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5-Azacitidine (5-AZA) is widely used for the treatment of higher-risk myelodysplastic syndromes. However, response and survival rates vary considerably, while indicated treatment duration remains undefined. For these reasons, factors determining response and survival are of major importance. Clinical, morphological, flow cytometry, cytogenetic and molecular factors are discussed in this review. Biomarkers predictive of response and prognosis, as well as their link to the mode of action of 5-AZA are also addressed, shifting the focus from clinical practice to investigational research. Their use could further improve prognostic classification of 5-AZA treated higher-risk myelodysplastic syndromes in the near future.

CD4+ T cells orchestrate immune responses and are actively engaged in shaping tumor immunity. Signal transducer and activator of transcription (STAT) signaling controls the epigenetic tuning of CD4+ T-cell differentiation and polarization, and perturbed STAT signaling networks in CD4+ T cells subvert antitumor immunity in malignancies. Azacitidine (AZA), the mainstay therapy for high-risk myelodysplastic syndromes (HR-MDS), affects CD4+ T-cell polarization and function, but whether this contributes to AZA efficacy is currently unknown. By using functional proteomic, transcriptomic, and mutational analyses in 73 HR-MDS patients undergoing AZA therapy, we demonstrate that responding patients exhibited a coordinated CD4+ T-cell immune response and downregulated the inflammatory cytokine signaling pathways in CD4+ T cells after AZA, in contrast to nonresponders who upregulated the same pathways. We further observed an AZA-mediated downregulation of intereukin-6 (IL-6)-induced STAT3 phosphorylation in CD4+FOXP3- conventional T cells (Tcons) that correlated independently with better response and survival, whereas it was also not associated with the mutation number and profile of the patients. The AZA-induced downregulation of IL-6/STAT3 axis in Tcons restored the STAT signaling architecture in CD4+ T-cell subsets, whereas STAT signaling networks remained disorganized in patients who upregulated IL-6/STAT3 activity in Tcons. Given the pivotal role of CD4+ T cells in adaptive immunity, our findings suggest that the downregulation of the IL-6/STAT3 pathway in Tcons potentially constitutes a previously unrecognized immune-mediated mechanism of action of AZA and sets the scene for developing rational strategies of AZA combinations with IL-6/STAT3 axis inhibitors., (© 2021 by The American Society of Hematology.)

Higher-risk Myelodysplastic syndromes (MDS) patients undergoing treatment with 5-azacytidine (AZA) are typically elderly with several comorbidities. However, the effect of comorbidities on the effectiveness and safety of AZA in real-world settings remains unclear. We analyzed data from 536 AZA-treated patients with higher-risk MDS, Myelodysplastic/Myeloproliferative neoplasms and low blast count Acute Myeloid Leukemia enrolled to the Hellenic National Registry of Myelodysplastic and Hypoplastic Syndromes. Multivariate analysis adjusted also for the International Prognostic Scoring System (IPSS), its revised version (IPSS-R) and the French Prognostic Scoring System (FPSS), demonstrated independent associations of overall and leukemia-free survival with estimated glomerular filtration rate (eGFR) <45 mL min -1 /1.73 m 2 (P = .039, P = .023, respectively), ECOG performance status <2 (P = .015, P = .006), and presence of peripheral blood blasts (P = .008, P = .034), while secondary MDS also correlated with significantly shorter leukemia-free survival (P = .039). Addition of eGFR <45 mL min -1 /1.73 m 2 , in IPSS-R and FPSS increased the predictive power of both models. Only FPSS ≤2 and eGFR <45 mL min -1 /1.73 m 2 predicted worse response to AZA in multivariate analysis, whereas eGFR <45 mL min -1 /1.73 m 2 correlated significantly with death from hemorrhage (P = .003) and cardiovascular complications (P = .006). In conclusion, in the second largest real-world series of AZA-treated MDS patients, we show that an eGFR <45 mL min -1 /1.73 m 2 is an independent predictor of worse response and survival. This higher cut-off, instead of the commonly used serum creatinine >2 mg/dL, can be utilized as a more precise indicator of renal comorbidity during AZA therapy. Incorporation of eGFR in the prognostic assessment of AZA-treated MDS patients may prove useful not only in routine practice, but also for the appropriate patient stratification in clinical trials with AZA combinations., (© 2020 John Wiley & Sons Ltd.)

The demethylating factor 5-azacytidine (5-AZA) improves survival in intermediate-2 and high-risk myelodysplastic syndrome (MDS) patients [according to the International Prognostic Score System (IPSS)] responding to treatment. However, the outcome of patients achieving stable disease (SD) is unclear. This retrospective study of the Hellenic MDS Study Group included 353 intermediate-2 or high IPSS risk patients treated with 5-AZA. Forty-four out of 86 (51.6%) patients achieving SD and continuing treatment with 5-AZA showed a lower risk of transformation of MDS to acute myeloid leukemia (AML) and increased overall survival (OS), compared to SD patients who discontinued the treatment (estimated median AML-free survival = 38 months, 95% CI = 10.7-65.3 vs 15 months, 95% CI = 10.4-19.6, P < .001; estimated median OS = 20 months, 95% CI = 5.5-34.5 vs 11 months, 95% CI = 5.8-16.2, P < .001). Moreover, SD patients continuing treatment with 5-AZA had no differences in AML-free survival compared to patients showing response to 5-AZA (estimated median AML-free survival = 38 months, 95% CI = 10.7-65.3 vs 31 months, 95% CI = 23.6-38.4, P = .45; estimated median OS 20 months, 95% CI = 5.5-34.5 vs 25 months, 95% CI = 21.3-28.7, P = .50). In conclusion, MDS patients achieving SD in the first 6 months of treatment with 5-AZA as best response should continue receiving 5-AZA as they may benefit from prolonged treatment., (© 2018 John Wiley & Sons, Ltd.)

