The major goal of the proposed studies is to test the hypothesis that a recombinant adenovirus expressing the tumor associated antigen GA733 (Ad.GA733-2) can be utilized to elicit a GA733 antigen-specific immune response in patients with metastatic colorectal cancer. The first step will be to produce Ag.GA733-2 for clinical use and to perform preclinical toxicity studies. Administration of Ag.GA733-2 and the mouse homologue Ad.mEGP will be performed in BALB/C mice. The intraperitoneal route will be utilized for the preclinical and clinical studies unless ongoing and future experiments demonstrate that the intradermal/subcutaneous route is efficacious. A range of virus doses will be tested in these animals. We will define the toxicity of this therapy by clinical parameters as well as necropsy. We will then perform a phase I study of intraperitoneal injection of Ad.GA733-2 in humans with metastatic colorectal cancer. We will define the toxicities of this treatment in humans at a range of dose levels as determined in the preclinical toxicity testing. We will define the toxicities of this treatment in humans at a range of dose levels as determined in the preclinical toxicity testing. We will attempt to determine the dose-limiting toxicities of this treatment in humans at a range of dose levels as determined in the preclinical toxicity testing. We will attempt to determine the dose-limiting toxicities and the mechanisms of toxicity of this treatment. As well, all patients treated will undergo extensive immunologic testing to determine the ability of intraperitoneal vaccination with Ad.GA733-2 to induce humoral and/or cellular immune responses (Project 4). We will also assess objective anti-tumor responses in these patients. Subsequent vaccination trials in metastatic colorectal cancer patients will be based upon the results of this phase I trial and Project 2. We anticipate, based on preliminary data obtained in mice, to conduct a subsequent phase I trial that focuses upon the combination of Ad.GA733-2 and interleukin-2. Future phase I trials may incorporate new vaccination strategies derived from Projects 1,2, and 4.
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