RNA Interference-Mediated Gene Silencing of Vascular Endothelial Growth Factor

A ngiogenesis is a well-known process that is essential for tumor growth beyond 2 mm.[1] Although numerous growth factors are involved, vascular endothelial growth factor (VEGF), in particular VEGF-A, has been shown to play an important role in tumor angi…     

Vascular Endothelial Growth Factor (VEGF) in Astrocytic Gliomas – A Prognostic Factor?

Survival in astrocytic gliomas is closely related to WHO tumor grade. Within one tumor grade, especially in grade II and III tumors, the clinical course is variable and can hardly be predicted by histological criteria. Neovascularization is a neuropathological hallmark in high grade gliomas and angiogenic factors may play an important role in malignant tumor progression. Therefore, 162 primary astrocytic gliomas (57 astrocytomas WHO grade II, 27 astrocytomas WHO grade III and 78 glioblastomas WHO grade IV) were investigated immunohistochemically for expression of vascular endothelial growth factor (VEGF), which is considered to represent the main angiogenic factor in astrocytic gliomas. Clinical data known to influence prognosis were documented. VEGF expression was found in 21 of 57 astrocytomas WHO grade II (36.8%), in 18 of 27 astrocytomas WHO grade III (66.7%) and in 50 of 78 glioblastomas (64.1%). A strong correlation between VEGF expression and survival was found within the whole study group, however, within one tumor grade no such correlation was obvious. In a multifactorial analysis VEGF expression was not found to be an independent prognostic factor in astrocytic gliomas.     

Acquired Resistance to Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors in Non–Small-Cell Lung Cancers Dependent on the Epidermal Growth Factor Receptor Pathway

Most advanced Non–Small-cell lung cancers (NSCLCs) with activating epidermal growth factor receptor (EGFR) mutations (exon 19 deletions or L858R) initially respond to the EGFR tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib. However, over time (median of 6–12 months), most tumors develop acquired resistance to EGFR TKIs. Intense research in these NSCLCs has identified two major mechanisms of resistance to gefitinib/erlotinib: secondary resistance mutations and “oncogene kinase switch" systems. The secondary T790M mutation occurs in 50% of EGFR-mutated patients with TKI resistance, and in vitro, this mutation negates the hypersensitivity of activating EGFR mutations. Sensitive detection methods have identified a proportion of TKI-naive tumors that carry T790M, and these resistant clones may be selected after exposure to gefitinib or erlotinib. Other secondary resistance mutations (D761Y, L747S, T854A) seem to be rare. The amplification of the MET oncogene is present in 20% of TKI-resistant tumors; however, in half of the cases with this “oncogene kinase switch" mechanism the T790M is coexistent. It is possible that other kinases (such as insulin-like growth factor-1 receptor [IGF-1R]) might also be selected to bypass EGFR pathways in resistant tumors. The growing preclinical data in EGFR-mutated NSCLCs with acquired resistance to gefitinib or erlotinib has spawned the initiation or conception of clinical trials testing novel EGFR inhibitors that in vitro inhibit T790M (neratinib, XL647, BIBW 2992, and PF-00299804), MET, or IGF-1R inhibitors in combination with EGFR TKIs, and heat shock protein 90 inhibitors. Ongoing preclinical and clinical research in EGFR-mutated NSCLC has the potential to significantly improve the outcomes of patients with these somatic mutations.     

Expression of Vascular Endothelial Growth Factor-C and Vascular Endothelial Growth Factor Receptor-3 in Ovarian Epithelial Tumors

