In this multi-center, randomized, open-label, prospective clinical trial, a total of 60 relapsed/refractory AML patients will be randomized into 2 groups. In the experimental arm, patients receive IAC regimen. In the control arm, patients receive other physician-directed regimen. The primary end point is complete remission rate.

In this multi-center, randomized, open-label, prospective clinical trial, a total of 60 relapsed/refractory AML patients will be randomized into 2 groups. Patients in the IAC arm receive the therapy consisting of idarubicin 10 mg/㎡/d on days 1-3, cytarabine 100mg/㎡/d on days 1-7 and cyclophosphamide at a dose of 350mg/㎡/d on the second day and the fifth day. In the control arm, patients received other physician-directed regimen including fludarabine, cytarabine with/without granulocyte stimulating factor(FLA±G) regimen,cytarabine plus daunorubicin(DA）regimen , decitabine,aclacinomycin and cytarabine(decitabine plus AA) regimen or AA regimen plus granulocyte stimulating factor. All the regimen in the control arm can not contain cyclophosphamide. The primary end point is complete remission. The second end points include overall survival, relapse-free survival and time to treatment failure.

Inclusion Criteria:

1. Age of less than 60 years old;
2. Patients that meet the diagnostic criteria(WHO 2008 criteria) of AML (except APL subtypes).
3. Patients with a confirmed pathologic diagnosis of AML which had relapsed or refractory.
4. Patients with ECOG score of ≤ 2;
5. Adult patients are willing to participate in the study and sign the informed consent by themselves or by their immediate family. Patients under 18 years old willing to participate should have their legal guardians sign the informed consent.

Exclusion Criteria:

1. Patients who had received reinduction therapy including cyclophosphamide are excluded. However, patients who had received regimens including cyclophosphamide before relapse are eligible.
2. Patients with other blood diseases(for example, haemophiliacs) are excluded.
3. Relapsed patients with only extramedullary leukemia;
4. After allogeneic hematopoietic stem cell transplantation;
5. With mutation of breakpoint cluster region-Abelson(BCR-ABL) fusion gene and in need of tyrosine kinase inhibitors therapy;
6. Acute panmyelosis with myelofibrosis and myeloid sarcoma patients;
7. Had other malignant tumor in need of treatment;
8. Had active cardiovascular disease;
9. Patients with other factors which were considered unsuitable to participate in the study by the investigators.