Foretinib inhibits angiogenesis,lymphangiogenesis and tumor growth of pancreatic cancer in vivo by decreasing VEGFR-2/3 and TIE-2 signaling

Foretinib, a multiple kinase inhibitor undergoing clinical trials, could suppress the activity of hepatocyte growth factor (HGF) receptor c-MET and vascular endothelial growth factor receptor-2 (VEGFR-2). In addition, Foretinib may inhibit two critical lymphangiogenic signaling receptors VEGFR-3 and TIE-2. However, the effect of Foretinib on lymphatic endothelial cells (LECs) in vitro and lymphangiogenesis in vivo is still unknown. We found Foretinib decreased basal- and HGF-induced c-MET activity at low concentrations. However, Foretinib only reduced the proliferation of pancreatic cancer cells at high concentration reflecting the intrinsic chemoresistance of pancreatic cancer cells. Foretinib inhibited VEGF-A, VEGF-C and Angiopoetin-2 (ANG-2)-stimulated tube formation and sprouting of LECs by reducing VEGFR-2, VEGFR-3 and TIE-2 activation and increased apoptosis of LECs. In xenograft animal study, Foretinib suppressed tumor growth by inhibiting proliferation, angiogenesis and lymphangiogenesis. Additionally, Foretinib inhibited angiogenesis and lymphangiogenesis more significantly and exhibited low detrimental effect in orthotopic animal study. Collectively, we suggested that Foretinib simultaneously inhibits cancer cells and LECs to reduce pancreatic tumor growth in vivo and demonstrated for the first time that Foretinib suppresses angiogenesis and lymphangiogenesis by blocking VEGFR-2/3 and TIE-2 signaling.     

VEGFR-3 在胃癌细胞中表达的意义

 目的 研究血管内皮生长因子受体（VEGFR-3）在胃癌细胞中表达的意义，探讨肿瘤淋巴管生成的分子生物学机制。方法 选择早期胃癌13例；进展期胃癌87例，其中无区域淋巴结转移者37例，有区域淋巴结转移者50例；选择正常胃粘膜10例设为对照组。应用免疫组织化学Envision TM两步法，检测正常胃粘膜和胃癌标本VEGF-C、VEGF-D、胃癌细胞中VEGF-3、淋巴管内皮细胞VEGFR-3和细胞间粘附分子-1（ICAM-1）的表达。结果 （1）VEGFR-3在对照组、早期胃癌组和进展期胃癌组中阳性表达率分别为30％、54％和68％，进展期胃癌组与对照组比较明显升高（P〈0．01）。（2）VEGF-C阳性表达与胃癌细胞VEGFR-3阳性表达有高度一致性（P〈0．01）。肿瘤淋巴管计数在胃癌细胞VDG—FR-3表达阳性组与阴性组中差异有显著性（P〈1．20 E-13），进展期胃癌肿瘤淋巴管计数在胃癌细胞VEGFR-3表达阳性组与阴性组中差异有显著性（P〈1．63 E-07）；其他各项指标在胃癌细胞VEGFR-3表达阳性与阴性组中差异无显著性。（3）Logistic回归分析显示胃癌细胞VEGFR-3阳性表达与VEGF-C阳性表达和肿瘤淋巴管计数相关程度高。结论 胃癌细胞中存在VEGFR-3高表达；胃癌细胞分泌的VEGF-C和VEGFR-3也可诱导肿瘤淋巴管生成。     

The tyrosine kinase inhibitor cediranib blocks ligand-induced vascular endothelial growth factor receptor-3 activity and lymphangiogenesis

Solid tumors express a range of factors required to sustain their growth and promote their dissemination. Among these are vascular endothelial growth factor-A (VEGF-A), the key angiogenic stimulant, and VEGF-C, a primary mediator of lymphangiogenesis. Small molecule tyrosine kinase inhibitors offer the potential to inhibit more than one kinase and impede tumor growth by multiple mechanisms. However, their potency toward individual targets can vary. Cediranib (RECENTIN; AZD2171) is an inhibitor of VEGF signaling that has been shown in experimental models to prevent VEGF-A-induced angiogenesis and primary tumor growth, yet the effects of cediranib on VEGF receptor (VEGFR)-3-mediated endothelial cell function and lymphangiogenesis are unknown. To better understand the activity of cediranib against VEGFR-3 and its associated signaling events compared with its activity against VEGFR-2, we used the receptor-specific ligands VEGF-E and VEGF-C156S. In human endothelial cells, cediranib inhibited VEGF-E-induced phosphorylation of VEGFR-2 and VEGF-C156S-induced phosphorylation of VEGFR-3 at concentrations of 相似文献   

