Targeted therapy against VEGFR and EGFR with ZD6474 enhances the therapeutic efficacy of irradiation in an orthotopic model of human non-small-cell lung cancer

Orthotopic and metastatic tumour models in preclinical cancer research

Mouse models of disease play a pivotal role at all stages of cancer drug development. Cell-line derived subcutaneous tumour models are predominant in early drug discovery, but there is growing recognition of the importance of the more complex orthotopic and metastatic tumour models for understanding both target biology in the correct tissue context, and the impact of the tumour microenvironment and the immune system in responses to treatment. The aim of this review is to highlight the value that orthotopic and metastatic models bring to the study of tumour biology and drug development while pointing out those models that are most likely to be encountered in the literature. Important developments in orthotopic models, such as the increasing use of early passage patient material (PDXs, organoids) and humanised mouse models are discussed, as these approaches have the potential to increase the predictive value of preclinical studies, and ultimately improve the success rate of anticancer drugs in clinical trials.

Molecular Radiobiology in Non-Small Cell Lung Cancer: Prognostic and Predictive Response Factors

Simple Summary

The identification of prognostic and predictive gene signatures of response to cancer treatment (radiotherapy) could help in making therapeutic decisions in patients affected by NSCLC. There are multiple proposals for gene signatures that attempt to predict survival or predict response to treatment (not radiotherapy), but they mainly focus on early stages or metastasis at diagnosis. In contrast, there have been few studies that raise these predictive and/or prognostic elements in nonmetastatic locally advanced stages, where treatment with ionizing radiation plays an important role. In this work, we review in depth previous works discovering the prognostic and predictive response factors in non-small cell lung cancer, specially focused on non-deeply studied radiation-based therapy.

Abstract

Non-small-cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide, generating huge economic and social impacts that have not slowed in recent years. Oncological treatment for this neoplasm usually includes surgery, chemotherapy, treatments on molecular targets and ionizing radiation. The prognosis in terms of overall survival (OS) and the different therapeutic responses between patients can be explained, to a large extent, by the existence of widely heterogeneous molecular profiles. The identification of prognostic and predictive gene signatures of response to cancer treatment, could help in making therapeutic decisions in patients affected by NSCLC. Given the published scientific evidence, we believe that the search for prognostic and/or predictive gene signatures of response to radiotherapy treatment can significantly help clinical decision-making. These signatures may condition the fractions, the total dose to be administered and/or the combination of systemic treatments in conjunction with radiation. The ultimate goal is to achieve better clinical results, minimizing the adverse effects associated with current cancer therapies.

Improving the Efficacy of Tumor Radiosensitization Through Combined Molecular Targeting

Chemoradiation, either alone or in combination with surgery or induction chemotherapy, is the current standard of care for most locally advanced solid tumors. Though chemoradiation is usually performed at the maximum tolerated doses of both chemotherapy and radiation, current cure rates are not satisfactory for many tumor entities, since tumor heterogeneity and plasticity result in chemo- and radioresistance. Advances in the understanding of tumor biology, a rapidly growing number of molecular targeting agents and novel technologies enabling the in-depth characterization of individual tumors, have fuelled the hope of entering an era of precision oncology, where each tumor will be treated according to its individual characteristics and weaknesses. At present though, molecular targeting approaches in combination with radiotherapy or chemoradiation have not yet proven to be beneficial over standard chemoradiation treatment in the clinical setting. A promising approach to improve efficacy is the combined usage of two targeting agents in order to inhibit backup pathways or achieve a more complete pathway inhibition. Here we review preclinical attempts to utilize such dual targeting strategies for future tumor radiosensitization.

Radiosensitisation of Hepatocellular Carcinoma Cells by Vandetanib

Hepatocellular Carcinoma (HCC) is increasing in incidence worldwide and requires new approaches to therapy. The combination of anti-angiogenic drug therapy and radiotherapy is one promising new approach. The anti-angiogenic drug vandetanib is a tyrosine kinase inhibitor of vascular endothelial growth factor receptor-2 (VEGFR-2) and RET proto-oncogene with radio-enhancement potential. To explore the benefit of combined vandetanib and radiotherapy treatment for HCC, we studied outcomes following combined treatment in pre-clinical models. Methods: Vandetanib and radiation treatment were combined in HCC cell lines grown in vitro and in vivo. In addition to 2D migration and clonogenic assays, the combination was studied in 3D spheroids and a syngeneic mouse model of HCC. Results: Vandetanib IC50s were measured in 20 cell lines and the drug was found to significantly enhance radiation cell kill and to inhibit both cell migration and invasion in vitro. In vivo, combination therapy significantly reduced cancer growth and improved overall survival, an effect that persisted for the duration of vandetanib treatment. Conclusion: In 2D and 3D studies in vitro and in a syngeneic model in vivo, the combination of vandetanib plus radiotherapy was more efficacious than either treatment alone. This new combination therapy for HCC merits evaluation in clinical trials.

Micellear Gold Nanoparticles as Delivery Vehicles for Dual Tyrosine Kinase Inhibitor ZD6474 for Metastatic Breast Cancer Treatment

The therapeutic index of poorly water-soluble drugs is often hampered due to poor pharmacokinetics, reduced blood retention, and lack of effective drug concentrations in the tumor region. In order to overcome these issues, drugs are often delivered by use of delivery vehicles to provide an enhanced therapeutic index. Gold nanoparticles synthesized in micellar networks of amphiphilic block copolymer (AuNM) provide an efficient nanocarrier for tissue- and site-specific drug delivery owing to their low cytotoxicity and immunogenicity. AuNM is formed by exploiting the properties of both inorganic Au material and an amphiphilic polymer of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEG-PPG-PEG). We further functionalized AuNM with the FDA-approved dual tyrosine kinase inhibitor ZD6474 and studied the physicochemical properties of the conjugate ZD6474-AuNM. Both AuNM and ZD6474-AuNM, with a diameter of ∼70 nm, were very stable at physiological pH. Conversely, at an acidic pH of 5.2, a slow sustained-release profile of ZD6474 was evident from AuNM, which could provide a method of facilitating release of the drug in an acidic tumor environment. In vitro, in triple-negative breast cancer cells, ZD6474-AuNM inhibited tumor cell proliferation, migration, and invasion and induced apoptosis. There was no detectable lysis of red blood cells observed when they were treated with AuNM and ZD6474-AuNM, confirming hemocompatibility. To reinforce the possibility of AuNM serving as a delivery vehicle, AuNM was conjugated with the IR680 dye for tracking, and this conjugate was systemically delivered in female nude mice bearing MDA-MB-231 human breast cancer xenografts. Fluorescence signal was retained in the tumor region in a temporal manner as compared to other organs, indicating passive retention of AuNM in the tumor locale. Moreover, delivery of ZD6474-AuNM in nude mice bearing MDA-MB-231 xenografts led to decreased tumor size as compared to the control group. The promising safety, targeting, and therapeutic results of systemic delivery of ZD6474 by AuNM provide an attractive alternative method for treating patients with metastatic breast cancer.

