1. Patients with acute myeloid leukaemia acc. to WHO, 2008 (AML in complete remission at transplant, i.e. blast counts < 5 % in bone marrow) or myelodysplastic syndrome acc. to WHO, 2008 (MDS with blast counts < 20 % in bone marrow during disease history) indicated for allogeneic haematopoietic progenitor cell transplantation but considered to be at increased risk for standard conditioning therapies according to the following criteria: