Skip to main content

Targeting epigenetic pathways in acute myeloid leukemia and myelodysplastic syndrome: a systematic review of hypomethylating agents trials



Aberrant DNA methylation has been identified as a key molecular event regulating the pathogenesis of myelodysplastic syndromes (MDS); myeloid neoplasms with an inherent risk of transformation to acute myeloid leukemia (AML). Based on the above findings, DNA hypomethylating agents (HMA) have been widely used to treat AML and MDS, especially in elderly patients and in those who are not eligible for allogeneic stem cell transplantation (SCT). Our goal was to determine if there is any therapeutic advantage of HMA vs. conventional care regimens (CCR) and indirectly compare the efficacy of azacitidine and decitabine in this patient population.


Eligible studies were limited to randomized controlled trials comparing HMA to CCR in adult patients with AML or MDS.


Overall survival (OS) rate was 33.2 vs. 21.4 % (RR 0.83, 95 % CI 0.71–0.98) and overall response rate (ORR) 23.7 vs. 13.4 % (RR 0.87, 95 % CI 0.81–0.93) for HMA and CCR, respectively. In subgroup analyses, only azacitidine treatment showed OS improvement (RR 0.75, 95 % CI 0.64–0.98) and not decitabine. Cytogenetic risk or bone marrow blast count did not have independent prognostic impact.


Collectively, these results demonstrate that HMA have superior outcomes compared to CCR and suggest that azacitidine in comparison to decitabine, may be more effective.


Myelodysplastic syndromes (MDS) are clonal hematopoietic stem cell disorders characterized by peripheral blood cytopenias, hypercellular bone marrows, and an inherent predisposition to transform to acute myeloid leukemia (AML) [1]. MDS are commonly associated with aging (age-related acquisition of genomic and epigenetic changes), environmental carcinogens, chemotherapy, and radiation exposure (therapy-related MDS) [2]. AML, an aggressive stem cell malignancy, with an annual incidence of 18,860 cases in the USA in 2014 [3], is characterized by ≥20 % bone marrow (BM) blasts and very poor outcomes with chemotherapy [4]. Although allogeneic stem cell transplantation (SCT) is the only curative treatment for high risk MDS and AML [5, 6], many patients are not eligible for transplantation due to advanced age, associated co-morbidities, and a limited donor pool [7]. Thus, there is an urgent need to develop new therapeutic approaches for these patients.

In the last decade, attention has turned to epigenetic changes in MDS/AML, especially aberrant DNA methylation, a molecular process playing a role in the regulation and expression of tumor suppressor genes and oncogenes, promoting dysplasia and blast transformation [8, 9]. These epigenetic modifications are distinguished from genetic mutations by their reversibility, making them potential therapeutic targets. Accordingly, the clinical and biological efficacy of hypomethylating agents (HMA) have been demonstrated in several in vitro/in vivo studies and clinical trials [8, 1013]. Despite the promising initial treatment responses, the survival outcome data with HMA have been inconsistent. Here, we provide a systematic review and pooled analysis of randomized clinical trials (RCT) comparing the outcomes of HMA vs. conventional care regimens (CCR) in patients with AML or MDS. CCR include best supportive care (BSC), intensive chemotherapy (IC), and low dose cytarabine (LDAC).

Materials and methods

Study selection criteria

Eligible studies were (1) RCTs, (2) assessing adult patients age ≥18 years with (3) morphologically proven diagnosis of AML or MDS with no previous allogeneic SCT, (4) treated with either HMA (azacitidine or decitabine) or CCR (BSC, LDAC or IC) in a setting of first-line treatment, and (5) including OS and treatment response outcomes. Trials were used only once in the analysis using the most updated available data.

Data sources

Literature search and review of relevant articles were limited to human studies. Key words included AML, MDS, azacitidine, and decitabine (Additional file 1: Table S1). Relevant studies were identified by searching PubMed, EMBASE, and Cochrane Database of Systematic Reviews up to October 2015. Additional relevant abstracts from the American Society of Hematology, the American Society of Clinical Oncology, and the European Hematology Association were also included into the literature search. A bibliography of identified articles and additional literatures from relevant references were further investigated manually to identify any relevant trials.

Data extraction

Two reviewers (SY and NDV) independently extracted data with a piloted extraction form. Any disagreement was resolved by consensus with other co-authors after review of full text.

