zd-6126 and Disease-Models--Animal

ZD6126 is a vascular-disrupting agent that affects the endothelial tubulin cytoskeleton causing selective occlusion of tumor vasculature and extensive tumor cell necrosis. The present study evaluated the antitumor and antivascular activities of ZD6126 in the clinically relevant murine renal cell carcinoma (RENCA) model and also evaluated biological response to therapy using color Doppler imaging as biomarker. Mice were implanted with RENCA tumor cells (day 0) and established tumors were treated with ZD6126 (100 mg/kg i.p.) or vehicle with repeated intermittent doses on day 10, 14 and 18. ZD6126 treatment led to a significant reduction in tumor size and was associated with extensive tumor necrosis and a reduction in tumor blood flow versus controls. MVD increased with intermittent treatment (day 10, 14 and 18). In an additional study, animals were treated at day 19 and quantitative three-dimensional microvascular corrosion casting was performed to enable detailed assessment of the tumor vascular architecture. Corrosion casting showed that tumor vessel architecture is affected by treatment, whereas pre-existing vessels in control tissues are practically not affected. Inter-vessel and inter-branch distances as well as vessel diameters are influenced by treatment. In conclusion, ZD6126 showed potent antitumor efficacy in the RENCA model and our data suggest that decrease in tumor blood flow may be a useful surrogate marker of treatment effect.

Topics: Adenocarcinoma; Animals; Apoptosis; Blotting, Western; Carcinoma, Renal Cell; Cell Line, Tumor; Cell Proliferation; Disease Models, Animal; Female; Immunoenzyme Techniques; Kidney Neoplasms; Lung Neoplasms; Mice; Mice, Inbred BALB C; Mice, Nude; Neovascularization, Pathologic; Organophosphorus Compounds

Endostatin is an anti-angiogenic agent that blocks endothelial cell proliferation, tumor growth, and metastasis. Several lines of direct evidence show that gliomas express high levels of endostatin. However, the anti-angiogenic activity and cellular mechanisms of endostatin from tumor cells have not been completely elucidated. In this study, we established C6 glioblastoma (GBM) xenografts in nude mice by subcutaneously injecting glioma cell lines, C6-null cells, and stable transfected-C6 cells overexpressing mock vector (C6-mock) and endostatin (C6-endo). We found that overexpression of endostatin in C6-endo cells significantly suppressed the expression of VEGF in tumor cells in vivo as well as in vitro. Furthermore, the tumor growth derived from C6-endo cells was inhibited. Our data demonstrate that endostatin could play a direct role in inhibiting tumor cells, and suggest that enhancing endostatin expression in gliomas could be an effective treatment strategy.

Topics: Adenocarcinoma; Angiogenesis Inhibitors; Animals; Apoptosis; Blotting, Western; Brain Neoplasms; Cell Line, Tumor; Cell Proliferation; Disease Models, Animal; Down-Regulation; Endostatins; Gene Expression; Genetic Vectors; Glioblastoma; Immunoenzyme Techniques; Lung Neoplasms; Male; Mice; Mice, Inbred BALB C; Mice, Nude; Organophosphorus Compounds; Rats; Vascular Endothelial Growth Factors

Antivascular agents that act by destabilizing microtubules, such as ZD6126 (N-acetylcolchinol-O-phosphate), are associated with adverse cardiovascular effects, including transient hypertension, cardiac ischemia, myocardial infarction, and increases in circulating levels of markers of cardiac damage (e.g., troponins). We investigated mechanisms underlying these effects of ZD6126 in rats by continuously monitoring their heart rate and blood pressure and by assessing heart histopathology and plasma troponin T levels. ZD6126 induced acute transient hemodynamic changes (hypertension and delayed tachycardia), which were associated with statistically significant increases in circulating troponin T levels (median level 3 hours after treatment with vehicle or 12.5 mg/kg ZD6126: <9 pg/mL and 563 pg/mL, respectively; P <.001 [two-sided Wilcoxon rank sum test]) and in the incidence of left ventricular myocardial fiber necrosis (incidence 24 hours after treatment with vehicle or 12.5 mg/kg ZD6126: 0/10 rats and 9/10 rats, respectively; P <.001 [two-sided Wilcoxon rank sum test]). Pretreatment of rats with atenolol and nifedipine ameliorated the acute hemodynamic changes and prevented ZD6126-induced increases in both troponin T and myocardial necrosis but did not prevent ZD6126-induced tumor necrosis in an Hras5 tumor xenograft model in nude rats. Our findings suggest that ZD6126-induced acute hemodynamic changes are a prerequisite for cardiac damage in rats.

Topics: Adrenergic beta-Antagonists; Animals; Anti-Arrhythmia Agents; Antihypertensive Agents; Antineoplastic Agents; Atenolol; Biomarkers; Calcium Channel Blockers; Disease Models, Animal; Drug Administration Schedule; Female; Heart; Hemodynamics; Hypertension; Myocardium; Neoplasms; Nifedipine; Organophosphorus Compounds; Random Allocation; Rats; Tachycardia; Transplantation, Heterologous; Troponin T; Vasodilator Agents

