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Acute myeloid leukemia (AML) has an aggressive course and a historically dismal prognosis. For many patients, hematopoietic stem cell transplantation (HSCT) represents the best option for cure, but access, utilization and health inequities on a global scale remain poorly elucidated.To describe patterns of global HSCT use in AML for a better understanding of global access, practices, and unmet needs internationally.Estimates of AML incident cases in 2016 were obtained from the Global Burden of Disease (GBD) 2019 study. HSCT activities were collected from 2009-2016 by the Worldwide Network for Blood and Marrow Transplantation (WBMT) through its member organizations. The primary endpoint was global and regional use (number of HSCT) and utilization of HSCT (number of HSCT/ number of incident cases) for AML. Secondary outcomes included trends from 2009 to 2016 in donor type, stem cell source and remission status at time of HSCT.Global AML incidence has steadily increased, from 102,000 (95% uncertainty interval (UI): 90,200-108,000) in 2009 to 118,000 (104,000-126,000) in 2016 (+16.2%). Over the same period, a +54.9% increase from 9,659 to 14,965 HSCT/year was observed globally, driven by an increase in allogeneic (+64.9%) with a reduction in autologous (-34.9%) HSCT. While the highest numbers of HSCT continue to be performed in high-resource regions, the largest increases were seen in resource-constrained regions [+94.6% in Africa/East Mediterranean Region (AFR/EMR); +34.7% in America-Nord Region (AMR-N)]. HSCT utilization was skewed towards high-resource regions [in 2016: AMR-N 18.4%, Europe (EUR) 17.9%, South-East Asia/Western Pacific Region (SEAR/WPR) 11.7%, America-South Region (AMR-S) 4.5% and AFR/EMR 2.8%]. For patients70 years of age, this difference in utilization was widened; AMR-N had the highest allogeneic utilization rate, increasing from 2009 to 2016 (30.6% to 39.9%) with continued low utilization observed in AFR/EMR (1.7% to 2.9%) and AMR-S (3.5% to 5.4%). Across all regions, total HSCT for AML in 1HSCT remains a central curative treatment modality in AML. Allogeneic HSCT for AML is rising globally but there are marked variations in regional utilization and practices, including types of graft source. Resource-constrained regions have the largest growth in HSCT use, but utilization rates remain low with a predilection for familial related donor sources and are typically offered in CR1. Further studies are necessary to elucidate the reasons, including economic factors, to understand and address these health inequalities and improve discrepancies in use of HSCT as a potentially curative treatment globally.

Used in the clinical practice for more than three decades, the all-trans retinoic acid (ATRA) rendered acute promyelocytic leukemia (APL) the most curable subtype of acute myeloid leukemia, and currently, its combination with arsenic trioxide (ATO) exceeded all expectations for a chemotherapy-free protocol. In terms of metabolic importance, ATRA can also modulate the mitochondria-mediated cellular metabolism and promote a shift from a glycolytic-driven metabolism to an oxidative phosphorylation profile, although this effect has never been demonstrated in APL. As part of the cellular metabolic machinery, mitochondrial DNA (mtDNA) content has been reported to be altered in different types of solid tumors with clinical implication on patient treatment outcomes, although its clinical significance in acute leukemias has not been investigated to the same extent. Particularly in acute promyelocytic leukemia (APL), the role of mtDNA content on prognostication is completely unknown. Considering that mostly APL samples display a glycolytic-driven metabolism, it is conceivable that APL patients harboring high mtDNA content may present a better response to ATRA-based therapies. To test this hypothesis, we determined the mtDNA content in samples from patients with APL enrolled in the International Consortium on Acute Promyelocytic Leukemia study (Rego et al. Blood. 2013 Mar 14;121(11):1935-43) and analyzed its relationship to treatment outcomes. Diagnostic bone marrow (BM) mononuclear cells from 156 consecutive patients with APL (median age: 35 years, range: 18-82 years; 45% male) were obtained at diagnosis. For comparison purposes, we also included peripheral blood (PB) from 293 age- and sex-adjusted healthy volunteers. First, we determined whether mtDNA content could be compared between PB mononuclear cells and BM. To do so, we measured the mtDNA content of 22 APL patients, for whom paired samples were available at the time of diagnosis and detected a strong correlation between PB and BM samples (Pearson correlation coefficient, r=0.78, 95% confidence interval, CI: 0.54 to 0.9). Next, we used the values of mtDNA higher than the 95 th percentile of healthy subjects (≥1.63. Note: this value represents a fold change relative to healthy control) to define APL patients with high mtDNA content. Patients that presented values within the range of normal control samples ( Disclosures Silveira: BMS/Celgene: Research Funding; Servier/Agios: Research Funding; Abbvie: Speakers Bureau; Astellas: Speakers Bureau. Pagnano: EMS: Other: Lecture; Jansenn: Other: Lecture; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pintpharma: Other: Lecture.

