cisplatin plus capecitabine failed to result in a longer overall survival duration than with the chemotherapy doublet plus placebo. The response rate and progression-free survival interval were significantly greater with bevacizumab, confirming some efficacy in advanced gastric cancer, but with inadequate benefit to justify the high cost of treatment. Evaluation of bevacizumab in the neoadjuvant and perioperative settings continues, hypothesizing that a higher response rate will translate into longer survival in patients with operable disease. Despite extensive research, the discovery of a reliable predictive biomarker for antiangiogenic therapy continues to elude the scientific and oncology communities, and mechanisms of primary and acquired resistance are incompletely understood. We are therefore currently unable to personalize antiangiogenic therapy for established indications, or use molecular selection for clinical trials evaluating novel indications.     

Targeting Signal Transduction Pathways in Metastatic Breast Cancer: A Comprehensive Review

Greater understanding of the underlying etiology and biology of breast cancer is enabling the clinical development of targeted therapies for metastatic breast cancer (MBC). Following the successful introduction of trastuzumab, the first human epidermal growth factor receptor (HER) biologically targeted therapy to become widely used in MBC patients, other agents have been developed. Novel agents include monoclonal antibodies such as pertuzumab, which bind to receptors on the cell surface, and tyrosine kinase inhibitors (TKIs) such as lapatinib, which target intracellular pathways such as that of the epidermal growth factor receptor. There is also growing clinical experience with antiangiogenic agents, particularly in combination with chemotherapy. These include the monoclonal antibody bevacizumab, which targets vascular endothelial growth factor receptor, and multitargeted TKIs with antiangiogenic and antiproliferative activities, such as sunitinib. Combination treatment with multiple agents targeting both the HER family and angiogenic pathways (e.g., trastuzumab plus bevacizumab) is also showing activity in the clinical setting. Despite recent advances, there are unanswered questions regarding the management of MBC with targeted agents. Future studies are necessary to determine the optimal combinations, doses, and schedules required to maximize clinical activity while minimizing toxicity. Despite the temptation to use a targeted agent in all patients, identification of patient subgroups most likely to benefit must be a key goal and will be critical to the successful future use of these treatments. The aim of this review is to summarize some of the key signaling pathways involved in tumor progression and some of the novel therapies that are in development for MBC.     

Drug insight: advances in renal cell carcinoma and the role of targeted therapies

In metastatic renal cell carcinoma (RCC) immunotherapy results in a small but important improvement in overall survival, but a need exists to develop more-effective systemic therapies. Recent developments in our understanding of the molecular biology of RCC have identified several pathways associated with the development of the disease. A number of strategies designed specifically to target these pathways have resulted. Initial studies have shown marked clinical benefits of so-called 'targeted therapies'. Sunitinib, sorafenib and axitinib are kinase inhibitors that inhibit the VEGF, platelet-derived growth factor and c-kit receptor tyrosine kinases. Bevacizumab is a monoclonal antibody that is directed against VEGF. Temsirolimus inhibits the mammalian target of rapamycin. These agents have all shown considerable activity with manageable toxicity in phase II and III studies in both previously treated and untreated patients. In phase III studies, sorafenib and bevacizumab have been associated with prolonged progression-free survival compared with placebo. Phase III data have shown improvements in progression-free and overall survival with sunitinib and temsirolimus, respectively, compared with interferon alfa. Additional studies are needed to determine the optimum utilization of these agents at the appropriate stage of disease and in the best combinations for maximal clinical benefit.     

Targeting Angiogenesis with Multitargeted Tyrosine Kinase Inhibitors in the Treatment of Non‐Small Cell Lung Cancer

It has been >35 years since the link between angiogenesis and the growth of tumors was first reported. Targeting angiogenesis became feasible with the availability of bevacizumab, an anti–vascular endothelial growth factor monoclonal antibody. Initial studies revealed that the combination of bevacizumab and chemotherapy led to longer overall survival times than with chemotherapy alone in patients with advanced colorectal cancer. Since then, drug development strategies have added small molecule tyrosine kinase inhibitors to the panel of antiangiogenic agents under evaluation; data from numerous trials are now available. The challenge now is to identify the optimal antiangiogenic agent for specific patient groups and to understand not only the mechanistic differences between agents, but also the variability in their antitumor activity across different tumor types and their differing side‐effect profiles. As in other solid tumors, angiogenesis contributes to the development of non‐small cell lung cancer (NSCLC), and this review summarizes the role of angiogenesis in this disease. We review the current developmental status of antiangiogenic tyrosine kinase inhibitors (including vandetanib, sunitinib, axitinib, sorafenib, vatalanib, and pazopanib) in NSCLC and conclude by briefly discussing the need for optimal patient selection and potential future directions.     

