2-(2-nitro-1h-imidazol-1-yl)-n-(2-2-3-3-3-pentafluoropropyl)acetamide and Colonic-Neoplasms

The endothelin-1 antagonist, Atrasentan (ABT-627) was used to modify perfusion in the human tumor xenograft model, HT29, growing in nude mice. Atrasentan produced a significant increase in perfusion, as measured in vivo by Gd-DTPA DCE-MRI. Changes in tumor hypoxia were assessed by comparing the binding of two hypoxia tracers, pimonidazole and EF5 given before and after Atrasentan administration. In vehicle-treated controls, the distribution of EF5 and pimonidazole was very similar. However, Atrasentan treatment was associated with decreased uptake of the second hypoxia tracer (EF5), relative to the first (pimonidazole). Although Atrasentan had no independent effect on the growth of HT29 tumors, Atrasentan combined with 20 Gy radiation led to a modest but significant increase in tumor growth delay compared to radiation alone.

Topics: Adenocarcinoma; Animals; Atrasentan; Colonic Neoplasms; Combined Modality Therapy; Etanidazole; Gadolinium DTPA; HT29 Cells; Humans; Hydrocarbons, Fluorinated; Hypoxia; Magnetic Resonance Imaging; Male; Mice; Mice, Nude; Nitroimidazoles; Perfusion; Pyrrolidines; Radiation-Sensitizing Agents; Radiotherapy; Treatment Outcome; Xenograft Model Antitumor Assays

Response to photodynamic therapy depends on adequate tumor oxygenation as well as sufficient accumulation of photosensitizer in the tumor. The goal of this study was to investigate the presence of hypoxia and retention of the photosensitizer Photofrin in the tumors of patients with intra-abdominal carcinomatosis or sarcomatosis.. Tumor nodules from 10 patients were studied. In nine of these patients, hypoxia was identified in histological sections of biopsied tumor after administration of the hypoxia marker 2-(2-nitroimidazol-1[H]-yl)-N-(2,2,3,3,3-pentafluoropropyl)acetamide (EF5). In separate tumor nodules from 10 patients, Photofrin uptake was measured by fluorescence after tissue solubilization.. Hypoxia existed in the tumors of five patients, with three of these patients demonstrating at least one severely hypoxic nodule. Physiological levels of oxygen were present in the tumors of four patients. An association between tumor size and hypoxia was not evident because some tumor nodules as small as approximately 2 mm in diameter were severely hypoxic. However, even these tumor nodules contained vascular networks. Three patients with severely hypoxic tumor nodules exhibited moderate levels of Photofrin uptake of 3.9 +/- 0.4 to 3.9 +/- 0.5 ng/mg (mean +/- SE). The four patients with tumors of physiological oxygenation did not consistently exhibit high tumor concentrations of Photofrin: mean +/- SE drug uptake among these patients ranged from 0.6 +/- 0.8 to 5.8 +/- 0.5 ng/mg.. Carcinomatosis or sarcomatosis of the i.p. cavity may exhibit severe tumor hypoxia. Photofrin accumulation in tumors varied by a factor of approximately 10x among all patients, and, on average, those with severe hypoxia in at least one nodule did not demonstrate poor Photofrin uptake in separate tumor samples. These data emphasize the need for reconsideration of the generally accepted paradigm of small tumor size, good oxygenation, and good drug delivery because this may vary on an individual tumor basis.

Topics: Appendiceal Neoplasms; Benzimidazoles; Binding, Competitive; Carbocyanines; Colonic Neoplasms; Dihematoporphyrin Ether; Etanidazole; Female; Gastrointestinal Neoplasms; Gastrointestinal Stromal Tumors; Humans; Hydrocarbons, Fluorinated; In Vitro Techniques; Intestine, Small; Male; Microscopy, Fluorescence; Ovarian Neoplasms; Oxygen; Photochemotherapy; Sarcoma

HCT116 human colon carcinoma xenografts were grown in nude mice. Frozen sections of control and irradiated tumors were stained and analysed for the distribution and extent of hypoxia and apoptosis. Tissue oxygen partial pressure was measured by immunohistochemical staining of hypoxia-dependent metabolites of the 2-nitroimidazole EF5. Apoptosis was assessed using a commercial kit which stains damaged DNA. Although the apoptosis stain was unlikely to exclude other forms of cell death (necrosis, pyknosis) all staining was found to associate with regions of near anoxia.

Topics: Animals; Apoptosis; Calibration; Cell Hypoxia; Colonic Neoplasms; DNA Damage; Etanidazole; Humans; Hydrocarbons, Fluorinated; Indicators and Reagents; Mice; Mice, Nude; Microscopy, Fluorescence; Oxygen; Partial Pressure; Tumor Cells, Cultured

Topics: Animals; Animals, Newborn; Antibodies, Monoclonal; Brain Ischemia; Colonic Neoplasms; Etanidazole; Humans; Hydrocarbons, Fluorinated; Hypoxia; Hypoxia, Brain; Immunohistochemistry; Male; Mice; Mice, Inbred C57BL; Mice, Nude; Myocardial Infarction; Rats; Rats, Sprague-Dawley; Transplantation, Heterologous; Tumor Cells, Cultured

We have investigated the hypoxia inducibility of vascular endothelial growth factor (VEGF) in multicellular tumor spheroids of HT29 cells using a monoclonal antibody to a fluorinated bioreductive drug, EF5 [2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)aceta mide], a chemical probe for hypoxia. We have shown that VEGF expression is predominantly localized in interior spheroid cells that are sufficiently hypoxic to bioreductively activate the 2-nitroimidazole and produce immunologically detectable adducts of the EF5 compound. Northern blotting analyses demonstrated that VEGF165 is the predominant form of VEGF produced by HT29 cells and that the phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate did not induce VEGF expression. This study demonstrates that VEGF expression is up-regulated in response to hypoxia and in the microenvironments found in human multicellular tumor spheroids. This investigation also illustrates the utility of the EF5 binding in multi-cellular tumor spheroids as a means of studying the expression and regulation of hypoxia-inducible genes.

Topics: Carcinoma; Colonic Neoplasms; Endothelial Growth Factors; Etanidazole; Gene Expression Regulation, Neoplastic; Humans; Hydrocarbons, Fluorinated; Hypoxia; In Situ Hybridization; Indicators and Reagents; Lymphokines; Neovascularization, Pathologic; Organoids; RNA, Messenger; RNA, Neoplasm; Tumor Cells, Cultured; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors