Intravenous Autologous CD19 CAR-T Cells for R/R B-ALL

Inclusion Criteria: * Patients with relapsed/refractory B-ALL in accordance with World Health Organization (WHO) classification by virtue of BM morphology, flow cytometry, cytogenetics and molecular genetics * Age between ≥13 to ≤ 65 years * No detectable leukaemia in the CSF (CNS-1) * CNS leukaemia without clinically evident neurological symptoms (CNS-2; with \<5 WBC per μL and cytology positive for blasts) * Adequate organ function as defined by a creatinine clearance \> 50 ml/min, serum total bilirubin \< 5 times the normal value, left ventricular ejection fraction \> 40% * ECOG performance status ≤ 2 * Life expectancy \> 3 months * Post allogeneic HSCT must be ≥ Day +100 with no evidence of active GVHD and not receiving immunosuppression * Female patients of child bearing age must have negative pregnancy test and is on highly effective contraception methods * Male patients must use highly effective contraception methods Exclusion Criteria: * Patients with CNS-3 leukaemia. * Active cancer (other than B-ALL). * Evidence of severe lung, heart (NYHA class III/IV, arrhythmia, AV block, uncontrolled hypertension), liver, or renal failure or severe neurologic disorder. * Presence of active autoimmune disease or atopic allergy. * HIV serology positivity. * Active Hepatitis B or C infection as evidenced by quantitative viral PCR assay. * Uncontrolled sepsis * Pregnant / nursing female. * Ongoing prednisolone \> 1mg/kg daily or equivalent. * Chemotherapy immunotherapy in the recent 4 weeks such as allogeneic cellular therapy weeks, anti-GVHD therapy.