Vaccine development for oral carcinoma is a major objective in our laboratories. In response to the PAR-99-158, we propose to perform phase I pilot clinical trial, using a novel DNA-based vaccination strategy. The vaccine is prepared by transferring tumor-derived DNA to a highly immunogenic cell line, which is genetically-modified to secrete interleukin-2 (IL-2) and which expresses both foreign class I MHC antigens and those shared with the donor of tumor DNA (HLA-A2). This type of cancer vaccine is based on the principle that tumor-associated antigens (TAAs) are products of mutated or dysregulated genes, which can be transferred from one cell type to another and stably expressed, altering the genotype and phenotype of the recipient cell. Our preliminary data in murine models of tumor growth indicate that the DNA-based vaccines induce strong antitumor immune responses and immunologic memory, leading to tumor rejection. We now propose to perform a phase I clinical trial for patients with advanced recurrent oral carcinoma, who will receive a series of autologous tumor DNA-based vaccines following surgery. The primary endpoints will be safety, toxicity and feasibility of generating the vaccine. The secondary objective will be induction and evaluation of the immune response against the autologous tumor. To implement this vaccination strategy, a master bank of IL-2 secreting semi-allogeneic HLA-A2 squamous cell carcinoma of the head and neck (SCCHN) cells will be prepared and tested for safety. These cells will serve as recipients of DNA derived from each patient's autologous tumor. After co-transfection of DNA and a hygromycin-resistance plasmid into the recipient cells, selection will be performed, and the transfected cells will be expanded, irradiated and delivered as a vaccine. Patients will be monitored prior to and after vaccination for the frequency of tumor-specific CD8+ and CD4+t cells in the peripheral circulation, using ELISPOT assays. Immunocompetence of patients will also be monitored. Additionally, preclinical studies will be performed using the vaccine presented by dendritic cells (DC) to T cells obtained from the DNA donor in order to demonstrate ex vivo generation of autotumor-specific T-cell responses. The preclinical studies will complement the clinical trial by providing insights into the mechanisms of tumor rejection and optimize conditions for monitoring of T-cell responses to this form of vaccine. It is expected that the vaccine combining several of the known requirements for generation of antitumor immune responses, namely, improved TAA presentation, allogeneic stimulation and IL-2 secretion, will benefit patients with oral carcinoma.
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