Objective： To explore the role of vascular endothelial growth factor-C （VEGF-C） in the process of angiogenesis, lymphangiogenesis and lymphatic metastasis in epithelial ovarian tumors. Methods： In situ hybridization and immunohistochemical staining for VEGF-C were performed in 30 epithelial ovarian carcinomas, 9 borderline tumors and 26 benign tumors. Endothelial cells were immunostained with anti-VEGFR-3 pAb and anti-CD31 mAb, and VEGFR-3 positive vessels and microvessel density （MVD） were assessed by image analysis. Results： VEGF-C mRNA and protein expression were detected in cytoplasm of carcinoma cells. VEGF-C mRNA and protein expression in ovarian epithelial carcinomas were significantly higher than those in borderline tumors and benign tumors （P〈0.05 or P〈0.01）. In ovarian epithelial carcinomas, VEGF-C protein expression, VEGFR-3 positive vessels and MVD were significantly higher in the cases of clinical stage Ⅲ-Ⅳ and with lymph node metastasis than those of clinical stage Ⅰ-Ⅱ and without lymph node metastasis respectively （P〈0.05 or P〈0.01）. VEGFR-3 positive vessels and MVD were significantly higher in VEGF-C protein positive tumors than negative tumors （P〈0.05）. VEGFR-3 positive vessels was significantly correlated with MVD（P〈0.01）. Conclusion： VEGF-C might play a role in lymphatic metastasis via lymphangiogenesis and angiogenesis in epithelial ovarian tumors, and VBEGF-C could be used as a biologic marker of metastasis in ovarian epithelial tumors.     

Vascular Endothelial Growth Factor Expression in Invasive Ductal Carcinoma of Breast

Objective： To detect the expression of VEGF and MVD count in invasive ductal carcinoma of breast to clarify the association of VEGF expression and MVD count with the clinicopathologic features. Methods： The expressions of VEGF, ER, PR, C-erbB-2 and MVD count in 88 cases of invasive ductal carcinoma of breast were examined by immunohistochemistry staining （SP-method）. Results： Sixty-two out of the eighty-eight specimens of breast carcinoma （70.45%） showed positive expression of VEGF. The positive rate of VEGF in cases with lymph node metastasis was higher than that without lymph node metastasis （P〈0.05）. The positive rate of VEGF in stage IIb-Ⅲ was higher than that in stage Ⅰ-Ⅱa （P〈0.05）. The positive rate of VEGF in C-erbB-2 positive group was higher than that in C-erbB-2 negative group （P〈0.05）. Higher expression of VEGF was observed in cases with higher tissue differentiation degree （P〈0.05）. Also, significant higher MVD count was observed in cases with higher tissue differentiation degree （P〈0.01）. The MVD count increased significantly with the increase of the expression of VEGF （P〈0.01）. Conclusion： The result of this study suggested that in invasive ductal carcinoma of breast, angiogenesis and metastasis were mediated mainly by VEGF. The expression of VEGF and MVD might be reference predictors for the biological behavior of breast carcinoma. The antiangiogenic therapy which used VEGF as a target would become a new method to treat patients who were C-erbB-2 positive in the future.     

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.     

Systemic Effects of Surgery: Quantitative Analysis of Circulating Basic Fibroblast Growth Factor (bFGF), Vascular Endothelial Growth Factor (VEGF) and Transforming Growth Factor Beta (TGF-β) in Patients with Breast Cancer Who Underwent Limited or Extended Surgery

Summary Background. To assess if feature, extent and duration of surgery could influence levels of systemic proangiogenic cytokines vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and transforming growth factor beta (TGF-β). Patients and methods. We collected blood samples from 82 consecutive breast cancer patients who underwent various types of surgery, classified according to the magnitude of tissue injury in: minimal (quadrantectomy), moderate (mastectomy without reconstruction), and heavy [mastectomy followed by reconstruction with transversus recto-abdominal muscle cutaneous flap (TRAM)]. Samples were collected one day before surgery (D₋₁), at the end of surgical tumor removal (D₀), and on 1st (D₊₁), 2nd (D₊₂) and 5th (D₊₅) day after surgery. Serum VEGF, bFGF and TGF-β levels were measured by the enzyme immunoassay method. Results. On average a continuous decrease was observed for all growth factors from the day before operation to the 5th day after operation. On day (D₊₅) an increase was observed for patients who underwent extended respect to moderate surgery. These differences were found statistically significant for bFGF and VEGF (p = 0.05 and p = 0.025 respectively). A statistically different trend for type of operation was observed also for TGF-β at 24–48 h: a minor reduction, compared to time of operation, was observed for minimal surgery, an intermediate reduction for moderate surgery and a higher decrease for extended surgery. Conclusions. Angiogenic cytokines perioperative levels could be increased on 5th day (D₊₅) by extent of surgery and should induce perioperative stimulation of residual cancer cells. A better understanding of the time interval during which the sequelae of events in wound healing occur may be the basis for defining new therapeutic strategies that can interfere with tumor outgrowth sparing wound healing processes.     

