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.     

Emerging Data with Antiangiogenic Therapies in Early and Advanced Non–Small-Cell Lung Cancer

Lung cancer is the leading cause of cancer-related mortality in the United States. Patients treated with adjuvant chemotherapy have a 5-year survival rate of 25% to 70% depending on stage, whereas those with advanced disease have a median survival of approximately 8 months when treated with standard platinum-based therapy. Improvements in our understanding of cancer biology have led to the development of novel agents that more precisely affect the target of interest, allowing for a more rational approach to clinical trial design. Angiogenesis, the growth of new vessels from preexisting vessels, is a fundamental step in tumor growth and progression. Inhibition of tumor-related angiogenesis has become an attractive target for anticancer therapy. Bevacizumab, a monoclonal antibody against vascular endothelial growth factor (VEGF), is the most studied antiangiogenic agent in patients with Non—Small-cell lung cancer (NSCLC). There was an improvement in overall survival when bevacizumab was combined with paclitaxel and carboplatin in patients with advanced NSCLC that was not seen when bevacizumab was combined with cisplatin and gemcitabine. Studies with bevacizumab in the adjuvant and advanced setting are ongoing in patients with NSCLC. Small-molecule inhibitors targeting the VEGF receptor and the tyrosine kinase receptor have also shown promise when combined with standard chemotherapy, but their role in the treatment of patients with NSCLC remains to be determined. This article reviews clinical trials that have incorporated antiangiogenic agents in the treatment of patients with NSCLC.     

Combined Inhibition of Vascular Endothelial Growth Factor and Epidermal Growth Factor Signaling in Non–Small-Cell Lung Cancer Therapy

Elucidation of molecular pathways that promote malignancies has led to the identification of the epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) as key components involved in regulation of tumor proliferation and angiogenesis, respectively. Biologic agents that target these individual pathways have proven effective in treating patients with advanced Non—Small-cell lung cancer (NSCLC), adding to previously available therapies and often with fewer side effects. However, inhibition of a single molecular pathway does not account for alternate pathways or biologic adaptations that eventually lead to resistance. Therefore, combining EGFR and VEGF inhibition is currently under investigation as a means to overcome resistance and promote synergy. Erlotinib, an anti-EGFR agent, and bevacizumab, an anti-VEGF agent, are both approved in NSCLC, demonstrating single-agent activity. The phase II trials evaluating the combination of erlotinib and bevacizumab have shown efficacy as first-line therapy or in patients with previously treated NSCLC either alone or with chemotherapy. Dual inhibition of EGFR and VEGF pathways has also been accomplished by the novel agents vandetanib and XL647, which are able to target both pathways. Vandetanib has also demonstrated activity in patients with advanced NSCLC either alone or with chemotherapy in phase I/II studies. Another novel agent, XL647, has demonstrated promising single-agent activity in patients who have been resistant to previous anti-EGFR therapy. Further evaluation of combined EGFR and VEGF inhibition is under investigation.     

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.     

Examining the safety profile of angiogenesis inhibitors: implications for clinical practice

Dysregulation of angiogenesis in solid tumors enables tumor growth and metastasis. Receptors that mediate angiogenesis, and their ligands, have been identified; among these, vascular endothelial growth factor (VEGF) and its receptor tyrosine kinase play a central role. In non-small cell lung cancer (NSCLC), clinical benefit has been shown with bevacizumab, which blocks VEGF binding to its receptors. In addition, small-molecule tyrosine kinase inhibitors are currently in clinical practice or development in several indications. The potential clinical benefit of antiangiogenic agents is accompanied by the need to understand their safety profiles, seek suitable combination regimens and identify patients able to tolerate one treatment over another. This is particularly relevant in cancers for which patients often present with advanced disease and suffer co-morbidities, requiring an agent that is both efficacious and well tolerated over long-term continuous treatment. Using literature from peer-reviewed journals, this review considers different antiangiogenic agents and their safety profiles, focusing on the potential impact of these data on the treatment of patients with NSCLC.     

