This laboratory in investigating the potential use of recombinant TNF as an antineoplastic agent using surgical isolation perfusion techniques to obtain high intravascular levels in clinical trials of limb and liver perfusion. Tissue specimens from the clinical trials taken before and after perfusion treatment, large animal studies, murine tumor models including xenografts in nude mice as well as a variety of murine tumors, tumor cell lines in vitro, and endothelial cells in culture are all being used as reagents to investigate the antitumor effects seen in the clinical trials of regional perfusion. Sequential biopsies from the clinical trials of melanoma have shown that there is a very rapid and specific necrosis in the tumor which spares adjacent normal tissue. This necrosis occurs without any evidence of fibrin or thrombus within the tumor microvasculature. Immunohistochemistry studies for adhesion molecules show an upregulation of ICAM, VCAM and ELAM in tumor vessels. Large animal studies combining chemotherapeutic agents with high-dose tumor necrosis factor in our isolated liver perfusion model in the pig are underway. These preclinical studies serve as a precursor to the second phase of the clinical trials in which a chemotherapy drug will be added to TNF liver perfusion. Studies using murine models are investigating the synergistic reactions between TNF and chemotherapeutic agents as well as using these tumor models to evaluate the mechanism of TNF activity in vivo. The impact of anticoagulation on the TNF antitumor response is being studied in these murine models. Possible correlation between tumor expression of angiogenic growth factors such as VEGF and EMAP and response to TNF treatment is under investigation. In vitro studies are underway using endothelial cells(HUVEC) evaluating both the production of tissue factor as well as the expression of cell culture adhesion molecules after treatment with TNF. Both of these endpoints are dramatically increased in a synergistic manner when TNF is combined with tumor supernatant and the factors that contribute to this synergistic reaction are being evaluated. Also the combined effects of chemotherapeutic agents as well as TNF on endothelial cell viability in the presence or absence of tumor supernatant is being studied.