Data items

The following information was extracted from individual trial reports: publication year, inclusion/exclusion criteria, sample size, median age, French-American-British (FAB) and World Health Organization (WHO) classification, BM blast count, cytogenetic risk categories, supportive care regimens, median follow-up, OS, treatment response, and mortality attributed to disease progression. Extracted from each study report were the number of patients treated with HMA or CCR, the proportion of patients with events (death, complete remission (CR), partial remission (PR)), subgroup data, hazard ratio (HR), 95 % CI, and p values. The primary outcome in this analysis was OS rate, and the secondary outcome was ORR (defined as rate of CR or PR). Trials reported outcomes with variable follow-up of 1–2 years; however, data from all studies were analyzed together with an assumption that median survival of AML patients without intensive chemotherapy or allogeneic SCT is less than 2 years in high-risk AML and MDS patients.

Assessment of bias risk

We used the Cochrane Collaboration’s tool [14], which evaluates random sequence generation, allocation concealment, blinding, incomplete outcome data, selective reporting, and other source of bias.

Statistical analysis

Statistical analyses were performed as described in a previous meta-analysis [15]. Briefly, the Cochrane Q statistic was used to estimate statistical heterogeneity, and the I 2 statistic was used to quantify inconsistency. The assumption of homogeneity was considered invalid if p < 0.10 and treatment effects were calculated with a random effects model. The funnel plot method was applied to assess publication bias. A two-sided p ≤ 0.05 was considered statistically significant in the RR and HR analysis without multiplicity correction. Pre-defined criteria including experimental agents (azacitidine vs. decitabine), cytogenetic risk, and BM blast count were used for the subgroup analyses to explore heterogeneity and to identify subgroups with differential benefit from HMA treatment (Table 2). RR and HR differences between subgroups were evaluated by regression models. Analysis calculations were performed using RevMan Version 5.3.


Search results

Our initial literature search yielded a total 254 potential abstracts (Fig. 1 and Additional file 1: Figure S1). Of this, 232 studies were excluded for being irrelevant to our analysis including editorials, study protocols, and commentaries. Total 22 articles were reviews in full text for their eligibility. Additional nine single arm studies [1624] and two retrospective studies [25, 26] were excluded from the analysis, as was one study [27] with no survival outcome report and five duplicate or ad hoc studies [2832]. With careful review of eligibility, a total of five open label multicenter phase III RCTs (four published articles [3336] and one abstract [37]) were selected for the current analysis. The characteristics of these trials are summarized in Table 1 and Additional file 1: Table S2.

Fig. 1
figure 1

Trial Selection Process for the Systematic Review

Table 1 Characteristics of trials included in the analysis


All trials included patients with morphologically confirmed AML or MDS and age of 18 years or greater. A total of 1755 patients were included in the analysis. Of these, 880 were treated with either azacitidine (n = 519) or decitabine (n = 361) and 875 with CCR including BSC (n = 384), LDAC (n = 422), and IC (n = 69) (Table 1). The range of median ages of patients on the selected trials was 68–75 years. Cytogenetic risk stratification was performed following South West Oncology Group (SWOG) [38] and International Prognostic Scoring System (IPSS) [39] categorization of AML and MDS, respectively. The number of patients with BM blast ≥30 %, oligoblastic AML (BM blasts 20–30 %), de novo AML, and intermediate/poor risk cytogenetic AML were 858, 366, 312, and 1278, respectively (Additional file 1: Table S2). The numbers of MDS patients with low and intermediate/high IPSS risk categorization were 7 and 636, respectively. Cytogenetic analysis was done on only 42 % of patients in one study [35], while additional studies [35, 37] failed to report subgroup outcomes according to cytogenetic risk and BM blast count. Three studies [33, 35, 36] included both AML and MDS patients and two studies [34, 37] included AML only (by FAB classification). Two trials [34, 37] included de novo AML patients without separate outcome report between transformed/secondary vs. de novo AML, and one of these studies included 158 patients with AML with myelodysplastic-related change (AML-MRC) [37]. Median follow-up was reported in only two studies [33, 36]. Forty-nine (53 %) CCR patients in one study [35] crossed over to the azacitidine arm, while the remaining studies did not have crossover options.

RR of OS rate and ORR

The combined estimate demonstrated an association of HMA treatment with significantly better OS rate of 33.2 vs. 21.4 % (RR 0.83, 95 % CI 0.71–0.98, p = 0.03) and higher ORR of 23.7 vs. 13.4 % (RR 0.87, 95 % CI 0.81–0.93, p = 0.0001) (Fig. 2). There was significant heterogeneity in OS (I 2 = 89 %, p < 0.00001) and ORR (I 2 = 63 %, p = 0.03) analyses across studies.

