EBV-specific T cell receptor gene transfer to target nasopharyngeal carcinoma

Abstract

Infusing EBV-specific T cells is an effective prophylactic and therapeutic treatment for EBV post transplant lymphoproliferative disease. However, extending this approach to treat NPC necessitates targeting viral antigens that are subdominant targets for T cells. Therefore we have explored the use of T cell receptor (TCR) gene transfer to rapidly and reliably generate such T cell responses from all patients. To ensure a widely applicable treatment we cloned the genes encoding the TCR from an LMP2- specific T cell that is restricted through HLA A*1101, an allele carried by >50% of the Chinese population. Genes encoding the TCR α and β chains were cloned into a single retroviral vector, separated by a self-cleaving 2A peptide to ensure equal expression. T cells were transduced with this retrovirus and within 3-5 days HLA:peptide pentamer staining detected the transferred TCR in 12-17% of CD8+ T cells and 7-12% of CD4+ T cells. TCR-transduced T cells expanded rapidly in vitro in response to antigen and showed high avidity for the target peptide (10-10M) in assays of interferon-γ release. To improve safety and efficacy, the TCR was modified by codon optimization and introduction of an additional disulphide-bond. This increased almost two-fold the proportion of T cells expressing the receptor. TCR-transduced CD4+ T cells produced multiple cytokines (including IL2) in response to LMP2 suggesting they could provide a helper function in vivo to aid persistence of CD8+ effectors. Both CD8+ and CD4+ transduced T cells lysed an A11+ NPC cell line expressing LMP2