In this phase clinical trail, we evaluate the efficacy and feasibility of azacytidine and venetoclax as leukemia debulking treatment followed by reduced intensity conditioning regimen consisting of Fludarabine + Busulfan + Melphalan as salvage treatment in patients with refractory AML .

In refractory AML, allogeneic hematopoietic stem cell transplantation (allo-HCST) is considered as the only curative regimen. In this phase II clinical trial, we plan to evaluate the efficacy and feasibility of new sequential transplantation protocol. All patients receive azacytidine and venetoclax as leukemia debulking treatment which is followed by reduced intensity conditioning regimen consisting of Fludarabine (150mg/m2) + Busulfan (6.4mg/kg) + Melphalan (70mg/m2). The graft-versus host disease (GVHD) prophylaxis regimen is based on reduced dose of post-transplantation cyclophosphamide (PT-CY) 40mg/kg day+3~+4, tacrolimus and low-dose anti-thymoglobulin (ATG, 2.5mg/kg) in case of HLA-matched unrelated donor or halo-donor transplantation.

Inclusion Criteria:

• refractory AML (no remission after 2 induction therapy, relapsed AML within 6 months of first complete remission (CR), relapse AML no CR after reinduction therapy), multiple relapse and refractory relapse AML
• patients with HLA matched related or unrelated donor (9~10/10) or haplo-identical related donor

Exclusion Criteria:

• Patients with poor liver function (enzyme >2N or bilirubin >2N)
• poor renal function (Scr >1.5N)
• poor cardiac function （EF<45%）
• inform consent not provided