Ablation of FAS confers allogeneic CD3– CAR T cells with resistance to rejection by T cells and natural killer cells

Allogeneic chimaeric antigen receptor T cells (allo-CAR T cells) derived from healthy donors could provide rapid access to standardized and affordable batches of therapeutic cells if their rejection by the host’s immune system is avoided. Here, by means of an in vivo genome-wide CRISPR knockout screen, we show that the deletion of Fas or B2m in allo- T cells increases their survival in immunocompetent mice. Human B2M^– allo-CAR T cells become highly sensitive to rejection mediated by natural killer (NK) cells, whereas FAS^– CAR T cells expressing normal levels of human leukocyte antigen I remain resistant to NK cells. CD3^– FAS^– CAR T cells outperformed CD3^– B2M^– CAR T cells in the control of leukaemia growth in mice under allogeneic pressure by T cells and NK cells. The partial protection of CD3^– FAS^– allo-CAR T cells from cellular rejection may improve the efficacy of allogeneic cellular therapies in patients with cancer.