非小细胞肺癌抗血管生成治疗研究进展

非小细胞肺癌（non-small cell lung cancer,NSCLC）的增殖、浸润、转移都需要新生血管的支持,抗血管生成治疗已成为一种重要治疗手段。血管内皮生长因子（vascular endothelial growth factor,VEGF）作为关键的促血管生成因子,是目前NSCLC抗血管生成治疗药物的主要靶点。这些药物主要包括以VEGF或其受体VEGFR为靶点的单克隆抗体,及阻断VEGFR下游信号通路传导的小分子酪氨酸激酶抑制剂（VEGFR-TKI）两类。目前有两种抗血管生成单克隆抗体,贝伐单抗及雷莫卢单抗,被批准联合化疗一线或二线治疗原位进展或转移的NSCLC。多种VEGFR-TKI治疗NSCLC的临床试验均以失败告终,目前仅有安罗替尼在我国被批准用于NSCLC的三线治疗,而尼达尼布联合化疗在二线治疗中也显示了良好的生存获益。本篇综述我们将回顾总结抗血管生成药物单药或与其他抗肿瘤药物联用成功应用于NSCLC治疗的临床研究数据。     

Targeting Angiogenesis in Cancer Therapy: Moving Beyond Vascular Endothelial Growth Factor

Angiogenesis, or the formation of new capillary blood vessels, occurs primarily during human development and reproduction; however, aberrant regulation of angiogenesis is also a fundamental process found in several pathologic conditions, including cancer. As a process required for invasion and metastasis, tumor angiogenesis constitutes an important point of control of cancer progression. Although not yet completely understood, the complex process of tumor angiogenesis involves highly regulated orchestration of multiple signaling pathways. The proangiogenic signaling molecule vascular endothelial growth factor (VEGF) and its cognate receptor (VEGF receptor 2 [VEGFR-2]) play a central role in angiogenesis and often are highly expressed in human cancers, and initial clinical efforts to develop antiangiogenic treatments focused largely on inhibiting VEGF/VEGFR signaling. Such approaches, however, often lead to transient responses and further disease progression because angiogenesis is regulated by multiple pathways that are able to compensate for each other when single pathways are inhibited. The platelet-derived growth factor (PDGF) and PDGF receptor (PDGFR) and fibroblast growth factor (FGF) and FGF receptor (FGFR) pathways, for example, provide potential escape mechanisms from anti-VEGF/VEGFR therapy that could facilitate resumption of tumor growth. Accordingly, more recent treatments have focused on inhibiting multiple signaling pathways simultaneously. This comprehensive review discusses the limitations of inhibiting VEGF signaling alone as an antiangiogenic strategy, the importance of other angiogenic pathways including PDGF/PDGFR and FGF/FGFR, and the novel current and emerging agents that target multiple angiogenic pathways for the treatment of advanced solid tumors.

Implications for Practice:

Significant advances in cancer treatment have been achieved with the development of antiangiogenic agents, the majority of which have focused on inhibition of the vascular endothelial growth factor (VEGF) pathway. VEGF targeting alone, however, has not proven to be as efficacious as originally hoped, and it is increasingly clear that there are many interconnected and compensatory pathways that can overcome VEGF-targeted inhibition of angiogenesis. Maximizing the potential of antiangiogenic therapy is likely to require a broader therapeutic approach using a new generation of multitargeted antiangiogenic agents.     

Vascular Endothelial Growth Factor Receptor Tyrosine Kinase Inhibitors in Non–Small-Cell Lung Cancer

Angiogenesis is essential for cancer growth and progression. Vascular endothelial growth factor (VEGF) plays a crucial role in angiogenesis. The addition of bevacizumab, an antibody to vascular endothelial growth factor (VEGF), to paclitaxel and carboplatin improves survival compared with chemotherapy alone in patients with previously untreated metastatic nonsquamous non–small-cell lung cancer (NSCLC). Vascular endothelial growth factor receptor tyrosine kinase inhibitors (VEGFR TKIs) are a new class of drugs that target the TK domain of the VEGF receptors. To evaluate the role of this class of agents in the treatment of NSCLC, some phase II and phase III studies using these agents alone or in combination with other agents have been completed. This review summarizes the currently available data on VEGFR TKIs in the treatment of NSCLC.     