With immune therapies on the rise, an in-depth understanding of the immunological changes in leukemic bone marrow (BM) niches becomes indispensable. Being an crucial part of the tumor microenvironment (TME) in solid tumours, tumour-associated macrophages are often associated with poor prognosis (Bruni et al. 2020). Yet, in acute myeloid leukaemia (AML) the role of macrophages has not been thoroughly studied. The expression of the M2-markers CD163 and CD206 in the AML BM cell population predicted poor clinical outcome. We identified that this expression emerges from a more mature (CD45 midSSC highHLA-DR +CD14 +CD16 +/-) myeloid cell population (hereafter called AML-associated macrophages - AAM) and not from the leukemic blasts. By employing flow cytometry analysis (FACS) we noted a decrease in the expression of the M1-marker (CD80) and an increase of the M2-markers CD163/CD206on AAM (n=70) compared to healthy donors (HD, n=10). Unsupervised clustering based on the CD163/CD206 levels detected on AAM generated 4 distinct clusters, whereby patients within the CD163 low/CD206 low cluster displayed better overall survival than the other clusters. In vitro, the co-culture of HD-derived M1 macrophages and AML primary/cell lines reduced AML growth via apoptosis induction and cell cycle arrest, while M2-macrophages promoted AML survival and phagocytosis/drug-resistance when treated with FLT3/BCL2 inhibitors. Primary AML cells were also able to repolarize M1- into M2-macrophages, suggesting that leukemic cells actively remodel their microenvironment. Next, we evaluated the impact of M2-macrophages on leukemogenesis in a patient derived xenograft (PDX) model, using the notoriously difficult to engraft primary Acute Promyelocytic Leukaemia (APL) cells (n=7 patient samples). Intra-BM injection of M2-macrophages and retro-orbital transplant of primary APL cells induced full-blown APL in NSGS mice. More strikingly, ex vivo culture of APL cells on M2-macrophages (48h) was sufficient to "train" these cells to engraft and induce fatal APL. Maintenance of self-renewal was shown in a secondary transplant and an enhanced frequency of leukemic stem cells was assessed by in vivo LTC-IC assays. To identify the biological changes acquired by leukemic blasts, we performed RNA sequencing comparing AML/APL samples at diagnosis to cells that were "trained" (48 h) on M2-macrophages or on MS5 mesenchymal BM stromal cells. Gene ontology and gene set enrichment analysis on the genes up-regulated upon M2 co-culture were significantly enriched for cell migration, cell cycle progression and oxidative phosphorylation (OXPHOS) signatures. In line with our RNAseq data, we noted improved in vivo homing of primary APL cells to the BM within 18 h post-transplant upon ex vivo M2 co-culture compared to diagnosis (n=7 APL blasts). Concurrently, we detected increased levels of surface protein expression Integrin-α4 (CD49d) and -α5 (CD49e) on APL/AML blast cells after M2 exposure. The CD49d expression remained high in primary and secondary transplants. Using seahorse measurements, we confirmed the increased respiration capacity (basal and maximum) of primary AML/APL cells (n=7) after exposure to M2 macrophages compared to MS5.FACS analysis revealed that M2-macrophages were able to transfer more mitochondria than MS5 cells to primary AML cells, which could underlie the observed increase in OXPHOS mitochondrial metabolism. Treatment with Etomoxir (50 µM), prevented the gain in functional respiration when AML blast were co-cultured on M2-macrophages, while no changes were observed for MS5 co-cultures, suggesting increased fatty acid oxidation to drive the OXPHO-like state. Finally, we noted that training on M2 macrophages significantly increased colony formation and endowed the cells with long term proliferation in liquid cultures for over 30 days. Overall, we reveal that the frequency of M2-macrophages is up-regulated in a subgroup of AML patients representing a group with poor prognosis. M2 macrophages can support leukemic growth and therapy-resistance, and support