Sorafenib Relapase Prophylaxis After HCT With PTBCy Regimen

Inclusion Criteria: * Patients must undergo allogeneic hematopoietic stem cell transplantation with post-transplantation bendamustine AND cyclophosphamide from any donor. * Patients must have high-risk myeloid malignancy as an indication for transplantation defined as: * acute myeloid leukemia not in hematological remission prior to transplantation, * ≥ 3 remission of acute myeloid leukemia, * any myeloid malignancy with bi-allelic tp53 mutation, * any myeloid malignancy with complex karyotype, * therapy-related myeloid malignancy not in MRD-negative response * myelodysplastic syndrome with very high IPSS-R risk * any myeloid malignancy with monosomal or t(3;3) karyotype, * any myeloid malignancy with ASXL1, bi-allelic tp53 or RUNX1 mutation, EVI1 overexpression * MDS/NPM unclassified not in hematologic remission. * Documented hematological remission in the bone marrow at the time of inclusion post-engraftment, measurable residual disease is allowed * First 100 days after allogeneic hematopoietic stem cell transplantation Exclusion Criteria: * successfully treated relapse between transplantation and enrollment * use of any other planned method for prophylaxis of relapse besides sorafenib * donor lymphocyte infusion prior to randomization * Second malignancy not in complete remission within 6 months prior to randomization * Moderate or severe cardiac disease: ejection fraction \<50%, unstable angina, stable angina NYHA class III or IV, chronic heart failure NYHA class III or IV, Lawn grade V arrhythmia, myocardial infarction within 3 months before inclusion * Stroke within 3 months of inclusion, unless related to the underlying malignancy * Severe decrease in pulmonary function: FEV1 \<50% or DLCO\<50% of predicted or respiratory distress or need for oxygen support; * Severe organ dysfunction: AST or ALT \>10 upper normal limits, bilirubin \>2 upper normal limits, creatinine \>2 upper normal limits * Creatinine clearance \< 30 mL/min * Uncontrolled bacterial or fungal infection at the time of enrollment defined by CRP\> 70 mg/L * Requirement for vasopressor support at the time of enrollment * Requirement for positive-pressure oxygen at the time of enrollment * Karnofsky index \<30% * Pregnancy * Somatic or psychiatric disorder making the patient unable to sign informed consent