真核细胞表达的重组蛋白VEGF-C对白血病细胞增殖与凋亡的影响

背景与目的:VEGF-C/VEGFR-2,3信号通路可诱导血管/淋巴管新生,促进实体肿瘤浸润和转移。近年来研究表明VEGF-C及其受体也在血液肿瘤细胞中表达,但其对白血病细胞的作用尚不清楚。本文拟探讨转染VEGF-C的CHO细胞(CHO/VEGF-C细胞)分泌的重组蛋白VEGF-C对VEGFR-3 白血病细胞的增殖及化疗药物诱导的凋亡的影响。方法:利用鸡胚绒毛尿囊膜观察CHO/VEGF-C细胞培养上清中重组VEGF-C诱导血管新生的作用。用RT-PCR和流式细胞术检测血液肿瘤细胞株中VEGF-C受体表达水平。采用噻唑蓝(MTT)法检测VEGF-C对白血病细胞株(NB4及K562)增殖的影响;AnnexinV/PI双染流式细胞术检测凋亡细胞以观察VEGF-C对化疗药物(Etoposide,DNR,AS2O3)诱导的VEGFR-3 阳性白血病细胞株的凋亡的作用。结果:CHO/VEGF-C细胞上清中的重组蛋白VEGF-C可以诱导鸡胚绒毛尿囊膜的血管新生。9例血液肿瘤细胞株中,NB4、HEL和RPMI8226表达VEGFR-3,HEL和TF-1表达VEGFR-2。与对照组(CHO/pcDNA3.1细胞上清)相比,重组蛋白VEGF-C可以促进VEGFR-3 白血病细胞NB4增殖(P24h=0.006,P48h=0.018),而对VEGRR-3-白血病细胞K562则没有明显作用;重组蛋白VEGF-C还具有抑制化疗药物(Etoposide、DNR、As2O3)诱导的NB4细胞凋亡的作用(P=0.019,0.013,0.042)。结论:重组蛋白VEGF-C不仅可诱导血管新生,而且可能通过VEGFR-3信号途径促进白血病细胞增殖及抗凋亡;推测VEGF-C/VEGFR-3信号途径可望作为白血病治疗的靶点。     

Human small cell lung cancer cells express functional VEGF receptors, VEGFR-2 and VEGFR-3

Studies have suggested that the vascular endothelial growth factors (VEGFs)/VEGF receptors (VEGF-Rs) system plays an important role in tumour growth and metastasis. We conducted the present study to clarify whether small cell lung cancer (SCLC) cells express functional VEGF-Rs and VEGFs, and their biological significance in the SCLC progression. We examined expression of VEGF and VEGF-C, and their receptors, VEGFR-2 and VEGFR-3, in five SCLC cell lines, NCI-H82, H209, H510, H526 and H660, by Western blotting. We evaluated whether hypoxic conditions up-regulate these protein expressions. We also examined whether VEGF addition and VEGF-D addition cause phosphorylation of the mitogen-activated protein kinase (MAPK) as well as VEGFR-2 and VEGFR-3. Further, we investigated whether VEGF addition and VEGF-D addition induced the proliferation and migration of the SCLC cells. VEGF, VEGF-C, VEGFR-2 and VEGFR-3 were detectable by Western blotting in all five SCLC cell lines,. The VEGF-Rs and VEGFs expression levels were increased by an incubation under hypoxic conditions in NCI-H82. VEGF addition and VEGF-D addition caused phosphorylation of MAPK as well as the VEGF-Rs themselves, and induced proliferation and migration of the SCLC cells. These results suggested potential of VEGF signal-pathway inhibitors as anti-cancer agents in SCLC treatment disturbing growth and migration of the cancer cells.     

The expression of vascular endothelial growth factor C and its receptors in non-small cell lung cancer.

