Phase II Study of Anti-CD19 CAR-T Cells Treating Leukemia Children

Inclusion Criteria: * Patients who were diagnosed as primary refractory or relapsed B-ALL. All the patients matched the diagnostic criteria of ALL according to the WHO classification and conducted morphological evaluation, immunophenotype analysis by flow cytometry (FCM), cytogenetic analysis by routine G-banding karyotype analysis, screen of 56 leukemia-related fusion genes by multiplex nested reverse transcriptase-polymerase chain reaction (RT-PCR), and quantification of fusion genes by real-time PCR with ABL1 as reference. Extramedullary diseases (EMDs) were confirmed CD19+ by FCM and evaluated by positron emission tomography/computed tomography (PET/CT), CT, MRI or ultrasonography. The patient relapsed during chemotherapy or failed from re-induction chemotherapy (including first and second-generation TKIs) after relapse or had a persistent positive minimal residual disease (MRD) for three months. Patients had positive CD19 expression on leukemia blasts by FCM (\>95% CD19 positive); * Age from 0 to 18 years old; * Children candidates can be recruited after the legal guardian or patient advocate has signed the treatment consent form and voluntary consent form; Exclusion Criteria: * Intracranial hypertension or unconscious; * Acute heart failure or severe arrhythmia; * Acute respiratory failure; * Other types of malignant tumors; * Diffuse intravascular coagulation; * Serum creatinine and/or blood urea nitrogen over 1.5 times than normal range; * Sepsis or other uncontrolled infection; * Uncontrolled diabetes mellitus; * Severe psychological disorder; * Obvious cranial lesions with cranial MRI; * More than 20 counts/ul leukemic cells in cerebrospinal fluid; * More than 30% leukemic cells in the blood; * Stage III WHO/ECOG score; * Organ recipients; * Pregnant or breastfeeding; * Active, uncontrolled infection, including hepatitis B, hepatitis C or human immunodeficiency virus (HIV);