fatal APL in PDX models. Even an in vitro exposure to M2 macrophages suffices to alter adhesion, homing and metabolic characteristics of leukemic blasts to allow efficient engraftment and fatal leukemogenesis. Our study uncovers how the TME can contribute to leukemic transformation which provides alternative avenues for therapeutic interventions. Disclosures Silveira: BMS/Celgene: Research Funding; Servier/Agios: Research Funding; Abbvie: Speakers Bureau; Astellas: Speakers Bureau. Quek: BMS/Celgene: Research Funding; Servier/Agios: Research Funding. Mota: Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astellas: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Technopharma: Speakers Bureau; Bristol Myer Squibb: Speakers Bureau; Bayer: Speakers Bureau; Pfizer: Speakers Bureau; AstraZeneca: Speakers Bureau; Astellas: Speakers Bureau; Ipsen: Speakers Bureau; Amgen: Speakers Bureau.

Background: Recently, the SLIT/ROBO axis became a therapeutic target for a variety of non-cerebral solid tumors because of its relevance in the regulation of angiogenesis, inflammatory cell chemotaxis, tumor cell migration and metastasis. In acute myeloid leukemia (AML), lower levels of SLIT2 expression were associated with poorer prognosis in studies that excluded patients with acute promyelocytic leukemia (APL) of the analysis (Golos et al., Arch Immunol 2019). Our group previously reported that higher SLIT2 expression was associated with improved overall survival, disease-free survival and decreased cumulative incidence of relapse. Subsequently, our in vitro functional studies indicated anti-proliferative effects exercised by exogenous SLIT2 peptide treatment in APL (Weinhauser et al., Blood 2018). Although, the expression of SLIT/ROBO was detected on leukemic cells, the fact that in healthy subjects the main source of SLIT2 derives from bone marrow stromal cells (BMSC) (Smith-Berdan et al., Cell Cycle 2012) was so far neglected in the context of hematological malignancies. Aims: Here, we expanded our data on the role of SLIT2 using lentivirally knocked down APL cells, and addressed the issue of the importance of BMSC-derived SLIT2 on APL development. Methods: NB4 and NB4R2 (RA-resistant) and primary APL cells (age, 25-47y; n=4) were transduced with shRNA-SLIT2 or shCT (control). After synchronization using double-thymidine block, transduced cells were submitted to proliferation and cell cycle assays. For the apoptosis analysis, cells were treated with ATO (1 µM) alone or in combination with RA (1 µM) for 24, 48 and 72 hours. The granulocytic differentiation in response to RA treatment alone (1 µM) or in combination with ATO (1 µM) for 48 and 72 hours, was evaluated based on the CD11b and CD11c levels. To assess the effect of SLIT2 silencing in BMSCs, HS5 and HS27A cell lines were transduced with shSLIT2 or shCT. Non-transduced NB4, NB4R2 and primary APL cells were co-cultured with engineered BMSCs and proliferation, apoptosis and granulocytic differentiation was performed in response to ATO alone or in combination with RA for 48 and 72 hours. In vivo assessment was performed using four 8-12 week-old C57/BL6PepBoy (CD45.1) lethally irradiated, transplanted with 5 x 106 hCG-PMLRARa blasts (CD45.2) transduced with shSlit2-murine and shCT. Results: Silencing SLIT2 in primary APL samples resulted in a significant increase in cell growth at the sixth day of culture compared to shCT samples (P.05). In contrast to shSLIT2 APL induced cell growth, co-culture of primary APL blast cells with transduced HS27A cells had no impact on proliferation, while the expression of the neutrophilic differentiation gene ELANE2 was significantly decreased in APL cells co-cultured with HS27A-shSLIT2.ConclusionSLIT2 is expressed in APL cells and exerts an anti-proliferative effect. On the other hand, SLIT2 produced by BMSC seemed to promote APL cellular stemness. Our results reinforce that SLIT2 function is cell type dependent and may be involved in the cross-talk between microenvironment and leukemic cells. Disclosures Figueiredo-Pontes: Novartis: Honoraria.

