EBV-Specific Cytotoxic T Lymphocytes by LMP2a- and EBNA3a-Specific T Cell Receptor Gene Transfer for Adoptive Therapy in EBV-Associated Hodgkin’s Disease and Post-Transplant Lymphoma.

Adoptive transfer of polyclonal EBV-specific T cell lines has been used as prophylaxis and therapy in patients with EBV-associated malignancies. However, this strategy is time-consuming and demands difficult generation of lymphoblastoid cell lines (LCLs) and corresponding T cells for each individual patient. We applied an alternative strategy to confer T cell immunity against EBV-antigens by isolating EBV antigen-specific T cell receptors (TCRs) for transduction of primary human T cells for adoptive therapy. Previously, we have demonstrated the feasibility of using peptide-pulsed dendritic cells (DC) for generating high-affinity EBV antigen-specific T cell lines and T cell clones. Based on this strategy, T cell clones directed against LMP2a and EBNA3a were generated and functionally analyzed. Monospecificity was demonstrated by homogeneous double staining with CD8 and appropriate tetramers. High avidity of T cell clones (< 0.01 μM) was shown by peptide titration in an ELISPOT assay for IFN-γ secretion. In addition, the cytokine secretion profiles of some of the T cell clones were tested by cytokine bead array assay. High secretion levels of IFN-γ, IL-2 as well as TNF-α after stimulation with the EBNA3a- or LMP2a-peptide were shown for the corresponding T cell clones. Potent TCRs from one LMP2a-specific, HLA-A2-restricted and one EBNA3a-specific, HLA-B8-restricted T cell clone were isolated and cloned into the retroviral vector MP71. Transduction efficiency of TCR-deficient T cell lines was > 40% (TCR-LMP2a) and > 30% (TCR-EBNA3a) as measured by tetramer staining. Both TCR-LMP2a- and TCR-EBNA3a-redirected T cell lines were functional as indicated by NFAT-mediated luciferase expression upon TCR-MHC-peptide ligation. Primary human T cells were successfully transduced with TCR-LMP2a (∼ 12% tetramer-positive) and TCR-EBNA3a (∼ 3% tetramer-positive). Importantly, both TCRs conferred similar cytolytic activity against EBV-transformed B cell lines. Our data support the development of TCR-transduced T cells for adoptive transfer in EBV-associated malignancies, including Hodgkin′ s disease and nasopharyngeal carcinoma in which only subdominant EBV antigens are expressed. The feasibility and the therapeutic potential of TCR-transduced T cells for adoptive transfer have already been shown in a clinical phase I trial in patients with metastatic melanoma. We believe that redirecting human PBLs is a rapid and efficient tool toward adoptive transfer in EBV-associated malignancies.