Should Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor Be Continued beyond Progressive Disease?

Epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) is almost exclusively effective in patients with activating EGFR mutations, and median time to progression in such patients is generally up to 12 months. Usually, treatment with EGFR-TKI is terminated when disease progression is confirmed; however, acute exacerbation after the withdrawal of EGFR-TKI has been reported. In this paper, we report a case of a 35-year-old patient whose disease rapidly progressed after discontinuation of gefitinib and then rapidly regressed after reintroduction of gefitinib. In addition, we summarize the cases of 3 other patients who could be safely treated with continued erlotinib in combination with pemetrexed after disease progression. Currently, the mechanism of acquired resistance is intensively investigated and a number of new agents, such as irreversible EGFR inhibitors or MET inhibitors, are under development; however, they are still unavailable in clinical setting. We believe that continuing EGFR-TKI treatment after disease progression should be an option in patients who previously responded to EGFR-TKI under the present circumstances.     

Overview of Transforming Growth Factor β Superfamily Involvement in Glioblastoma Initiation and Progression

Glioblastoma, also known as glioblastoma multiforme (GBM), is the most aggressive of human braintumors and has a stunning progression with a mean survival of one year from the date of diagnosis. High cellproliferation, angiogenesis and/or necrosis are histopathological features of this cancer, which has no efficientcurative therapy. This aggressiveness is associated with particular heterogeneity of the tumor featuring multiplegenetic and epigenetic alterations, but also with implications of aberrant signaling driven by growth factors. Thetransforming growth factor β (TGFβ) superfamily is a large group of structurally related proteins including TGFβsubfamily members Nodal, Activin, Lefty, bone morphogenetic proteins (BMPs) and growth and differentiationfactor (GDF). It is involved in important biological functions including morphogenesis, embryonic development,adult stem cell differentiation, immune regulation, wound healing and inflammation. This superfamily is alsoconsidered to impact on cancer biology including that of GBM, with various effects depending on the member. TheTGFβ subfamily, in particular, is overexpressed in some GBM types which exhibit aggressive phenotypes. Thissubfamily impairs anti-cancer immune responses in several ways, including immune cells inhibition and majorhistocompatibility (MHC) class I and II abolishment. It promotes GBM angiogenesis by inducing angiogenicfactors such as vascular endothelial growth factor (VEGF), plasminogen activator inhibitor (PAI-I) and insulinlikegrowth factor-binding protein 7 (IGFBP7), contributes to GBM progression by inducing metalloproteinases(MMPs), “pro-neoplastic” integrins (αvβ3, α5β1) and GBM initiating cells (GICs) as well as inducing a GBMmesenchymal phenotype. Equally, Nodal promotes GICs, induces cancer metabolic switch and supports GBMcell proliferation, but is negatively regulated by Lefty. Activin promotes GBM cell proliferation while GDFyields immune-escape function. On the other hand, BMPs target GICS and induce differentiation and sensitivityto chemotherapy. This multifaceted involvement of this superfamily in GBM necessitates different strategiesin anti-cancer therapy. While suppressing the TGFβ subfamily yields advantageous results, enhancing BMPsproduction is also beneficial.     

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.     

Phase 2 Study of Dose-Dense Doxorubicin and Cyclophosphamide Followed by Eribulin Mesylate With or Without Prophylactic Growth Factor for Adjuvant Treatment of Early-Stage Human Epidermal Growth Factor Receptor 2–Negative Breast Cancer

Background

Eribulin has significantly improved overall survival for patients with metastatic breast cancer who received ≥ 2 prior chemotherapy regimens for advanced disease. This trial assessed eribulin as adjuvant therapy for patients with early-stage breast cancer.