RADVAN: a randomised phase 2 trial of WBRT plus vandetanib for melanoma brain metastases - results and lessons learnt

BACKGROUND

Brain metastases occur in up to 75% of patients with advanced melanoma. Most are treated with whole-brain radiotherapy (WBRT), with limited effectiveness. Vandetanib, an inhibitor of vascular endothelial growth factor receptor, epidermal growth factor receptor and rearranged during transfection tyrosine kinases, is a potent radiosensitiser in xenograft models. We compared WBRT with WBRT plus vandetanib in the treatment of patients with melanoma brain metastases.

METHODS

In this double-blind, multi-centre, phase 2 trial patients with melanoma brain metastases were randomised to receive WBRT (30 Gy in 10 fractions) plus 3 weeks of concurrent vandetanib 100 mg once daily or placebo. The primary endpoint was progression-free survival in brain (PFS brain). The main study was preceded by a safety run-in phase to confirm tolerability of the combination. A post-hoc analysis and literature review considered barriers to recruiting patients with melanoma brain metastases to clinical trials.

RESULTS

Twenty-four patients were recruited, six to the safety phase and 18 to the randomised phase. The study closed early due to poor recruitment. Median PFS brain was 3.3 months (90% confidence interval (CI): 1.6-5.6) in the vandetanib group and 2.5 months (90% CI: 0.2-4.8) in the placebo group (P=0.34). Median overall survival (OS) was 4.6 months (90% CI: 1.6-6.3) and 2.5 months (90% CI: 0.2-7.2), respectively (P=0.54). The most frequent adverse events were fatigue, alopecia, confusion and nausea. The most common barrier to study recruitment was availability of alternative treatments.

CONCLUSIONS

The combination of WBRT plus vandetanib was well tolerated. Compared with WBRT alone, there was no significant improvement in PFS brain or OS, although we are unable to provide a definitive result due to poor accrual. A review of barriers to trial accrual identified several factors that affect study recruitment in this difficult disease area.

Preparation, characterization, and evaluation of antitumor effect of Brucea javanica oil cationic nanoemulsions

The purpose of this study was to prepare Brucea javanica oil cationic nanoemulsions (BJO-CN) with BJO as drug as well as oil phase and chitosan as cationic inducer, to explore the practical suitability of using cationic nanoemulsions for oral delivery of mixed oil, and to test its bioavailability and antitumor effect. BJO-CN was prepared by chitosan solution stirring method and then characterized physicochemically. The obtained BJO-CN had a spherical morphology with a positive zeta potential of 18.9 mV and an average particle size of 42.36 nm, showing high colloidal stability. The drug loading of BJO-CN was 91.83 mg·mL⁻¹, determined by high-performance liquid chromatography with precolumn derivatization. Pharmacokinetic studies revealed that, compared with BJO emulsion (BJO-E) (the dosage of BJO-CN and BJO-E was equal to 505 mg·kg⁻¹, calculated by oleic acid), BJO-CN exhibited a significant increase in the area under the plasma drug concentration–time curve over the period of 24 hours and relative bioavailability was 1.6-fold. Furthermore, the antitumor effect of BJO-CN in the orthotopic mouse model of lung cancer was evaluated by recording the median survival time and the weight of lung tissue with tumor, hematoxylin and eosin staining, and immunohistochemical technique. Results of anticancer experiments illustrated that, even though the administrated dosage in the BJO-CN group was half of that in the BJO-E group, BJO-CN exhibited similar antitumor effect to BJO-E. Moreover, BJO-CN had good synergistic effect in combination therapy with vinorelbine. These results suggested that cationic nanoemulsions are an effective and promising delivery system to enhance the oral bioavailability and anticancer effect of BJO.

Rapid Cancer Fluorescence Imaging Using A γ-Glutamyltranspeptidase-Specific Probe For Primary Lung Cancer

BACKGROUND: We set out to examine the activity of γ-glutamyltranspeptidase (GGT) in lung cancer and the validity of γ-glutamyl hydroxymethyl rhodamine green (gGlu-HMRG) for intraoperative imaging of primary lung cancer. METHODS: GGT activities and mRNA expression levels of GGT1 (one of the GGT subtypes) in five human lung cancer cell lines were examined by fluorescence imaging and quantitative reverse transcription polymerase chain reaction. In vivo imaging of an orthotopic A549 xenograft model in nude mice was performed to confirm its applicability to intraoperative imaging. Furthermore, ex vivo imaging of 73 specimens from lung cancer patients were performed and analyzed to calculate the sensitivity/specificity of gGlu-HMRG for lung cancer diagnosis. RESULTS: GGT activities and mRNA expression levels of GGT1 are diverse depending on cell type; A549, H441, and H460 showed relatively high GGT activities and expression levels, whereas H82 and H226 showed lower values. In the in vivo mouse model study, tiny pleural dissemination and hilar/mediastinal lymph node metastasis (less than 1 mm in diameter) were clearly detected 15 minutes after topical application of gGlu-HMRG. In the ex vivo study of specimens from patients, the sensitivity and specificity of gGlu-HMRG were calculated to be 43.8% (32/73) and 84.9% (62/73), respectively. When limited to female patients, never smokers, and adenocarcinomas, these values were 78.9% (15/19) and 73.7% (14/19), respectively. CONCLUSIONS: Although GGT activity of lung cancer cells vary, gGlu-HMRG can serve as an intraoperative imaging tool to detect small foci of lung cancer when such cells have sufficient GGT activity.

Molecular Targeting of Growth Factor Receptor Signaling in Radiation Oncology

Ionizing radiation has been shown to activate and interact with multiple growth factor receptor pathways that can influence tumor response to therapy. Among these receptor interactions, the epidermal growth factor receptor (EGFR) has been the most extensively studied with mature clinical applications during the last decade. The combination of radiation and EGFR-targeting agents using either monoclonal antibody (mAb) or small-molecule tyrosine kinase inhibitor (TKI) offers a promising approach to improve tumor control compared to radiation alone. Several underlying mechanisms have been identified that contribute to improved anti-tumor capacity after combined treatment. These include effects on cell cycle distribution, apoptosis, tumor cell repopulation, DNA damage/repair, and impact on tumor vasculature. However, as with virtually all cancer drugs, patients who initially respond to EGFR-targeted agents may eventually develop resistance and manifest cancer progression. Several potential mechanisms of resistance have been identified including mutations in EGFR and downstream signaling molecules, and activation of alternative member-bound tyrosine kinase receptors that bypass the inhibition of EGFR signaling. Several strategies to overcome the resistance are currently being explored in preclinical and clinical models, including agents that target the EGFR T790 M resistance mutation or target multiple EGFR family members, as well as agents that target other receptor tyrosine kinase and downstream signaling sites. In this chapter, we focus primarily on the interaction of radiation with anti-EGFR therapies to summarize this promising approach and highlight newly developing opportunities.