Expression of vascular endothelial growth factor (VEGF)-C and that of its receptors were assessed in non-small cell lung cancer. Immunohistochemistry revealed positive VEGF-C expression in 38.7% (24/62) of the patients studied. A significant positive correlation was found between VEGF-C in cancer cells and VEGF receptor-3 (VEGFR-3) in vascular endothelial cells, but not between VEGF-C in cancer cells and VEGFR-2 in endothelial cells. In this cohort of lung cancer patients, VEGF-C expression was significantly associated with lymph node metastasis, lymphatic vessel invasion, and worse outcomes after the operation. Although the independent prognostic impact of VEGF-C and VEGFR-3 was not clear, VEGFR-2 expression in endothelial cells retained the independency as the prognostic indicator. In light of these findings, we conclude that VEGF-C plays an important role in lymphatic invasion/metastasis and tumour progression in non-small cell lung cancer.     

VEGF-C 及VEGFR-3 在肝细胞癌中的表达

 目的　探讨VEGF-C、VEGFR-3、微血管密度（MVD）、微淋巴管密度（LVD）及肝细胞癌临床病理特征之间的关系。方法　取肝细胞癌组织标本60例，正常肝组织标本20例。采用反转录聚合酶链反应（RT-PCR）方法分析其中VEGF-C及VEGFR-3 mRNA 的表达，以免疫组织化学法检测肝癌MVD及LVD，并分析四者与肝癌临床病理特点之间的关系。结果　肝癌组织VEGF-C、VEGFR-3 mRNA表达、MVD及LVD高于正常肝组织（P＜0.01）；肝癌组织中，VEGF-C与VEGFR-3表达、MVD及LVD均呈正相关（P＜0.01），VEGF-C及VEGFR-3表达与肝癌肝内转移、门静脉癌栓形成及淋巴转移相关（P＜0.01），MVD与肝癌肝内转移、门静脉癌栓形成相关（P＜0.01），LVD与淋巴转移相关（P＜0.01）。结论　肝细胞癌组织中VEGF-C及VEGFR-3表达增多，可能通过参与血管、淋巴管生成促进肿瘤的侵袭、转移。     

非小细胞肺癌组织中VEGF-C和VEGFR-3的表达及其临床意义

背景与目的:血管内皮生长因子-C(vascularendothelialgrowthfactorC,VEGF-C)和VEGFR-3是促进恶性肿瘤淋巴管形成的重要因子,其表达与恶性肿瘤的淋巴结转移关系密切。本文旨在研究VEGF-C和VEGFR-3蛋白在非小细胞肺癌(non-smallcelllungcancer,NSCLC)组织中的表达及其临床意义。方法:应用免疫组化方法检测77例NSCLC组织中VEGF-C和VEGFR-3表达情况,分析其与肿瘤淋巴管密度(lymphaticvesseldensity,LVD)、肿瘤的大小、癌的组织类型、组织分化程度、淋巴结转移情况、临床复发和术后生存期的关系。结果:77例NSCLC组织中有45例(58%)VEGF-C阳性,32例(42%)VEGFR-3阳性。NSCLC组织中VEGF-C表达与肿瘤组织的分化程度有关(r=-0.32,P=0.018);VEGF-C及VEGFR-3表达与肿瘤的淋巴结转移、LVD、肿瘤大小及术后生存期有关。NSCLC组织中VEGF-C与VEGFR-3表达相关(r=0.23,P=0.045)。结论:VEGF-C和VEGFR-3表达与NSCLC的淋巴结转移、预后相关,它的高表达提示肺癌患者容易出现淋巴结转移和预后不良。     

Role of vascular endothelial growth factor receptor-3/Flt-4 in early-stage cervical cancer

The present study was designed to investigate the role of vascular endothelial growth factor receptor (VEGFR)-3/Flt-4 in the early stages of cervical cancer. VEGFR-3/Flt-4 expression, vascular endothelial growth factor (VEGF)-C and VEGF-D in the early stages (Ia-IIa) of cervical cancer in 41 patients was examined by immunohistochemical analysis. Additionally, the VEGFR-3/Flt-4-marked vascular density (MVD) was examined and the relationship of these factors with clinicopathological factors was analyzed. VEGFR-3/Flt-4 was found to be expressed in lymphatic endothelial cells and, to a certain extent, in vascular endothelial cells. The VEGFR-3/Flt-4-positive vessels were largely distributed in the stroma surrounding the tumor tissues, and these vessels were morphologically divided into blood and lymphatic vessels, respectively. Cancer cells were found to express VEGF-C, VEGF-D and VEGFR-3/Flt-4, and their positive expression rate was 48.7% (20/41), 58.5% (24/41) and 63.4% (26/41), respectively. VEGFR-3/Flt-4 expression in the cancer cells of the cervical cancer patients in our study was found to be correlated to the clinical stage, lymph node metastasis, lymphatic invasion and expression of VEGF-C and VEGF-D. However, this expression was unrelated to menstrual status, histological grade and histological classification. MVD was correlated to the clinical stage and expression of VEGF-C and VEGF-D, but was unrelated to menstrual status, histological grade, histological classification, lymph node metastasis and lymphatic invasion. In conclusion, VEGFR-3/Flt-4 plays an important role in the early stages of cervical cancer.     