In this study, we investigated the incidence and prognostic impact of monosomal karyotype (MK) in 405 higher-risk Myelodysplastic Syndromes (MDS) patients treated with 5-AZA. The MK was present in 66 out of 405 (16.3%) patients, most of whom had complex karyotype (CK). MK was strongly associated with CK and the cytogenetic risk defined according to IPSS-R, as well as with high-risk disease, according to IPSS (P = .029), IPSS-R (P < .001), and WPSS (P < .001) classification systems. The overall response rate (ORR) was not different between MK+ and MK- patients (46.6% vs. 46.2%). At 28 months median follow-up, the median duration of response was 11 months in the entire cohort, 9.5 months in MK+ patients and 11 months in MK-patients (P = .024). The estimated median time to transformation to acute myeloid leukemia for MK+ patients was 17 months vs. 23 months for MK- patients (P = .025). The estimated median OS for MK+ patients was 12 months vs. 18 months for MK- patients (P < .001). Multivariate Cox regression analysis revealed that performance status (P < .001), IPSS-R (P < .001), and MK (P = .002) were independently associated with overall survival (OS). In a subgroup consisting of high and very-high risk patients according to IPSS-R, MK- patients showed better OS rates compared to MK+ patients (estimated median OS: 17 months vs. 12 months, P = .002). In conclusion, we found that MK is associated with reduced OS in patients with higher-risk MDS treated with 5-AZA. Furthermore, we showed that in MDS with high or very-high IPSS-R risk score, MK can further distinguish patients with worse outcome., (© 2018 Wiley Periodicals, Inc.)

Purpose: Azacitidine is the mainstay of high-risk myelodysplastic syndromes (MDS) therapy, but molecular predictors of response and the mechanisms of resistance to azacitidine remain largely unidentified. Deregulation of signaling via Stat3 and Stat5 in acute myeloid leukemia (AML) is associated with aggressive disease. Numerous genes involved in cell signaling are aberrantly methylated in MDS, yet the alterations and the effect of azacitidine treatment on Stat3/5 signaling in high-risk MDS have not been explored., Experimental Design: We assessed longitudinally constitutive and ligand-induced phospho-Stat3/5 signaling responses by multiparametric flow cytometry in 74 patients with MDS and low blast count AML undergoing azacitidine therapy. Pretreatment Stat3/5 signaling profiles in CD34(+)cells were grouped by unsupervised clustering. The differentiation stage and the molecular properties of the CD34(+)G-CSF-inducible Stat3/5 double-positive subpopulation were performed by flow cytometry and quantitative real-time PCR in isolated MDS progenitors., Results: The pretreatment Stat3/5 signaling profiles in CD34(+)cells correlated strongly with response and cytogenetics and independently predicted event-free survival. We further identified a CD34(+)G-CSF-inducible Stat3/5 double-positive subpopulation (DP subset) whose pretreatment levels were inversely associated with treatment response and cytogenetics. The kinetics of the DP subset followed the response to azacitidine and the disease course, whereas its molecular characteristics and cellular hierarchy were consistent with a leukemia propagating cell phenotype., Conclusions: Our findings provide a novel link among Stat3/5 signaling and MDS pathobiology and suggest that the Stat3/5 signaling biosignature may serve as both a response biomarker and treatment target., (©2015 American Association for Cancer Research.)

Objectives: The demethylating factor 5-Azacytidine (5-AZA) improves survival of patients with myelodysplastic syndromes (MDS) in randomized control trials but the results in 'real life' are controversial., Methods: In this retrospective study, we evaluated the outcome of 56 high-risk MDS patients who were treated with 5-AZA between 2005 and 2013. 5-AZA was administered in an outpatient basis at a dose 75 mg/m(2) s.c. with the following schedule: 5 days on/weekend off/2 days on (5/2/2)., Results: The overall response rate (ORR) was 50%; 21.2% patients achieved complete response (CR), 3.8% partial response (PR), and 25% hematologic improvement (HI); 34.6% had stable disease (SD) and 15.4% showed progressive disease (PD). The estimated median event free survival (EFS) and overall survival (OS) were 11 and 17 months, respectively. Interestingly, the estimated time to acute myeloid leukemia transformation was 30 months, which refers to patients who responded to AZA treatment or remained stable. Patients who responded to the 5-AZA achieving CR, PR, and HI had better EFS and OS compared to the patients who had SD or PD. In addition, Δ WHO Classification-based Prognostic Score System (ΔWPSS), which represents the improvement of WPSS risk group before and after treatment, was associated with significantly improved OS and better EFS. Finally, the response to treatment was not associated with the expression of p53., Conclusions: In conclusion, 5-AZA is an effective treatment for high-risk MDS. Improved OS and EFS were found mainly in patients who responded to the treatment while ΔWPSS seems to represent a promising future prognostic tool.