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.     

Clinical data for anti-angiogenic agents in previously treated advanced breast cancer

The vascular endothelial growth factor (VEGF) ligand and its receptor represent key targets for anti-angiogenic agents in the therapy of breast cancer. Such agents include bevacizumab, sunitinib, sorafenib and vandetanib; all of which are currently in clinical development for breast cancer. The most extensively studied of these agents is bevacizumab, and a phase III trial of this agent in combination with capecitabine demonstrated a significant improvement in response rate for the combination regimen compared with capecitabine alone in patients previously treated for metastatic breast cancer. However, the lack of a corresponding significant improvement in progression-free and overall survival may be attributable to the nature of breast cancer tumour progression. Preclinical studies suggest that VEGF may be the predominant pro-angiogenic factor expressed at early disease stages, whereas other angiogenic factors may be more important in advanced disease. Clinical evidence is not yet available, but this theory suggests that bevacizumab may be more effective when used earlier in the course of breast cancer therapy.     

Reappraisal of the role of bevacizumab in the therapeutic strategy in advanced renal cell carcinoma

Increased understanding of the molecular pathophysiology of metastatic renal cell carcinoma (mRCC) has led to development of antiangiogenic therapies in the past 5 years that significantly improved the prognosis. Vascular endothelial growth factor (VEGF) is a major growth factor in tumor angiogenesis and is implicated in tumor progression of several types of cancer, including mRCC. Use of 2 distinct approaches resulted in clinical efficacy in blocking the VEGF pathway: small molecule tyrosine kinase inhibitors (sunitinib, sorafenib, axitinib, pazopanib) and the humanized anti-VEGF monoclonal antibody bevacizumab that binds circulating VEGF and prevents activation of the VEGF receptor. In the 2 large phase III trials AVOREN and CALGB 90206, bevacizumab combined with interferon alfa demonstrated its efficacy as a first-line therapy in terms of progression-free survival. Nevertheless, in the era of targeted therapies, other studies are still needed to better obtain the maximal clinical benefit of bevacizumab. The aim of this overview is to report the current role of bevacizumab in the treatment of metastatic kidney cancer and to highlight possible combinations or sequential strategies that involve other targeted agents.     

Safety of bevacizumab in patients with metastatic breast cancer

Five randomized phase III trials - AVF2119g, E2100, AVADO, RIBBON-1, and RIBBON-2 - have reported data on the efficacy and safety of bevacizumab, combined with a variety of chemotherapy agents and in various settings, in patients with metastatic breast cancer (MBC). The E2100 trial demonstrated a significant improvement in progression-free survival according to the independent review facility, from 5.8 to 11.3 months when bevacizumab was combined with paclitaxel (p < 0.0001) as first-line therapy in patients with HER2-nonamplified MBC; subsequent trials of bevacizumab as first-line (AVADO, RIBBON-1) and second-line (RIBBON-2) therapy for patients with HER2-nonamplified MBC have also met their primary end point of prolonging progression-free survival (PFS). Accumulating safety data for bevacizumab in MBC show that it is generally well tolerated and associated with predictable adverse events, including hypertension and proteinuria. The majority of adverse events are mild and manageable, but bevacizumab is also associated with some severe toxicities. The management of bevacizumab-related adverse events in MBC has improved with increased experience. This review summarizes bevacizumab efficacy in MBC and focuses on bevacizumab-related toxicities as reported in 5 phase III clinical trials. Current adverse event management strategies, based on guidelines and experience from these trials, are outlined.     