The purpose of this study was to examine the effects of ZD6126, a novel vascular-targeting agent, on tumour growth and angiogenesis in an orthotopic model of gastric cancer. TMK-1 human gastric adenocarcinoma cells were injected into the gastric wall of nude mice. After the tumours were established (day 14), therapy was initiated. Mice (n=11-12/group) received (a). vehicle, (b). ZD6126 at 100 mg x kg day(-1) i.p. one time per week or (c) ZD6126 at 100 mg x kg day(-1) i.p. five times per week. Tumour mass, volume and the presence or absence of peritoneal carcinomatosis were determined at sacrifice on day 38. Tumours from each group were stained for markers of blood vessels, proliferation and apoptosis. To further define the time frame of the vascular-targeting effects of chronic therapy with ZD6126, TMK-1 cells were again injected into the gastric wall of mice in a second experiment. On day 14, a single i.p. injection of ZD6126 100 mg x kg(-1) mouse(-1) or vehicle was delivered. Groups of three mice each were killed and the tumours harvested at days 1, 3 and 5 post-ZD6126 injection. Tumours were processed and stained for endothelial and tumour cell apoptosis and proliferation. No overt toxicity was observed with ZD6126 therapy. ZD6126 led to a marked inhibition of tumour growth (82% decrease vs control (P<0.001)). ZD6126 also led to a significant decrease in the incidence of peritoneal carcinomatosis (10 out of 12 controls, vs one out of 12 ZD6126) (P<0.01). Histological analysis of tumours revealed large regions of central necrosis in the treated group, as well as a dramatic increase in tumour cell apoptosis (7.4-fold increase (P<0.001)), consistent with the vascular-targeting activity of ZD6126. Mice treated with ZD6126 demonstrated a 59% decrease in PCNA-positive cells (P< 0.02), indicating reduced tumour cell proliferation. In addition, tumours treated with ZD6126 exhibited a 40% decrease in microvessel density (P<0.05). Results from mice treated with a single injection of ZD6126 demonstrated the acute effects this agent has on the tumour vasculature. The ratio of endothelial cell apoptosis to endothelial cell proliferation was increased within 24 h of a single injection. In conclusion, ZD6126 significantly inhibited tumour growth and metastasis in an orthotopic model of human gastric adenocarcinoma, without detectable problematic adverse effects. These data suggest that ZD6126 may be worthy of investigation in the treatment of primary gastric adenocar

Topics: Adenocarcinoma; Animals; Apoptosis; Cell Division; Disease Models, Animal; Disease Progression; Endothelial Cells; Humans; Mice; Mice, Nude; Neoplasm Metastasis; Neovascularization, Pathologic; Organophosphorus Compounds; Peritoneal Neoplasms; Stomach Neoplasms; Tumor Cells, Cultured

Metastases require a functional blood supply for progressive growth. Thus, therapies that target metastatic vasculature have potential clinical utility. The effects of the vascular-targeting agent (VTA), ZD6126, and the anti-angiogenic agent, ZD6474, on vascular development and function within metastases were compared in an experimental liver metastasis model. Ras-transformed PAP2 fibroblasts were injected into the mesenteric veins of SCID mice to produce a control liver metastasis burden of approximately 40% at 14 days. Mice given a single dose of ZD6126 (200 mg/kg, i.p.) on day 13 were examined 24 h later. Histology revealed a significant reduction in metastatic burden, associated with extensive tumor necrosis, increased tumor cell apoptosis and a reduction in tumor-associated vasculature. In vivo videomicroscopy (IVVM) revealed disrupted, non-functional vascular channels within metastases, with no blood flow. Mice given ZD6474 on days 4 to 10 (50 mg/kg daily, oral gavage) were examined on day 11. Histology revealed a lower metastatic burden, significant reductions in metastasis size and vasculature, and a significant increase in tumor cell apoptosis. IVVM revealed extensive reductions in vascularity and blood flow within metastases. Neither ZD6126 nor ZD6474 treatment affected surrounding normal liver tissue. This study shows that both agents can reduce experimental liver metastasis with no apparent effect on normal vasculature. However, these reductions were attained through distinct effects on the metastatic vasculature. Understanding differences in the modes of action of VTAs and anti-angiogenic agents will be important in optimizing their clinical application and in developing appropriate combination strategies.

Topics: Angiogenesis Inhibitors; Animals; Apoptosis; Blood Vessels; Cell Line, Transformed; Disease Models, Animal; Female; Liver Neoplasms; Mice; Mice, SCID; Microscopy, Video; Neoplasm Metastasis; Neoplasm Transplantation; Neovascularization, Pathologic; Organophosphorus Compounds; Piperidines; Quinazolines

ZD6126 is a vascular targeting agent that disrupts the tubulin cytoskeleton of proliferating neo-endothelial cells. This leads to the selective destruction and congestion of tumour blood vessels in experimental tumours, resulting in extensive haemorrhagic necrosis. In this study, the dose-dependent activity of ZD6126 in rat GH3 prolactinomas and murine RIF-1 fibrosarcomas was assessed using two magnetic resonance imaging (MRI) methods. Dynamic contrast-enhanced (DCE) MRI, quantified by an initial area under the time-concentration product curve (IAUC) method, gives values related to tumour perfusion and vascular permeability. Multigradient recalled echo MRI measures the transverse relaxation rate T(2)*, which is sensitive to tissue (deoxyhaemoglobin). Tumour IAUC and R(2)* (=1/T(2)*) decreased post-treatment with ZD6126 in a dose-dependent manner. In the rat model, lower doses of ZD6126 reduced the IAUC close to zero within restricted areas of the tumour, typically in the centre, while the highest dose reduced the IAUC to zero over the majority of the tumour. A decrease in both MRI end points was associated with the induction of massive central tumour necrosis measured histologically, which increased in a dose-dependent manner. Magnetic resonance imaging may be of value in evaluation of the acute clinical effects of ZD6126 in solid tumours. In particular, measurement of IAUC by DCE MRI should provide an unambiguous measure of biological activity of antivascular therapies for clinical trial.

Topics: Animals; Area Under Curve; Biomarkers, Tumor; Disease Models, Animal; Dose-Response Relationship, Drug; Fibrosarcoma; Magnetic Resonance Imaging; Mice; Necrosis; Organophosphorus Compounds; Pituitary Neoplasms; Prolactinoma; Rats; Regional Blood Flow