Decitabine In Combined With Vitamine C Improved The Outcome In Elderly Acute Myeloid Leukemia Patients

ObjectiveDecitabine(DAC)had been shown to improve the response of elderly patients with acute myeloid leukemia(AML),also vitamin C(VC)was conformed to be able to inhibit the proliferation of malignant cells.This study is aimed to explore the efficacy and safety of the combination treatment of DAC and VC in untreated elderly AML patients.Furthermore,mechanism of the combination agents work NB4 and HL60 cell lines is also investigated,which will be hopefully provide a theoretical basis for this new therapy.MethodsWe retrospectively analyzed the clinical outcomes and adverse events of 73 untreated elderly AML patients who received DCAG＋VC(n=39)or DCAG(n=34)induction and consolidation regimen.All patients enrolled were over 60 years old with newly diagnosed de novo or secondary AML according to the International Working Group(IWG)criteria[19],they were hospitalized in Jiangsu Province Hospital From November 2010 to April 2016.CR and survival was evaluated.In vitro experiment,single agent VC or DAC or linear a combination of these two agents was administrated in NB4 and HL60 human leukemic cell lines.Cell proliferation was determined by CCK8 assay.Cell apoptosis was analyzed by flow cytometry(FCM).TET2 expression was detected by real-time polymerase chain reaction(qPCR)and Western blot analysis,and the activity of TET2 enzyme was measured by enzyme-linked immunosorbent assay(ELISA).Results1.Patients who received DCAG+VC regimen presented a higher completeremission(CR)rate than those who received the DCAG regimen.In two groups,76.9%and 44.1%(p=0.004)patients achieved CR after one cycle of induction chemotherapy respectively,84.6%and 70.6%of them(p=0.148)achieved CR after two cycles induction respectively.The median OS was significant improved in the DCAG+VC group compared with the DCAG group(15.3m vs.9.3m;p=0.039).There was no obvious additional toxicity observed in the combination treatment group.2.Single agent DAC and VC could inhibit the growth and proliferation of NB4 and HL60 cells,and the inhibitory effect was found dose-and time-dependent.The combination of 2.5μmol/L DAC and 0.3mmol/L VC significantly inhibited the proliferation of the leukemia cell lines than single agent DAC and VC,which revealed the synergistic effect of these two agents.3.Flow cytometry analyse showed that the apoptosis of leukemia cells was increased after 48h treatment of combination of DAC and VC.4.The results of RT-qPCR and Western blot showed that the expression of TET2 gene was increased after 48h of DAC treatment in two cell lines,while TET2 expression was not found obvious change after 48h of VC treatment.ELISA analyse showed that both VC and DAC could increase the activity of TET2 hydroxylase.TET2 enzyme activity can be further promoted after the simultaneous treatment of these two agents in both cells.Conclusions1.The combination administration of VC to DCAG regimen appeared to improve CR and OS in newly diagnosed elderly patients with AML.2.The synergy of VC with DAC inhibited the growth of NB4 and HL60 cells and induced apoptosis,which may be associated with the up-regulation of TET2 expression and TET2 enzyme activity.