Introduction: Meningioma 1 (MN1) gene was described as a prognostic marker for AML patients with normal karyotype (Carturan et al. Oncotarget 2016). In addition, MN1 high expression was linked to RA resistance and was shown to be necessary and sufficient to transform common myeloid progenitors in a MEIS1/AbdB-like HOX protein complex-dependent manner. However, the relevance of the copresence of MN1 overexpression in AML patients with mutations of the FLT3 and/or NPM1 genes is unknown. Moreover, it is also unknown the functional effects of MN1 in the biology of leukemic blasts harboring FLT3 mutations and if it may modulate the response to FLT3 inhibitors, such as quizartinib (AC220) and midostaurin (PKC). Aims: Herein, we investigated the prognostic impact of MN1 expression across multiple transcriptomic platforms and AML data sets. Additionally, we transduced different AML cell lines to evaluate the impact of MN1 on cell survival and differentiation. Methods: Three different AML series (1th: GSE6891, 240 patients, 2nd: TCGA, 113 patients and 3rd: BeatAML, 139 patients) were used. All patients presented similar gender distribution, were above 18y and treated by the 3+7 scheme. All genes from the RNAseq (TCGA) were pre-ranked according to their differential expression comparing tumors with high and low expression of MN1, using their median expression rate as the cutoff. GSEA was performed using the Reactome, KEGG and Hallmarks databases. Additionally, we transduced 07 AML cell lines with the MN1 gene and the control. For those cells, clonogenicity and proliferation rate was evaluated to identify which cell lines are sensitive and resistant to MN1. Drug induced apoptotic rate was assessed for FLT3-ITD- cell lines when treated with AraC (10 nM) and FLT3-ITD+ cell lines (MOLM13/MV411) upon treatment with PKC and AC220 over a time period of 24, 48 and 72 h. Apoptosis was further confirmed by cleaved Caspase-3/PARP detection. The myeloid differentiation in response to PMA treatment (100 ng/ml) was determined by the surface levels of CD11b, CD11c, CD14, CD15, CD61 and HLADR. Results: In all three AML series, high MN1 levels higher than the median (hereafter called High MN1) were associated with lower frequency of FLT3 and NPM1 mutations (P Disclosures Heuser: Bayer Pharma AG, Berlin: Research Funding; Synimmune: Research Funding.

