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 wasachieved, 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 trialand agreed to take effective contraceptive measures during the trial until their lastvisit;
5. Organ function is normal, and the following laboratory indicators are met within oneweek of enrollment: creatinine clearance rate ≥ 60 mL/min (according to the CockcroftFault formula); AST and ALT ≤ 3 × Upper limit of normal value range (ULN), totalbilirubin ≤ 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 therequirements of the study.

Exclusion Criteria:

1. Failure to achieve complete hematological remission, including residual extramedullaryinfiltration;
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 nervoussystem leukemia;
6. Active autoimmune diseases, such as SLE, rheumatoid arthritis, etc;
7. Currently suffering from clinically significant active cardiovascular diseases, suchas uncontrolled arrhythmia, uncontrolled hypertension, congestive heart failure, anygrade 3 or 4 heart disease determined according to the New York Heart Association (NYHA) functional classification (see Appendix 1), or having a history of myocardialinfarction 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 hepatitisB 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 aninformed consent form.