SummaryMyelodysplastic syndrome represents a heterogenous group of clonal diseases affecting the hematopoietic stem cells underlied by different somatic gene mutations and/or altered epigenetic regulation induced by the disturbed microenvironment, as well as changes in the immune surveillance system. In many patients, the MDS is preceded by a period of non-clonal or clonal cytopenias of a non-clear significance that are determined by age-associated somatic mutations and increased leukemia risks resulting into a higher cellular proliferation, inefficient clonal growth, suppression of normal hematopoiesis, and, finally, into altered differentiation, thus causing accumulation of blast forms and a risk of evolving into acute leukemia. Substantial data on prevalence and impact of mutations on the prognosis in myelodysplastic syndrome was accessed by multiple groups however the results of several published studies are controversial. Thus we have performed an unconventional meta-analysis by accessing resulting confidence intervals both by statistical means and by creating pulled database with available individual patient data. 12 studies with 1238 patients were analyzed. The observed prevalence of mutations was the subject to significant variability (95%CI: ASXL1 13.6-29.8%; DNMT3A 7.3-12.9%; EZH2 2.4-7.0%; U2AF1 3.7-13.8%; TET2 14.2-32.5%; RUNX1 3.9-13.7%; TP53 4.7-15.2%; SRSF2 7.1-28.1%; RAS 2.2-15,1%; SF3B1 4.4-12.2%; CBL 0.1-8.9%; None, 8.0-23.3%; р<0.0001). The analysis of response to hypomethylating agents revealed improved response in patients with TP53 (95% CI 49-55%, p=0.0003), TET2(95% CI 49-52%, p=0.0001) and SRSF2 (95% CI 48-54%, p=0.0005) mutations; however the survival was worse in TP53 mutated patients (95% CI 44-49%, p=0.002) and better in SF3B1 mutated disease (95% CI 47-54%, p=0.01). The magnitude of difference was less than previously reported. The study confirmed the previous reports on the impact of TP53, TET2 and SF3B1 mutations on prognosis. Further studies on the potential prognostic markers are required, especially in patients with absence of conventional mutations.

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Aplastic anemia (АА) is the most common clinical form of bone marrow failure which is still considered as a non-malignant disorder. However, development secondary myelodysplastic syndrome and acute myeloid leukemia (MDS/AML) in long-term AA survivors is confirmed by numerous studies. Treatment of the patients with secondary MDS/AML remains unresolved problem. The aim of present study was to evaluate efficacy of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in secondary MDS/AML evolving from AA, and to determine the factors influencing clinical outcomes. The study included 26 patients with MDS/AML, previously treated with immunosuppressive treatment due to acquired AA. Median age was 25 (range, 9-45) years at the moment of MDS/AML diagnosis. Eight patients who had no available compatible donors, received chemotherapy alone, 18 patients received allo-HSCT (from matched related donor (n=6), matched unrelated donor (n=9), haploidentical donor (n=3)). Groups were comparable in pre-transplant characteristics of patients.The 2-year overall survival (OS) in the chemotherapy alone group was 0%, being 53.1% in HSCT group [(95% CI 41-65.2), p=0.024]. For the patients being in remission state at the time of allo-HSCT, the 4-year OS comprised 80% [(95% CI, 65-95), p=0.021] vs 27 % in non-remission group. The use of peripheral blood as a source of graft was associated with higher OS (p=0.014). Allo-HSCT remains the only potentially curative method for treatment of secondary MDS/AML from AA and should be performed as soon as possible in the case of registered evolution of AA to MDS/AML. Remission state at the time of allo-HSCT is the main predictor for a successful transplantation.