Epidermal Growth Factor Receptor Mutation Status and Adjuvant Chemotherapy in Resected Advanced Non–Small-Cell Lung Cancer

IntroductionThis study was to assess the association of epidermal growth factor receptor (EGFR) mutation status and efficacy of adjuvant chemotherapy in patients with fully resected IIIA-N2 non–small-cell lung cancer (NSCLC).Materials and MethodsTumor samples (n = 150) from patients with IIIA-N2 NSCLC who either had or had not received paclitaxel plus carboplatin or vinorelbine plus carboplatin doublet adjuvant chemotherapy were analyzed for EGFR mutations. The association of the presence of EGFR mutations and survival was assessed.ResultsMutations were identified in 43 (28.7%) patients (n = 25 in the no chemotherapy [observation] arm and n = 18 in the chemotherapy arm). Patients with EGFR mutations had statistically significant improved disease-free survival (41 months [95% CI, 25.1-56.9 months] vs. 20 months [95% CI, 15.0-25.0 months]; 2P = .005) and overall survival (50 months [95% CI, 37.6-62.4 months] vs. 25 months [95% CI, 20.8-29.2 months]; 2P = .001), regardless of treatment. The patients with wild-type EGFR had greater overall survival with chemotherapy compared with no adjuvant therapy (hazard ratio [HR] 4.748 [95% CI, 2.844-7.928]; 2P < .001). In contrast, in patients with EGFR mutation in the observation group compared with the chemotherapy group had longer median disease-free survival (49 months [95% CI, 35.1-62.9 months] for the observation arm vs. 30 months [95% CI, 23.8-36.2 months] for the chemotherapy arm, 2P = .195) and overall survival (59 months [95% CI, 43.9-74.1 months] vs. 33 months [95% CI, 24.7-41.3 months]; 2P = .050).ConclusionsIn this exploratory study, the status of EGFR mutations was associated with different clinical outcomes in patients with resected IIIA-N2 NSCLC. Further studies are required to confirm that a patient's adjuvant treatment may be customized to their EGFR mutational status.     

Extending Outcomes: Epidermal Growth Factor Receptor–Targeted Monoclonal Antibodies in Non–Small-Cell Lung Cancer

The epidermal growth factor receptor (EGFR) pathway plays an important part in the formation of many epithelial malignancies and has been the target of intensive drug development. Although the small-molecule EGFR tyrosine kinase inhibitors (TKIs) have an established role as single-agent therapy in the second- or third-line treatment of patients with advanced Non—Small-cell lung cancer (NSCLC), they have failed to demonstrate any additive benefit when combined with standard cytotoxic chemotherapy. Monoclonal antibodies (MoAbs) to EGFR are a distinct class of agents that differ significantly from the TKIs in their interaction with the EGFR pathway. A number of MoAbs targeting EGFR are currently in development and their clinical usefulness in the treatment of NSCLC is discussed, with particular attention given to cetuximab.     

Current Status of Anti–Human Epidermal Growth Factor Receptor 2 Therapies: Predicting and Overcoming Herceptin Resistance

Human epidermal growth factor receptor 2-overexpressing (HER2+) breast cancer occurs in 20% to 25% of cases and is associated with poor prognosis. Trastuzumab (Herceptin; Genentech, South San Francisco, CA) is a monoclonal antibody targeting the HER2 extracellular domain that has been shown to significantly reduce relapse rates. However, some patients with HER2+ tumors do not respond to Herceptin, and 60% to 85% of patients with HER2+ metastatic breast cancer acquire resistance within a short time period. In this review, we discuss proposed mechanisms of action of trastuzumab and trastuzumab resistance and various drugs that have been developed to overcome drug resistance. We introduce the basal molecular subtype as a predictor of increased risk in HER2+ breast cancer and a possible alternative cause of drug resistance.