The researchers developed BE-CAR7 T cells using base editing, an advanced CRISPR technology that precisely changes individual letters in DNA without cutting it[1][2][4]. These universal CAR T cells are made from donor T cells, have their CD7 and CD52 markers removed, making them invisible to immune-suppressing drugs, and add a CAR receptor targeting CD7 on leukemic T cells[2][3][4]. In a phase I study, 11 patients with T-cell acute lymphoblastic leukemia (8 children and 2 adults) who had failed standard therapy[1][2][3] received the treatment. All patients achieved complete morphological remission 28 days after a single infusion[1][2]. 82% of patients entered a deep remission that allowed stem cell transplantation to restore immunity[1][2][3][4]. 64% of patients remain in remission 3 to 36 months after treatment[1][3][4]. Side effects included low blood counts, cytokine release syndrome, and rashes, which were manageable[4]. The treatment destroys all T cells, including leukemic ones, and enables subsequent transplantation[2][4][5].