Number of patients with neutrophil engraftment: Absolute Neutrophil Count (ANC) > 500/μL and hemoglobin level remaining above 10 g/dL without transfusion support, with tests showing at least 2.5% donor cells present. Primary graft failure is defined as absence of establishment of adequate donor hematopoiesis by day 42 with bone marrow cellularity < 5%, peripheral White Blood Count (WBC) < 500/μL, peripheral ANC < 100/μL, and/or platelets < 10,000/μL by day 120 with absence of megakaryocytes in the bone marrow (in the absence of disease relapse).