oxi-4503 and Liver-Neoplasms

Preclinical research indicate that vascular disrupting agent (VDA) treatment induces extensive tumor death but also a systemic mobilization of bone marrow derived cells including endothelial progenitor cells (EPC) leading to revascularization and renewed growth within the residual tumor. This study investigates if combination of VDA with the anti-angiogenic agent Sunitinib increases the treatment efficacy in a colorectal liver metastases mouse model.. CBA mice with established liver metastases were given a single dose of OXi4503 at day 16 post tumor induction, a daily dose of Sunitinib starting at day 14 or day 16 post tumor induction or a combination of Sunitinib given daily from day 14 or day 16 post tumor induction in combination with a single dose of OXi4503 at day 16. Treatment was terminated at day 21 post tumor induction and its effects were assessed using stereological and immunohistochemical techniques. Long term effects were assessed in a survival study.. Combination with long (7 day) Sunitinib treatment lead to liver toxicity but this was ameliorated in the shorter (5 day) treatment without significantly altering the effects on tumor reduction. Combination treatment resulted in significant reduction of viable tumor, reduction in tumor vasculature, reduction in tumor proliferation, increase in tumor apoptosis and prolonged mouse survival compared to control and single arm treatments. Complete tumor eradication was not achieved. Redistribution of E-cadherin and strong up regulation of ZEB1 and Vimentin were observed in the surviving tumor; indicative of epithelial to mesenchymal transition (EMT), a mechanism that could contribute to tumor resistance.. Combination treatment significantly reduces viable tumor and prolongs animal survival. EMT in the surviving tumor may prevent total tumor eradication and could provide novel targets for a more lasting treatment.

Topics: Angiogenesis Inhibitors; Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Cadherins; Chemical and Drug Induced Liver Injury; Colorectal Neoplasms; Diphosphates; Epithelial-Mesenchymal Transition; Humans; Indoles; Liver Neoplasms; Male; Mice; Mice, Inbred CBA; Protein Kinase Inhibitors; Pyrroles; Stilbenes; Sunitinib; Vimentin; Xenograft Model Antitumor Assays; Zinc Finger E-box-Binding Homeobox 1

We aimed to test the ability of texture analysis to differentiate the spatial heterogeneity of (125)I-A5B7 anti-carcinoembryonic antigen antibody distribution by nano-single photon emission computed tomography (SPECT) in well-differentiated (SW1222) and poorly differentiated (LS174T) hepatic metastatic colorectal cancer models before and after combretastatin A1 di-phosphate anti-vascular therapy.. Nano-SPECT imaging was performed following tail vein injection of 20 MBq (125)I-A5B7 in control CD1 nude mice (LS174T, n=3 and SW1222, n=4), and CA1P-treated mice (LS174T, n=3; SW1222, n=4) with liver metastases. Grey-level co-occurrence matrix textural features (uniformity, homogeneity, entropy and contrast) were calculated in up to three liver metastases in 14 mice from control and treatment groups.. Before treatment, the LS174T metastases (n=7) were more heterogeneous than SW1222 metastases (n=12) (uniformity, P=0.028; homogeneity, P=0.01; contrast, P=0.045). Following CA1P, LS174T metastases (n=8) showed less heterogeneity than untreated LS174T controls (uniformity, P=0.021; entropy, P=0.006). Combretastatin A1 di-phosphate-treated SW1222 metastases (n=11) showed no difference in texture features compared with controls (all P>0.05).. Supporting the potential for novel imaging biomarkers, texture analysis of (125)I-A5B7 SPECT shows differences in spatial heterogeneity of antibody distribution between well-differentiated (SW1222) and poorly differentiated (LS174T) liver metastases before treatment. Following anti-vascular treatment, LS174T metastases, but not SW1222 metastases, were less heterogeneous.

Topics: Angiogenesis Inhibitors; Animals; Antibodies, Monoclonal; Carcinoembryonic Antigen; Cell Line, Tumor; Colorectal Neoplasms; Diphosphates; Female; Heterografts; Humans; Iodine Radioisotopes; Liver Neoplasms; Mice; Mice, Nude; Neoplasm Metastasis; Phenotype; Radiopharmaceuticals; Stilbenes; Tomography, Emission-Computed, Single-Photon

Epithelial to mesenchymal transition (EMT) is considered an important mechanism in tumor resistance to drug treatments; however, in vivo observation of this process has been limited. In this study we demonstrated an immediate and widespread EMT involving all surviving tumor cells following treatment of a mouse model of colorectal liver metastases with the vascular disruptive agent OXi4503. EMT was characterized by significant downregulation of E-cadherin, relocation and nuclear accumulation of β-catenin as well as significant upregulation of ZEB1 and vimentin. Concomitantly, significant temporal upregulation in hypoxia and the pro-angiogenic growth factors hypoxia-inducible factor 1-alpha, hepatocyte growth factor, vascular endothelial growth factor and transforming growth factor-beta were seen within the surviving tumor. The process of EMT was transient and by 5 days after treatment tumor cell reversion to epithelial morphology was evident. This reversal, termed mesenchymal to epithelial transition (MET) is a process implicated in the development of new metastases but has not been observed in vivo histologically. Similar EMT changes were observed in response to other antitumor treatments including chemotherapy, thermal ablation, and antiangiogenic treatments in our mouse colorectal metastasis model and in a murine orthotopic breast cancer model after OXi4503 treatment. These results suggest that EMT may be an early mechanism adopted by tumors in response to injury and hypoxic stress, such that inhibition of EMT in combination with other therapies could play a significant role in future cancer therapy.

