• 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;

• Age range from 18 to 70 years old, regardless of gender;

• The Eastern Oncology Collaborative Group (ECOG) physical fitness score is 0-2 points;

• 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;

• 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%;

• Life expectancy greater than 8 weeks;

• Voluntarily sign an informed consent form to understand and comply with the requirements of the study.