Fig. 2
figure 2

a Risk Ratio of the OS Rate. b Risk Ratio of the Overall Response Rate

Subgroup analyses

Azacitidine treatment was associated with significantly better OS compared to CCR (HR 0.67, 95 % CI 0.56–0.79, p < 0.00001), while no statistically significant OS benefit was observed in the decitabine treatment group (HR 0.86, 95 % CI 0.73–1.02, p = 0.08) (Table 2), partially explaining the heterogeneity in the OS analysis (Additional file 1: Figure S2A). Both azacitidine (RR 0.87, 95 % CI 0.78–0.97, p = 0.01) and decitabine (RR 0.86, 95 % CI 0.76–0.98, p = 0.03) treatments showed a higher ORR when each was compared to CCR with no RR difference between both treatments relative to CCR (p = 0.97) (Additional file 1: Figure S3). There was no statistically significant association of OS with cytogenetic risk, BM blast count, and use of LDAC or IC supplemental to BSC (Table 2 and Additional file 1: Figure S2B-D). Additional subgroup analyses directly comparing the OS rates of HMA and LDAC in AML patients revealed no significant difference (21.8 vs. 12.1 %, RR 0.77, 95 % CI 0.52–1.16, p = 0.21) between HMA and LDAC. Azacitidine treatment was associated with significantly better OS rates compared to LDAC (RR 0.66, 95 % CI 0.49–0.87, p = 0.004); however, no significant OS benefit over LDAC was seen in the decitabine subgroup (RR 0.97, 95 % CI 0.92–1.02, p = 0.24) (Additional file 1: Figure S4 and Table S4).

Table 2 Subgroup analysis of overall survival from available data

Bias analysis

All five trials were open-labeled RCT. Random sequence generation and allocation concealment were performed adequately in all studies. The adequacy of blinding was judged by whether treatment response was evaluated by a third person who did not know the treatment group of the patients. Only one study [34] performed blinded assessment. Treatment response was assessed by unblinded reviewers in one study [36], and blinding status was unclear in three studies [33, 35, 37]. The baseline demographic characteristics were balanced in all trials (Table 1 and Additional file 1: Table S2), and potential sources of bias are described in Additional file 1: Table S3. OS and treatment response analyses showed significant heterogeneity, largely attributable to the HMA agent. The observed funnel plot asymmetry can be explained as a function of experimental agents (Additional file 1: Figure S1).


We performed a systematic review and pooled analysis to compare the outcomes of HMA vs. CCR in patients with AML and MDS. The combined analyses revealed statistically significant OS and CR/PR benefit with HMA therapy in comparison to CCR (Fig. 2). These results confirm that HMA are reasonable therapeutic options with survival advantage, especially for elderly and transplant ineligible AML and MDS patients.

Aberrant DNA methylation has been suggested as a dominant mechanism of MDS progression to AML, and patients with MDS and AML have been shown to have unique patterns and abundance of aberrant DNA methylation compared to normal controls [40, 41], thus representing a suitable therapeutic target. Azacitidine (5-azacytidine) is metabolized into decitabine (5-aza-2′-deoxycytidine), which forms a covalent protein-DNA adduct, depleting intracellular methyl-transferase, leading to reversal of DNA hypermethylation on tumor suppressor genes and induction of apoptosis [8, 1013]. As such, DNA demethylation has been widely accepted as the primary mechanism of cytotoxicity of HMA and a previous study showed the association of CDKN2B (that encodes p15 INK4B) pre-treatment methylation level with treatment response to azacitidine [42]. However, interestingly, our subgroup analyses demonstrated an association of OS benefit with azacitidine treatment, but not with decitabine (Table 2), similar to a recent retrospective study with AML patients that showed superior outcomes with azacitidine therapy in comparison to decitabine [25]. Furthermore, Fandy et al. showed that reversal of methylation on four tumor suppressor genes (p15 INK4B, CDH-1, DAPK-1, and SOCS-1) had no prognostic impact on clinical response to the combination treatment of azacitidine and entinostat (histone deacetylase inhibitor) [43, 44]. Collectively, these results indicate potential cytotoxic mechanisms that are independent to DNA demethylation.

Both azacitidine and decitabine have been shown to induce DNA damage and cell cycle arrest, however, to different extents [45, 46], suggesting DNA damage as a possible underlying mechanism of HMA-induced cytotoxicity. However, a similar degree of γ-H2AX expression was observed in both responders and non-responders to azacitidine and entinostat treatment [43], questioning the role of DNA damage. Further studies are needed to define the role of DNA damage in the cytotoxic effect of azacitidine. In a recent study, azacitidine, but not decitabine, was shown to inhibit RNA methylation on cytosine 38 and 48 of tRNAAsp, which are target sites of DNMT2, and reduce the metabolic activity in myeloid cell lines. This suggests that azacitidine induces cytotoxicity via tRNA demethylation rather than DNA although the detailed mechanisms still remain to be answered. Also, Roulois et al. showed that the anti-tumor effect of low-dose decitabine may depend on viral mimicry, activating MDA5/MAVS/IRF7 RNA recognition pathway in colorectal cancer-initiating cells [47], and its role in myeloid neoplasms need further investigation.

