In this trial the investigators will evaluate the outcomes of 4 pre-defined groups of individuals according to the therapeutic intervention. The investigators will determine the outcome of each group by monitoring the survival and the response rates of patients with FLT3-ITD AML relapse after allo-HSCT.

The preliminary data of the investigators demonstrate potent activity of Sorafenib combined with Donor lymphocyte infusions (DLI) in relapse of FLT3-ITD+ Acute myeloid leukemia (AML) after allogeneic hematopoietic cell transplantation (allo-HSCT). The investigators therefore launched an observational multicenter trial. The outcomes are assessed in 4 pre-defined groups of individuals according to the therapeutic intervention (chemotherapy-alone-group, chemotherapy/DLI group, sorafenib alone group and sorafenib/DLI group). The specific interventions to the subjects of the study are assigned by the individual transplant center. The investigators will determine the outcome of each group by monitoring the survival and the response rates (complete remission, disease burden reduction, no response) of patients with FLT3-ITD AML relapse after allo-HSCT.

Inclusion Criteria:

• Histology/PCR proven relapse of FLT3-ITD+ AML after allo-HSCT
• Age ≥18 years
• Treatment with either chemotherapy-alone, chemotherapy/DLI, sorafenib alone or sorafenib/DLI
• Written informed consent
• Ability to understand the nature of the study and the study related procedures and to comply with them

Exclusion Criteria:

• Age < 18 years
• Lack of informed consent
• Patients that cannot be classified in one of the 4 groups: chemotherapy-alone-group, chemotherapy/DLI group, sorafenib alone group and sorafenib/DLI group

Patients with relapse of FLT3-ITD AML after allogeneic hematopoietic stem cell transplantation