However life-long treatment with TKI may not be feasable in several cases due to side effects such as growth retardation, non-compliance and resistance. This protocol evaluates the feasibility of SCT following a reduced intensity conditioning regimen (RIC) consisting of fludarabine, melphalan, thiotepa and thymoglobuline (ATG). Matched siblings and matched unrelated donors are permitted for stem cell donation. In case of unrelated donors tissue typing has to be done by high resolution molecular typing. Donors with 10/10 or 9/10 identical allels in the human leukocyte antigen (HLA) system are accepted. Preferred stem cell source is bone marrow but peripheral blood stem cells and umbilical cord blood are also allowed. Graft-versus-Host-Disease (GvHD)-prophylaxis is achieved with cyclosporine A and mycophenolate mofetil.