Hepatocelluar carcinoma (HCC) is a leading cause of cancer death worldwide. There are essentially no effective systemic therapies for this disease and relapses aider local therapies are very common. In previous work we have shown that both the murine and human T cell repertoires can recognize alpha fetoprotein (AFP)-derived peptide epitopes in the context of MHC. In a murine tumor model of genetic immunotherapy, AFP can serve as a tumor rejection antigen. In an extensive mapping of human AFP we have identified 4 immunodominant peptide epitopes in the context of HLA-A2.1. We have initiated a clinical trial testing their safety and immunogenicity. In this proposal, I request support to continue this translational research with two specific aims:
AIM 1. AFP IMMUNOTHERAPY CLINICAL TRIALS FOR HCC. (1) AFP Peptide Dendritic Cell Trial. Patients with HCC whose tumors produce AFP and are HLA-A2.1 will be immunized, in a dose-escalation phase I/II trial, with dendritic cells (DC) pulsed with four immunodominant AFP peptides. The main goals are determination of safety and an optimal dose. Trial monitoring includes a careful immunological analysis, using ELISPOT and tetramer assays, to develop biomarkers of effective immunization for further clinical testing of our original hypothesis of the immunogenicity of AFP. (2) AFP-Engineered Dendritic Cell Trial. In this phase I/II trial, patients with AFP+ HCC will be immunized with autologous DC transduced with a recombinant adenovirus vector expressing human AFP. This is the most powerful means of antitumor AFP-based immunization in our preclinical models. Immunological monitoring will include the determination of T cell responses to immunodominant and subdominant epitopes.
AIM 2. PRECLINICAL TESTING OF AFP DNA-BASED VACCINES. DNA-based vaccines can generate T cell responses and protective immunity and have clear practical advantages over DC-based vaccines. However, the levels of protection observed thus, far with AFP plasmid or AFP virus alone are inferior to gene-modified DC. I propose to use the same animal models that have allowed the development of the clinical trials in Aim 1 to test promising avenues aimed at enhancing the immune stimulatory ability of DNA-based vaccines. These approaches include the addition of a GM-CSF expression cassette, the use of Sindbis backbones, and/or boosting antigen-specific responses with replication incompetent viral vectors (prime-boost strategy). In summary, I propose a clinically-oriented research program that translates this original work into novel, evidence-based immnunotherapy trials for hepatocellular carcinoma.
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