Phase I Study of CD19-CAR-T2 Cells for Patients With Chemotherapy Resistant or Refractory CD19+ Acute Leukemia

Inclusion Criteria: * Patient with relapsed and/or refractory CD19 positive B-cell acute leukemia * Eastern Cooperative Oncology Group (ECOG) performance status 《 3 * ALT/ AST 《 3x normal * Bilirubin \< 2.0 mg/dl * Creatinine \< 2.5 mg/dl and less than 2.5x normal for age * LVEF》 45% * Accept white blood cell collection * Provide informed consent Exclusion Criteria: * Previous treatment with investigational gene or cell therapy medicine products * Solitary extramedullary relapse * Active hepatitis B , hepatitis C or HIV infection * Uncontrolled active infection * Presence of grade 2-4 acute or extensive chronic GVHD * Active CNS involvement: epilepsy, paresis, aphasia, stroke, severe head trauma, * Dementia, Parkinson's disease, cerebellar disease, organic brain syndrome, uncontrolled mental illness, etc. * Any uncontrolled active medical disorder that would preclude participation as outlined. * Received non-diagnostic purposes major surgery within the past 4 weeks * Participated in any other clinical study within the past 4 weeks * Used murine biological products (except blinatumomab), unless it is proved no anti-mouse antibodies exist. * Pregnancy or breast-feeding women * Use of prohibited drugs: * Steroids: Therapeutic doses of steroids must be stopped \> 72 hours prior to CD19-CAR-T2 Cells infusion * Allogeneic cellular therapy: Any donor lymphocyte infusions (DLI) must be completed \> 4 weeks prior to CD19-CAR-T2 Cells infusion * GVHD therapies: Any drug used for GVHD must be stopped \> 4 weeks prior to CD19-CAR-T2 Cells infusion * Chemotherapy: i. The following drugs must be stopped \> 1 week prior to CTL019 infusion and should not be administered concomitantly or following lymphodepleting chemotherapy: hydroxyurea, vincristine, 6-mercaptopurine, 6-thioguanine, methotrexate \<25 mg/m2, cytosine arabinoside \< 10 mg/m2/day, asparaginase; ii. The following drugs must be stopped \> 4 weeks prior to CTL019 infusion: salvage chemotherapy (e.g. clofarabine, cytosine arabinoside \> 100 mg/m2, anthracyclines, cyclophosphamide), excluding the required lymphodepleting chemotherapy drugs * Any situation that may increase the risk of the test or interfere with the test results