GENE-MODIFIED DENDRITIC CELLS FOR TUMOR IMMUNOTHERAPY

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DESCRIPTION: (Applicant's Abstract) Infection with human papilloma viruses (HPV) has become a major public health concern because of their high prevalence, increasing incidence, and oncogenicity. HPV-mediated oncogenicity has been mapped to the E6 and E7 open reading frames and has been associated with more than 90% of cervical carcinomas. Although E6 and E7 expressed from HPV-transformed cells can serve as effective targets for cytotoxic responses in animal models, natural cell mediated immunity to HPV in humans is surprisingly poor. Recently, dendritic cells (DC) have been identified as potent, professional APC which stimulate T cells to recognize and respond to specific antigens. Peptide pulsed DC have been shown to generate potent antitumor cytotoxic responses in animal models and one human trial. Peptide epitopes are presented by DC in association with HLA molecules, with different HLA alleles associating with different peptides. However, the identification of peptides with immunogenic epitopes which can be presented in association with the vast array of HLA alleles in the population is an arduous task. Thus the introduction of genes encoding the immunogen of interest into DC and the subsequent selection of optimal epitopes by DC T cell interactions is attractive for the generation of immunity. However gene transfer into human DC by transfection or retroviral transduction has proven difficult due to their non-proliferative status. Adeno-associated virus (AAV) vectors have recently been identified as highly promising vehicles for gene therapy because of their wide host range, lack of cytopathogenicity, stable integration, and ability to transduce nonproliferating cellular targets. The applicant has demonstrated sustained and efficient transduction of primary human monocyte-macrophages, also APCs closely related to DCs in function and ontogeny. In this study she will test the induction of HLA-restricted, antigen-specific CTL following introduction of the HPV E7 transforming gene into DC by AAV vector transduction. In vivo transplantation of syngeneic transduced murine DC will be tested for protection from tumor challenge and effects on previously existing tumors as well as for the induction of memory responses. Lastly, DCs from patients with HPV16+ cervical cancers will be transduced with AAV-E7 and tested for their ability to generate CTL which lyse autologous tumor cells. These studies will 1) test the generation of tumor-specific immunity following AAV vector transduction of the gene encoding the immunogen into DCs, 2) potentially simplify and facilitate the development of molecular vaccines, 3) provide important preclinical information regarding the use of AAV vectors for tumor immunotherapy and may form the groundwork for the development of gene-based immune strategies against cancer.