Emerging antiangiogenic therapies for non-small-cell lung cancer

Lung cancer remains the leading cause of cancer-related deaths. Antiangiogenic therapy has increasingly been studied for advanced non-small-cell lung cancer (NSCLC). Bevacizumab is the only approved antiangiogenic agent for NSCLC and has shown progression-free survival benefits in large Phase III studies and an overall survival benefit in the Phase III E4599 trial in advanced nonsquamous NSCLC. New antiangiogenic treatment strategies are being evaluated that target multiple receptors within a family (VEGF receptor [VEGFR]-1, VEGFR-2) or multiple angiogenic pathways (targets VEGFR and PDGF receptor pathways), and agents that inhibit alternative mediators of angiogenesis (integrins and established vasculature). As data become available from ongoing studies, it will be important to determine how these new antiangiogenic agents will best fit into the current NSCLC treatment paradigm.     

Emerging antiangiogenic therapies for non-small-cell lung cancer

Lung cancer remains the leading cause of cancer-related deaths. Antiangiogenic therapy has increasingly been studied for advanced non-small-cell lung cancer (NSCLC). Bevacizumab is the only approved antiangiogenic agent for NSCLC and has shown progression-free survival benefits in large Phase III studies and an overall survival benefit in the Phase III E4599 trial in advanced nonsquamous NSCLC. New antiangiogenic treatment strategies are being evaluated that target multiple receptors within a family (VEGF receptor [VEGFR]-1, VEGFR-2) or multiple angiogenic pathways (targets VEGFR and PDGF receptor pathways), and agents that inhibit alternative mediators of angiogenesis (integrins and established vasculature). As data become available from ongoing studies, it will be important to determine how these new antiangiogenic agents will best fit into the current NSCLC treatment paradigm.     

Role of Anti-angiogenesis Agents in Treating NSCLC: Focus on Bevacizumab and VEGFR Tyrosine Kinase Inhibitors

OPINION STATEMENT: Successful inhibition of angiogenesis with the anti-vascular endothelial growth factor (VEGF) antibody bevacizumab has improved the efficacy seen with standard cytotoxic therapy in NSCLC. The addition of bevacizumab to first-line chemotherapy improved response rate and progression free survival and added 2 months to median overall survival for those patients with advanced stage NSCLC on the treatment arm of E4599. Bevacizumab is now a standard agent to add to frontline carboplatin and paclitaxel for patients with newly diagnosed NSCLC who meet the eligibility criteria from the landmark E4599 trial. Unfortunately about half of all patients are not eligible either because they have squamous histology, brain metastases, or are on anti-coagulation. Ongoing trials are further exploring the safety of bevacizumab in these patient populations, as well as in combination with other cytotoxic regimens. Exploration of other applications of bevacizumab in the second-line and adjuvant setting are ongoing as well. The largest class of drugs that block angiogenesis are the multi-targeted tyrosine kinase inhibitors (TKIs) that target the VEGF receptor (VEGFR). These drugs are still in development, and though two are now on the market for treating other malignancies, their role in NSCLC is under investigation. These agents have the advantages of hitting multiple targets, convenient oral administration, and potential for lower cost. Their lack of target specificity leads to unexpected toxicity, but also promising efficacy. For example, the overall objective response rate of 9.5% with single agent sunitinib compares similarly to that of pemetrexed or docetaxel in previously treated NSCLC patients, but toxicity, notably fatigue, lead to discontinuation in 38% of patients. Hypertension, hemorrhage and cavitation are common toxicities amongst this class of agents. Rash, fatigue, myalgia, and hand-foot syndrome are more specifically seen with TKIs. These compounds may also be synergistic or additive with traditional cytotoxic chemotherapy drugs and other novel compounds. In early trials sorafenib as a single agent has shown no clinical response in previously treated NSCLC patients, whereas clinical benefit in combination with erlotinib or chemotherapy has been seen in early studies. Vandetanib has demonstrated objective responses as a single agent and in combination with chemotherapy in previously treated NSCLC patients. A phase I trial of AZD2171 with carboplatin and paclitaxel in newly diagnosed advanced stage NSCLC also demonstrated promising results with 6 of 15 patients achieving partial responses. NSCLC specific trials are also underway, or in development for pazopanib, axitinib, AMG 706, XL647, enzastaurin, and other TKIs. Other anti-angiogenesis agents with different mechanisms of action include thalidomide and its derivatives, monoclonal antibodies to the VEGFRs, and VEGF Trap, a chimeric molecule which combines extracellular portions of VEGFR1 and VEGFR2 with the Fc portion of immunoglobulin G1 to form a molecule that binds and "traps" VEGF. Despite modest improvements, prognosis continues to be poor for patients with advanced NSCLC. Bevacizumab is a first step into the world of angiogenesis inhibitors for NSCLC and though it only offers a modest survival benefit in a limited patient population, it paves the way for the development of the next generation of anti-angiogenesis inhibitors. We can hope that further improvements in survival will follow.     

