c-Kit M541L variant is related to ineffective hemopoiesis predisposing to clonal evolution in 3D in vitro biomimetic co-culture model of bone marrow niche.

Hematopoietic stem cell (HSC) maintenance in vitro is challenging because stem cell survival relies on cell-to-cell contacts and paracrine signals from bone marrow (BM) microenvironment. Indeed, HSCs easily differentiate in conventional culture systems, and in vitro study of stem cell biology, leukemogenesis, and evolutionary trajectories is limited. 3D-culture systems can mimic tissue architecture and microenvironment thus preserving HSC phenotype. In this study, we developed a calcium alginate hydrogel-based 3D co-culture system of BM mononuclear cells (BMMCs) and BM-derived mesenchymal stem cells (BM-MSCs) to study hemopoiesis in health and disease, such as biological roles of c-Kit M541L somatic mutation of unknown significance. BMMCs and peripheral blood stem cells were obtained from an acute myeloid leukemia patient who experienced graft failure and his haploidentical donor, and from a healthy donor. Cells embedded in alginate scaffolds were cultured for up to 21 days, and flow cytometry immunophenotyping was performed at baseline and every seven days. Our results showed suitability of our 3D culture system in preserving HSC vitality and phenotype throughout the culture period, and also in maintaining composition and vitality of total BMMCs. Moreover, 3D in vitro culture results suggested that M541L c-Kit somatic mutation could be a loss-of-function alteration by reducing HSC maintenance ability thus quickly promoting differentiation, as documented by in vivo graft failure and in vitro absence of long-term culture stability. In conclusions, our 3D BM-like biomimetic culture system allowed long-term stemness maintenance, making it a valid and effective tool for in vitro study of physiological and pathological hemopoiesis.

Clinical efficacy of azacytidine and venetoclax and prognostic impact of Tim-3 and galectin-9 in acute myeloid leukemia and high-risk myelodysplastic syndromes: A single-center real-life experience.

Treatment of acute myeloid leukemia (AML) and high-risk myelodysplastic syndromes (MDS) is difficult in older patients with comorbidities and high-risk disease factors. Venetoclax, the first-in-class Bcl-2 inhibitor, has proven efficacy and safety in combination with azacytidine for treatment of high-risk myeloid diseases. In this single-center real-life retrospective study, a total of 27 consecutive patients treated with azacytidine plus venetoclax were included, and clinical outcomes, hematological improvements, and biomarkers of responsiveness to therapy were compared to those observed in an historical cohort of 95 consecutive patients treated with azacytidine as single agent. Azacytidine plus venetoclax was effective and safe in older and frail AML and high-risk MDS patients, with median overall survival of 22.3 months, higher than that reported in phase III trial (14.7 months), and higher than that of historical cohort (5.94 months). Progression-free survival was higher in patients treated with the drug combination compared to those treated with azacytidine as single agent (p = 0.0065). Clinical benefits might increase when azacytidine and venetoclax are administered as upfront therapy (p = 0.0500). We showed that Tim-3 expression could be a promising therapeutic target in refractory/relapsed patients, and galectin-9 a biomarker of responsiveness to therapy. Moreover, patients treated with azacytidine and venetoclax displayed a higher overall survival regardless the presence of negative prognostic markers at diagnosis (e.g., increased WT1 copies and/or normalized blast count). These encouraging results in a real-world setting supported efficacy and safety of azacytidine plus venetoclax as upfront therapy in AML and high-risk MDS, with clinical outcomes comparable to those of clinical trials when an appropriate venetoclax management with bone marrow assessment at every first, second, fourth, and eighth cycle, and dose adjustments for toxicities are performed.

WT1 Expression Levels Combined with Flow Cytometry Blast Counts for Risk Stratification of Acute Myeloid Leukemia and Myelodysplastic Syndromes.

Wilm's tumor 1 (WT1), a zinc-finger transcription factor and an epigenetic modifier, is frequently overexpressed in several hematologic disorders and solid tumors, and it has been proposed as diagnostic and prognostic marker of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). However, the exact role of WT1 in leukemogenesis and disease progression remains unclear. In this real-world evidence retrospective study, we investigated prognostic role of WT1-mRNA expression levels in AML and MDS patients and correlations with complete blood counts, flow cytometry counts, and molecular features. A total of 71 patients (AML, n = 46; and MDS, n = 25) were included in this study, and WT1 levels were assessed at diagnosis, during treatment and follow-up. We showed that WT1 expression levels were inversely correlated with normal hemopoiesis in both AML and MDS, and positively associated with blast counts. Flow cytometry was more sensitive and specific in distinguishing normal myeloid cells from neoplastic counterpart even just using linear parameters and CD45 expression. Moreover, we showed that a simple integrated approach combining blast counts by flow cytometry, FLT3 mutational status, and WT1 expression levels might be a useful tool for a better prognostic definition in both AML and MDS patients.

Different circumstances of the first venous thromboembolism among younger or older heterozygous carriers of the G20210A polymorphism in the prothrombin gene.

BACKGROUND AND OBJECTIVES: The G20210A polymorphism in the prothrombin gene is a common cause of inherited thrombophilia. Scarce information is available about the circumstances of the heralding thrombotic manifestation at different ages. The aim of this study was to determine the risk of spontaneous or secondary venous thromboembolism (VTE) among younger and older carriers of the G20210A prothrombin polymorphism. DESIGN AND METHODS: We performed a case-control study, investigating 650 patients with a first objectively documented deep venous thrombosis of the legs or pulmonary embolism and 703 individuals with no history of vascular disease. In all of them we carried out laboratory screening for antithrombin III, protein C and protein S deficiencies, and for the presence of the factor V Leiden and the G20210A prothrombin polymorphisms. RESULTS: After adjustment for other inherited causes of thrombophilia (deficiency of antithrombin III, protein C or S, factor V Leiden) the overall risk for VTE associated with the prothrombin polymorphism was 3.4 times higher than in the controls (95% CI, 2.0 to 5.8). Stratification according to the age and to the circumstances of the first event revealed an increased risk of spontaneous VTE only among the patients older than 45 years in comparison with age-matched controls (odds ratio 4.4, 95% CI 1.8 to 10.6); among the younger individuals the risk was increased for secondary VTE (odds ratio 4.8, 95% CI, 2.3 to 9.8) but not for spontaneous VTE. INTERPRETATION AND CONCLUSIONS: The clinical penetrance of the thrombotic tendency associated with the G20210A prothrombin polymorphism is more expressed in the presence of a circumstantial risk factor (oral contraceptives, pregnancy, surgery, trauma) and in the presence of older age, which acts as an additional circumstantial risk factor. Accordingly, such situations should not discourage from carrying out laboratory screening.