Introduction: Described as a well know marker of worse prognosis in acute myeloid leukemia (AML), MN1 overexpression has been associated with inv(16) or EVI1 overexpression (Heuser et al., Blood 2007). The promoter region of the MN1 gene has Retinoic Acid Response Elements (RAREs), and higher levels of MN1 expression have been associated with decreased response to retinoic acid (RA) in vitro. Nevertheless, in the context of acute promyelocytic leukemia, little is known about MN1 gene expression and functionality in vivo. Aims: Here, we investigated the effects of in vitro treatment with RA plus arsenic trioxide (ATO) in APL cell lines and primary blasts overexpressing MN1. Additionally, we quantified MN1 expression and correlated its levels with treatment outcome in a cohort of patients enrolled in the International Consortium on Acute Leukemia (ICAPL2006) study. Methods: Primary leukemic blasts from hCG-PMLRARα transgenic mice (TM; n=2) and APL patients (age, 36-45y; n=2) were transduced with MN1 or empty vector (EV, control) to evaluate cell proliferation, differentiation and apoptosis. Confirmatory assays were performed using transduced NB4 and NB4R2 (RA-resistant) cell lines. After synchronization using double thymidine block, transduced cells were submitted to proliferation and clonogenic (treated with RA and ATO, as well) assays. To evaluate the apoptotic rate, cells were treated with ATO (1 µM) alone or in combination with RA (1 µM each), for 24, 48 and 72 hours. The granulocytic differentiation in response to RA treatment alone (1 µM) or in combination with ATO (1 µM) was evaluated based on the CD11b and CD11c surface levels. In addition, 116 patients (age, 18-82y; 51% males) with newly diagnosed APL enrolled in the ICAPL2006 study were included. To validate our data, Bootstrap resampling procedure with 1000 repetitions from the original database was performed to assess the model bias. Results: Primary APL cells transduced with MN1 (from TM/APL patients) presented higher proliferation rates compared to controls (P.05), while NB4R2-MN1 cells were able to form colonies in the presence of ATO (P.05). In accordance with our results using primary APL samples, ATO treatment (alone or in combination with RA) does not modulate the drug-induced apoptosis in a time-dependent manner in NB4 and NB4R2-MN1 cells (P Disclosures Pagnano: Sandoz: Consultancy; Pint Pharma: Consultancy; Abbvie: Consultancy. Tallman:International Conference in Leukemia: Honoraria; 14th Annual Miami Cancer Meeting: Honoraria; New Orleans Summer Cancer Conference: Honoraria; Indy Hematology Review: Honoraria; ADC Therapeutics: Research Funding; Arog Pharmaceuticals: Research Funding; Cellerant Therapeutics: Research Funding; Orsenix: Membership on an entity's Board of Directors or advisory committees, Research Funding; UpToDate: Patents & Royalties; Mayo Clinic: Honoraria; Rigel: Membership on an entity's Board of Directors or advisory committees; Nohla: Membership on an entity's Board of Directors or advisory committees, Research Funding; Salzberg Weill Cornall MSKCC Seminar in Hematologic Malignancies: Honoraria; BioSight: Membership on an entity's Board of Directors or advisory committees, Research Funding; Daiichi-Sankyo: Membership on an entity's Board of Directors or advisory committees; KAHR: Membership on an entity's Board of Directors or advisory committees; Bioline: Membership on an entity's Board of Directors or advisory committees, Research Funding; University of Oklahoma Medical Center: Honoraria; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy; Danbury Hospital Tumor Board: Honoraria; Hematology Oncology of Indiana: Honoraria. Dillon:Abbvie: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; TEVA: Consultancy, Honoraria. Heuser:Bayer Pharma AG, Berlin: Research Funding; Synimmune: Research Funding. Löwenberg:Up-to-Date", section editor leukemia: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Agios Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Astex: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; CELYAD: Membership on an entity's Board of Directors or advisory committees; Chairman Scientific Committee and Member Executive Committee, European School of Hematology (ESH, Paris, France): Membership on an entity's Board of Directors or advisory committees; Chairman, Leukemia Cooperative Trial Group HOVON (Netherlands: Membership on an entity's Board of Directors or advisory committees; Clear Creek Bio Ltd: Consultancy, Honoraria; Editorial Board "European Oncology & Haematology": Membership on an entity's Board of Directors or advisory committees; Elected member, Royal Academy of Sciences and Arts, The Netherlands: Membership on an entity's Board of Directors or advisory committees; Frame Pharmaceuticals: Equity Ownership; Hoffman-La Roche Ltd: Membership on an entity's Board of Directors or advisory committees; Royal Academy of Sciences and Arts, The Netherlands: Membership on an entity's Board of Directors or advisory committees; Supervisory Board, National Comprehensive Cancer Center (IKNL), Netherland: Membership on an entity's Board of Directors or advisory committees.

