Identification of Novel Α-Fetoprotein-specific T Cell Receptors to Redirect Human T Cells for Hepatocellular Carcinoma Immunotherapy

Abstract Hepatocellular carcinoma (HCC) is the major form of liver cancer for which there is no effective therapy. Genetic modification with T cell receptors (TCR) specific for HCC-associated antigens, such as α-fetoprotein (AFP), can potentially redirect human T cells to specifically recognize and kill HCC tumor cells to achieve antitumor effects. In this study, by using lentivector and peptide immunization, we identified a population of CD8-T cells in HLA-A2 transgenic AAD mice that recognized AFP158 epitope on human HCC cells. Adoptive transfer of the AFP158-specific CD8-T cells from immunized AAD mice eradicated HepG2 tumor xenografts as large as 2cm in diameter in immunocompromised NSG mice. We then established T cell hybridoma clones from the AFP158-specific mouse CD8-T cells and identified three sets of paired TCR genes out of 5 hybridomas. Expression of the murine TCR genes redirected primary human T cells to bind HLA-A2/AFP158 tetramer. The TCR gene-engineered human T cells (TCR-T) specifically recognized HLA-A2+AFP+ HepG2 tumor cells and produced effector cytokines. Importantly, the TCR-T cells could specifically kill HLA-A2+AFP+ HepG2 tumor cells without significant toxicity to normal hepatocytes in vitro. Adoptive transfer of the AFP-specific human TCR-T cells could eradicate HepG2 tumors in NSG mice. Conclusion We have identified novel AFP-specific murine TCR genes that can redirect human T cells to specifically recognize and kill HCC tumor cells, and those AFP158-specific TCRs have a great potential to engineer a patient’s autologous T cells to treat HCC tumors.