Inclusion Criteria:

        Screening:

          -  signed informed consent

          -  Age ≥18 years

          -  patients with MDS or AML after conventional chemotherapy or allogeneic HSCT and
             positive molecular marker such as t(6,9), NPM1 pos. or CD34+ or CD117+ in the case of
             an allogeneic HSCT

        Treatment:

          -  MDS or AML without haematological relapse (blasts <5% in the bone marrow), and

          -  decrease of CD34 donor chimerism (<80%) after allogeneic related or unrelated HSCT in
             CD34+ or CD117+ MDS or AML or

          -  increase in the AML-specific molecular marker in the quantitative PCR for t(6,9),
             NPM1+ AML >1% after conventional chemotherapy or allogeneic HSCT or

          -  persistence of the (above) MRD levels >1% (relative to the reference gene) after
             conventional chemotherapy or allogeneic HSCT

          -  leukocytes > 3 Gpt/l and platelets >75 Gpt/l (transfusion independent)

        Exclusion Criteria:

          -  Known history of hypersensitivity to any of the drugs used or their constituents or to
             drugs with similar chemical structure,

          -  Participation of the patient in another clinical trial within the last 4 weeks before
             the inclusion

          -  addiction or other disorders that do not allow the concerned person, to assess the
             nature and scope and possible consequences in the clinical investigation

          -  pregnant or breast feeding women

          -  women of childbearing potential, except women who meet the following criteria:

               -  post-menopausal (12 months natural amenorrhea or 6 months amenorrhea with serum
                  FSH >40 U/ml)

               -  postoperative (6 weeks after hysterectomy with or without bilateral ovariectomy )

               -  regular and proper use of a contraceptive method with error rate <1% per year
                  (e.g., implants, depot injections, oral contraceptives, intrauterine device, IUD)
                  during study treatment and up to 1 year after completion of therapy

               -  sexual abstinence during study treatment and up to 1 year after completion of
                  therapy

               -  Vasectomy of the partner

          -  Men who do not use one of the following types of effective contraception during study
             treatment and up to 1 year after completion of therapy:

               -  sexual abstinence

               -  State post-vasectomy

               -  Condom

          -  Evidence that the participating person is not expected to comply with the protocol
             (such as lack of cooperation)

          -  Uncontrolled active infection

          -  Severe hepatic impairment (AST and ALT may not exceed three times the normal) or liver
             cirrhosis or malignant liver tumor

          -  Dialysis dependent renal dysfunction

          -  Known severe congestive heart failure, incidence of clinically unstable cardiac or
             pulmonary disease These criteria are not for the screening phase up to a known
             allergic reaction to azacitidine or intolerance to apply.