Prognostic Significance of Early Peripheral Blood Blasts Clearance Following Induction Chemotherapy for Adult Acute Myeloid Leukemia.

Early bone marrow blast clearance, defined by a remission marrow obtained on day 14 post-induction, is an independent prognostic indicator of CR, OS, EFS and RFS in adult AML. The prognostic significance of early peripheral blood blast clearance is unknown. We sought to evaluate the relationship between time to peripheral blood blast clearance post-induction and results of the day+14 bone marrow in a cohort of 100 adult AML patients homogeneously-treated at Emory University, between 1997 and 2004. Patients with acute promyelocytic leukemia were excluded from this analysis. In this cohort, median time to peripheral blood blast clearance was 5 days (range, 1–18). Patients were divided into 2 groups: early blast clearance (< 5 days; n=43; EBC) and delayed blasts clearance (≥ 5 days; n=57; DBC). Patient characteristics are summarized in the Table. EBC patients presented with a lower WBC (8.4 vs. 32.4) and LDH (99 vs. 389), but had comparable cytogenetic risks. Remission day+14 marrow, defined as a hypocellular marrow (<20%) with <5% blasts morphologically, was attained in 74% and 79% in the EBC and DBC groups, respectively. However, a trend for improved relapse-free and overall survival was observed in the EBC group. In conclusion, our analysis shows that early peripheral blood blasts clearance post-induction chemotherapy does not correlate with a remission day 14 marrow but may predict improved outcomes.