Cytogenetic risk and BM blast counts are known to be independent prognostic factors in AML and MDS [39, 4850]. However, in our study, subgroup analysis according to cytogenetic risk or BM blast count failed to show any RR difference (Table 2). Ninety-eight percent of MDS patients enrolled in three trials [33, 35, 36] had intermediate or high IPSS risk and two studies [34, 37] included only AML patients whose prognosis is known to be dismal, partially explaining why there was no subgroup difference.

Previously, LDAC has been shown to be associated with higher response rates compared to supportive care in elderly AML or MDS patients who were not candidates for allogeneic SCT [51]. As such, three trials [34, 36, 37] in the current analysis incorporated LDAC as their control regimens. In a subgroup analysis comparing HMA and LDAC in AML patients, the OS rate in LDAC treatment group was significantly lower than that of azacitidine, but not decitabine, suggesting that azacitidine may be a better therapeutic option in this patient group (Additional file 1: Figure S4).

We recognize several limitations of the current analysis. First, there was significant heterogeneity in the OS analysis (I 2 = 89 %, p < 0.00001). The primary source of heterogeneity was experimental agents as shown in intra-subgroup homogeneity of three azacitidine trials [3537] (I 2 = 0 %, p = 0.38) as well as two decitabine trials [33, 34] (I 2 = 0 %, p = 0.85). Although the proportion of females in decitabine studies was relatively higher, other demographic profiles or clinical parameters were not substantially different from azacitidine trials (Table 1 and Additional file 1: Table S2). BM morphologic abnormalities were shown to be associated with worse prognosis in de novo AML [52], and 32.4 % of patients (n = 158) in one azacitidine study [37] had AML-MRC, which may result in heterogeneity of treatment outcomes. However, a recent ad hoc study with AML-MRC patients [53] showed significantly higher OS and CR/CRi rates with azacitidine, similar to the original data, rendering this possibility less likely. Second, in one study [35], 53 % of patients who were initially randomized to the CCR group crossed over to azacitidine treatment. However, the outcomes of these patients were analyzed along with the CCR group, which may underestimate the efficacy of azacitidine. Third, inclusion of LDAC and IC as BSC in three studies [34, 36, 37] may have contributed to the heterogeneity, although the result from direct comparison of HMA and LDAC was not significantly different from the original analysis (Additional file 1: Figure S4). Fourth, schedule and administration method and number of cycles of HMA used in the individual studies were different, potentially generating additional heterogeneity based on previous studies that showed better treatment response with prolonged azacitidine treatment [54] and lower bioavailability of subcutaneous azacitidine compared to intravenous administration (AUC values 89 %) [55]. Lastly, the maximum tolerated dose (MTD) of decitabine is known to be 1500–2000 mg/m2/course [56]. However, decitabine trials in our analysis used a 10–25 mg/m2/day dose, which is significantly lower than the MTD. This is based on previous phase I trial that focused on pharmacodynamics rather than MTD [57]. The optimal dose-schedule of decitabine, an S-phase specific agent, needs be further investigated in the future study.

Our systematic review and pooled analyses have identified several areas that require further study. First, the mechanisms of action of HMA and their therapeutic targets remain to be poorly defined. Inhibition of tRNA has been suggested as a potential mechanism of azacitidine; however, details supporting this need further elucidation. Recently, activation of the MDA5/MAVS RNA recognition pathway was suggested as an underlying mechanism of decitabine-induced cytotoxicity in colorectal cancer-initiating cells, and its role in myeloid neoplasm requires further elucidation. Second, the benefit of initial treatment response with decitabine failed to translate into OS improvement, supporting the possibility that the superior OS with azacitidine may result from better disease control, the mechanisms of which remain unknown. In the same context, the optimal dose of decitabine still remains to be defined. Third, potential biomarkers that might have prognostic relevance with regards to response to HMA therapy, including nucleoside transporters like hCNT1 [58] and cytosine deaminase activity [59], also need further study. Finally, a second-generation HMA has been developed to reduce elimination of decitabine by cytidine deaminase, thereby increasing the in vivo exposure of decitabine. A recent phase I clinical trial with SGI-110 (dinucleotide of decitabine and deoxyguanosine) demonstrated a comparable safety profile to decitabine with a significantly longer half-life [60]. An ongoing phase II clinical trial (NCT01261312) will hopefully provide more data in regards to the clinical activity of second generation HMA.


