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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Solid tumors consist of several components, including normal and stromal cells, extracellular matrix, and vasculature. To grow and metastasize, tumors must stimulate the development of new vasculature through a process known as angiogenesis. Unlike normal blood vessels, tumor blood vessels are chaotic, irregular, and leaky, which leads to uneven delivery of nutrients and therapeutic agents to the tumor. Conventional therapies target neoplastic cells within a tumor; however, tumor vasculature is emerging as an important target for anticancer therapy. Antiangiogenic therapy offers several potential advantages as an approach to cancer treatment, notably physical accessibility and genetic stability of target cells. Vascular endothelial growth factor (VEGF), a central mediator of angiogenesis, has emerged as an important target for antiangiogenic therapy. In preclinical studies, treatment of human tumor xenografts in immunodeficient mice with the anti-VEGF monoclonal antibody A4.6.1 led to reduced tumor vessel permeability and caused vascular regression. The reduced vascular permeability, resulting from inhibition of VEGF, led to increased delivery of oxygen and therapeutic agents to tumors. Anti-VEGF therapy was effectively combined with other treatment modalities, including radiation, antihormonal, antibody, and chemotherapies in multiple preclinical models. Currently, several phase 3 clinical trials in various cancer types are under way to establish the efficacy of antiangiogenic therapy with a recombinant humanized anti-VEGF monoclonal antibody, bevacizumab (Avastin, rhuMAb-VEGF; Genentech, South San Francisco, CA), in combination with chemotherapeutic agents.
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PMID:Tumor angiogenesis and accessibility: role of vascular endothelial growth factor. 1251 32

Vascular endothelial growth factor promotes angiogenesis, an important mediator of growth and metastasis in human breast cancer. Bevacizumab, a monoclonal antibody to vascular endothelial growth factor, is under investigation as an anti-angiogenic agent. This phase I/II trial evaluated the safety and efficacy of bevacizumab in patients with previously treated metastatic breast cancer. Seventy-five patients were treated with escalating doses of bevacizumab ranging from 3 mg/kg to 20 mg/kg administered intravenously every other week. Tumor response was assessed before the sixth (70 days) and 12th (154 days) doses. Safety was evaluated during every cycle. Eighteen patients were treated at 3 mg/kg, 41 at 10 mg/kg, and 16 at 20 mg/kg. Four patients discontinued study treatment because of an adverse event. Hypertension was reported as an adverse event in 17 patients (22%). The overall response rate was 9.3% (confirmed response rate, 6.7%). The median duration of confirmed response was 5.5 months (range, 2.3 to 13.7 months). At the final tumor assessment on day 154, 12 of 75 patients (16%) had stable disease or an ongoing response. The optimal dose of bevacizumab in this trial was 10 mg/kg every other week and toxicity was acceptable. These data support the initiation of trials in metastatic breast cancer combining bevacizumab with chemotherapy.
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PMID:A phase I/II dose-escalation trial of bevacizumab in previously treated metastatic breast cancer. 1461 32

Erlotinib (Tarceva) is an orally available selective small-molecule inhibitor of HER1/EGFR tyrosine kinase with a 50% inhibitory concentration of 2 nM for purified tyrosine kinase. This agent has been shown to produce stasis or regression of tumor growth in human cancer xenograft models, including non-small-cell lung cancer models. Ongoing preclinical investigations indicate that inhibition of the MAPK and Atk signaling pathways downstream of HER1/EGFR may be required for optimal antitumor effects. Erlotinib exhibits inhibition of MAPK and Atk kinases at concentrations higher than those required for HER1/EGFR tyrosine kinase inhibition; such findings suggest that maximal inhibition of HER1/EGFR, requiring high erlotinib doses, is necessary for optimum antitumor activity. These considerations are supported by tumor models, including non-small-cell lung cancer models, showing dose-related antitumor effects up to high doses of erlotinib. Erlotinib exhibits additive antitumor effects when combined with chemotherapeutic agents (cisplatin, doxorubicin, paclitaxel, gemcitabine [Gemzar], and capecitabine [Xeloda]), radiation therapy, and other targeted agents (e.g., bevacizumab [Avastin]). Recent studies indicate that erlotinib inhibits the EGFRvIII mutant at concentrations higher than those required for inhibition of wild-type receptor. Ongoing investigation will help to determine optimal dosing and dose frequency of erlotinib in various cancers in the clinical setting.
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PMID:Erlotinib: preclinical investigations. 1468 18

