The purpose of this study is to evaluate the safety and efficacy of chimeric antigen receptor 19 (CD19-CAR-T2 Cells) infusions in 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