Closing faucets: the role of anti-angiogenic therapies in malignant pleural diseases

Malignant pleural effusion (MPE) represents 15-35 % of pleural effusions and markedly worsens the prognosis and quality of life of patients with cancer. Malignant mesothelioma (MM) and lung adenocarcinoma are the most frequent primary and secondary causes, respectively, of MPE. Effective treatments for cancer-related MPE are warranted in order to improve symptoms, reduce the number of invasive pleural procedures, and prolong patient life. Since angiogenesis plays a key role in MPE development, the potential role of bevacizumab and other anti-angiogenic therapies have been explored in this review. No relevant phase III trials have specifically analysed the benefit from adding bevacizumab to platinum-based chemotherapy in lung cancer-related MPE. However, small retrospective series reported 71.4-93.3 % MPE control rate, a reduction in invasive procedures, and a safe profile with this combination. Being approved for the first-line treatment of non-squamous advanced NSCLC, the addition of bevacizumab should be considered for patients presenting with MPE. In addition, further studies in this are recommended. In MM, the addition of bevacizumab to platinum-based chemotherapy did not meet primary endpoints in two phase II trials. However, the beneficial results on OS reported in comparison with historical cohorts and the statistically significant benefit on PFS and OS observed in the phase III MAPS trial foretell an eventual role for the combination of platinum/pemetrexed/bevacizumab as front-line systemic therapy for pleural MM. To date, no other anti-angiogenic drug has showed significant benefit in the treatment of patients with either MPE or MM. However, new promising drugs such as ramucirumab or recombinant human endostar warrant further investigation.

Therapeutic targeting of polo-like kinase 1 using RNA-interfering nanoparticles (iNOPs) for the treatment of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) remains the most common cause of cancer death worldwide due its resistance to chemotherapy and aggressive tumor growth. Polo-like kinase 1 (PLK1) is a serine-threonine protein kinase which is overexpressed in cancer cells, and plays a major role in regulating tumor growth. A number of PLK1 inhibitors are in clinical trial; however, poor tumor bioavailability and off-target effects limit their efficacy. Short-interfering-RNA (siRNA) holds promise as a class of therapeutics, which can selectively silence disease-causing genes. However, siRNA cannot enter cells without a delivery vehicle. Herein, we investigated whether RNAi-interfering nanoparticles could deliver siRNA to NSCLC cells and silence PLK1 expression in vitro and in vivo. iNOP-7 was non-toxic, and delivered siRNA with high efficiency to NSCLC cells. iNOP-7-PLK1 siRNA silenced PLK1 expression and reduced NSCLC growth in vitro. Notably, iNOP-7 delivered siRNA to orthotopic lung tumors in mice, and administration of iNOP-7-PLK1 siRNA reduced lung tumor burden. These novel data show that iNOP-7 can deliver siRNA against PLK1 to NSCLC cells, and decrease cell proliferation both in vitro and in vivo. iNOP-7-PLK1 siRNA may provide a novel therapeutic strategy for the treatment of NSCLC as well as other cancers which aberrantly express this gene.

Therapeutic integration of new molecule-targeted therapies with radiotherapy in lung cancer

Lung cancer is the most common form of the disease and the leading cause of cancer deaths worldwide. Non-small-cell lung cancer (NSCLC) accounts for approximately 80-85% of all lung cancers. Forty percent of all cases present with stage III, and many of them are considered inoperable (staged IIIA with mediastinal lymph node involvement) or stage IIIB disease. Concurrent platinum-based chemotherapy and thoracic radiation has demonstrated survival benefits in these patients. We review the role of new target agents in combination with radiotherapy in stage III NSCLC. Antiangiogenics improve tumor oxygenation thereby improving the therapeutic efficacy of irradiation in models. Bevacizumab in combination with thoracic radiation has shown high toxicity. However, other antiangiogenic agents are more promising. Radiation activates epidermal growth factor receptor (EGFR) pathways, inducing radioresistance, cell proliferation and enhanced DNA repair. After promising data from preclinical models and early clinical trials, cetuximab did not show any benefit in a recent phase III trial. Panitumumab and nimotuzumab are under evaluation. Gefitinib has been investigated in combination with radiotherapy for unresectable stage III NSCLC, but results in maintenance treatment after chemoradiotherapy were not encouraging. Erlotinib has also been tested in a phase II trial with chemoradiotherapy. Other new pathways and agents are being studied, such as m-TOR pathway, bortezomib, heat shock protein 90 (Hsp90) inhibition, histone deacetylase inhibitors (HDACS), aurora kinases, mitogen activated protein kinases (MARK) and PARP inhibitors.

Radiation-induced VEGF-C expression and endothelial cell proliferation in lung cancer

BACKGROUND

The present study was undertaken to investigate whether radiation induces the expression of vascular endothelial growth factor C (VEGF-C) through activation of the PI3K/Akt/mTOR pathway,subsequently affecting endothelial cells.

MATERIALS AND METHODS

Radiotherapy-induced tumor micro-lymphatic vessel density (MLVD) was determined in a lung cancer xenograft model established in SCID mice. The protein expression and phosphorylation of members of the PI3K/Akt/mTOR pathway and VEGF-C secretion and mRNA expression in irradiated lung cancer cells were assessed by Western blot analysis, enzyme-linked immunosorbent assays (ELISAs), and reverse transcriptase-polymerase chain reaction (RT-PCR). Moreover, specific chemical inhibitors were used to evaluate the role of the PI3K/Akt/mTOR signaling pathway. Conditioned medium (CM) from irradiated control-siRNA or VEGF-C-siRNA-expressing A549 cells was used to evaluate the proliferation of endothelial cells by the MTT assay.

RESULTS

Radiation increased VEGF-C expression in a dose-dependent manner over time at the protein but not at the mRNA level. Radiation also up-regulated the phosphorylation of Akt, mTOR, 4EBP, and eIF4E, but not of p70S6K. Radiation-induced VEGF-C expression was down-regulated by LY294002 and rapamycin (both p < 0.05). Furthermore, CM from irradiated A549 cells enhanced human umbilical vein endothelial cell (HUVEC) and lymphatic endothelial cell (LEC) proliferation, which was not observed with CM from irradiated VEGF-C-siRNA-expressing A549 cells.

CONCLUSIONS

Radiation-induced activation of the PI3K/Akt/mTOR signaling pathway increases VEGF-C expression in lung cancer cells, thereby promoting endothelial cell proliferation.

Orthotopic lung cancer murine model by nonoperative transbronchial approach

PURPOSE

The aim of this work was to establish a novel orthotopic human non-small cell lung cancer (NSCLC) murine xenograft model by a nonsurgical, transbronchial approach.

DESCRIPTION

Male athymic nude mice and human NSCLC cell lines, including A549, H460, and H520 were used. Under direct visualization of the vocal cords, a 23-gauge blunt-tip slightly curved metal catheter was introduced into the trachea to the bronchus, and 2.5×10(5) tumor cells mixed with Matrigel (BD Biosciences, Mississauga, Ontario, Canada) were administered into the lung. Mice were monitored using weekly microcomputed tomography scans for tumor formation.

EVALUATION

When the tumor size reached more than 4 mm in diameter, the animals were euthanized, and the tumor tissue was evaluated histopathologically. Of 37 mice studied, 34 were confirmed to have tumor formation: 29 developed solitary tumors and 5 had multifocal lesions. There was no evidence of extrapleural dissemination or effusion.

CONCLUSIONS

Transbronchial delivery of tumor cells enabled the establishment of a novel orthotopic human NSCLC murine xenograft model. This clinically relevant preclinical model bearing a solitary nodule is of value for a variety of in vivo research studies.