Vascular Endothelial Growth Factor Pathway—Targeted Therapy as Initial Systemic Treatment of Patients with Renal Cancer

Advanced renal cancer is known to be largely refractory to traditional DNA- and DNA repair—targeted chemotherapy. Until recently, immunotherapy had been the mainstay for the treatment; however, it is effective in only a small proportion of patients. Advances in the understanding of the association between the von Hippel—Lindau pathway and angiogenesis and their role in the development of renal cancer has led to the development of highly effective vascular endothelial growth factor (VEGF) pathway—targeted inhibitors. Several such novel agents have demonstrated increased clinical benefit, progression-free survival, and superior quality of life in large, randomized phase III clinical trials, and additional VEGF pathway inhibitors are currently being studied. This review will summarize the major clinical trials and practical recommendations for the most studied VEGF inhibitors, including sunitinib, sorafenib, and bevacizumab; introduce novel VEGF inhibitor agents; outline side effects and toxicities; and discuss sequential and combination therapy with these agents.     

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.     

Antiangiogenic agents in combination with chemotherapy in patients with advanced non-small cell lung cancer

Most patients with non-small cell lung cancer (NSCLC) present with advanced disease requiring systemic chemotherapy. Treatment with the antiangiogenic agent bevacizumab in combination with standard platinum-based doublet chemotherapy has been shown to improve outcomes in patients with advanced NSCLC. Several multitargeted antiangiogenic tyrosine kinase inhibitors (e.g., sorafenib, sunitinib, cediranib, vandetanib, BIBF 1120, pazopanib, and axitinib) are also being evaluated in combination with standard chemotherapy. Here we review current clinical data with combination therapy involving antiangiogenic agents and cytotoxic chemotherapy in patients with advanced NSCLC.     

Treatment of metastatic breast cancer: second line and beyond

Increasing use of standard chemotherapy, especially anthracycline- and taxane-based therapies, in early-stage breast cancer has led to a corresponding increase in heavily pretreated and/or treatment-resistant cases of metastatic breast cancer (MBC). Thus, second and later lines of MBC therapy frequently involve the clinically challenging picture of progressive disease and limited treatment options. While several prognostic factors have been identified to aid treatment selection in MBC patients, treatment is palliative and aimed at prolonging survival, controlling symptoms, and maximizing patients' quality of life. No globally accepted standard exists for meeting these goals, and treatment patterns vary according to region. The list of available agents for the treatment of MBC is increasing with newer chemotherapeutic agents and molecular-targeted therapies. Within recent years, several single-agent and combination chemotherapy regimens have been shown to improve progression-free survival and reduce symptoms of disease in clinical studies in patients with resistant and/or heavily pretreated MBC. However, at present, the demonstrated benefits of these medical interventions have usually not included extension of overall survival times. It is hoped that in the near future, ongoing refinements to treatment approaches used in second-line settings and beyond will allow meaningful improvements in symptom control and survival in MBC.     

Target therapy in metastatic renal cell carcinoma

Metastatic RCC with 38,000 new cases diagnosed in the United States every year is notoriously resistant to conventional chemotherapy and is almost invariably an incurable condition. New biologic drugs are beginning to break this resistance, reflecting in the registration of four innovative agents for treatment of advanced RCC in the last 2 years, bevacizumab, sorafenib, sunitinib and temsirolimus. Small-molecule multikinase inhibitors targeting VEGF receptors (sunitinib and sorafenib) can prolong time to progression and preserve quality of life when used in newly diagnosed or previously treated patients. The anti-VEGF antibody bevacizumab enhances response rate and prolongs disease control when added to interferon. Temsirolimus, mammalian target of rapamycin inhibitor, prolongs the survival duration of patients with poor-risk disease. In this review, we report pre-clinical data, data relative to registrative phase III trials, and guideline indications for an optimal use of these new agents that are revolutionising the management of metastatic Renal Cell Carcinoma.     

Patients With Metastatic Breast Cancer Using Bevacizumab as a Treatment: Is There Still a Role for it?

