Clinical trials of antiangiogenic therapy for hepatocellular carcinoma

Angiogenesis is a promising therapeutic target to inhibit tumor growth. This review summarizes data from clinical trials of antiangiogenic agents in hepatocellular carcinoma. A systematic search of PubMed was performed to identify clinical trials of specific antiangiogenic agents in hepatocellular carcinoma treatment, particularly phase III trials involving treatment guidelines for advanced hepatocellular carcinoma. Sorafenib is the only systemic drug approved for the treatment of advanced hepatocellular carcinoma. Two large-scale, randomized phase III trials using sorafenib involving patients with unresectable HCC showed a significant survival benefit compared with placebo control groups. However, subsequent phase III trials of antiangiogenic agents in hepatocellular carcinoma have failed to improve survival compared with standard treatment protocols using sorafenib. The efficacy of antiangiogenic agents in combination with other drugs, transarterial chemoembolization, and surgical resection is currently being investigated. Future research is expected to optimize antiangiogenic therapies in combination with standard treatment with sorafenib.     

Antiangiogenic Therapies in Early-Stage Breast Cancer

Angiogenesis, which is crucial for the growth and spread of cancer cells, has become an important target for antineoplastic therapies in a variety of malignant tumors. Vascular endothelial growth factor and its receptor promote formation of new blood vessels in tumors. Several drugs, most notably the monoclonal antibody bevacizumab, have been developed to inhibit this process. Clinical trials utilizing bevacizumab and other antiangiogenic drugs in metastatic breast cancer have demonstrated enhanced response rates and prolonged progression-free survival, though no overall survival benefit has been seen. Trials are now under way exploring the use of antiangiogenic agents in patients with early stage breast cancer. We performed a comprehensive review of the published literature (English language), US National Institutes of Health clinical trials registry (ClinicalTrials.gov), and established cooperative groups that revealed approximately 75 clinical trials, completed or ongoing, utilizing antiangiogenic drugs in early-stage breast cancer. A number of phase II trials in the neoadjuvant setting have reported preliminary results suggesting response rates similar to those seen with traditional anthracycline-plus-taxane combination regimens. Most of these early trials have not yet met any survival endpoints. Studies are also ongoing in the adjuvant setting, and these have not yet been reported. The toxicities associated with these agents are similar to those that have been reported in the metastatic trials. Most of these side effects are grade 1 or 2 and are easily manageable; however, there remain a small percentage of patients who sustain life-threatening vascular events, bleeding, or wound-healing complications. This number is significantly higher in patients receiving antiangiogenic drugs when compared with controls. While we eagerly await completion and results of this impressive portfolio of studies in early breast cancer with antiangiogenic agents, there is an urgent need for a more rational patient/antiangiogenic therapy selection with greater insight into predictive factors for toxicities, therapy efficacy, and clinical benefit.     

Biomarkers of angiogenesis for the development of antiangiogenic therapies in oncology: tools or decorations?

Since 2004, four antiangiogenic drugs have been approved for clinical use in patients with advanced solid cancers, on the basis of their capacity to improve survival in phase III clinical studies. These achievements validated the concept introduced by Judah Folkman that the inhibition of tumor angiogenesis could control tumor growth. It has been suggested that biomarkers of angiogenesis would greatly facilitate the clinical development of antiangiogenic therapies. For these four drugs, the pharmacodynamic effects observed in early clinical studies were important to corroborate activities, but were not essential for the continuation of clinical development and approval. Furthermore, no validated biomarkers of angiogenesis or antiangiogenesis are available for routine clinical use. Thus, the quest for biomarkers of angiogenesis and their successful use in the development of antiangiogenic therapies are challenges in clinical oncology and translational cancer research. We review critical points resulting from the successful clinical trials, review current biomarkers, and discuss their potential impact on improving the clinical use of available antiangiogenic drugs and the development of new ones.     

抗血管生成药物在铂耐药卵巢癌中的应用进展

化疗药物在铂耐药卵巢癌治疗中应用非常局限,近年来,多项试验表明抗血管生成药物有改善铂耐药卵巢癌患者预后的作用。本文根据作用机制的不同,把抗血管生成药物分为血管内皮生长因子抑制剂、血管内皮生长因子受体抑制剂、酪氨酸激酶抑制剂和整合素抑制剂,分别阐述其在铂耐药卵巢癌治疗中的研究进展。     

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 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.     

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.     

Mechanisms and future directions for angiogenesis-based cancer therapies.