In an analysis of prospective randomized controlled trials in elderly patients with AML or MDS, HMA therapy was associated with improved response rates and OS in comparison to CCR, which included BSC, LDAC, and IC. Further analysis demonstrated that the observed survival benefit was restricted to azacitidine therapy, suggesting that azacitidine may be a better therapeutic option in AML and MDS patients. Finally, we also conclude on the need for additional mechanistic and epigenetic work to better understand mechanisms of action of HMA, optimal dosing strategies, and the identification of prognostic markers and biomarkers to help better predict and monitor response to therapy with these agents.


  1. Tefferi A, Vardiman JW. Myelodysplastic syndromes. N Engl J Med. 2009;361(19):1872–85.

    Article  CAS  PubMed  Google Scholar 

  2. Corey SJ, Minden MD, Barber DL, Kantarjian H, Wang JC, Schimmer AD. Myelodysplastic syndromes: the complexity of stem-cell diseases. Nat Rev Cancer. 2007;7(2):118–29.

    Article  CAS  PubMed  Google Scholar 

  3. Siegel R, Ma J, Zou Z, Jemal A. Cancer statistics, 2014. CA Cancer J Clin. 2014;64(1):9–29.

    Article  PubMed  Google Scholar 

  4. Löwenberg B, Downing JR, Burnett A. Acute myeloid leukemia. N Engl J Med. 1999;341(14):1051–62.

    Article  PubMed  Google Scholar 

  5. Stone RM. How I, treat patients with myelodysplastic syndromes. Blood. 2009;113(25):6296–303.

    Article  CAS  PubMed  Google Scholar 

  6. Rowe JM, Tallman MS. How I treat acute myeloid leukemia. Blood. 2010;116(17):3147–56.

    Article  CAS  PubMed  Google Scholar 

  7. Deschler B, de Witte T, Mertelsmann R, Lübbert M. Treatment decision-making for older patients with high-risk myelodysplastic syndrome or acute myeloid leukemia: problems and approaches. Haematologica. 2006;91(11):1513–22.

    PubMed  Google Scholar 

  8. Di Croce L, Raker VA, Corsaro M, et al. Methyltransferase recruitment and DNA hypermethylation of target promoters by an oncogenic transcription factor. Science. 2002;295(5557):1079–82.

    Article  PubMed  Google Scholar 

  9. Herman JG, Umar A, Polyak K, et al. Incidence and functional consequences of hMLH1 promoter hypermethylation in colorectal carcinoma. Proc Natl Acad Sci U S A. 1998;95(12):6870–5.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  10. Jüttermann R, Li E, Jaenisch R. Toxicity of 5-aza-2′-deoxycytidine to mammalian cells is mediated primarily by covalent trapping of DNA methyltransferase rather than DNA demethylation. Proc Natl Acad Sci U S A. 1994;91(25):11797–801.

    Article  PubMed  PubMed Central  Google Scholar 

  11. Nieto M, Samper E, Fraga MF, González de Buitrago G, Esteller M, Serrano M. The absence of p53 is critical for the induction of apoptosis by 5-aza-2'-deoxycytidine. Oncogene. 2004;23(3):735–43.

  12. Jones PA, Taylor SM, Mohandas T, Shapiro LJ. Cell cycle-specific reactivation of an inactive X-chromosome locus by 5-azadeoxycytidine. Proc Natl Acad Sci U S A. 1982;79(4):1215–9.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  13. Lyko F, Brown R. DNA methyltransferase inhibitors and the development of epigenetic cancer therapies. J Natl Cancer Inst. 2005;97(20):1498–506.

    Article  CAS  PubMed  Google Scholar 

  14. Moher D, Liberati A, Tetzlaff J, Altman DG, Group P. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. J Clin Epidemiol. 2009;62(10):1006–12.

    Article  PubMed  Google Scholar 

  15. Yun S, Vincelette ND, Segar JM, et al. Comparative effectiveness of newer tyrosine kinase inhibitors versus imatinib in the first-line treatment of chronic-phase chronic myeloid leukemia across risk groups: a systematic review and meta-analysis of eight randomized trials. Clin Lymphoma Myeloma Leuk. 2016.

  16. Steensma DP, Baer MR, Slack JL, et al. Multicenter study of decitabine administered daily for 5 days every 4 weeks to adults with myelodysplastic syndromes: the Alternative Dosing for Outpatient Treatment (ADOPT) trial. J Clin Oncol. 2009;27(23):3842–8.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  17. Kantarjian H, Oki Y, Garcia-Manero G, et al. Results of a randomized study of 3 schedules of low-dose decitabine in higher-risk myelodysplastic syndrome and chronic myelomonocytic leukemia. Blood. 2007;109(1):52–7.