OPINION STATEMENT: Over the last few decades, the angiogenesis mechanism has increasingly been studied and implicated in cancer pathophysiology. At present, it is known that angiogenesis plays a relevant role in tumor growth, and more importantly many new molecules exists can potentially interfere with this process. Bevacizumab, a humanized monoclonal antibody targeting the vascular endothelial growth factor A (VEGF-A) now commonly used in the treatment of colorectal, renal cell, and brain cancer, is the first anti-angiogenesis drug delivered in combination with chemotherapy that has consistently shown clinical efficacy in the treatment of breast cancer. Since the ECOG 2100 trial has shown that bevacizumab added to paclitaxel as a first-line treatment for advanced breast cancer nearly doubled the time to progression and tumor response rate, its approval was granted almost worldwide. However, other phase III trials revealed a smaller absolute improvement in progression-free survival (PFS) and response rates, and no trials yet have demonstrated survival enhancement which led to a great controversy and debate over the use of bevacizumab. The discrepancy between PFS and overall survival also raises the question of whether or not bevacizumab has been applied sub-optimally in some of the studies, if a predictive biomarker(s) exists to select the group of patients whom would receive the greatest benefit and what is the appropriate clinical end-point for approval and funding of new targeted agents. In this article we will review the bevacizumab mechanism of action and the clinical trials that assessed its benefit in the treatment of metastatic breast cancer (MBC).     

Therapy innovations: tyrosine kinase inhibitors for the treatment of pancreatic neuroendocrine tumors

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) show limited sensitivity to cytotoxic agents, requiring the search for novel therapies. Recently, data from a phase III trial demonstrated that sunitinib produces a clinically significant improvement in progression-free survival in patients with unresectable, advanced, or metastatic GEP-NETs. Based on this finding, sunitinib became the first targeted drug approved for the treatment of GEP-NETs, paving the way for the approval of other anticancer agents in this drug-orphan disease. To date, results of trials involving other multitargeted tyrosine kinase inhibitors, such as sorafenib, the monoclonal antibody bevacizumab, and insulin-like growth factor 1 receptor inhibitors, have also shown promising results, and some are already being studied in phase III trials. This review updates the results of ongoing trials using inhibitors of growth factors and tyrosine kinase receptors involved in the carcinogenesis of GEP-NETs.     

Antiangiogenic therapy for breast cancer

Angiogenesis is an important component of cancer growth, invasion and metastasis. Therefore, inhibition of angiogenesis is an attractive strategy for treatment of cancer. We describe existing clinical trials of antiangiogenic agents and the challenges facing the clinical development and optimal use of these agents for the treatment of breast cancer. Currently, the most promising approach has been the use of bevacizumab, a humanized monoclonal antibody directed against the most potent pro-angiogenic factor, vascular endothelial growth factor (VEGF). Small molecular inhibitors of VEGF tyrosine kinase activity, such as sorafenib, appear promising. While, the role of sunitinib and inhibitors of mammalian target of rapamycin (mTOR) in breast cancer has to be defined. Several unanswered questions remain, such as choice of drug(s), optimal duration of therapy and patient selection criteria.     

Beyond bevacizumab: antiangiogenic agents

Angiogenesis is a rational target for the treatment of patients with non-small-cell lung cancer (NSCLC). In the E4599 trial, the vascular endothelial growth factor (VEGF)-targeted antibody bevacizumab combined with carboplatin/paclitaxel improved both progression-free survival (PFS) and overall survival (OS) compared with chemotherapy alone. However responses to bevacizumab are usually transient and resistance inevitably develops. Thus other targets should be considered for future antiangiogenic strategies. A number of antiangiogenic agents with a variety of targets are in clinical development for NSCLC. Several multitargeted receptor tyrosine kinase inhibitors (TKIs) such as sorafenib, cediranib, and BIBF 1120, with activity against vascular endothelial growth factor receptor (VEGFR) and other proangiogenic pathways (eg, fibroblast growth factor [FGF] and platelet-derived growth factor [PDGF] pathways) are in clinical development for NSCLC. Many of these TKIs have shown clinical activity in early trials, both alone and in combination with chemotherapy. Other promising agents in development include inhibitors of the angiopoietin/TIE2 pathway, integrin-targeted agents, vascular disrupting agents, and delta-like ligand-4/Notch pathway inhibitors.