Introduction: Leg ulcers (LUs) are a cutaneous complication of sickle cell anemia (SCA), whose etiology is considered multifactorial. In the search for new candidates for modulators of SCA clinical events, recent evidence suggests the significant role of mechanisms related to post-transcriptional regulation, especially microRNAs (miRNAs). Thus, the analysis of miRNAs miR-21 and miR-130a differential expression in patients with SCA becomes an interesting approach, since both act in the regulation of several biological mechanisms related to the pathophysiology of LU, especially the tissue repair process. In addition, these miRNAs have already been related to the regulation of serum leptin levels, a strong angiogenic pleiotropic hormone that acts in the healing process of skin lesions. Therefore, the aim of the study was to investigate the influence of miR-21 and miR-130a and serum leptin levels on the development of LUs in SCA patients. Methods: After analyzing medical records, 60 SCA patients were selected. Patients who presented some of the main clinical manifestations that may have etiology due to the underlying disease (for example: osteonecrosis, stroke, priapism and acute chest syndrome) were not included. Patients with a history of LU were considered cases, and those who did not develop this complication (n=20), were considered control (median age: 26 years, range: 19-61, 50% males). The control group was called "HbSS-Control" and the case group was divided into two subgroups: Active leg ulcer group, composed of 19 patients with active LU at the time of blood collection (median age: 35 years, range: 24-56, 68% males), and healed leg ulcer group, composed of 21 patients with healed LU at the time of blood collection (median age: 34 years, range: 22-52, 43% males). In addition, it was analyzed a group of 10 donors with normal hemoglobin profile (median age: 25 years, range: 20-30, 50% males), identified as "HbAA-Control". Expression levels of miRNAs extracted from peripheral blood, using mirVanaTM PARIS Kit (Invitrogen™) were evaluated by RT-qPCR technique utilizing TaqMan® probes. Serum leptin levels of the patients were evaluated employing the ELISA method (Human Leptin ELISA Kit, Millipore®). Mann-Whitney and Kruskal-Wallis tests were applied to compare continuous variables. Results: Up-regulation of both miRNAs was observed in the active leg ulcer group in contrast to the healed leg ulcer (miR-21: P Disclosures No relevant conflicts of interest to declare.

Introduction: Recent evidence suggests that coagulation activation is involved in the pathogenesis of progressive organ failure in Sickle Cell Anemia (SCA). In addition, generation of neutrophil extracellular traps (NETosis), one of the components of immunothrombosis, has been associated with the pathogenesis of both venous thromboembolism and SCA. NETosis is a complex process that involves the orchestrated participation of several proteins such as peptidyl arginine deaminase (PADI4), neutrophil elastase (ELANE) and myeloperoxidase (MPO). PADI4 mediates histone citrulination, an essential step for NETosis. Accordingly, its inhibition has been recently cited as a potential therapeutic strategy for diseases in which NETosis are thought to play a relevant pathogenic role such as SCA. Although attractive, investment in PADI4 inhibitors in SCA requires gathering of more convincing evidences of the role of this enzyme in its pathogenesis. Herein, we used two cohorts of patients to investigate the expression of NETosis regulators (PADI4, ELANE and MPO) in SCA at steady state and during acute crisis, and to assess whether PADI4 activity is increased in any of these states. Methods: patients were recruited from two different centers in Brazil. Whole blood samples were obtained from patients from cohort 1 at steady state or during acute crisis (within 24 hours from admission). mRNA was obtained from granulocytes isolated by Ficoll gradient and gene expression of PADI4, ELANE, and MPO were measured by qPCR. In patients from cohort 2, PADI4 and MPO activity were measured in samples obtained within 24 hours from admission and after patient discharge (convalescence) using commercial kits in serum (MPO, Myeloperoxidase activity assay kit; ab105136) and plasma (PADI4, PAD4 Inhibitor Screening Assay Kit; Cayman chemical). Healthy individuals from the same geographic region were used as controls for each cohort, independently Results: In total, 54 steady state patients, 27 acute crisis and 40 healthy volunteers were evaluated for mRNA expression of NETosis regulators. Patients in acute crisis expressed higher levels of PADI4, MPO and ELANE compared to both healthy volunteers and patients in steady-state. Furthermore, plasma activity of PADI4 was higher in acute crisis when compared to healthy individuals (7.36x106 vs 5.24x106; P= 0.002), with no decrease after discharge (median of 13.5 days after admission) (7.36x106vs 7.41x106; P= 0.004). No differences were observed in serum MPO activity during acute crisis. Conclusion: we demonstrate that the mRNA expression of NETosis regulators, including PADI4, is increased in SCA; and that this increase is associated with higher levels of PADI4 activity in plasma during acute crisis. These results support the concept of PADI4 inhibition as a therapeutic strategy for acute episodes of SCA, and warrant additional studies in this area. Disclosures No relevant conflicts of interest to declare.