Improvement of orthotopic lung cancer mouse model via thoracotomy and orotracheal intubation enabling in vivo imaging studies

Investigation of molecular mechanisms and the efficiency of novel therapeutics for the treatment and prevention of a disease require accurate and accessible preclinical models. Recent developments in personalized medicine employing molecular medicine concepts have favored mice because their genetic make-up is well known and easy to manipulate. For lung cancer, however, orthotopic models in mice are difficult to create due to their narrow glottis openings which act as obstacles to intubation. In the present study, we develop an orotracheal intubation device which gives a clearer view of the narrow mouse glottis and increases the success rate of intubation. We achieved anesthetization via orotracheal intubation using this novel device and then performed a thoracotomy by making an incision between the fourth and fifth intercostal ribs on the right side of the chest. Lung tumor cells were then inoculated at this site. Tumor formation was monitored through bioluminescence optical and magnetic resonance (MR) imagings, which was confirmed by histological analysis. Temperature drop (<35) and/or loss of body weight (>30% of the initial body weight) observed during any procedure were used as interruption criteria. This method exhibited high tumorigenicity (100%) and a low mortality rate (8%) at specific sites making it ideal for creating orthotopic lung tumor models and making it particularly useful for sequential follow-up studies using in vivo image analysis.

Tumor cell expression of vascular endothelial growth factor receptor 2 is an adverse prognostic factor in patients with squamous cell carcinoma of the lung

A robust immunohistochemical (IHC) assay for VEGFR2 was developed to investigate its utility for patient tailoring in clinical trials. The sensitivity, specificity, and selectivity of the IHC assay were established by siRNA knockdown, immunoblotting, mass spectrometry, and pre-absorption experiments. Characterization of the assay included screening a panel of multiple human cancer tissues and an independent cohort of non-small cell lung carcinoma (NSCLC, n = 118) characterized by TTF-1, p63, CK5/6, and CK7 IHC. VEGFR2 immunoreactivity was interpreted qualitatively (VEGFR2 positive/negative) in blood vessels and by semi-quantitative evaluation using H-scores in tumor cells (0-300). Associations were determined among combinations of VEGFR2 expression in blood vessels and tumor cells, and clinico-pathologic characteristics (age, sex, race, histologic subtype, disease stage) and overall survival using Kaplan-Meier analyses and appropriate statistical models. VEGFR2 expression both in blood vessels and in tumor cells in carcinomas of the lung, cervix, larynx, breast, and others was demonstrated. In the validation cohort, 99/118 (83.9%) NSCLC tissues expressed VEGFR2 in the blood vessels and 46/118 (39.0%) showed high tumor cell positivity (H-score ≥10). Vascular and tumor cell expression were inversely correlated (p = 0.0175). High tumor cell expression of VEGFR2 was associated with a 3.7-fold reduction in median overall survival in lung squamous-cell carcinoma (SCC, n = 25, p = 0.0134). The inverse correlation between vascular and tumor cell expression of VEGFR2 and the adverse prognosis associated with high VEGFR2 expression in immunohistochemically characterized pulmonary SCC are new findings with potential therapeutic implications. The robustness of this novel IHC assay will support further evaluation of its utility for patient tailoring in clinical trials of antiangiogenic agents.

MiR-200c increases the radiosensitivity of non-small-cell lung cancer cell line A549 by targeting VEGF-VEGFR2 pathway

MicroRNAs (miRNAs) have been demonstrated to participate in many important cellular processes including radiosensitization. VEGF family, an important regulator of angiogenesis, also plays a crucial role in the regulation of cancer cell radiosensitivity. VEGFR2 mediates the major growth and permeability actions of VEGF in a paracrine/autocrine manner. MiR-200c, at the nexus of epithelial-mesenchymal transition (EMT), is predicted to target VEGFR2. The purpose of this study is to test the hypothesis that regulation of VEGFR2 pathway by miR-200c could modulate the radiosensitivity of cancer cells. Bioinformatic analysis, luciferase reporter assays and biochemical assays were carried out to validate VEGFR2 as a direct target of miR-200c. The radiosensitizing effects of miR-200c on A549 cells were determined by clonogenic assays. The downstream regulating mechanism of miR-200c was explored with western blotting assays, FCM, tube formation assays and migration assays. We identified VEGFR2 as a novel target of miR-200c. The ectopic miR-200c increased the radiosensitivity of A549 while miR-200c down-regulation decreased it. Besides, we proved that miR-200c radiosensitized A549 cells by targeting VEGF-VEGFR2 pathway specifically, thus leading to inhibition of its downstream pro-survival signaling transduction and angiogenesis, and serves as a potential target for radiosensitizition research.

Microenvironment and radiation therapy

Dependency on tumor oxygenation is one of the major features of radiation therapy and this has led many radiation biologists and oncologists to focus on tumor hypoxia. The first approach to overcome tumor hypoxia was to improve tumor oxygenation by increasing oxygen delivery and a subsequent approach was the use of radiosensitizers in combination with radiation therapy. Clinical use of some of these approaches was promising, but they are not widely used due to several limitations. Hypoxia-inducible factor 1 (HIF-1) is a transcription factor that is activated by hypoxia and induces the expression of various genes related to the adaptation of cellular metabolism to hypoxia, invasion and metastasis of cancer cells and angiogenesis, and so forth. HIF-1 is a potent target to enhance the therapeutic effects of radiation therapy. Another approach is antiangiogenic therapy. The combination with radiation therapy is promising, but several factors including surrogate markers, timing and duration, and so forth have to be optimized before introducing it into clinics. In this review, we examined how the tumor microenvironment influences the effects of radiation and how we can enhance the antitumor effects of radiation therapy by modifying the tumor microenvironment.

Addition of vandetanib to chemotherapy in advanced solid cancers: a meta-analysis

The addition of vandetanib to chemotherapy has been shown to have a marked effect on patients with advanced cancers who had failed previous chemotherapy. We carried out a meta-analysis to determine the efficacy and safety of vandetanib compared with chemotherapy in patients with advanced cancers. For this meta-analysis, we selected randomized clinical trials that compared vandetanib-based therapy (VBT) with the matched chemotherapy or placebo alone in patients with advanced cancers. The outcomes included overall survival (OS), progression-free survival (PFS), the objective response rate, and toxicities. Hazard ratios (HRs) and odds ratios were reported with 95% confidence intervals (CIs). A total of 14 eligible trials were included for the meta-analysis, with 2995 patients in the VBT group and 2479 patients in the control group. A significant improvement was observed in PFS (HR 0.76, 95% CI 0.68-0.86 in all cancers, HR 0.80, 95% CI 0.70-0.90 in lung cancer, HR 0.54, 95% CI 0.40-0.74 in thyroid cancer) and in objective response rate (odds ratio 2.09, 95% CI 1.42-3.07) in the VBT group. However, no significant difference was found in OS (HR 0.96, 95% CI 0.90-1.03). The subgroups of patients with non-small-cell lung cancer who benefited from vandetanib therapy were identified as those with a history of smoking (HR 0.87, 95% CI 0.80-0.95) and an adenocarcinoma histology (HR 0.85, 95% CI 0.77-0.94). In addition, patients who received VBT had an increased incidence of adverse events such as rash, diarrhea, and neutropenia. The addition of vandetanib to chemotherapy significantly improves PFS in patients with locally advanced or metastatic cancers, especially lung and thyroid cancer.

