- One or more of the following three clinically-significant cytopenias: platelet count less than 50,000/microliters or platelet-transfusion-dependence (requiring at least 4 platelet transfusions in the 8 weeks prior to study entry, see definition of platelet transfusion units at 8.2.1); neutrophil count less than 500/microliters; hemoglobin less than 9.0 g/dL or red cell transfusion-dependence (requiring at least 4 transfusions of PRBCs (adult patient 4 units PRBC, pediatric patients at least 10ml/kg/transfusion) in the eight weeks prior to study entry.