CD19/CD22-targeted Chimeric Antigen Receptor Engineered T Cell (CART) in B-Cell Acute Lymphoblastic Leukemia.

Inclusion Criteria: * Male or female patients with CD19+/CD22+ relapsed/refractory B-cell acute lymphoblastic leukemia who have a dismal prognosis (estimated survival from several months to \<2 year). The study will enroll 20 evaluable patients as follows: * Age 6-65 years. * Left ventricular ejection fractions≥ 0.5 by echocardiography. * Creatinine \< 1.6 mg/dL. * Aspartate aminotransferase/aspartate aminotransferase \< 3x upper limit of normal. * Bilirubin \<2.0 mg/dL. * Karnofsky performance status ≥ 60 * Expected survival time ≥ 3 months (according to investigator's judgement) Exclusion Criteria: * Pregnant or lactating women. * Uncontrolled active infection. * Active hepatitis B or hepatitis C infection. * Class III/IV cardiovascular disability according to the New York Heart Association Classification. * HIV infection. * Patients with history of seizure * Active central nervous system leukemia