Marrow failure status was defined using standard clinical criteria. Mild: ANC <1500/μL, platelet count <150x10⁹/L to 50x10⁹/L, or Hb ≥8 to <11 g/dL. Moderate: ANC <1000/μL, platelet count <50x10⁹/L, or Hb <8 g/dL. Severe: ANC <500/μL, platelet count <20x10⁹/L, or Hb <8 g/dL. The lowest value of the 3 cell lineages defined the level of marrow failure. Hematological response to therapy was defined a priori as at least 1 of the following: increase in platelet count of >20x10⁹/L over count at enrollment, observed on 2 consecutive occasions at least 2 weeks apart without transfusion; increase in Hb of at least 1 g/dL over level recorded at enrollment observed on 2 consecutive occasions at least 2 weeks apart without transfusion; and increase in ANC of at least 500/μL over level recorded at enrollment observed on 2 consecutive occasions at least 2 weeks apart. It should be noted that 3 patients (patients 5, 6, and 7) showed evidence of more sustained response in counts compared with the other patients in whom response was seen at limited time points.

-, not applicable; √, yes; Hb, hemoglobin.