[EGFR-dependent impact of indol-3-carbinol on radiosensitivity of lung cancer cells]

背景与目的

吲哚-3-甲醇（indole-3-carbinol, I3C）是十字花科蔬菜中一种主要的有效植物化学物质，且具有防癌和抗癌作用。本研究旨在观察I3C是否影响表皮生长因子受体（epidermal growth factor receptor, EGFR）表达水平不同的肺癌细胞放射敏感性。

方法

采用MTT和克隆形成实验方法分别检测肺癌细胞的生长和存活率；siRNA转染方法降低细胞中EGFR蛋白表达水平；Western blot和RT-PCR法分别测定EGFR蛋白和mRNA的表达。

结果

采用无明显毒副作用的5 μmol/L剂量的I3C预处理明显降低了EGFR表达阳性的人肺腺癌H1975和人肺鳞癌H226细胞对γ-射线照射的放射敏感性，而I3C对EGFR表达阴性的人肺鳞癌NIH-H520细胞的放射敏感性则影响非常小。Western blot结果显示I3C可以增加H1975和H226细胞中EGFR蛋白的表达水平和Y845位点磷酸化水平。EGFR siRNA降低了NIH-H1975细胞中EGFR蛋白的表达，增加了细胞的放射敏感性，并有效地降低和抑制了I3C导致的细胞耐辐射效应。

结论

我们的研究结果首次证实I3C可以通过调节EGFR表达和磷酸化水平从而影响肺癌细胞的放射治疗敏感性，提示EGFR可能是I3C影响肺癌放射治疗敏感性的重要靶蛋白。

PolyIC GE11 polyplex inhibits EGFR-overexpressing tumors

Phage display has identified the dodecapeptide YHWYGYTPQNVI (GE11) as a ligand that binds to the epidermal growth factor receptor (EGFR) but does not activate the receptor. Here, we compare the EGFR binding affinities of GE11, EGF, and their polyethyleneimine-polyethyleneglycol (PEI-PEG) conjugates. We found that although GE11 by itself does not exhibit measurable affinity to the EGFR, tethering it to PEI-PEG increases its affinity markedly, and complex formation with polyinosine/cytosine (polyIC) further enhances the affinity to the submicromolar range. PolyIC/PPGE11 has a similar strong antitumor effect against EGFR overexpressing tumors in vitro and in vivo, as polyIC/polyethyleneimine-polyetheleneglycol-EGF (polyIC/PP-EGF). Absence of EGFR activation, as previously shown by us and easier production of GE11 and GE11 conjugates, confer polyIC/PPGE11 a significant advantage over similar EGF-based polyplexes as a potential therapy of EGFR overexpressing tumors.

Polymorphisms of the vascular endothelial growth factor gene and severe radiation pneumonitis in non-small cell lung cancer patients treated with definitive radiotherapy

Vascular endothelial growth factor (VEGF) is a major mediator of angiogenesis and lung cancer progression. We hypothesized that VEGF polymorphisms may modulate the risk of radiation pneumonitis (RP) in non-small cell lung cancer (NSCLC) patients treated with definitive radiotherapy. We genotyped three potentially functional VEGF single nucleotide polymorphisms (-460 T > C [rs833061], -634 G > C [rs2010963] and +936 C > T [rs3025039]) and estimated the associations of their genotypes and haplotypes with severe radiation pneumonitis (RP ≥grade 3) in 195 NSCLC patients. We found that the VEGF genotypes of rs2010963 and rs3025039 single nucleotide polymorphisms as well as the -460C/-634G/+936C haplotype were predictors of RP development (adjusted hazard ratio [adjHR] = 2.33, 95% confidence interval [CI], 1.01-5.37, P = 0.047 for CC vs GG genotypes; adjHR = 28.13, 95% CI, 5.24-151.02, P < 0.001 for TT vs CC genotypes; and adjHR = 2.51, 95% CI, 1.27-4.98, P = 0.008 for T-C-T vs C-G-C haplotypes). In addition, there was a trend towards reduced RP risk in patients carrying an increased number of protective VEGF genotypes. Our data suggest that VEGF polymorphisms can modulate the risk of radiation pneumonitis in NSCLC patients treated with definitive radiotherapy. Large and independent studies are needed to confirm our findings.

Combined MEK and VEGFR inhibition in orthotopic human lung cancer models results in enhanced inhibition of tumor angiogenesis, growth, and metastasis

PURPOSE

Ras/Raf/mitogen-activated protein-extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK signaling is critical for tumor cell proliferation and survival. Selumetinib is a potent, selective, and orally available MEK1/2 inhibitor. In this study, we evaluated the therapeutic efficacy of selumetinib alone or with cediranib, an orally available potent inhibitor of all three VEGF receptor (VEGFR) tyrosine kinases, in murine orthotopic non-small cell lung carcinoma (NSCLC) models.

EXPERIMENTAL DESIGN

NCI-H441 or NCI-H460 KRAS-mutant human NSCLC cells were injected into the lungs of mice. Mice were randomly assigned to treatment with selumetinib, cediranib, paclitaxel, selumetinib plus cediranib, or control. When controls became moribund, all animals were sacrificed and assessed for lung tumor burden and locoregional metastasis. Lung tumors and adjacent normal tissues were subjected to immunohistochemical analyses.

RESULTS

Selumetinib inhibited lung tumor growth and, particularly at higher dose, reduced locoregional metastasis, as did cediranib. Combining selumetinib and cediranib markedly enhanced their antitumor effects, with near complete suppression of metastasis. Immunohistochemistry of tumor tissues revealed that selumetinib alone or with cediranib reduced ERK phosphorylation, angiogenesis, and tumor cell proliferation and increased apoptosis. The antiangiogenic and apoptotic effects were substantially enhanced when the agents were combined. Selumetinib also inhibited lung tumor VEGF production and VEGFR signaling.

CONCLUSIONS

In this study, we evaluated therapy directed against MEK combined with antiangiogenic therapy in distinct orthotopic NSCLC models. MEK inhibition resulted in potent antiangiogenic effects with decreased VEGF expression and signaling. Combining selumetinib with cediranib enhanced their antitumor and antiangiogenic effects. We conclude that combining selumetinib and cediranib represents a promising strategy for the treatment of NSCLC.

[Targeted therapies and radiation therapy in non-small cell lung cancer]

Lung cancer is the leading cause of cancer-related death. Between 80-85% of lung cancers are non-small cell lung carcinomas. One third of the patients are diagnosed with locally advanced stage. In this condition, concomitant radio-chemotherapy is the standard treatment for patients with good performance status. Despite important improvements in the last years, non-small cell lung carcinoma prognosis remains poor, with high rates of both local recurrences and metastases. The heterogeneity of molecular characteristics of non-small cell lung carcinoma cells and a better knowledge of potential targets offer promising developments for new pharmacologic agents. Hereafter we will review the currently most studied pathways and the most promising ones for the treatment of locally advanced unresectable non-small cell lung carcinoma. Two of the most attractive pathways where new agents have been developed and assessed in combination with thoracic radiotherapy or radiochemotherapy are the EGFR pathway (either with the use of monoclonal antibodies or tyrosine kinase inhibitors) and the angiogenesis inhibition. The development of targeted agents could lead to individualized therapeutic combinations taking into account the intrinsic characteristics of tumor cells. Pharmacological modulation of tumour cells radiosensitivity by targeted therapies is only starting, but yet offers promising perspectives.

