CD19 and B-cell chronic lymphocytic leukemia: Foremost anti-CD19 CAR-T cell therapies have proven remarkable efficacy in B-cell acute lymphoblastic leukemia (B-ALL), chronic lymphocytic leukemia (CLL)9–11, and B-NHL12–15, however, these CARs can become ineffective due to CD19 antigen loss or downregulation16,17.