Blinatumomab Plus Reduced-dose Chemotherapy in Treating B-ALL

Inclusion Criteria: * 1\. Before enrollment, patients must be diagnosed with de novo precursor B-cell acute lymphoblastic leukemia and be negative for Philadelphia chromosome. The diagnostic criteria refer to the 2022 WHO classification; 2. Age≥15 years， ≤59 years; 3. Eastern Cooperative Oncology Group (ECOG) performance status score of 0-2; 4. Expected survival time ≥ 2 months; 5. No organ dysfunction that would restrict the use of this protocol during the screening period; 6. Understand the study and sign the informed consent form. 7. Men, women of childbearing age (only postmenopausal women who have been menopausal for at least 12 months can be considered infertile), and their partners voluntarily take effective contraceptive measures deemed effective by the investigator during the treatment period and for at least 12 months after the last dose of the study drug. Exclusion Criteria: * 1\. Patients with known central nervous system (CNS) involvement of ALL; 2. Diseases with abnormal heart, lung, liver, kidney, or other organ functions that may limit the patient's participation in this trial (including but not limited to severe infections, uncontrolled diabetes, severe heart failure or angina, active pulmonary tuberculosis, asthma, COPD, bronchiectasis, etc.); 3. Cardiac ultrasound LVEF \< 45%; 4. History of other malignancies within the past 5 years, excluding localized thyroid cancer and in situ skin cancer; 5. Serum total bilirubin \> 1.5 ULN (upper limit of normal); ALT or AST \> 2.5 ULN; serum creatinine \> 1.5 ULN; 6. Known HIV infection; 7. Conditions affecting the use of the study drug as assessed by the investigator; 8. Unable to understand or comply with the study protocol.