    Article  CAS  PubMed  Google Scholar 

  18. Lee JH, Jang JH, Park J, et al. A prospective multicenter observational study of decitabine treatment in Korean patients with myelodysplastic syndrome. Haematologica. 2011;96(10):1441–7.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  19. Iastrebner M, Jang JH, Nucifora E, et al. Decitabine in myelodysplastic syndromes and chronic myelomonocytic leukemia: Argentinian/South Korean multi-institutional clinical experience. Leuk Lymphoma. 2010;51(12):2250–7.

    Article  CAS  PubMed  Google Scholar 

  20. Issa JP, Garcia-Manero G, Giles FJ, et al. Phase 1 study of low-dose prolonged exposure schedules of the hypomethylating agent 5-aza-2'-deoxycytidine (decitabine) in hematopoietic malignancies. Blood. 2004;103(5):1635–40.

  21. Cashen AF, Schiller GJ, O'Donnell MR, DiPersio JF. Multicenter, phase II study of decitabine for the first-line treatment of older patients with acute myeloid leukemia. J Clin Oncol. 2010;28(4):556–61.

    Article  CAS  PubMed  Google Scholar 

  22. Silvermann LR HJ, Demakos EP, et al. Azacitidine (Aza C) in myelodysplastic syndromes (MDS), CALGB studies 8421 and 8921. Ann Hematol. 1994;68:A12.

    Google Scholar 

  23. Maurillo L, Venditti A, Spagnoli A, et al. Azacitidine for the treatment of patients with acute myeloid leukemia: report of 82 patients enrolled in an Italian Compassionate Program. Cancer. 2012;118(4):1014–22.

    Article  CAS  PubMed  Google Scholar 

  24. Al-Ali HK, Jaekel N, Junghanss C, et al. Azacitidine in patients with acute myeloid leukemia medically unfit for or resistant to chemotherapy: a multicenter phase I/II study. Leuk Lymphoma. 2012;53(1):110–7.

    Article  CAS  PubMed  Google Scholar 

  25. Smith BD, Beach CL, Mahmoud D, Weber L, Henk HJ. Survival and hospitalization among patients with acute myeloid leukemia treated with azacitidine or decitabine in a large managed care population: a real-world, retrospective, claims-based, comparative analysis. Exp Hematol Oncol. 2014;3(1):10.

    Article  PubMed  PubMed Central  Google Scholar 

  26. van der Helm LH, Scheepers ER, Veeger NJ, et al. Azacitidine might be beneficial in a subgroup of older AML patients compared to intensive chemotherapy: a single centre retrospective study of 227 consecutive patients. J Hematol Oncol. 2013;6:29.

    Article  PubMed  PubMed Central  Google Scholar 

  27. Kantarjian H, Issa JP, Rosenfeld CS, et al. Decitabine improves patient outcomes in myelodysplastic syndromes: results of a phase III randomized study. Cancer. 2006;106(8):1794–803.

    Article  CAS  PubMed  Google Scholar 

  28. Seymour JF, Fenaux P, Silverman LR, et al. Effects of azacitidine compared with conventional care regimens in elderly (≥75 years) patients with higher-risk myelodysplastic syndromes. Crit Rev Oncol Hematol. 2010;76(3):218–27.

    Article  PubMed  PubMed Central  Google Scholar 

  29. Silverman LR, Fenaux P, Mufti GJ, et al. Continued azacitidine therapy beyond time of first response improves quality of response in patients with higher-risk myelodysplastic syndromes. Cancer. 2011;117(12):2697–702.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  30. Silverman LR, McKenzie DR, Peterson BL, et al. Further analysis of trials with azacitidine in patients with myelodysplastic syndrome: studies 8421, 8921, and 9221 by the Cancer and Leukemia Group B. J Clin Oncol. 2006;24(24):3895–903.

    Article  CAS  PubMed  Google Scholar 

  31. Seymour JF, Döhner, H, Butrym, A, et al. Azacitidine (AZA) versus conventional care regimens (CCR) in older patients with newly diagnosed acute myeloid leukemia (>30% bone marrow blasts) with morphologic dysplastic changes: a subgroup analysis of the AZA-AML-001 Trial 2014, Blood.

  32. Becker H, Suciu, S, Rüter, B, Platzbecker, U, Giagounidis, A. Selleslag, D. et al. Low-dose decitabine vs best supportive care in older patients with AML and low blast counts: results of a subgroup analysis of the randomized phase III study 06011 of the EORTC Leukemia Cooperative Group and German MDS Study Group2013, Blood.

