Preferential disruption of HLA-A/B enhances allogeneic CAR-T cell expansion and antitumor capacity in B cell malignancies

Background: Although chimeric antigen receptor T (CAR-T) cells have been proven to be an effective way of treating B cell malignancies, a lot of patients could not benefit from it because of failure in CAR-T cell manufacturing, disease progression and unaffordable price. The study aimed to explore universal CAR-T cell products to extend the clinical accessibility. Methods The antitumor activity of CRISPR/Cas9 edited allogeneic anti-CD19 CAR-T (CAR-T19) cells was assessed in vitro , in animal models, and in patients with relapsed/refractory (R/R) acute B cell lymphoblastic leukemia (B-ALL) or B cell lymphoma. Results B2M − /TRAC − universal CAR-T19 (U-CAR-T19) cells exhibited powerful anti-leukemia abilities both in vitro and in animal models, as did primary CD19 + leukemia cells from leukemia patients. However, expansion or anti-tumor efficacy of U-CAR-T19 cells was not observed in six patients with R/R B cell malignancies. Accordingly, significant activation of natural killer (NK) cells by U-CAR-T19 cells was proven both clinically and in vitro . HLA-A − /B − /TRAC − novel CAR-T19 (nU-CAR-T19) cells were constructed with similar tumoricidal capacity but resistance to NK cells in vitro . Surprisingly, robust expansion of nU-CAR-T19 cells, along with rapid eradication of CD19 + B cells, was observed in the peripheral blood and bone marrow of three patients with R/R B-ALL. The patients achieved complete remission with no detectable minimal residual disease 14 days after the infusion of nU-CAR-T19 cells. Two patients had grade 2 cytokine release syndrome, which was managed using an IL-6 receptor blocker. Most importantly, no graft-versus-host-disease was observed in any patient, suggesting the safety of TRAC-disrupted CAR-T cells generated using the CRISPR/Cas9 method for clinical application. Conclusions The "off-the-shelf" allogeneic nU-CAR-T19 cells showed a strong response in R/R B-ALL. nU-CAR-T19 cells have the potential to be a promising new approach for treating R/R B cell malignancies.