The primary objective of this study was to evaluate the efficacy of MTBF conditioning regimen of salvageable allo-HSCT in patients with relapsed or refractory acute myeloid leukemia. The secondary purpose of the study was to observe the safety of MTBF regimen in these patients.

High-intensity conditioning regimen prior to allogeneic hematopoietic stem cell transplantation (allo-HSCT) can maximize the clearance of leukemia cells, but is often associated with increased pretreatment-related toxicity and transplant-related mortality. In order to enhance its anti-tumor effect without increasing or even decreasing its tissue toxicity, and then prolong the overall survival of AML patients, we optimized the conditioning regimen before allo-HSCT transplantation: (1) The classical Thiotepa/Busulfan/Fludarabine (TBF) regimen will be adopted to reduce the conditioning associated toxicity, ensure graft implantation to the maximum extent and reduce the recurrence rate; ② At the same time, mitoxantrone hydrochloride liposome will be added to avoid the disadvantages of weak immunosuppressive effect and weak anti-leukemia effect, and MTBF pretreatment scheme will be finally explored. It has been applied in the pre-treatment of salvage allo-HSCT in 3 patients with relapsed and refractory acute myeloid leukemia with good safety. Up to the present follow-up time of 4 months, all 3 patients have disease free survival. To evaluate the safety and efficacy of this protocol, we intend to include more patients undergoing salvage allo-HSCT for relapsed or refractory (R/R) AML.

Inclusion Criteria:

• The subjects voluntarily joined the study, signed the informed consent, had good compliance, and cooperated with the follow-up;
• Age 18-65 years old (including upper and lower limits);
• No gender limitation
• Relapsed or refractory (R/R) acute myeloid leukemia can not achieve complete remission by chemotherapy, and has the indication of salvage allogeneic hematopoietic stem cell transplantation.
• R/R AML was defined as: ① Initial treatment cases that failed after 2 courses of standard chemotherapy; ② After CR consolidation and intensive treatment, relapse within 12 months; ③ Recurred 12 months later, but conventional chemotherapy was ineffective; ④ Two or more relapses; ⑤ Extramedullary leukemia persists; ⑥Leukemia cells in peripheral blood or the proportion of bone marrow original cells >0.050 or the occurrence of extramedullary leukemia cell infiltration after CR.
• Could tolerate allogeneic hematopoietic stem cell transplantation.

Exclusion Criteria:

• Hypersensitivity to any investigational drug or its components;

• Uncontrolled systemic diseases (e.g. active infections, uncontrolled hypertension, diabetes, etc.)

• Cardiac function and disease meet one of the following conditions:

  1. Long QTc syndrome or QTc interval>480 ms;
  2. Complete left bundle branch block, II or III degree atrioventricular block;
  3. Serious and uncontrolled arrhythmia requiring drug treatment;
  4. American New York Heart Association rating ≥ III degree;
  5. Cardiac ejection fraction (LVEF) is less than 60%;
  6. History of myocardial infarction, unstable angina pectoris, severe unstable ventricular arrhythmia or He has any arrhythmia requiring treatment, clinical history of serious pericardial disease, or acute ischemia or activity ECG evidence of abnormal conduction system;

• Active infection of hepatitis B and hepatitis C;

• Human immunodeficiency virus (HIV) infection;

• Patients with other malignant tumors;

• History of drug abuse (non-medical use of narcotic drugs or psychotropic drugs) or history of drug dependence (sedative hypnotics, analgesics, narcotics, stimulants and psychotropic drugs, etc.);

• History of mental illness or cognitive impairment;

• Other investigators determined that participation in this study was not appropriate.