  33. Lübbert M, Suciu S, Baila L, et al. Low-dose decitabine versus best supportive care in elderly patients with intermediate- or high-risk myelodysplastic syndrome (MDS) ineligible for intensive chemotherapy: final results of the randomized phase III study of the European Organisation for Research and Treatment of Cancer Leukemia Group and the German MDS Study Group. J Clin Oncol. 2011;29(15):1987–96.

    Article  PubMed  Google Scholar 

  34. Kantarjian HM, Thomas XG, Dmoszynska A, et al. Multicenter, randomized, open-label, phase III trial of decitabine versus patient choice, with physician advice, of either supportive care or low-dose cytarabine for the treatment of older patients with newly diagnosed acute myeloid leukemia. J Clin Oncol. 2012;30(21):2670–7.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  35. Silverman LR, Demakos EP, Peterson BL, et al. Randomized controlled trial of azacitidine in patients with the myelodysplastic syndrome: a study of the Cancer and Leukemia Group B. J Clin Oncol. 2002;20(10):2429–40.

    Article  CAS  PubMed  Google Scholar 

  36. Fenaux P, Mufti GJ, Hellstrom-Lindberg E, et al. Efficacy of azacitidine compared with that of conventional care regimens in the treatment of higher-risk myelodysplastic syndromes: a randomised, open-label, phase III study. Lancet Oncol. 2009;10(3):223–32.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  37. Dombret H, Seymour, JF, Butrym, A, et al. Results of a phase 3, multicenter, randomized, open-label study of azacitidine (AZA) vs conventional care regimens (CCR) in older patients with newly diagnosed Acute Myeloid Leukemia (AML). EHA 19th congress2014.

  38. Slovak ML, Kopecky KJ, Cassileth PA, et al. Karyotypic analysis predicts outcome of preremission and postremission therapy in adult acute myeloid leukemia: a Southwest Oncology Group/Eastern Cooperative Oncology Group Study. Blood. 2000;96(13):4075–83.

    CAS  PubMed  Google Scholar 

  39. Greenberg PL, Tuechler H, Schanz J, et al. Revised international prognostic scoring system for myelodysplastic syndromes. Blood. 2012;120(12):2454–65.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  40. Jiang Y, Dunbar A, Gondek LP, et al. Aberrant DNA methylation is a dominant mechanism in MDS progression to AML. Blood. 2009;113(6):1315–25.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  41. Figueroa ME, Skrabanek L, Li Y, et al. MDS and secondary AML display unique patterns and abundance of aberrant DNA methylation. Blood. 2009;114(16):3448–58.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  42. Raj K, John A, Ho A, et al. CDKN2B methylation status and isolated chromosome 7 abnormalities predict responses to treatment with 5-azacytidine. Leukemia. 2007;21(9):1937–44.

    Article  CAS  PubMed  Google Scholar 

  43. Fandy TE, Herman JG, Kerns P, et al. Early epigenetic changes and DNA damage do not predict clinical response in an overlapping schedule of 5-azacytidine and entinostat in patients with myeloid malignancies. Blood. 2009;114(13):2764–73.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  44. Robertson KD, Bhalla KN. Missteps in “tango” for epigenome targeting. Blood. 2009;114(13):2569–70.

    Article  CAS  PubMed  Google Scholar 

  45. Karpf AR, Moore BC, Ririe TO, Jones DA. Activation of the p53 DNA damage response pathway after inhibition of DNA methyltransferase by 5-aza-2'-deoxycytidine. Mol Pharmacol. 2001;59(4):751–7.

  46. Palii SS, Van Emburgh BO, Sankpal UT, Brown KD, Robertson KD. DNA methylation inhibitor 5-Aza-2'-deoxycytidine induces reversible genome-wide DNA damage that is distinctly influenced by DNA methyltransferases 1 and 3B. Mol Cell Biol. 2008;28(2):752–71.

  47. Roulois D, Loo Yau H, Singhania R, et al. DNA-demethylating agents target colorectal cancer cells by inducing viral mimicry by endogenous transcripts. Cell. 2015;162(5):961–73.

    Article  CAS  PubMed  Google Scholar 

  48. Greenberg P, Cox C, LeBeau MM, et al. International scoring system for evaluating prognosis in myelodysplastic syndromes. Blood. 1997;89(6):2079–88.

    CAS  PubMed  Google Scholar 

  49. Byrd JC, Mrózek K, Dodge RK, et al. Pretreatment cytogenetic abnormalities are predictive of induction success, cumulative incidence of relapse, and overall survival in adult patients with de novo acute myeloid leukemia: results from Cancer and Leukemia Group B (CALGB 8461). Blood. 2002;100(13):4325–36.

