Post hoc analysis of the relationship between baseline white blood cell count and survival outcome in a randomized Phase III trial of decitabine in older patients with newly diagnosed acute myeloid leukemia

In a Phase III trial, 485 patients (≥65 years) with newly diagnosed acute myeloid leukemia received decitabine 20 mg/m(2) intravenously for 5 days every 4 weeks or a treatment choice (supportive care or cytarabine 20 mg/m(2) subcutaneously for 10 days every 4 weeks). We summarized overall and progression-free survival by baseline white blood cell count using two analyses: 5×10(9)/L; ≤10 or >10×10(9)/L. There were 446 deaths (treatment choice, n=227; decitabine, n=219). Median overall survival was 5.0 (treatment choice) versus 7.7 months (decitabine; nominal P=0.037). Overall survival differences between white blood cell groups were not significant; hazard ratios (HRs) favored decitabine. Significant progression-free survival differences favored decitabine for groups 1-5×10(9)/L (P=0.005, HR =0.67), greater than 5×10(9)/L (P=0.027, HR =0.71), and up to 10×10(9)/L (P=0.003, HR =0.72). There was a trend toward improved outcome with decitabine, regardless of baseline white blood cell count.