Vandetanib restores head and neck squamous cell carcinoma cells' sensitivity to cisplatin and radiation in vivo and in vitro

PURPOSE

We investigated whether vandetanib, an inhibitor of the tyrosine kinase activities of vascular endothelial growth factor receptor-2 (VEGFR-2), epidermal growth factor receptor (EGFR), and rearranged during transfection (RET), could augment the antitumor activity of radiation with or without cisplatin in preclinical in vitro and in vivo models of human head and neck squamous cell carcinoma (HNSCC).

EXPERIMENTAL DESIGN

OSC-19 and HN5 HNSCC cells that were cisplatin and radioresistant were treated with vandetanib, cisplatin, and radiation alone or in combination in vitro and in vivo using an orthotopic nude mouse model. Treatment effects were assessed using clonogenic survival assay, tumor volume, bioluminescence imaging, tumor growth delay, survival, microvessel density, tumor and endothelial cell apoptosis, and EGFR and Akt phosphorylation data.

RESULTS

Vandetanib plus cisplatin radiosensitized HNSCC cells in vitro and in vivo. The combination treatment with vandetanib, cisplatin, and radiation was superior to the rest of treatments (including the double combinations) in antitumoral effects, prolonging survival, decreasing cervical lymph node metastases in vivo. It also increased both tumor and tumor-associated endothelial cell apoptosis and decreased microvessel density in vivo. An analysis of tumor growth delay data revealed that vandetanib plus cisplatin enhanced radioresponse in vivo. All vandetanib-containing treatments inhibited EGFR and Akt phosphorylation in vitro and in vivo.

CONCLUSION

The addition of vandetanib to combination therapy with cisplatin and radiation was able to effectively overcome cisplatin and radioresistance in in vitro and in vivo models of HNSCC. Further study of this regimen in clinical trials may be warranted.

Radiogenomics predicting tumor responses to radiotherapy in lung cancer

The recently developed ability to interrogate genome-wide data arrays has provided invaluable insights into the molecular pathogenesis of lung cancer. These data have also provided information for developing targeted therapy in lung cancer patients based on the identification of cancer-specific vulnerabilities and set the stage for molecular biomarkers that provide information on clinical outcome and response to treatment. In addition, there are now large panels of lung cancer cell lines, both non-small-cell lung cancer and small-cell lung cancer, that have distinct chemotherapy and radiation response phenotypes. We anticipate that the integration of molecular data with therapy response data will allow for the generation of biomarker signatures that predict response to therapy. These signatures will need to be validated in clinical studies, at first retrospective analyses and then prospective clinical trials, to show that the use of these biomarkers can aid in predicting patient outcomes (eg, in the case of radiation therapy for local control and survival). This review highlights recent advances in molecular profiling of tumor responses to radiotherapy and identifies challenges and opportunities in developing molecular biomarker signatures for predicting radiation response for individual patients with lung cancer.

Epidermal growth factor receptor expression modulates antitumor efficacy of vandetanib or cediranib combined with radiotherapy in human glioblastoma xenografts

PURPOSE

The purpose of this study was to determine the ability of radiation therapy (RT) combined with the tyrosine kinase inhibitors (TKI) vandetanib (antiepidermal growth factor receptor [EGFR] plus antivascular endothelial growth factor receptor [anti-VEGFR]) and cediranib (anti-VEGFR) to inhibit glioblastoma multiforme (GBM) growth. A secondary aim was to investigate how this regimen is modulated by tumor EGFR expression.

METHODS AND MATERIALS

Radiosensitivity was assessed by clonogenic cell survival assay. VEGF secretion was quantified by enzyme-linked immunosorbent assay. GBM (U87MG wild-type EGFR [wtEGFR] and U87MG EGFR-null) xenografts were treated with vandetanib, cediranib, and RT, alone or in combinations. Excised tumor sections were stained for proliferative and survival biomarkers.

RESULTS

In vitro, U87MG wtEGFR and U87 EGFR-null cells had similar growth kinetics. Neither TKI affected clonogenic cell survival following RT. However, in vivo, exogenous overexpression of wtEGFR decreased tumor doubling time (T2x) in U87MG xenografts (2.70 vs. 4.41 days for U87MG wtEGFR vs. U87MG vector, respectively). In U87MG EGFR-null cells, TKI combined with radiation was no better than radiation therapy alone. In U87MG wtEGFR, RT in combination with vandetanib (but not with cediranib) significantly increased tumor T2x compared with RT alone (T2x, 10.4 days vs. 4.8 days; p < 0.001). In vivo, growth delay correlated with suppression of pAkt, survivin, and Ki67 expression in tumor samples. The presence of EGFR augmented RT-stimulated VEGF release; this effect was inhibited by vandetanib.

CONCLUSIONS

EGFR expression promoted tumor growth in vivo but not in vitro, suggesting a microenvironmental effect. GBM xenografts expressing EGFR exhibited greater sensitivity to both cediranib and vandetanib than EGFR-null tumors. Hence EGFR status plays a major role in determining a tumor's in vivo response to radiation combined with TKI, supporting a "personalized" approach to GBM management.

Dual inhibition of vascular endothelial growth factor receptor and epidermal growth factor receptor is an effective chemopreventive strategy in the mouse 4-NQO model of oral carcinogenesis

Despite recent therapeutic advances, several factors, including field cancerization, have limited improvements in long-term survival for oral squamous cell carcinoma (OSCC). Therefore, comprehensive treatment plans must include improved chemopreventive strategies. Using the 4-nitroquinoline 1-oxide (4-NQO) mouse model, we tested the hypothesis that ZD6474 (Vandetanib, ZACTIMA) is an effective chemopreventive agent. CBA mice were fed 4-NQO (100 μg/mL) in their drinking water for 8 weeks and then randomized to no treatment or oral ZD6474 (25 mg/kg/d) for 24 weeks. The percentage of animals with OSCC was significantly different between the two groups (71% in control and 12% in the ZD6474 group; P ≤ 0.001). The percentage of mice with dysplasia or OSCC was significantly different (96% in the control and 28% in the ZD6474 group; P ≤ 0.001). Proliferation and microvessel density scores were significantly decreased in the ZD6474 group (P ≤ 0.001 for both). Although proliferation and microvessel density increased with histologic progression in control and treatment cohorts, epidermal growth factor receptor and vascular endothelial growth factor receptor-2 phosphorylation was decreased in the treatment group for each histologic diagnosis, including mice harboring tumors. OSCC from ZD6474-treated mice exhibited features of epithelial to mesenchymal transition, as shown by loss E-cadherin and gain of vimentin protein expression. These data suggest that ZD6474 holds promise as an OSCC chemopreventive agent. They further suggest that acquired resistance to ZD6474 may be mediated by the expression of an epithelial to mesenchymal transition phenotype. Finally, the data suggests that this model is a useful preclinical platform to investigate the mechanisms of acquired resistance in the chemopreventive setting.

[Effects of rh-endostar in combination with radiotherapy on rats with lung cancer]

BACKGROUND AND OBJECTIVE

Radiation sensitivity is closely related to tissue oxygen, and rh-endostatin can induce the high level of oxygen content in tumor by "normalizing" tumor angiogenesis which is associated with radiotherapy sensitivity. The aim of this study is to observe the effect of combination of radiotherapy with rh-endostatin in the rats with lung cancer.