    Article  CAS  PubMed  Google Scholar 

  50. Patel JP, Gönen M, Figueroa ME, et al. Prognostic relevance of integrated genetic profiling in acute myeloid leukemia. N Engl J Med. 2012;366(12):1079–89.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  51. Miller KB, Kim K, Morrison FS, et al. The evaluation of low-dose cytarabine in the treatment of myelodysplastic syndromes: a phase-III intergroup study. Ann Hematol. 1992;65(4):162–8.

    Article  CAS  PubMed  Google Scholar 

  52. Weinberg OK, Seetharam M, Ren L, et al. Clinical characterization of acute myeloid leukemia with myelodysplasia-related changes as defined by the 2008 WHO classification system. Blood. 2009;113(9):1906–8.

    Article  CAS  PubMed  Google Scholar 

  53. Seymour JF. DH, Butrym A, Wierzbowska A, Selleslag D, Jang JH, et al. Azacitidine (AZA) versus conventional care regimens (CCR) in older patients with newly diagnosed acute myeloid leukemia (>30% bone marrow blasts) with morphologic dysplastic changes: a subgroup analysis of the AZA-AML-001 Trial2014, Blood: 124 (21).

  54. Prebet T, Sun Z, Figueroa ME, et al. Prolonged administration of azacitidine with or without entinostat for myelodysplastic syndrome and acute myeloid leukemia with myelodysplasia-related changes: results of the US Leukemia Intergroup trial E1905. J Clin Oncol. 2014;32(12):1242–8.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  55. Marcucci G, Silverman L, Eller M, Lintz L, Beach CL. Bioavailability of azacitidine subcutaneous versus intravenous in patients with the myelodysplastic syndromes. J Clin Pharmacol. 2005;45(5):597–602.

    Article  CAS  PubMed  Google Scholar 

  56. Sachs JR, Mayawala K, Gadamsetty S, Kang SP, de Alwis DP. Optimal dosing for targeted therapies in oncology: drug development cases leading by example. Clin Cancer Res. 2016;22(6):1318–24.

    Article  CAS  PubMed  Google Scholar 

  57. Blum W, Klisovic RB, Hackanson B, et al. Phase I study of decitabine alone or in combination with valproic acid in acute myeloid leukemia. J Clin Oncol. 2007;25(25):3884–91.

    Article  CAS  PubMed  Google Scholar 

  58. Rius M, Stresemann C, Keller D, et al. Human concentrative nucleoside transporter 1-mediated uptake of 5-azacytidine enhances DNA demethylation. Mol Cancer Ther. 2009;8(1):225–31.

    Article  CAS  PubMed  Google Scholar 

  59. Qin T, Jelinek J, Si J, Shu J, Issa JP. Mechanisms of resistance to 5-aza-2'-deoxycytidine in human cancer cell lines. Blood. 2009;113(3):659–67.

  60. Issa JP, Roboz G, Rizzieri D, et al. Safety and tolerability of guadecitabine (SGI-110) in patients with myelodysplastic syndrome and acute myeloid leukaemia: a multicentre, randomised, dose-escalation phase 1 study. Lancet Oncol. 2015;16(9):1099–110.

    Article  CAS  PubMed  Google Scholar 

Download references


This work was supported by predoctoral fellowships to NDV from the Mayo Foundation for Education and Research and Bressler Alpert Society Research Award to SY.

Authors’ contributions

SY, NDV, MEFZ, and MMP contributed to the conception and design of the study and searching for trials. SY, NDV, IA, KDR, MEFZ, and MMP were involved in the acquisition, analysis, and interpretation of the data. SY, NDV, IA, KDR, MEFZ, and MMP helped in drafting the article. All authors read and approved the final manuscript.

Competing interests

The authors declare that they have no competing interest.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Seongseok Yun.

Additional file

Additional file 1: Figure S1.

Funnel plot. Figure S2. Subgroup analysis of OS rate from available data. Figure S3. Subgroup analysis of ORR from available data. Figure S4. Comparison of OS rates between HMA vs. LDAC in AML patients. Table S1. Search detail in PubMed, EMBASE, and Cochrane database of systematic review. Table S2. Additional characteristics of randomized trials. Table S3. Risk of bias assessment of studies according to Cochrane risk bias assessment tool. Table S4. Characteristics of trials (ad hoc studies) comparing HMAs and LDAC in AML patients. (DOC 1145 kb)

Rights and permissions

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Yun, S., Vincelette, N.D., Abraham, I. et al. Targeting epigenetic pathways in acute myeloid leukemia and myelodysplastic syndrome: a systematic review of hypomethylating agents trials. Clin Epigenet 8, 68 (2016).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: