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The immunogenicity of virus-derived 2A sequences in immunocompetent individuals


Genetic engineering of T cells for adoptive immunotherapy in cancer patients has shown significant promise. To ensure optimal antitumor activity and safety, the simultaneous expression of multiple genes is frequently required, and short viral-derived 2A sequences are increasingly preferred for this purpose. Concerns exist, however, that these virus-derived sequences may induce unwanted immune responses, and thus diminish persistence of the gene-modified cells after adoptive transfer. Whereas such responses were absent in immunocompromised recipients, potential immunogenicity in immunocompetent individuals remains a concern. We now address whether ex vivo T cell responses can be elicited against the most widely used 2A sequences (2A-Thosea asigna virus (TAV) or 2A-equine rhinitis virus (ERAV), specifically) in immunocompetent individuals. We used a potent ex vivo culture system previously validated to induce T cell responses even against weakly immunogenic antigens. Of the sixteen donors tested, only five released very low levels of interferon-γ in response to 2A-TAV peptide mixtures (single peptide specificity in three donors, adjacent self-antigen peptide specificity in one donor and nonspecific reactivity in one donor). None of them produced cytotoxic activity or responded to 2A-ERAV. These results suggest that exposure to viral-derived 2A sequences is unlikely to produce unwanted T cell responses in immunocompetent individuals and further supports their continued use for studies of human gene therapy.

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CA is supported by Oncosuisse (BIL KFS 02506-08-2009), NIH-NHLBI T32 HL092332 (Trainee) and an American Society for Blood and Marrow Transplantation (ASBMT)/Celgene New Investigator Award 2012; HEH is supported by a Dan L Duncan Chair, P50 CA126752, PO1 CA94237 and a SCOR from the Leukemia and Lymphoma Society; MKB is supported by a Fayez Sarofim Chair and a CPRIT award (RP110553); GD is supported by NIH R01 CA142636, a Leukemia and Lymphoma Society Translational Research grant and W81XWH-10-10425 Department of Defense, Technology/Therapeutic Development Award; BS is supported by NIH R01 CA131027, a Leukemia and Lymphoma Society Translational Research grant and a CPRIT award (RP120298). We also appreciate the support of shared resources in the cancer center support grant P30CA125123.

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Correspondence to B Savoldo.

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Arber, C., Abhyankar, H., Heslop, H. et al. The immunogenicity of virus-derived 2A sequences in immunocompetent individuals. Gene Ther 20, 958–962 (2013).

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  • 2A sequences
  • polycistronic vectors
  • T cell gene transfer
  • immunogenicity

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