To Evaluate the Safety and Efficacy of Human CD19 Targeted DASH CAR-T Cells Injection for Subjects With R/R B-ALL

Subjects with relapsed/refractory B-cell acute lymphoblastic leukemia can participate if all eligibility criteria are met. Tests required to determine eligibility including disease assessments, a physical exam, Electrocardiograph, Computed tomography（CT）/Magnetic Resonance Imaging(MRI)/Positron Emission Tomography（PET）, and blood draws. Subjects will receive preconditioning chemotherapy prior to the infusion of human CD19 targeted DASH CAR-T Cells injection. After the infusion, subjects will be followed for adverse events, pharmacokinetic/pharmacodynamics characteristics, efficacy of human CD19 targeted DASH CAR-T cells. Study procedures may be performed while hospitalized.