Expression and function of vascular endothelial growth factor receptor-1 on human colorectal cancer cells

Vascular endothelial growth factor (VEGF) is associated with tumor angiogenesis and poor prognosis in human colorectal cancer (CRC). VEGF receptor-1 (VEGFR-1 or Flt-1) is a high-affinity receptor for VEGF and is typically considered specific to endothelial cells. Here we report the expression and function of VEGFR-1 in CRC cell lines. VEGFR-1 was expressed in all CRC cell lines studied as determined by RT-PCR, Western blot analysis, FACS, and ELISA. Treatment of the human CRC cell lines HT-29 and SW480 with VEGF-A (a ligand for both VEGFR-1 and -2) or VEGF-B (a ligand specific for VEGFR-1) led to activation of Erk-1/2, SAPK/JNK, and translocation of the p65 subunit of nuclear factor-kappaB into the nucleus. Both VEGF-A and -B led to significant induction of cell motility and invasiveness of CRC cells. Stimulation of cells with VEGF-A or -B also led to larger and more numerous colonies in soft agar. However, activation of VEGFR-1 did not increase CRC cell proliferation. In contrast to the previous paradigm that VEGFRs are not present on tumor cells of epithelial origin, we found that VEGFR-1 is present and functional on CRC cells, and activation by VEGF family ligands can activate processes involved in tumor progression and metastasis.     

Vascular endothelial growth factor C promotes tumor lymphangiogenesis and intralymphatic tumor growth

Many solid tumors produce vascular endothelial growth factor C (VEGF-C), and its receptor, VEGFR-3, is expressed in tumor blood vessels. To study the role of VEGF-C in tumorigenesis, we implanted MCF-7 human breast carcinoma cells overexpressing recombinant VEGF-C orthotopically into severe combined immunodeficient mice. VEGF-C increased tumor growth, but unlike VEGF, it had little effect on tumor angiogenesis. Instead, VEGF-C strongly promoted the growth of tumor-associated lymphatic vessels, which in the tumor periphery were commonly infiltrated with the tumor cells. These effects of VEGF-C were inhibited by a soluble VEGFR-3 fusion protein. Our data suggest that VEGF-C facilitates tumor metastasis via the lymphatic vessels and that tumor spread can be inhibited by blocking the interaction between VEGF-C and its receptor.     

Crosstalk between angiogenesis and lymphangiogenesis in tumor progression.

Extensive studies have identified reliable markers of lymphatic endothelial cells, and mechanisms and molecules that regulate development and growth of the lymphatic vessels. Vascular endothelial growth factors (VEGF)-C and VEGF-D, and their cognate receptor tyrosine kinase, VEGF receptor-3 (VEGFR-3), are critical regulators of lymphangiogenesis. By binding to its endothelial cell surface receptors VEGFR-1 and VEGFR-2, VEGF-A mediates vascular leakage, endothelial proliferation and migration. Angiopoietin-2 (Ang-2) is expressed at sites of blood vessel remodeling and invasion, and factors that induce angiogenesis in vivo, such as VEGF-A, upregulate Ang-2 in endothelial cells. In this review, we summarize the literature concerning the crosstalk between angiogenesis and lymphangiogenesis in tumor progression, that is, involvement of VEGF-C, VEGF-D and VEGFR-3 in angiogenesis, and the role played by VEGF-A and Ang-2 in lymphangiogenesis, respectively.     

