Prospective, Single-arm, Multicenter Clinical Study on Haploidentical Hematopoietic Stem Cell Transplantation in Patients With MRD Positive CD19+ALL Treated With Conditioning Regimens Containing Blinatumomab

Inclusion Criteria: 1. Diagnosed as acute B-ALL with CD19+ according to the 2022 WHO classification criteria. After induction and intensified chemotherapy, complete hematological remission was achieved, but MRD was positive by flow cytometry; 2. Age range from 18 to 70 years old, regardless of gender; 3. The Eastern Oncology Collaborative Group (ECOG) physical fitness score is 0-2 points; 4. Female patients of childbearing age who had a negative pregnancy test before the trial and agreed to take effective contraceptive measures during the trial until their last visit; 5. Organ function is normal, and the following laboratory indicators are met within one week of enrollment: creatinine clearance rate ≥ 60 mL/min (according to the Cockcroft Fault formula); AST and ALT ≤ 3 × Upper limit of normal value range (ULN), total bilirubin ≤ 2 × ULN; Echocardiography (ECHO) shows left ventricular ejection fraction (LVEF) ≥ 50%; 6. Life expectancy greater than 8 weeks; 7. Voluntarily sign an informed consent form to understand and comply with the requirements of the study. Exclusion Criteria: 1. Failure to achieve complete hematological remission, including residual extramedullary infiltration; 2. Previously received hematopoietic stem cell transplantation; 3. Received systemic chemotherapy within 2 weeks; 4. Previously received treatment with Blinatumomab; 5. Have a history of central nervous system leukemia or present with central nervous system leukemia; 6. Active autoimmune diseases, such as SLE, rheumatoid arthritis, etc; 7. Currently suffering from clinically significant active cardiovascular diseases, such as uncontrolled arrhythmia, uncontrolled hypertension, congestive heart failure, any grade 3 or 4 heart disease determined according to the New York Heart Association (NYHA) functional classification (see Appendix 1), or having a history of myocardial infarction within 6 months prior to screening; 8. Chronic obstructive pulmonary disease with whole lung dysfunction; 9. Other serious diseases that may restrict patients from participating in this test (such as advanced infection, uncontrollable diabetes); 10. Concomitant arteriovenous thrombosis or hypercoagulable state; 11. Known human immunodeficiency virus (HIV) infection, or chronic infection of hepatitis B virus (HBsAg positive) or hepatitis C virus (anti-HCV positive) beyond drug control; 12. Pregnant or lactating women; 13. Severe allergies to other monoclonal antibodies in the past; 14. Those who are unable to understand, comply with the research protocol or sign an informed consent form.