Vascular Endothelial Growth Factor Polymorphisms: Role in Response and Toxicity of Tyrosine Kinase Inhibitors

Angiogenesis is central to the growth of normal tissues and tumors. Inhibiting this pathway has been a strategy for drug development for tumors not responsive to most agents used in chemotherapy. Notably, signaling mediated by vascular endothelial growth factor (VEGF) is a key target because aberrant signaling via this pathway is frequently associated with neoangiogenesis in tumors. The drug-discovery effort to blunt VEGF signaling has led to the approval of bevacizumab and several receptor tyrosine kinase inhibitors (TKIs) that have shown efficacy in the clinical management of breast, colorectal, lung, and kidney cancer. Understanding the genetic variability in VEGF and VEGF receptor has led to identifying genotypic variations (single nucleotide polymorphisms [SNPs]) associated with treatment outcome and toxicity. Notably, identification of SNPs in VEGF associated with angiogenesis inhibitor treatment-induced hypertension and outcome provides exciting opportunities for personalized medicine to improve outcome and reduced toxicity with these novel TKIs.     

The evolving role of VEGF-targeted therapies in the treatment of metastatic colorectal cancer

Therapies that target angiogenesis and the VEGF pathway are a component of treatment for patients with metastatic colorectal cancer (mCRC). Bevacizumab is a humanized monoclonal antibody that binds to VEGFA. Chemotherapy plus bevacizumab has led to improved outcomes for mCRC patients. Despite these benefits, progressive disease invariably ensues. Multiple members of the VEGF family can potentially contribute to tumor angiogenesis and/or evasion of antiangiogenic therapy if one pathway should be inhibited. Aflibercept, a new biological agent, is a multiple angiogenic factor trap that prevents not only VEGFA, but also VEGFB and PlGF from activating their native receptors. Key clinical data for bevacizumab and aflibercept for treatment of mCRC, clinical evidence for use of these agents beyond progression, and the search for angiogenic biomarkers to better define patients most likely to benefit from these interventions will be reviewed.     

The Role of Anti–Epidermal Growth Factor Receptor and Anti–Vascular Endothelial Growth Factor Therapies in the Treatment of Non–Small-Cell Lung Cancer

Standard first-line therapy for non–small-cell lung cancer (NSCLC) with platinum-based agents, given in combination with cytotoxic compounds, has reached a relative plateau in its therapeutic efficacy. Novel molecular targeted agents acting on specific pathways have emerged as effective agents for treating NSCLC; some have already produced positive results in phase III trials. Notably, inhibition of the vascular endothelial growth factor (VEGF) pathway with an anti-VEGF antibody, bevacizumab, and targeting the epidermal growth factor receptor (EGFR) pathway with a small-molecule EGFR tyrosine kinase inhibitor erlotinib or a monoclonal antibody (cetuximab) have demonstrated prolonged survival in patients with advanced disease in both the first- and second-line settings. The heterogeneity of signaling processes leading to tumor cell survival and proliferation supports the targeting of multiple signaling pathways as an effective anticancer treatment strategy. Consequently, rational combinations of molecular targeted agents might offer superior clinical efficacy and an alternative treatment option to patients refractory to, or unable to tolerate, standard chemotherapy. The challenge lies in determining which molecular entities should be pursued and the best approach to combine them. This review discusses the potential clinical utility of combining bevacizumab and erlotinib to inhibit both angiogenesis and EGFR signaling as a valid nonchemotherapeutic approach for the treatment of NSCLC. Other combinations of novel therapies that block EGFR and angiogenic pathways, as well as complementary signaling pathways, with unique modes of action and low toxicity profiles could offer an increased repertoire of individualized treatment options for patients with advanced NSCLC.     