Background : The recent efforts to uncover the molecular heterogeneity of myelodysplastic syndromes (MDS), mainly by new sequencing technologies, allow the comprehensive identification of driver mutations and/or altered gene expression recurrently found in a recognizable fraction of patients. Ongoing efforts are being made to clarify the impact of molecular changes on clinical phenotype and prognosis, as well as their role in the pathogenesis of MDS. Refining risk stratification allows the proposition of risk-adapted therapy and may shed light in biology of MDS. Aims: Based on the gene expression of selected metabolic targets, we aimed to design a score system that improves MDS overall survival prediction. Patients and methods: Clinical, mutations and transcriptomic data from CD34+ cells from 159 MDS patients and 17 healthy volunteers freely available at Gene Expression Omnibus (GEO/NCBI: GSE58831) were used in the present work. Forty-one genes related to metabolic processes, previously demonstrated as deregulated among diverse neoplastic conditions, were ranked and asked for differential expression and prognostic impact. Each gene was dichotomized according to Receiving-Operating Curve (ROC) and Cox Proportional-Hazard Model was used for multivariate analysis using gender, age and IPSS-R as cofounders. Genes independently associated with overall survival (OS) were selected to compose the Molecular-Based Score (MBS) and integer weight of each one was defined according Hazard Ratio (HR). Survival curves were constructed using Kaplan-Meyer method and compared with Log-Rank Test. ROC c-statistic was used to measure the predictive function of MBS. Prediction accuracy of MBS was cross-validated by a nonparametric bootstrap procedure with 1,000 resamplings of the original cohort allowing replacement and also estimated their respective 95% confidence interval (95% CI) computing the bias-corrected and accelerated bootstrap interval. Results: Among selected genes, 18 were differentially expressed between CD34+ cells from MDS and healthy volunteers. Fifteen genes predict OS in univariate analysis, of which ACLY (HR: 0.48; 95%CI: 0.24 - 0.96; P=0.04), ANPEP (HR: 2.16; 95%CI: 1.08 - 4.31; P=0.02), PANK1 (HR: 0.43; 95%CI: 0.19 - 0.98; P=0.04), PKM (HR: 2.01; 95%CI: 1.02 - 3.93; P=0.04) and SLC25A5 (HR: 0.52; 95%CI: 0.27 - 0.99; P=0.05) were independently associated with OS. Higher expression of ANPEP and PKM, as well as lower expression of ACLY, PANK1 and SLC25A5 were considered to integer high risk being attributed weight 2 for each condition. MBS varied from 0 to 10 (median=2) and was calculated as: MBS Low-Risk =0 (MBS-LR; n=28); MBS Intermediate-Risk=2 and 4 (MBS-IR; n=90) and High-Risk: ≥6 (MBS-HR; n=48). The modeled MBS showed a ROC c-statistic of 0.699 (95%CI: 0.603 - 0.794) and HR=3.05 (95%CI: 1.81 - 5.05; P Figure Disclosures No relevant conflicts of interest to declare.

