Deeper and Early Molecular Response is a Good Predictor for Risk of Relapse in Patients with Acute Promyelocytic Leukemia

Background: Conventional treatment of acute promyelocytic leukemia (APL) including all-trans retinoic acid (ATRA) with anthracycline had led to good patient response and survival. However, instances of relapse continue to occur, and remain the major problem with this course of treatment. Patients and Methods: We collected the data of patients with newly diagnosed APL for the period 2004 to 2014, retrospectively. Data analysis included age, sex, initial white blood cell (WBC) count, coagulopathy and PML-RARα subtype. We also correlated PML-RARα fusion transcript level during treatment with outcome. Results: A total of 33 patients were ultimately included in this study. Twenty-nine patients achieved complete hematologic remission(CHR) and 24 patients achieved complete molecular remission(CMR). The median overall survival duration was 92.8 months. Patient relapse and initially high WBC count were 2 factors associated with poor survival (P = 0.003; P = 0.015). Eight patients relapsed and the relapse-free survival (RFS) was 41.8 months. A reduction exceeding 4 log of PML-RARα transcript level after induction and undetectable PML-RARα transcript after treatment was associated with better RFS (P = 0.028). Conclusions: Deeper molecular response after induction therapy was associated with a reduction in relapse and could be used to predict risk of relapse in newly diagnosed patient under conventional treatment.