Refractory and relapsed (R/R) acute lymphoblastic leukemia (ALL) patients with active disease always have a dismal outcome. Chimeric antigen receptor (CAR) T-cell therapy targeting to Cluster of Differentiation Antigen 19 (CD19) has been proved as a potent approach to attain remission in B-cell R/R patients. Therefore, the investigators conduct atrial to evaluate the the efficacy and safety of locally producing CAR T cells targeting CD19, and to analyze the outcome of enrolled B-cell ALL patients with active disease or persistent residual disease.

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).