METHODS

Immediate lewis cancerous ascetic injection method was used to make rats tumors bearing model, then the rats was divided into four groups randomly: group A was treated with saline; group B was treated with rh-endostatin; group C was treated with irradiation and group D was treated with rh-endostatin and irradiation. After all rats were treated, inhibition rates and the tumor growth curve were calculated. Immunohistochemisty was adopted to check the expressions of vascular endothelial growth factor (VEGF) and microvessel density (MVD).

RESULTS

Compared with group A, the growth rates of the tumors in the other group were obviously slower, and the tumor weights were significantly different form group A (P < 0.05). Compared with the other groups, the tumor weights of group D were obviously reduced (P < 0.05). Compared with group A, VEGF and MVD of other three groups were reduced (P < 0.05), and group D were significantly cut down.

CONCLUSION

Combination with radiotherapy and rh-endostatin could inhibit the lung cancer significantly in rats. The possible mechanisms are to decrease the expression ofVEGF and inhibit the production of angiogenesis.

新型分子靶向药物联合放疗在肺癌中的应用

非小细胞肺癌（non-small cell lung cancer, NSCLC）约占肺癌总病例数的80%-85%，对于Ⅲ期患者来说，NSCLC约占肺癌总病例数的40%。不可切除Ⅲ期NSCLC的治疗为以铂类为基础的化疗联合胸部放疗。本文将综述正在研发中且有可能用于联合治疗的新型靶向制剂。其中最具前景的策略之一为表皮生长因子受体（epidermal growth factor receptor, EGFR）通路的抑制。放疗可激活EGFR信号，通过诱导细胞增殖并增强DNA修复而导致放疗抵抗。几项临床前模型研究表明西妥昔单抗与放疗联合具有协同效应。几项Ⅱ期试验评估了西妥昔单抗与放疗同步使用的安全性与疗效，结果喜人。吉非替尼对多种细胞系具有放疗增敏作用，其与放疗的联合已被试验用于不可切除Ⅲ期NSCLC的治疗。然而，放化疗后使用吉非替尼作为维持治疗的结果不容乐观。一项Ⅰ期试验评估了厄洛替尼与放化疗联合的疗效。放疗可通过损伤细胞膜、DNA以及微血管内皮细胞而诱导肿瘤死亡，而这反过来可增加促血管生成生长因子的产生。抗血管生长制剂可降低血管密度，但可改善肿瘤的含氧量。应用血管内皮生长因子受体（vascular endothelial growth factor receptor, VEGFR）抑制剂可通过阻断亚致死量辐射损伤的修复而增强放疗对人NSCLC的疗效。厄洛替尼、贝伐珠单抗与胸部放疗联合试验正在进行中。该三种药物联合治疗的新策略尚需制订。由于放疗可增强HSP90分子伴侣的功能从而引起肺癌细胞的放疗抵抗，此通路的阻断剂可通过抑制HIF-1α和VEGF的表达进而抑制肺癌细胞的生存和血管生成，因而可能用于减少放疗抵抗。在NSCLC和间皮瘤的临床前模型中，Aurora激酶抑制剂似乎对放疗具有增效作用。

BMS-690514, a VEGFR and EGFR tyrosine kinase inhibitor, shows anti-tumoural activity on non-small-cell lung cancer xenografts and induces sequence-dependent synergistic effect with radiation

Background:

Non-small-cell lung cancer (NSCLC) is an aggressive disease in which vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF) are implicated in tumour growth, tumour resistance to radiation and chemotherapy, and disease relapse. We have investigated the anti-tumoural effects of BMS-690514, an inhibitor of both vascular endothelial growth factor receptor (VEGFR) and epidermal growth factor receptor (EGFR) signalling pathways, as a single agent and in combination with ionising radiation (IR) on several NSCLC cell lines.

Methods:

Radiosensitisation of several NSCLC cell lines by BMS-690514 was assessed in vitro using clonogenic assay and in vivo using nude mice.

Results:

In vitro studies showed that BMS-690514 alone decreases clonogenic survival of NSCLC cells lines but no potential enhancement of IR response was observed in the combination. In tumour-bearing mice, BMS-690514 alone inhibits the growth of NSCLC xenografts, including the T790M mutation-harbouring H1975 tumour. The concomitant combination of BMS-690514 and radiation did not increase mice survival in comparison with treatment with IR alone. In contrast, BMS-690514 markedly enhances the anti-tumour effect of radiation in a sequential manner on H1299 and H1975 xenografts. Immunohistochemistry revealed a qualitative reduction in vessel area after administrations of BMS-690514, compared with vehicle-treated controls, suggesting that revascularisation may explain the schedule dependency of the tumour-growth delay observed.

Conclusion:

The results of association with radiation show that BMS-690514 may be a successful adjuvant to clinical radiotherapy. These findings are of translational importance because the clinical benefits of anti-EGFR and anti-VEGFR therapy might be schedule dependent.

New molecular targeted therapies integrated with radiation therapy in lung cancer

Non-small-cell lung cancer (NSCLC) accounts for approximately 80%-85% of all cases of lung cancer; for patients with stage III disease, it accounts for approximately 40% of all cases. The treatment for unresectable stage III NSCLC is the combination of platinum-based chemotherapy and thoracic radiation. In this article, new targeted agents under investigation for possible integration into the combined therapy are reviewed. One of the most promising strategies is the inhibition of the epidermal growth factor receptor (EGFR) pathway. Radiation activates EGFR signaling, leading to radio-resistance by inducing cell proliferation and enhanced DNA repair. Several preclinical models have shown synergistic activity when cetuximab was combined with radiation therapy. Some phase II trials have evaluated the safety and efficacy of synchronous cetuximab and radiation therapy with promising results. Gefitinib has a radiosensitizing effect on cell lines and has been investigated in combination with radiation therapy for unresectable stage III NSCLC. However, disappointing results were observed in the maintenance treatment with gefitinib after chemoradiation therapy. Erlotinib has been tested in a phase I trial with chemoradiation therapy. Radiation induces tumor death by damaging cell membranes, DNA, and microvascular endothelial cells, which in response increase proangiogenic growth factors. Antiangiogenic agents reduce vascular density but improve tumor oxygenation. Use of vascular endothelial growth factor receptor (VEGFR) inhibitors enhances the therapeutic efficacy of irradiation in human NSCLC by hindering the repair of sublethal radiation damage. Trials combining erlotinib and bevacizumab with thoracic radiation are ongoing. New strategies must be developed for the integration of this triple-combination treatment. As radiation therapy enhances HSP90 chaperone function, causing radio-resistant lung cancer cells, therapeutic agents that block this path are likely candidates for decreasing radio-resistance by suppressing HIF-1alpha and VEGF expression and thus inhibiting the survival and angiogenic potential of lung cancer cells. Aurora kinase inhibitors with radiation therapy seem to have an additive effect in preclinical models in NSCLC and mesothelioma.

