Identification of Functional HLA-A*01:01-Restricted Epstein-Barr Latent Membrane Protein 2-Specific T-Cell Receptors

Background: Adoptive transfer of genetically engineered T cells expressing antigen-specific T-cell receptors (TCRs) is an appealing therapeutic approach for Epstein-Barr virus (EBV)-associated malignancies of latency type II/III that express EBV antigens (LMP1/2). Patients who are HLA-A*01:01 positive could benefit from such products, since no T cells recognizing any EBV-derived peptide in this common HLA allele have been found thus far.

Methods: HLA-A*01:01-restricted EBV-LMP2-specific T cells were isolated using peptide major histocompatibility complex (pMHC) tetramers. Functionality was assessed by production of interferon gamma (IFN-γ) and cytotoxicity when stimulated with EBV-LMP2-expressing cell lines. Functionality of primary T cells transduced with HLA-A*01:01-restricted EBV-LMP2-specific TCRs was optimized by knocking out the endogenous TCRs of primary T cells (∆TCR) using CRISPR-Cas9 technology.

Results: EBV-LMP2-specific T cells were successfully isolated and their TCRs were characterized. TCR gene transfer in primary T cells resulted in specific pMHC tetramer binding and reactivity against EBV-LMP2-expressing cell lines. The mean fluorescence intensity of pMHC-tetramer binding was increased 1.5-2 fold when the endogenous TCRs of CD8+ T cells was knocked out. CD8+/∆TCR T cells modified to express EBV-LMP2-specific TCRs showed IFN-γ secretion and cytotoxicity toward EBV-LMP2-expressing malignant cell lines.

Conclusions: We isolated the first functional HLA-A*01:01-restricted EBV-LMP2-specific T-cell populations and TCRs, which can potentially be used in future TCR gene therapy to treat EBV-associated latency type II/III malignancies.