Genetic ablation of HLA class I, class II, and the T cell receptor enables allogeneic T cells to be used for adoptive T cell therapy.

Adoptive immunotherapy can induce sustained therapeutic effects in some cancers. Antitumor T cell grafts are often individually prepared in vitro from autologous T cells, which requires an intensive workload and increased costs. The quality of the generated T cells can also be variable, which affects the therapy's antitumor efficacy and toxicity. Standardized production of antitumor T cell grafts from third-party donors will enable widespread use of this modality if allogeneic T cell responses are effectively controlled. Here, we generated HLA class I, class II, and T cell receptor triple knockout (tKO) T cells by simultaneous knockout of the B2M, CIITA and TRAC genes through Cas9/sgRNA ribonucleoprotein electroporation. Although HLA deficient T cells were targeted by natural killer cells, they persisted better than HLA sufficient T cells in the presence of allogeneic peripheral blood mononuclear cells (PBMC) in immunodeficient mice. When transduced with a CD19 chimeric antigen receptor (CAR) and stimulated by tumor cells, tKO CAR-T cells persisted better when cultured with allogeneic PBMC compared with TRAC and B2M double-knockout T cells. The CD19 tKO CAR-T cells did not induce graft-versus-host disease, but retained antitumor responses. These results demonstrated the benefit of HLA class I, class II, and TCR deletion in enabling allogeneic-sourced T cells to be used for off-the-shelf adoptive immunotherapy.