Effects of irradiation on tumor cell survival, invasion and angiogenesis

Ionizing irradiation is a widely applied therapeutic method for the majority of solid malignant neoplasms, including brain tumors where, depending on localization, this might often be the only feasible primary intervention.Without doubt, it has been proved to be a fundamental tool available in the battlefield against cancer, offering a clear survival benefit in most cases. However, numerous studies have associated tumor irradiation with enhanced aggressive phenotype of the remaining cancer cells. A cell population manages to survive after the exposure, either because it receives sublethal doses and/or because it successfully utilizes the repair mechanisms. The biology of irradiated cells is altered leading to up-regulation of genes that favor cell survival, invasion and angiogenesis. In addition, hypoxia within the tumor mass limits the cytotoxicity of irradiation, whereas irradiation itself may worsen hypoxic conditions, which also contribute to the generation of resistant cells. Activation of cell surface receptors, such as the epidermal growth factor receptor, utilization of signaling pathways, and over-expression of cytokines, proteases and growth factors, for example the matrix metalloproteinases and vascular endothelial growth factor, protect tumor and non-tumor cells from apoptosis, increase their ability to invade to adjacent or distant areas, and trigger angiogenesis. This review will try to unfold the various molecular events and interactions that control tumor cell survival, invasion and angiogenesis and which are elicited or influenced by irradiation of the tumor mass, and to emphasize the importance of combining irradiation therapy with molecular targeting.

The angiogenetic pathway in malignant pleural effusions: Pathogenetic and therapeutic implications

Increased permeability of the pleural microvasculature is generally attributed to the substances that are released in inflammatory and malignant pleural effusions, although the exact pathogenetic mechanisms of malignant pleural effusions are unclear. Current therapies used to prevent the re-accumulation of pleural fluid and relieve symptoms are of variable efficacy and may cause serious adverse effects. Understanding the mechanisms of fluid accumulation would hopefully permit the development of more specific, effective and safer treatment modalities. Angiogenesis, pleural vascular increased permeability and inflammation are considered central to the pathogenesis of malignant pleural effusions. Vascular endothelial growth factor (VEGF) is a member of the VEGF/platelet-derived factor gene family and consists of at least six isoforms. Since it was shown that VEGF contributes to the formation of malignant pleural effusions, there have been some attempts to implicate, therapeutically, this finding using different molecules (ZD6474, PTK 787 and bevacizumab). However, the role of the biological axis of VEGF and angiopoietins needs further investigation in both the pathogenesis and the treatment of malignant pleural effusion. In both non-small-cell lung carcinoma and breast cancer, it has been shown that the ligand for CXCR4, CXCL12 or SDF-1α, exhibited peak levels of expression in organs that were the preferred destination for their respective metastases. Recent findings imply that new therapeutic strategies aimed at blocking the SDF-1-CXCR4 axis may have significant applications for patients by modulating the trafficking of hemato/lymphopoietic cells and inhibiting the metastatic behavior of tumor cells as well. The purpose of this report is to review novel pathogenetic and therapeutic implications regarding the angiogenetic pathways in malignant pleural effusions.

Effectiveness of combined modality radiotherapy of orthotopic human squamous cell carcinomas in Nu/Nu mice using cetuximab, tirapazamine and MnSOD-plasmid liposome gene therapy

Hypoxic regions limit the radiocontrollability of head and neck carcinomas. Whether or not combinations of plasmid/liposome mediated overexpression of normal tissue protective manganese superoxide dismutase (MnSOD), cetuximab (C225), and the hypoxic cytotoxin tirapazamine (TPZ) enhanced radiotherapeutic effects was tested in a CAL-33 orthotopic mouse cheek tumor model. The tumor volume continued to increase in the control (untreated) mice, with a ninefold increase by 10 days when the tumors exceeded 2 cm(3). The mice receiving 14 Gy only showed reduced tumor growth to 3.1+/-0.1 fold at day 10. The mice receiving MnSOD-PL, C225, TPZ plus 14 Gy had the best outcome with 0.7+/-0.1 fold increase in tumor volume by 10 days (p=0.015) compared to irradiation only. The addition of MnSOD-PL, TPZ, and C225 to irradiation optimized the therapeutic ratio for the local control of hypoxic region-containing CAL-33 orthotopic tumors.

Radiosensitising agents for the radiotherapy of cancer: novel molecularly targeted approaches

BACKGROUND

The efficacy of radiotherapy (RT) for cancer treatment is limited by normal tissue toxicity and by the intrinsic or acquired radioresistance of many tumours. Therefore, continuing efforts are conducted to identify radiosensitising agents that preferentially sensitise tumour cells to the cytotoxic action of RT. Recent progresses in molecular oncology have uncovered an array of novel targets, which may be exploited for RT enhancement.

OBJECTIVE

To survey the patent literature of the past 4 years pertaining to the development of molecularly targeted agents as potential tumour radiosensitisers.

METHODS

Patents were searched with a set of relevant keywords using several search engines. A Medline search on the same topics was performed in parallel.

RESULTS/CONCLUSION

A total of 48 patents/applications were selected. These concerned agents target molecular components of pathways involved in DNA damage repair, cell growth and survival signalling, apoptosis modulation and tumour angiogenesis. Current trials of some of these agents may reveal their value as clinical radiosensitisers.

The interaction of radiation therapy and antiangiogenic therapy

Since its beginning in the early 1970s, the field of angiogenesis research has grown rapidly and it has now become apparent that the endothelial cell is a critical regulator of the malignant phenotype. Multiple antiangiogenic agents have now been used in the clinic yet a better understanding of the process of angiogenesis is still needed before these agents can be successfully incorporated into clinical practice. Although antiangiogenic agents offer great therapeutic potential, preclinical and clinical studies suggest that these agents will have a delayed onset of activity and may only induce disease stabilization for patients with advanced malignancy. The use of radiation therapy for cancer is also associated with therapeutic challenges that are distinct from those that might be expected with antiangiogenic agents. Thus, the use of angiogenesis inhibitors in combination with radiation therapy should help to overcome the limitations of each leading to enhanced efficacy and diminished toxicity. The goal of this review is to provide an update of ongoing progress and current challenges related to the use of angiogenesis inhibitors with radiation therapy.

EGFR Inhibition in the Treatment of Non-Small Cell Lung Cancer

Epidermal growth factor receptor (EGFR) inhibitors have introduced the concept of targeted therapy to the treatment of non-small cell lung cancer (NSCLC). These agents appear most effective in patients with tumors that are highly dependent on EGFR signaling pathways, a population that disproportionately includes females, nonsmokers, individuals of East Asian origin, and patients with adenocarcinoma histology. Currently available EGFR-inhibiting drugs include the tyrosine kinase inhibitors (TKIs) erlotinib, gefitinib, and lapatinib, which are administered orally and interfere with the intracellular tyrosine kinase domain, and the monoclonal antibodies (mAbs) cetuximab and panitumumab, which are administered intravenously and interfere with extracellular ligand binding. While the use of EGFR TKIs as monotherapy prolongs survival in metastatic NSCLC, they have demonstrated no benefit when added to conventional, cytotoxic chemotherapy. In contrast, the anti-EGFR mAb cetuximab appears most effective when combined with chemotherapy or radiation. Despite dramatic initial responses to treatment in some cases, NSCLC eventually becomes resistant to EGFR inhibition. Possible mechanisms include secondary mutations that interfere with drug binding, oncogenic pathways driven by other receptor tyrosine kinases, and independent activity of downstream signaling molecules. Efforts to overcome such resistance include irreversibly binding EGFR TKIs, multi-targeted TKIs, and combinations with chemotherapy, radiation, and other targeted therapies.