Targeting angiogenesis represents a new strategy for the development of anticancer therapies. New targets derived from proliferating endothelial cells may be useful in developing anticancer drugs that prolong or stabilize the progression of tumors with minimal systemic toxicities. These drugs may also be used as novel imaging and radiommunotherapeutic agents in cancer therapy. In this review, the mechanisms and control of angiogenesis are discussed. Genetic and proteomic approaches to defining new potential targets on tumor vasculature are then summarized, followed by discussion of possible antiangiogenic treatments that may be derived from these targets and current clinical trials. Such strategies involve the use of endogenous antiangiogenic agents, chemotherapy, gene therapy, antiangiogenic radioligands, immunotherapy, and endothelial cell-based therapies. The potential biologic end points, toxicities, and resistance mechanisms to antiangiogenic agents must be considered as these therapies enter clinical trials.     

Antiangiogenesis Therapy in Breast Cancer

Increased expression of the vascular endothelial growth factor (VEGF) is a poor prognostic factor in breast cancer, indicating that antiangiogenic therapies may improve outcomes. Novel antiangiogenic agents targeting the proangiogenic VEGF ligand and receptor tyrosine kinase inhibitors have been developed. Of these, bevacizumab, a humanized monoclonal antibody directed against VEGF, is very promising in breast cancer. A large phase 3 clinical trial demonstrated a statistically significant improvement in progression-free survival with the addition of bevacizumab to paclitaxel as first-line treatment of advanced breast cancer, establishing the benefit of antiangiogenic therapy in breast cancer. Additional studies of bevacizumab in the metastatic, adjuvant, and neoadjuvant settings are underway. Ongoing trials are also evaluating the efficacy of multitargeted tyrosine kinase inhibitors in advanced breast cancer. This article reviews the results of the key trials evaluating antiangiogenic agents in breast cancer with particular emphasis on bevacizumab and future directions of antiangiogenic therapy.     

Update on Anti-angiogenic Treatment for Malignant Gliomas

Malignant gliomas are the most common primary brain tumor found in adults. Unfortunately, the prognosis for these type of tumors remains dismal despite aggressive treatment with surgical resection, radiation and chemotherapy. Therefore, therapeutics aimed at disrupting the angiogenesis of these tumors is being utilized in to improve survival outcomes and quality of life. This paper reviews the history of antiangiogenic agents in malignant gliomas, discusses the FDA approval of bevacizumab as monotherapy in recurrent glioblastoma and the subsequent controversy, and analyzes the most recent newly diagnosed trials of RTOG 0825 and AVAglio. Additionally, the results of the latest trials with antiangiogenic agents and possible biomarkers are reviewed. Multiple questions remain regarding the potential benefit of antiangiogenic treatments in patients with glioblastoma. Future clinical trials should be designed to learn more about these drugs, to optimize their future use.     

Combining antiangiogenics to overcome resistance: rationale and clinical experience

Antiangiogenic therapies are now well established in oncology clinical practice; however, despite initial optimism, the results of late-phase trials, especially in the adjuvant setting, have largely proved disappointing. In the context of metastatic disease, resistance to antiangiogenic agents arises through a range of mechanisms, including the development of alternative angiogenic pathways. One of the proposed strategies to overcome this resistance is to combine antiangiogenic agents with different mechanisms of action. Early-phase clinical trials assessing the tolerability and efficacy of different combinations of antiangiogenic drugs, including those that target the VEGF pathway or the angiopoietins, as well as vascular disrupting agents, are increasing in number. An example of this strategy is the combination of sorafenib and bevacizumab, which has elicited major responses in different tumor types, including ovarian carcinoma and glioblastoma. However, overlapping and cumulative toxicities pose a real challenge. This review summarizes the preclinical rationale for this approach and current clinical experience in combining antiangiogenic therapies.     

Angiogenic inhibitors: a new therapeutic strategy in oncology

Angiogenesis is a multistep, complex and tightly regulated process that is necessary for tumor growth and metastasis. Based on data of preclinical models, several antiangiogenic compounds has been shown to modify activated tumor endothelium, which suggests that these compounds can improve cytotoxic drug delivery. Such agents have entered clinical trials as single agents or in combination with cytotoxic drugs, and have shown promising antitumor activity. The pharmacodynamic and pharmacokinetic characteristics of antiangiogenic drugs are reviewed here. Most of the early clinical testing of these agents was conducted in patients with advanced disease resistant to standard therapies. Phase III trials compared the efficacy of standard chemotherapy alone with standard chemotherapy in combination with an experimental angiogenesis inhibitor. Although some of these studies were negative or controversial, recent studies validated in large clinical trials with an anti-vascular endothelial growth factor antibody demonstrated significant clinical benefit and renewed enthusiasm for this therapeutic strategy. This review describes the clinical studies of antiangiogenic agents and highlights the challenges related to choosing appropriate strategies for the selection of patients, study design and choice of appropriate endpoints for the studies' development.     

