B2M and glycogen storage disease VI: CRISPR-Cas9 helped edit allogeneic CAR-T cells by knocking out TCRα subunit constant chain (TRAC),55,56 beta-2 microglobulin (B2M), and PD-1 genes of donor T cells to avoid graft-versus-host disease while mitigating host immune cell elimination of allogeneic CAR-T cells.55