The majority of sporadic clear cell renal cell carcinoma (RCC) is characterized by loss of heterozygosity of the von Hippel-Lindau (VHL) tumor suppressor gene and somatic inactivation of the remaining VHL allele. The resulting VHL gene silencing leads to induction of hypoxia-regulated genes including vascular endothelial growth factor (VEGF). Thus, therapeutic inhibition of VEGF holds promise for treatment of this historically refractory malignancy. An antibody to VEGF (bevacizumab, Avastin) has demonstrated a significant prolongation of time to disease progression compared with placebo in patients with metastatic RCC. Interferon-alpha (IFN-alpha) is a standard initial cytokine therapy in RCC with a modest response rate and a survival advantage demonstrated in randomized trials. We hypothesized that the addition of anti-VEGF therapy to IFN-alpha would prolong survival in untreated metastatic RCC patients. A Phase III trial is now being conducted randomizing untreated, metastatic clear cell RCC patients to IFN-alpha alone or IFN-alpha plus Avastin.
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PMID:Cancer and Leukemia Group B 90206: A randomized phase III trial of interferon-alpha or interferon-alpha plus anti-vascular endothelial growth factor antibody (bevacizumab) in metastatic renal cell carcinoma. 1510 58

Advanced colorectal cancer remains an urgent health concern, despite improvements in systemic chemotherapy. Targeted therapeutics promise effective tumor therapy with minimal side effects. Angiogenesis (the formation of new blood vessels) is essential for tumor growth and metastasis and may be an ideal target in the search for new antineoplastic agents. Vascular endothelial growth factor is one of the best characterized of the proangiogenic growth factors that regulate angiogenesis and is a logical target in colorectal cancer therapy. Bevacizumab (Avastin; Genentech Inc.; South San Francisco, CA), a humanized murine monoclonal antibody directed at vascular endothelial growth factor, is being evaluated in the treatment of various types of cancer. It has shown promising efficacy in phase II clinical trials in patients with metastatic colorectal cancer. Addition of bevacizumab at a dose of 5 mg/kg to chemotherapy (5-fluorouracil plus leucovorin) resulted in a higher objective response rate (40% versus 17%), longer time to disease progression (9.0 versus 5.2 months), and longer median survival time (21.5 versus 13.8 months). Hypertension and thrombosis were the principal safety concerns, but were manageable. Further phase II/III studies of bevacizumab, administered with 5-fluorouracil plus leucovorin, with or without irinotecan and/or oxaliplatin, in colorectal cancer, are under way.
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PMID:Targeted therapy of colorectal cancer: clinical experience with bevacizumab. 1517 11

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.
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PMID:Non-small cell lung cancer and antiangiogenic therapy: what can be expected of bevacizumab? 1517 12

The treatment of colorectal cancer has undergone enormous changes in the past decade. From a disease with a single treatment option (ie, fluorouracil, a modestly effective drug), the treatment options have evolved to include at least five new classes of antineoplastic agents. Among the considerable number of recently approved drugs, two are monoclonal antibodies and are the testing ground for our rapidly emerging knowledge about cancer cell biology. Cetuximab (Erbitux) targets the epidermal growth factor receptor, an important molecule involved with cell cycling, survival, invasion, and metastasis. Bevacizumab (Avastin) neutralizes the vascular endothelial growth factor, blocking its ability to activate its receptor on the endothelial cells. The development of both antibodies resulted from decades of research in molecular and cell biology, as well as preclinical and clinical studies, and signals a new paradigm where the tumor cells' own unique features are exploited in a rational way.
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PMID:Monoclonal antibodies: the foundation of therapy for colorectal cancer in the 21st century? 1521 93