Molecular imaging of antiangiogenic agents

Many novel antiangiogenic agents are currently in various phases of clinical testing. These agents tend to be cytostatic, and therefore few responses are observed with conventional imaging by computerized tomography. Furthermore, toxicity with these agents is seen when the maximum-tolerated dose is combined with chemotherapy. Hence, there is a need to develop imaging strategies that can determine the minimum and optimum biologically active doses.There is increasing awareness of the need to obtain evidence of drug activity through the use of surrogate markers of the biologic mechanism of action during early clinical trials, in addition to determining the pharmacokinetics, toxicity profile, and maximum-tolerated dose. One of the major impediments to the rapid development of antiangiogenic agents in the past has been the lack of validated assays capable of measuring an antiangiogenic effect directly in patients. Recently, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has emerged as a useful technique for noninvasive imaging of tumor vasculature in preclinical and clinical models.The problem of tumor heterogeneity remains to be addressed. The major challenge is the standardization of the technique worldwide for the purpose of early clinical studies that are likely to be multicenter. Convincing data on correlations between changes observed through molecular imaging and changes in tumor angiogenesis, and hence tumor biology, are still lacking. Whether this would translate into a survival advantage remains to be seen.The ultimate test of the surrogate biological end points determined by molecular imaging will occur in randomized phase III trials. Results of the first randomized trial that showed a survival advantage in favor of antiangiogenic agents were released at the American Society of Clinical Oncology meeting in 2003. There it was reported that the combination of 5-fluorouracil, leucovorin, and irinotecan (Camptosar; Pfizer Pharmaceuticals; New York, NY) with anti-vascular endothelial growth factor antibody (bevacizumab-Avastin; Genentech, Inc.; South San Francisco, CA) was superior to the chemotherapy regimen alone when used to treat patients with metastatic colorectal cancer. However, until further phase III clinical trials confirm these results, surrogate end points of clinical efficacy of the newer agents are urgently needed so that development of ineffective drugs can be halted early. This review briefly discusses the role of molecular imaging in general, and DCE-MRI in particular, in relation to treatment with antiangiogenic agents and highlights some of the difficulties encountered in this area.     

Metronomic therapy for breast cancer

Conventional cytotoxic chemotherapeutic drugs treat cancer either by direct killing or by inhibition of growth of cycling tumor cells. In addition, evidence suggests that cytotoxic agents may inhibit tumor growth through an antiangiogenic mechanism. "Metronomic" or frequent continuous administration of the same chemotherapeutic agents at lower doses may optimize their antiangiogenic properties. The effectiveness of metronomic chemotherapy regimens can be improved significantly by concurrent administration of antiangiogenic, endothelial-specific drugs. Preclinical studies have shown that integrating chemotherapy with antiangiogenic drugs can improve efficacy and circumvent the toxicity and drug resistance associated with standard or high-dose chemotherapy. Preliminary clinical studies have shown similar results. Further confirmation of this concept is required with randomized, controlled clinical trials.     

Metronomic therapy for breast cancer

Conventional cytotoxic chemotherapeutic drugs treat cancer either by direct killing or by inhibition of growth of cycling tumor cells. In addition, evidence suggests that cytotoxic agents may inhibit tumor growth through an antiangiogenic mechanism. "Metronomic" or frequent continuous administration of the same chemotherapeutic agents at lower doses may optimize their antiangiogenic properties. The effectiveness of metronomic chemotherapy regimens can be improved significantly by concurrent administration of antiangiogenic, endothelial-specific drugs. Preclinical studies have shown that integrating chemotherapy with antiangiogenic drugs can improve efficacy and circumvent the toxicity and drug resistance associated with standard or high-dose chemotherapy. Preliminary clinical studies have shown similar results. Further confirmation of this concept is required with randomized, controlled clinical trials.     

小细胞肺癌分子靶向治疗研究进展

分子靶向治疗药物包括抗肿瘤血管生成剂、生长因子受体抑制剂、Scr酪氨酸激酶抑制剂、重组分子N-901、抗细胞凋亡因子Bcl-2抑制剂、Hh信号通路抑制剂等.其中抗肿瘤血管生成剂如贝伐单抗和沙力度胺均进行了大量的Ⅱ、Ⅲ试验研究用以评估其在治疗小细胞肺癌(SCLC)方面的疗效及毒性;Scr酪氨酸激酶抑制剂正在进行Ⅰ、Ⅱ期的临床试验,结果 尚未得出;重组分子N-901也正在进行一项针对广泛期SCLC的Ⅱ期的临床试验,另外Bcl-2及Hh信号通路抑制剂正在进行初期的临床试验.初步的研究数据表明SCLC对于靶向治疗不敏感,其原因有待于进一步研究.     

