Early treatment Response and events definition
To identify the early prognostic factors, we evaluated leukemic blasts counts in bone marrow by morphology on days 46 and minimal residual disease(MRD) on days 19 and 46 during first induction.Diagnosis of complete remission(CR) was based solely on bone marrow morphology with a cutoff value of 5% of leukemic blasts on treatment day 46.Bone marrow MRD no lower than 10-5 is defined as positive.It is considered as good (Prednisone good responders, PGR) if the peripheral blast count on treatment day 5 is lower than 1×109/L, whereas it is poor(PPR) if patients show no lower than 1×109/L.Patients were defined as having a poor early response(PER) if MRD≥1% on day treatment 19.
FISH andcytogenetic risk group
Pretreatment bone marrow (BM) aspirates were taken at diagnosis and at least 1-2 milliliters of bone marrow aspirates were analyzed by fluorescence in situ hybridization(FISH) for CDKN2A deletion,BCR-ABL1 fusion gene,TEL-AML1 fusion gene,E2A-PBX1 fusion gene,MLL rearrangement,MYC translocation,SIL-TAL1 fusion gene,P53-CEP17,CRLF2 rearrangement.We analyzed interphase cells according to the instructions of the probe manufacturer(America Abbott).
Patients were divided into two exclusionary cytogenetic risk groups based on the following cytogenetic abnormalities:high risk (BCR-ABL1,MLL rearrangements, chromosome <44 or t[17;19]/E2A-HIF) or intermediate risk (all extra cases with abnormal or normal cytogenetics).