CAR-T Cell Therapy Targeting to CD19 for R/R ALL

Inclusion Criteria: * Diagnosed as CD19+ B-cell acute lymphoblastic leukemia; * Fail to achieve remission, or with persistent residual disease after at least 2 cycles of consolidation; * With an estimated survival of higher than 3 months (according to investigator's judgement); * Sufficient organ function: left ventricular ejection fractions≥ 0.5 by echocardiography, creatinine \< 1.6 mg/dL, aspartate aminotransferase/aspartateaminotransferase \< 3 x upper limit of normal, bilirubin \<2.0 mg/dL; * Karnofsky performance status ≥ 60 or ECOG ≤ 2. Exclusion Criteria: * Intolerant to immunosuppressive chemotherapies; * With active infection or other uncontrolled complications; * With history of seizure; * Active hepatitis B or hepatitis C infection and HIV infection; * Pregnant or lactating women, or patients refusing to take effective contraception measures; * Other contraindications that considered inappropriate to participate in this trial (according to investigator's judgement).