Effectiveness and Safety of Blinatumomab and Donor Lymphocyte Infusion in Maintenance Therapy After Allogeneic Hematopoietic Stem Cell Transplantation for High-risk Ph Negative B Cell Acute Lymphoblastic Leukemia

Prior treatment

• Major organ surgery within the past six weeks.
• Drug abuse or chronic alcoholism that may interfere with study assessments.
• Prior organ transplantation (excluding hematopoietic stem cell transplantation).

Other illness

• History of hypersensitivity or severe adverse reactions to the study drug or structurally similar compounds, as assessed by the investigator to preclude participation.
• Severe pulmonary dysfunction (obstructive and/or restrictive ventilatory impairment).
• Active infection or uncontrolled bleeding, as assessed by the investigator to preclude safe administration of the study drug.
• History of thrombosis, embolism, cerebral hemorrhage, or other significant vascular events within the past year.
• Psychiatric disorders or other conditions that impair the ability to provide informed consent or comply with study procedures.
• Other conditions deemed by the investigator to make the patient unsuitable for participation.

Lab values

• Severe cardiac dysfunction, including:Left ventricular ejection fraction (EF) \<60%.Clinically significant arrhythmias (e.g., ventricular tachycardia, atrial fibrillation, second-degree heart block).Prolonged QTc interval (men \>450 ms; women \>470 ms).Myocardial infarction within the past year.Symptomatic coronary artery disease requiring medication.
• Severe hepatic impairment:ALT or total bilirubin (TBIL) \>3× upper limit of normal (ULN).
• Severe renal impairment:Serum creatinine (Cr) \>2× ULN.24-hour creatinine clearance (Ccr) \<50 mL/min.

Other

• Pregnant or lactating women, or women of childbearing potential unwilling to use effective contraception.

• Age 14-65 years (inclusive), regardless of gender.
• Newly diagnosed B-ALL with CD19 expression on leukemic cells (regardless of CD19 positivity rate).
• Ph-negative B-ALL with high-risk features post-allo-HSCT .
• ≥2 months post-transplant with hematopoietic reconstitution.
• Bone marrow morphology in remission and MRD-negative before enrollment.
• ECOG performance status \<3 and Karnofsky score ≥70.
• No history of grade III/IV graft-versus-host disease (GVHD) and no active GVHD at enrollment.
• Adequate organ function:AST and ALT ≤3× upper limit of normal (ULN), total bilirubin ≤2×ULN.Serum creatinine ≤2×ULN or creatinine clearance ≥50 mL/min (calculated by Cockcroft-Gault formula).Left ventricular ejection fraction (LVEF) ≥50% by echocardiography (ECHO).
• Expected survival \>3 months.
• Voluntary provision of written informed consent, with ability to understand and comply with study requirements.