Relevance of angiogenesis in neuroendocrine tumors

While traditional cytotoxic drugs have shown limited efficacy in neuroendocrine tumors (NETs), their biological features have been characterized and can be exploited therapeutically. Their most prominent trait is an extraordinary vascularization in low-grade NETs and an hypoxia-dependent angiogenesis in high-grade NETs, which is associated to a significant expression of many proangiogenic molecules. Therefore, several antiangiogenic compounds have been tested in these malignancies, and among these, sunitinib has demonstrated activity in pancreatic NET patients by dually targeting the VEGFR and PDGFR pathways. In spite of these efficacious clinical results, apparent resistance to antiangiogenic therapies has been described in NET animal models and in clinical trials. Therefore, overcoming antiangiogenic resistance is a crucial step in the subsequent development of antiangiogenic therapies. Several strategies have been postulated to fight resistance, but preclinical studies and clinical trials will investigate and address these therapeutic approaches in the coming years in order to overcome resistance to antiangiogenic therapies in NETs.     

阿帕替尼治疗恶性肿瘤的临床研究进展

随着抗血管生成靶向治疗的发展,作用于血管内皮生长因子（vascular endothelial growth factor,VEGF）及其血管内皮生长因子受体（vascular endothelial growth factor receptor ,VEGFR）信号通路的抗肿瘤药物越来越受到广泛的关注。血管内皮细胞生长因子受体- 2（vascular endothelial growth factor receptor 2,VEGFR- 2）抑制剂阿帕替尼是一种高效抗血管生成药物,是最新上市的口服分子靶向抗肿瘤药物之一。阿帕替尼在人体生物利用度高,安全性及耐受性良好。上市前后一系列大规模的随机、对照临床试验证实阿帕替尼在多种恶性肿瘤中具有一定的客观有效率和生存获益,如胃癌、非小细胞肺癌（non-small cell lung cancer ,NSCLC ）、乳腺癌等,尤其是在胃癌中。2014年该药在中国批准上市应用于临床治疗晚期胃癌。目前正在进行胃癌、肺癌、肝癌、食管癌、结直肠癌等多种恶性肿瘤的Ⅱ/ Ⅲ期临床试验,以探讨其单独或联合抗肿瘤活性。本文就阿帕替尼抗肿瘤机制、对不同类型肿瘤的临床疗效、安全性及不良反应、药物相互作用、耐药及生物标志物等最新研究进展进行综述,以加深对该药抗肿瘤应用的了解,为临床实践提供参考,并期望为恶性肿瘤患者的治疗带来一些新的选择。      

Combination of antiangiogenic therapy with other anticancer therapies: results, challenges, and open questions.

Angiogenesis is necessary for tumor growth. Drug discovery efforts have identified several potential therapeutic targets on endothelial cells and selective inhibitors capable of slowing tumor growth or producing tumor regression by blocking angiogenesis in in vivo tumor models. Certain antiangiogenic therapeutics increase the activity of cytotoxic anticancer treatments in preclinical models. More than 75 antiangiogenic compounds have entered clinical trials. Most of the early clinical testing was conducted in patients with advanced disease resistant to standard therapies. Several phase III trials have been undertaken to compare the efficacy of standard chemotherapy versus the same in combination with an experimental angiogenesis inhibitor. Preliminary results of the clinical studies suggest that single-agent antiangiogenic therapy is poorly active in advanced tumors. Although some of the results of combination trials are controversial, recent positive outcomes with an antivascular endothelial growth factor antibody combined with chemotherapy as front-line therapy of metastatic colorectal cancer have renewed enthusiasm for this therapeutic strategy. This article presents an overview of experimental and clinical studies of combined therapy with antiangiogenic agents and highlights the challenges related to the appropriate strategies for selection of the patients, study design, and choice of proper end points for preclinical and clinical studies using these agents.     

Inhibition of Angiogenesis for the Treatment of Metastatic Melanoma

Metastatic malignant melanoma is a uniformly fatal disease. Tumor growth and metastasis are associated with angiogenesis and lymphangiogenesis. Proangiogenic factors are associated with higher disease burdens and worse outcomes in melanoma. Accordingly, many agents that target angiogenesis have been studied in melanoma. Angiogenesis is a complex, multifaceted process with many potential therapeutic targets. So far, monoclonal antibodies, immune conjugates, tyrosine kinase inhibitors, immunomodulatory agents, and other therapies have been tested in the phase 2 or phase 3 setting for the treatment of metastatic melanoma. The antiangiogenic agents that have been tested to date offer little activity as single agents, but in combination with cytotoxic agents prolong progression-free survival. We explore data from published phase 2 and phase 3 trials in addition to the purported mechanisms of action of antiangiogenic agents.