Allogenic Stem Cell Transplantation for Children, Adolescents and Young Adults With Relapsed or Refractory AML

Inclusion Criteria: * Aged between 0-21 years * Patients suffering from either refractory de novo AML or relapsed AML or patients with very high risk AML in CR1 * In sexually active patients two reliable contraception methods are used. This includes every combination of a hormonal contraceptive (such as injection, transdermal patch, implant, cervical ring) or of an intrauterine device(IUD) with a barrier method (e.g. diaphragm, cervical cap, or condom) or with a spermicide. * Written informed consent of patient, parents or legal guardians Exclusion Criteria: * Severe renal impairment (GFR \< 30% predicted for age) * Pregnant or lactating females * Current participation in another clinical trial * Patients ≥ 12 years old for Group 1 ("BuCyMel") (patients younger that 12 years continue to be included)