A Single-arm, Prospective Study of TBI + BUMEL As a Conditioning Regimen for Salvage HSCT in Patients with R/R AML

Inclusion Criteria:

1. Age between 14 and 70 years (inclusive of the age limits);
2. Patients diagnosed with relapsed/refractory (R/R) AML, meeting the World Health Organization (WHO) 2016 AML diagnostic criteria, must meet one of the following definitions:

   Relapsed AML: Leukemic cells reappear in peripheral blood or bone marrow blasts \>5% after achieving complete remission (CR, CRi) (excluding other causes such as bone marrow regeneration following consolidation chemotherapy), or extramedullary leukemic infiltration occurs.

   Refractory AML:Initial cases that do not respond to two courses of standard treatment. Relapse within 12 months after consolidation therapy. Relapse after 12 months with no response to conventional chemotherapy. Two or more relapses. Persistent extramedullary leukemia.
3. Heart, liver, and kidney function must meet the following criteria:

   Alanine aminotransferase (ALT) and Aspartate aminotransferase (AST) ≤ 3× the upper limit of normal (ULN); Total bilirubin ≤ 3× ULN; Serum creatinine ≤ 2× ULN or creatinine clearance ≥ 40 mL/min; Left ventricular ejection fraction (LVEF), as measured by echocardiography or multi-gated acquisition (MUGA) scan, must be within the normal range (\>50%).
4. Availability of a suitable allogeneic donor;
5. Life expectancy of ≥3 months;
6. Karnofsky Performance Status (KPS) ≥ 60%, Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2;
7. The patient understands the study protocol and voluntarily signs the informed consent form.

Exclusion Criteria:

1. Patients had serious adverse reactions to investigational drugs such as allergies;
2. Patients with a history of immunodeficiency, or other acquired or congenital diseases, immunodeficiency diseases, and a history of organ transplantation;
3. Patients with hypertension, ventricular arrhythmia requiring clinical intervention, acute coronary syndrome, congestive heart failure, stroke, or other grade III or higher cardiovascular events within 6 months;
4. Patients received Class II or higher surgery within 4 weeks prior to enrollment;
5. Patient has an active and difficult-to-control infection, including but not limited to active fungal, bacterial, or viral infections that require systemic treatment, such as active HIV, hepatitis B or C;
6. Patient has active central nervous system leukemia infiltration;
7. Pregnant or lactating patients;
8. Patient is currently participating in another clinical studies;
9. Other conditions where the investigator deems the patient unsuitable for inclusion.