Therapeutic application of noncytotoxic molecular targeted therapy in gliomas: growth factor receptors and angiogenesis inhibitors

Growth factor receptors and angiogenesis play major roles in the oncogenesis of gliomas. Over the last several years, several noncytotoxic molecular targeted therapies have been developed against growth factor receptors and tumor angiogenesis. In gliomas, two main anti-growth factor receptor strategies have been evaluated in phase I/II clinical trials: (a) small molecule tyrosine kinase inhibitors (TKIs) and (b) monoclonal antibodies that target growth factors or growth factor receptors other than vascular endothelial growth factor (VEGF). Up to now, few glioma patients have responded to small TKIs (0%-14%) or monoclonal antibodies (three case reports) delivered as a single agent. Greater doses, combined therapies, as well as the identification of molecular biomarkers predictive of response and resistance are important in order to optimize drug delivery and improve efficacy. Antiangiogenic therapies are promising for the treatment of gliomas. Thalidomide and metronomic chemotherapy were the first antiangiogenic strategies evaluated, but they have shown only modest activity. Recent studies of bevacizumab, an anti-VEGF antibody, and irinotecan, a topoisomerase I inhibitor, have demonstrated a high response rate, suggesting that targeted antiangiogenic therapies may play a significant role in the management of high-grade gliomas in the future. However, the toxicity profiles of these agents are not fully defined and the radiological evaluation of possible tumor response is challenging. Clinical evaluation of several VEGF receptor TKIs is currently ongoing; one of these inhibitors, cediranib, has already demonstrated interesting activity as a single agent. The integrin inhibitor cilengitide represents another promising strategy.     

Non-small cell lung cancer and antiangiogenic therapy: what can be expected of bevacizumab?

There is an urgent need for new therapies to treat non-small cell lung cancer (NSCLC), as progress with current chemotherapy regimens has been limited. The roles of vascular endothelial growth factor (VEGF) in promoting tumor angiogenesis, maintaining existing vasculature, and contributing to resistance to traditional therapies, together with its negative prognostic significance in NSCLC, make it an appropriate target for therapy. Bevacizumab (Avastin; Genentech Inc., South San Francisco, CA), a monoclonal antibody directed against VEGF, has shown promise in treating a number of different cancers. In a recent phase II trial in patients with advanced metastatic NSCLC, the addition of bevacizumab to standard carboplatin/paclitaxel chemotherapy produced a significantly longer time to progression (32.1 versus 18.4 weeks) and greater response rate (31% versus 19% [not significant]) than chemotherapy alone. In the subset of patients with nonsquamous histologies, response rates and survival were further enhanced, with a mean survival time of 17.9 months versus 12.3 months with chemotherapy alone. Bevacizumab was generally well tolerated and did not appear to increase the incidences or severities of the nausea/vomiting, neuropathy, and renal toxicity that are typically associated with carboplatin/paclitaxel chemotherapy. Adverse events in phase I and II studies included hypertension, thrombosis, proteinuria (with occasional nephrotic syndrome), and epistaxis. Serious tumor-related bleeding episodes (hemoptysis/hematemesis) appear to be the main safety concern in patients with NSCLC, with squamous cell histology as a possible risk factor. Further work is needed to identify the best way to use bevacizumab in NSCLC, including use in combination with other biologic agents and in the adjuvant setting.     

The potential of antiangiogenic therapy in non-small cell lung cancer.

The long-term prognosis for patients with advanced non-small cell lung cancer (NSCLC) remains poor despite the availability of several cytotoxic chemotherapy regimens. The use of targeted therapies, particularly those against the key mediator of angiogenesis vascular endothelial growth factor (VEGF), has the potential to improve outcomes for NSCLC patients. Bevacizumab, a recombinant humanized monoclonal anti-VEGF antibody, is the most clinically advanced antiangiogenic agent in NSCLC. In a phase III study, bevacizumab showed significantly improved overall and progression-free survival when used in combination with standard first-line chemotherapy in patients with advanced NSCLC. Bevacizumab was generally well tolerated in patients with NSCLC; however, tumor-related bleeding adverse events have been noted in some patients, predominantly those with squamous cell histology or centrally located tumors. Several small-molecule VEGF receptor tyrosine kinase inhibitors have also shown promise in phase I and II trials in NSCLC. This review summarizes the most important findings of angiogenesis inhibitors in NSCLC and discusses the potential for the use of these novel agents in different settings of NSCLC.     

