Ren et al. used CRISPR/Cas9 technology to knock out endogenous TCR, B2M and PD1 genes simultaneously, resulting in allogeneic CAR-T cells lacking TCR, HLA-I and PD1 molecules, which decreased their allogenic activity and avoided graft-versus-host disease, as well as enhanced antitumor efficacy [64]. The gene discussed is B2M; the disease is graft versus host disease.