Adjuvant therapy with chemotherapy and/or radiation therapy in addition to surgery improves outcome for patients with high-risk carcinomas of the colon or rectum. For colon cancer, fluorouracil (5-FU) combined with leucovorin is a current standard of care that improves long-term survival. A recent European trial (MOSAIC) has documented significant improvement in 3-year disease-free survival when oxaliplatin (Eloxatin) was added to infusional 5-FU and leucovorin in the FOLFOX regimen. Two US cooperative group trials will evaluate the addition of antiangiogenesis therapy with bevacizumab (Avastin) to chemotherapy. A third trial will evaluate FOLFOX, irinotecan (Camptosar) combined with infusional 5-FU and leucovorin (FOLFIRI), and the sequential use of FOLFOX followed by FOLFIRI. In rectal cancer, postoperative 5-FU-based chemotherapy combined with irradiation can improve both local tumor control and survival. The German Rectal Cancer Group has recently reported that preoperative combined-modality therapy is less toxic and more effective in preventing local tumor relapse compared to similar treatment given postoperatively. A coordinated pair of cooperative group clinical trials will evaluate oral capecitabine (Xeloda) as a radiation enhancer in the preoperative setting, and the FOLFOX and FOLFIRI regimens compared to 5-FU and leucovorin following surgery. Predictive and prognostic molecular markers will be studied in these new adjuvant therapy clinical trials for both colon and rectal cancer with the goal of developing future regimens tailored to individual patients. There has been a recent and dramatic increase in the pace of drug development for colorectal cancer which holds promise to further improve curative therapy as part of a multidisciplinary approach in the surgical adjuvant setting.
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PMID:Current status of adjuvant therapy for colorectal cancer. 1521 94

There is an urgent need for new therapies to treat non-small cell lung cancer (NSCLC) because current chemotherapy regimens are of limited effectiveness. The role of vascular endothelial growth factor in promoting tumor angiogenesis, in maintaining existing vasculature, and in resistance to traditional therapies, together with its negative prognostic significance in NSCLC, make it an appropriate target for therapy. Bevacizumab (Avastin), a monoclonal antibody directed against vascular endothelial growth factor, 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 significantly increased the time to progression and increased the response rate when compared with chemotherapy alone. This was particularly impressive in the subset of patients with non-squamous histology. Bevacizumab is generally well tolerated and did not appear to increase the incidence or severity of nausea/vomiting, neuropathy and renal toxicity, which 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) seem to be the main safety concern in patients with NSCLC, with squamous cell histology as a possible risk factor. Present ongoing studies are under way in NSCLC including (a) a Phase II neo-adjuvant study in combination with paclitaxel and carboplatin in patients with stage IB-IIA NSCLC; (b) a Phase I/II study of bevacizumab in combination with the epidermal growth factor receptor tyrosine kinase inhibitor agent, Tarceva, in patients with previously treated NSCLC; and (c) an Eastern Cooperative Group randomized Phase III study of paclitaxel and carboplatin with/without bevacizumab in patients with previously untreated IIIB (malignant pleural effusion) or metastatic NSCLC. These studies will help to establish the role of bevacizumab in NSCLC.
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PMID:Anti-vascular endothelial growth factor monoclonals in non-small cell lung cancer. 1521 70

Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen in vitro and an angiogenic inducer in a variety of in vivo models. Hypoxia has been shown to be a major inducer of VEGF gene transcription. The tyrosine kinases Flt-1 (VEGFR-1) and Flk-1/KDR (VEGFR-2) are high-affinity VEGF receptors. The role of VEGF in developmental angiogenesis is emphasized by the finding that loss of a single VEGF allele results in defective vascularization and early embryonic lethality. VEGF is critical also for reproductive and bone angiogenesis. Substantial evidence also implicates VEGF as a mediator of pathological angiogenesis. In situ hybridization studies demonstrate expression of VEGF mRNA in the majority of human tumors. Anti-VEGF monoclonal antibodies and other VEGF inhibitors block the growth of several tumor cell lines in nude mice. Clinical trials with various VEGF inhibitors in a variety of malignancies are ongoing. Very recently, an anti-VEGF monoclonal antibody (bevacizumab; Avastin) has been approved by the Food and Drug Administration as a first-line treatment for metastatic colorectal cancer in combination with chemotherapy. Furthermore, VEGF is implicated in intraocular neovascularization associated with diabetic retinopathy and age-related macular degeneration.
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PMID:Vascular endothelial growth factor: basic science and clinical progress. 1529 83


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