T cell receptor gene-modified allogeneic T cells with siRNA for endogenous T cell receptor induce efficient tumor regression without graft-versus-host disease.

Adoptive immunotherapy using genetically engineered patient-derived lymphocytes to express tumor-reactive receptors is a promising treatment for malignancy. However, utilization of autologous T cells in this therapy limits the quality of gene-engineered T cells, thereby inhibiting the timely infusion of the cells into patients. In this study, we evaluated the anti-tumor efficacy and the potential to induce graft-versus-host disease (GVHD) in T cell receptor (TCR) gene-engineered allogeneic T cells that downregulate the endogenous TCR and HLA class I molecules with the aim of developing an "off-the-shelf" cell product with expanded application of genetically engineered T cells. We transduced human lymphocytes with a high-affinity TCR specific to the cancer/testis antigen NY-ESO-1 using a novel retrovirus vector with siRNAs specific to the endogenous TCR (siTCR vector). These T cells showed reduced expression of endogenous TCR and minimized reactivity to allogeneic cells in vitro. In non-obese diabetic/SCID/γcnull mice, TCR gene-transduced T cells induced tumor regression without development of GVHD. A lentivirus-based CRISPR/Cas9 system targeting β-2 microglobulin in TCR gene-modified T cells silenced the HLA class I expression and prevented allogeneic CD8+ T cell stimulation without disrupting their anti-tumor capacity. This report is the first demonstration that siTCR technology is effective in preventing GVHD. Adoptive cell therapy with allogeneic T cells engineered with siTCR vector may be useful in developing an "off-the-shelf" therapy for patients with malignancy.