Vascular endothelial growth factor C and vascular endothelial growth factor receptor 2 are related closely to the prognosis of patients with ovarian carcinoma

BACKGROUND: The vascular endothelial growth factor (VEGF) family and VEGF receptors (VEGFR) play an essential role in the angiogenesis of both pathologic and nonpathologic conditions. However, the prognostic significance of VEGF and VEGFR expression in ovarian carcinoma is unclear. METHODS: The tissue expression levels of VEGF-A, VEGF-C, VEGFR-2, and VEGFR-3 in 80 specimens of ovarian carcinoma were examined immnohistochemically. The results obtained were analyzed clinicopathologically. RESULTS: VEGF-A, VEGF-C, VEGFR-2, and VEGFR-3 were expressed both in tumor cells and in adjacent endothelial cells of blood and lymph vessels. The tissue expressions of VEGF-C and VEGFR-2 were correlated significantly with tumor extension, including peritoneal metastases outside the pelvic cavity (P = 0.0010 and P = 0.0008, respectively), lymph node metastases (P = 0.0030 and P = 0.0018, respectively), and positive ascitic cytology (P = 0.025 and P = 0.0016, respectively). Conversely, there was no significant correlation between VEGF-A and VEGFR-3 expression and clinicopathologic features of ovarian carcinoma. Logistic regression analysis revealed that the expressions of VEGF-C and VEGFR-2 also were independent risk factors for peritoneal and lymph node metastases. Survival curves determined by the Kaplan-Meier method and in univariate analysis demonstrated that high expression levels of VEGF-C and VEGFR-2 were associated with the 5-year survival rate. In multivariate analysis, high expression levels of VEGF-C and VEGFR-2 emerged as independent indicators for disease-specific survival. CONCLUSIONS: High tissue expression of VEGF-C and VEGFR-2 reflects the aggressiveness of the spread of tumor in ovarian carcinoma. Thus, both have predictive value for identifying high-risk patients who have a poor prognosis.     

The role of the VEGF-C/VEGFR-3 axis in cancer progression

Vascular endothelial growth factor (VEGF) receptor 3 (VEGFR-3) (also called VEGFR-3) is activated by its specific ligand, VEGF-C, which promotes cancer progression. The VEGF-C/VEGFR-3 axis is expressed not only by lymphatic endothelial cells but also by a variety of human tumour cells. Activation of the VEGF-C/VEGFR-3 axis in lymphatic endothelial cells can facilitate metastasis by increasing the formation of lymphatic vessels (lymphangiogenesis) within and around tumours. The VEGF-C/VEGFR-3 axis plays a critical role in leukaemic cell proliferation, survival, and resistance to chemotherapy. Moreover, activation of the VEGF-C/VEGFR-3 axis in several types of solid tumours enhances cancer cell mobility and invasion capabilities, promoting cancer cell metastasis. In this review, we discuss the novel function and molecular mechanism of the VEGF-C/VEGFR-3 axis in cancer progression.     

VEGF-A and VEGFR-3 correlate with nodal status in operable non-small cell lung cancer: inverse correlation between expression in tumor and stromal cells

BACKGROUND: Lymph node metastasis is an essential determinant for stage and clinical management of non-small cell lung cancer (NSCLC). The vascular endothelial growth factors (VEGFs) and receptors (VEGFRs) are fundamental molecules in angiogenesis and lymphangiogenesis. We aimed to explore the correlations between nodal metastasis and the expression of VEGFs and VEGFRs in tumor cells and in tumor-related stroma. PATIENTS AND METHODS: Tumor tissue samples from 335 resected patients with stage I-IIIA NSCLC were obtained and tissue microarrays were constructed from duplicate cores of tumor cells and surrounding stromal tissue from each resected specimen. Immunohistochemistry was used to evaluate the expression of VEGF-A, VEGF-C, and VEGF-D and VEGFR-1, VEGFR-2 and VEGFR-3. RESULTS: There were 232 N0 and 103 N+ patients (76 N1, 27 N2). In multivariate analyses, low stromal VEGF-A expression (P=0.018) is associated with N+ status. In tumor cells, strong correlations exist between high VEGF-A expression (P=0.032) and N+ status, and high VEGFR-3 expression (P<0.001) and N2-status. CONCLUSION: The converse impact by stromal VEGF-A versus tumor cell VEGF-A expression on nodal metastasis may allude the importance of the tumor-stroma interaction when trying to understand lymphatic metastasis in NSCLC.     

