Hepatocellular carcinoma (HCC) is a leading cause of cancer death globally and there are essentially no effective systemic therapies for this disease. In the previous grant period, we made several novel observations about the immunobiology of this malignancy. Both the murine and human T cell repertoires can recognize alpha fetoprotein (AFP), an oncofetal protein produced by a majority of HCC. In a murine tumor model of genetic immunotherapy, AFP can serve as a tumor rejection antigen. We have performed extensive epitope mapping of hAFP and have identified 4 immunodominant and as many as 10 subdominant peptide epitopes in the context of HLA-A2.1. Finally, we have initiated an AFP peptide trial in patients with HCC and are able to detect T cell responses to these immunodominant peptide epitopes. In this competitive renewal, we request support to continue this translational research program with three specific aims:
Aim 1. AFP Peptide Clinical Trial. In this phase I/II trial, AFP/A2.1-positive HCC patients are immunized with four immunodominant AFP peptides [hAFP137-145, hAFP158-166, hAFP325-334 and hAFP542-550] emulsified in incomplete Freund's adjuvant. Peripheral T cell responses will be measured by ELISPOT and tetramer assays. This study will allow us to determine if AFP-derived peptides are immunogenic in vivo.
Aim 2. AFP-Engineered Dendritic Cell Trial. In this phase I/II trial, patients will be immunized with autologous dendritic cells (DC) transduced with a recombinant adenovirus vector expressing human AFP. T cell responses to immunodominant and subdominant epitopes will be measured. In this clinical trial, we will determine whether tumor antigen-engineered DC can generate polyclonal responses in vivo.
Aim 3. Construction and Preclinical Testing of AFP DNA Vaccines. Plasmid-based DNA vaccines are capable of generating strong T cell responses and protective immunity. We propose to modify our first generation AFP DNA vaccine to improve these responses and test them in both protection and hepatocarcinogenesis models. In summary, we propose a largely clinically-directed research program that translates this original work into novel, evidence-based immunotherapy trials for hepatocellular carcinoma.
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