Topics: Angiogenic Proteins; Animals; Antineoplastic Agents; Apoptosis; beta Catenin; Cadherins; Cell Hypoxia; Colorectal Neoplasms; Diphosphates; Down-Regulation; Epithelial-Mesenchymal Transition; Female; Gene Expression Regulation, Neoplastic; Humans; Liver Neoplasms; Male; Mammary Neoplasms, Experimental; Mice; Mice, Inbred BALB C; Mice, Inbred CBA; Neoplasm Proteins; Neoplasm Transplantation; Neoplasm, Residual; Stilbenes; Up-Regulation

Treatment of solid tumors with vascular disrupting agent OXi4503 results in over 90% tumor destruction. However, a thin rim of viable cells persists in the tumor periphery following treatment, contributing to subsequent recurrence. This study investigates inherent differences in the microenvironment of the tumor periphery that contribute to treatment resistance.. Using a murine colorectal liver metastases model, spatial morphological and molecular differences within the periphery and the center of the tumor that may account for differences in resistance to OXi4503 treatment were investigated. H&E staining and immunostaining were used to examine vessel maturity and stability, hypoxia and HIF1α levels, accumulation of immune cells, expression of proangiogenic factors/receptors (VEGF, TGF-β, b-FGF, and AT1R) and expression of EMT markers (ZEB1, vimentin, E-cadherin and β-catenin) in the periphery and center of established tumors. The effects of OXi4503 on tumor vessels and cell kinetics were also investigated.. Significant differences were found between tumor periphery and central regions, including association of the periphery with mature vessels, higher accumulation of immune cells, increased growth factor expression, minimal levels of hypoxia and increased evidence of EMT. OXi4503 treatment resulted in collapse of vessels in the tumor center; however vasculature in the periphery remained patent. Similarly, tumor apoptosis and proliferation were differentially modulated between centre and periphery after treatment.. The molecular and morphological differences between tumor periphery and center may account for the observed differential resistance to OXi4503 treatment and could provide targets for drug development to totally eliminate metastases.

Topics: Animals; Antineoplastic Agents; Apoptosis; beta Catenin; Cadherins; Cell Hypoxia; Cell Line, Tumor; Cell Proliferation; Colorectal Neoplasms; Diphosphates; Drug Resistance, Neoplasm; Fibroblast Growth Factors; Homeodomain Proteins; Hypoxia-Inducible Factor 1, alpha Subunit; Kruppel-Like Transcription Factors; Liver Neoplasms; Male; Mice; Mice, Inbred CBA; Stilbenes; Transforming Growth Factor beta; Tumor Microenvironment; Vascular Endothelial Growth Factor A; Vimentin; Zinc Finger E-box-Binding Homeobox 1

OXi4503 retards tumor growth in a dose-dependent manner and improves survival in a murine model of colorectal liver metastases. This agent causes extensive vascular shutdown by selectively altering the tubulin cytoskeleton within the endothelial cells of tumor vessels. The destruction of tumor vessels is incomplete, however, and tumor revascularization occurs after the treatment. This study evaluates the pattern of microcirculatory changes and alterations to the ultrastructural properties of the tumor vasculature that result from OXi4503 treatment. Male CBA mice were induced with liver metastases via an intrasplenic injection of a murine-derived colorectal cell line. After administering a single intraperitoneal dose of OXi4503, changes in tumor perfusion, microvascular architecture and permeability were assessed at various time points. One hour after a 100-mg/kg dose of OXi4503, a significant decrease in the percentage of tumor perfusion (63.96+/-1.98 in controls versus 43.77+/-2.71 in treated mice, P<0.001) was observed, which was still evident 5 days after the treatment. Substantial tumor microvascular damage and minimal normal liver injury were observed. Tumor vascular permeability was significantly elevated 45 min after the OXi4503 treatment (67.5+/-3.60 in controls versus 80.5+/-2.24 microg/g, P<0.05). The findings suggest that OXi4503 selectively targets tumor vessels and causes immediate microvascular destruction. Even at the maximum tolerated dose, however, residual patent tumor vessels were still present after treatment, implying incomplete tumor destruction. A combination of OXi4503 with other chemotherapeutic modalities might achieve complete tumor eradication and improve long-term survival.

Topics: Angiogenesis Inhibitors; Animals; Blood Vessels; Capillaries; Capillary Permeability; Carcinogens; Colorectal Neoplasms; Dimethylhydrazines; Diphosphates; Evans Blue; Laser-Doppler Flowmetry; Liver Neoplasms; Male; Mice; Mice, Inbred CBA; Microscopy, Confocal; Microscopy, Electron, Scanning; Regional Blood Flow; Stilbenes; Tissue Fixation