Novel peptides suppress VEGFR-3 activity and antagonize VEGFR-3-mediated oncogenic effects

Vascular endothelial growth factor receptor 3 (VEGFR-3) supports tumor lymphangiogenesis. It was originally identified as a lymphangiogenic factor expressed in lymphatic endothelial cells. VEGFR-3 was detected in advanced human malignancies and correlated with poor prognosis. Our previous studies show that activation of the VEGF-C/VEGFR-3 axis promotes cancer metastasis and is associated with clinical progression in patients with lung cancer, indicating that VEGFR-3 is a potential target for cancer therapy. In this study, we developed eight peptides targeting VEGFR-3. Two peptides strongly inhibited the kinase activity of VEGFR-3 and suppressed VEGF-C-mediated invasion of cancer cells. Moreover, these peptides abolished VEGF-C-induced drug resistance and tumor initiating cell formation. This study demonstrates the therapeutic potential of VEGFR-3-targeting peptides.     

The balance of VEGF-C and VEGFR-3 mRNA is a predictor of lymph node metastasis in non-small cell lung cancer

A positive association between vascular endothelial growth factor-C (VEGF-C) expression and lymph node metastasis has been reported in several cancers. However, the relationship of VEGF-C and lymph node metastasis in some cancers, including non-small cell lung cancer (NSCLC), is controversial. We evaluated the VEGF-C and vascular endothelial growth factor receptor-3 (VEGFR-3) expression in NSCLC samples from patients who had undergone surgery between 1998 and 2002 using real-time quantitative RT-PCR and immunohistochemical staining. We failed to find a positive association between VEGF-C and VEGFR-3 mRNA expression and lymph node metastasis in NSCLC. An immunohistological study demonstrated that VEGF-C was expressed not only in cancer cells, but also in macrophages in NSCLC, and that VEGFR-3 was expressed in cancer cells, macrophages, type II pneumocytes and lymph vessels. The VEGF-C/VEGFR-3 ratio of the node-positive group was significantly higher than that of the node-negative group. Immunohistochemical staining showed that VEGFR-3 was mainly expressed in cancer cells. The immunoreactivity of VEGF-C and VEGFR-3 was roughly correlated to the mRNA levels of VEGF-C and VEGFR-3 in real-time PCR. VEGF-C mRNA alone has no positive association with lymph node metastasis in NSCLC. The VEGF-C/VEGFR-3 ratio was positively associated with lymph node metastasis in NSCLC. This suggests that VEGF-C promotes lymph node metastasis while being influenced by the strength of the VEGF-C autocrine loop, and the VEGF-C/VEGFR-3 ratio can be a useful predictor of lymph node metastasis in NSCLC.     

Inhibition of VEGFR-3 activation with the antagonistic antibody more potently suppresses lymph node and distant metastases than inactivation of VEGFR-2

Lymph nodes are the first site of metastases for most types of cancer, and lymph node status is a key indicator of patient prognosis. Induction of tumor lymphangiogenesis by vascular endothelial growth factor-C (VEGF-C) has been shown to play an important role in promoting tumor metastases to lymph nodes. Here, we employed receptor-specific antagonist antibodies in an orthotopic spontaneous breast cancer metastasis model to provide direct evidence for the key role of VEGFR-3 activation in metastasis. Inhibition of VEGFR-3 activation more potently suppressed regional and distant metastases than inactivation of VEGFR-2, although VEGFR-2 blockade was more effective in inhibiting angiogenesis and tumor growth. Despite prominent proliferation, metastases were not vascularized in any of the control and treatment groups, indicating that the growth of metastases was not dependent on angiogenesis at the secondary site for the duration of the experiment. Systemic treatment with either VEGFR-2 or VEGFR-3 antagonistic antibodies suppressed tumor lymphangiogenesis, indicating that VEGFR-3 signaling affects the rate of tumor cell entry into lymphatic vessels through both lymphangiogenesis-dependent and independent mechanisms. Combination treatment with the anti-VEGFR-2 and anti-VEGFR-3 antibodies more potently decreased lymph node and lung metastases than each antibody alone. These results validate the concept of targeting the lymphatic dissemination and thereby very early steps of the metastatic process for metastasis control and suggest that a combination therapy with antiangiogenic agents may be a particularly promising approach for controlling metastases.