Prediction of FLAG ± Ida Regimen Efficacy in Patients with Relapsed/ Refractory Acute Myeloid Leukemia

Abstract

Aim. To assess the efficacy of FLAG/FLAG-Ida regimen and to identify factors that influence remission, duration of disease-free survival (DFS) and overall survival (OS) of patients with relapsed/refractory acute myeloid leukemia (AML). Materials & Methods. The trial included 54 patients (28 men and 26 women), median age was 37 years (range 18-70 years). 27 (50 %) out of 54 patients had refractory AML and 27 (50 %) patients had relapsed AML. FLAG and FLAG-Ida regimens were administered as induction therapy. 37 (68.5 %) patients received bone marrow transplantation. Molecular genetic and cytogenetic examinations were performed prior to therapy and on the 28^th day after the start of treatment. WT1 gene expression was evaluated on the 14^th-16^th day of treatment. Results. Complete remission (CR) was achieved in 42 (77.8 %) out of 54 patients. Refractoriness to therapy was observed in 9 (16.7 %) out of 54 patients, mortality was 5.5 % (3/54). Remission rate was higher in patients with relapsed AML compared with refractory AML: 85.2 % (23/27) and 70.4 % (19/27), respectively. On the 14^th-16^th day of treatment patients with blast cell count ≥ 10 % in bone marrow (BM) showed significantly lower CR rate (60 %) compared with the group of patients with < 10 % blast cells in BM (89.6 %; p = 0.024) and shorter DFS (median 7.6 vs. 17.6 months, respectively; p = 0.03). Median DFS in patients with WT1 expression reduction to < 1 log on the 14^th-16^th day was 5 vs. 18 months in patients without WT1 expression reduction (p = 0.01). DFS varied in groups of patients with blast cell count < 10 % in BM on the 14^th-16^th day of treatment based on the level of WT1 expression reduction (p = 0.04). MRD-negative patients (57.1 %) showed significantly longer DFS and OS compared with MRD-positive patients (median DFS was 17.6 vs. 5.2 months, respectively, p = 0.02; median OS was 19 vs. 6.9 months, p = 0.0002). Median DFS and OS were different only in ELN low- and high-risk groups (median not reached vs. 5.2 months, respectively, p = 0.039; median not reached vs. 10.2 months, p = 0.039). Conclusion. FLAG and FLAG-Ida are effective and safe regimens in the treatment of relapsed/refractory AML. Achieving remission depends on neither the risk group nor the time of relapse occurrence. The blast cell count in BM on the 14^th-16^th day of FLAG/FLAG-Ida treatment is a prognostic factor determining achievement and duration of remission. WT1 expression level in the early post-induction period is a sensitive DFS marker. MRD status and molecular genetic risk (ELN) group affiliation are essential prognostic factors determining DFS and OS.