Abstract 2190: Engineering off-the-shelf T cell receptor fusion construct (TRuC) T cells

The T-Cell Receptor (TCR) can be functionally split into antigen recognition mediated by the TCRα/β heterodimer and signal transduction triggered by the CD3 complex comprising CD3ϵ/γ, CD3ϵ/δ and CD3ζ/ζ dimers. Unlike antibodies, the TCR recognizes its cognate peptide antigen only when presented on human leukocyte antigen (HLA) molecules. Recently, we reported that tethering an antibody-derived binder to one of the TCR subunits redirects T cells to specifically kill tumor cells independent of HLA. Different from CAR-T cells, the T cell receptor fusion constructs (TRuC™) are integrated into the natural TCR and require all TCR subunits for receptor translocation to the cell surface. The development of off-the-shelf TRuC-T cells is desirable to shorten the vein-to-vein production time and reduce manufacturing costs. Here, we describe the generation of TRuC-T cells expressing a fully functional TRuC TCR without alloreactivity. Inactivation of the endogenous TRAC gene employing CRISPR/Cas9 endonuclease disrupts natural TCR formation. Yet, replacing the endogenous TCRα subunit with a human TCRα constant region without variable domain to avoid alloreactivity is insufficient for TRuC TCR expression. A functional TRuC TCR, however, can be created by substituting the following constructs for the inactivated TRAC gene: (i) murine TCRα and β constant domains without variable domains, (ii) chimeric human/murine TCRα and β constant regions or (iii) TCRγ and δ constant domains. Off-the-shelf TRuC-T cells upregulate activation markers, secrete cytokines, and kill tumor cells in an antigen-specific manner. Importantly, the genome-engineered TRuC-T cells lack alloreactivity as demonstrated in mixed lymphocyte reactions and clear tumors in NSG xenograft models without signs of Graft versus host disease (GvHD). Our findings warrant further development of allogeneic TRuC-T cells for cancer therapy. Citation Format: Julie Donaghey, Philippe Kieffer-Kwon, Troy Patterson, Tiffany Chan, Holly Horton, Robert Tighe, Dario A. Gutierrez, Daniel Getts, Robert Hofmeister. Engineering off-the-shelf T cell receptor fusion construct (TRuC) T cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2190.