CD19/CD20 Dual-CAR-T in B-cell Leukemia Patients

Inclusion Criteria: 1. Relapsed and refractory B-cell acute malignancies with: * Relapsed after competed remission, could not get competed remission after at more than 1 course of chemotherapy (including MRD≥0.1%); * MRD≥0.1% after allogeneic hematopoietic stem cell transplantation(HSCT), or recurrence after complete remission or MRD ≥ 0.1% after HSCT; * Refractory: at least two courses of chemotherapy did not achieve complete remission or MRD ≥ 0.1%; 2. Patients must have evaluable evidence of disease, including minimal residual disease (MRD); 3. Ph + patients who meet the following criteria can register:Failure to tolerate TKI or TKI treatment failure, or failure to transplant; 4. Double positive expression of CD19 / CD20 in B cells; 5. Ages 1 to 70 years, including boundary values; 6. ECOG score 0-3 points; 7. Women of childbearing age (15-49 years old) must receive a pregnancy test within 7 days prior to initiation of treatment and the results are negative; male and female patients with fertility must use an effective contraceptive to ensure 3 months after discontinuation of treatment during the study period not pregnant inside. 8. Patients who voluntarily sign informed consent and are willing to comply with treatment plans. Exclusion Criteria: 1. patients with organ failure: * Heart: NYHA heart function grade IV; * Liver: Grade C that achieves Child-Turcotte liver function grading; * Kidney: kidney failure and uremia; * Lung: symptoms of respiratory failure; * Brain: a person with a disability; 2. Active infections that are difficult to control; 3. Human immunodeficiency virus (HIV) positive; 4. Liver and kidney function: total bilirubin \> 5 × ULN, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) \> 5 × ULN, serum creatinine clearance rate 60mL / min; 5. GVHD ≥ 2 or anti-GVHD treatment; 6. Received allogeneic cell therapy within 4 weeks, such as donor lymphocyte infusion; 7. Subject received anti-tumor treatment (chemotherapy, mAb, or hormone) for less than 1 week; 8. Central nervous system white blood that is symptomatic or uncontrolled by systemic chemotherapy and intrathecal chemotherapy (a large number of tumor cells in CSF, white blood cell count \>15WBCs/mL); 9. intracranial hypertension or unconsciousness; respiratory failure; diffuse vascular internal coagulation; 10. pregnant or lactating women; 11. The patient does not agree to use effective contraception during the treatment period and for the next 3 months; 12. Patients who participate in other clinical studies at the same time; 13. The investigator believes that there are other factors that are not suitable for inclusion or influence the subject's participation or completion of the study.