Dual EGFR-VEGF Pathway Inhibition: A Promising Strategy for Patients With EGFR-Mutant NSCLC

The VEGF pathway has been recognized as a key mediator of angiogenesis to support tumorigenesis. Multiple therapeutic agents targeting VEGF and VEGF receptors have been developed and approved for use in NSCLCs. Preclinical studies have found that the VEGF and EGFR pathways share common downstream signaling, and these pathways can function exclusively of one another during oncogenesis. In EGFR-mutant NSCLCs, up-regulated EGFR signaling increases VEGF through hypoxia-independent mechanisms, and elevated VEGF, in turn, contributes to the emergence of resistance to EGFR tyrosine kinase inhibitors (TKIs). In clinical trials, the addition of anti-VEGF therapy to EGFR TKIs considerably improved clinical outcomes. In recently reported large randomized studies, the addition of bevacizumab or ramucirumab to EGFR TKIs substantially improved progression-free survival in patients with TKI-naive EGFR-mutant NSCLC. This article reviews the preclinical and clinical data supporting dual inhibition of EGFR and VEGF in EGFR-mutant NSCLC as a way to improve patient outcomes.     

Update on antiangiogenic treatment of advanced non-small cell lung cancer (NSCLC)

Bevacizumab is a monoclonal antibody that specifically inhibits vascular endothelial growth factor, and is the first antiangiogenic agent to be approved for first-line treatment of advanced non-small cell lung cancer (NSCLC). Evidence from two large phase III trials demonstrates that bevacizumab combined with chemotherapy improves outcomes for patients with non-squamous NSCLC. In patients with adenocarcinoma without epidermal growth factor receptor (EGFR) mutation, a median overall survival of 18.0 months is achieved. Several post-registration phase IV studies have confirmed bevacizumab’s efficacy and tolerability profile and have clarified the eligibility criteria. Clinical research is still ongoing to define the role of bevacizumab in different settings, such as single-agent bevacizumab for continuation maintenance therapy in advanced disease, treatment beyond disease progression, adjuvant therapy in early-stage NSCLC, or bevacizumab in combination with other targeted agents. A number of antiangiogenic tyrosine kinase inhibitors (TKI) have also been investigated in phase II and III trials. None of these drugs has proven significant clinical benefit in unselected patient populations. This article reviews the extensive information from randomized trials and large observational studies for bevacizumab in advanced NSCLC, and shortly describes the current clinical development of antiangiogenic monoclonal antibodies, TKIs and related compounds.     

Unanswered questions: monoclonal antibodies in the treatment of advanced non-small-cell lung cancer

First-line platinum-based doublets is established as the standard of care for advanced non-small-cell lung cancer (NSCLC). Nevertheless, in this field a plateau of effectiveness has been reached during the last years. One new area of exploration in NSCLC therapeutics lies in the use of tyrosine-kinase inhibitors (TKIs) or monoclonal antibodies (mAbs) to target vascular endothelial growth factor (VEGF) and its receptors, and epidermal growth factor receptor (EGFR). The results of randomized trials testing mAbs against VEGF (bevacizumab) and EGFR (cetuximab) are challenging the paradigm of the platinum doublets as the gold standard in advanced NSCLC. Despite the interesting results that have thus far been collected, the benefit of these new agents, both in terms of balancing between advantages and toxicity and the associated health economic burden, is modest. Here we discuss the use of bevacizumab and cetuximab, the mAbs for which the largest amount of data in the treatment of advanced NSCLC exists. However, despite our having a significant amount of data on these two mAbs, we still have much to learn: Which patients are appropriate for these treatments; for how long are the treatments beneficial, and what are the molecular and clinicalpredictors? We must continue to study these important problems in treating NSCLC.