Introduction: FOXO3A is a transcription factor shown to be involved in all-trans retinoic acid (ATRA)-induced granulocytic differentiation and apoptosis in acute promyelocytic leukemia (APL). Its biological activity may be significantly enhanced upon metformin, raising the possibility that ATRA and Metformin may act synergistically; which could be useful to overcome ATRA resistance. Despite progress in APL treatment, approximately 10-15% of patients will relapse after treatment with ATRA and anthracyclines and frequently present with ATRA resistance. Relapsed patients respond well to arsenic trioxide (ATO) treatment, but the cost of ATO is a significant barrier in many countries. Aims: Here, we investigated the effects of in vitro treatment with ATRA plus metformin in APL cell lines and primary blasts, and quantified FOXO3A expression and correlated its levels with treatment outcome in a cohort of patients enrolled in the International Consortium on Acute Leukemia (ICAPL2006) study. Finally, we evaluated the effect of induced overexpression of FOXO3A gene in regards to cell viability and proliferation. Methods: Primary leukemic blasts from hCG-PMLRARα transgenic mice (TM; n=4) and APL patients (age, 25-47y; n=4) were treated with metformin alone (5mM/ 10mM) or in combination with ATRA (1µM) and evaluated for cell viability. In addition, 106 patients (age, 18-82y) with newly diagnosed APL enrolled in the ICAPL2006 study were included. As controls, eight samples of bone marrow mononuclear cells (BMMC) from healthy volunteers (age, 18-60y) were analyzed. To validate our data, FOXO3A transcript levels from an independent cohort was used (31 patients from Amazonia!, Probe n. 204131_s_at, and five normal BMMC samples included in the same databank). NB4/NB4R2 (ATRA-resistant) cell lines were transduced with FOXO3A or empty vector (control). After synchronization using double thymidine block, transduced cells were submitted to proliferation and cell cycle assays. For dose-response curves, cells were treated with graded concentrations of ATRA, ATO and metformin. For the apoptosis analysis, cells were treated with ATRA (1µM), metformin (5mM) and combination for 24, 48 and 72 hours. The granulocytic differentiation in response to ATRA treatment was evaluated based on the CD11b surface levels. Results: In primary cells (from TM/APL patients) a 2-fold reduction in viable cells was observed after metformin and metformin plus ATRA treatment (P Disclosures Tallman: BioSight: Other: Advisory board; Daiichi-Sankyo: Other: Advisory board; ADC Therapeutics: Research Funding; AROG: Research Funding; AbbVie: Research Funding; Cellerant: Research Funding; Orsenix: Other: Advisory board. Ganser:Novartis: Membership on an entity's Board of Directors or advisory committees. Lowenberg:Editorial Board "European Oncology & Haematology": Membership on an entity's Board of Directors or advisory committees; Royal Academy of Sciences and Arts, The Netherlands: Membership on an entity's Board of Directors or advisory committees; Supervisory Board, National Comprehensive Cancer Center (IKNL), Netherlands: Membership on an entity's Board of Directors or advisory committees; Clear Creek Bio Ltd: Consultancy, Honoraria; international Scientific Advisory Board, Institute Gustave Roussy, Paris: Membership on an entity's Board of Directors or advisory committees; Chairman Scientific Committee and Member Executive Committee, European School of Hematology (ESH, Paris, France): Membership on an entity's Board of Directors or advisory committees; Elected member, Royal Academy of Sciences and Arts, The Netherlands: Membership on an entity's Board of Directors or advisory committees; Editorial Board "The Netherlands Journal of Medicine": Membership on an entity's Board of Directors or advisory committees; Editorial Board "International Journal of Hematology": Membership on an entity's Board of Directors or advisory committees; "Up-to-Date", section editor leukemia: Membership on an entity's Board of Directors or advisory committees; Agios Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Astex: Consultancy; Chairman, Leukemia Cooperative Trial Group HOVON (Netherlands): Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees.

Background: The Slit-Robo pathway has been shown to participate in the pathogenesis of several malignant diseases in addition to its physiologic role during the development of the central nervous system (CNS). However, the relevance of the Slit-Robo pathway in acute promyelocytic leukemia (APL) is presently unknown. We investigated the status of the Slit-Robo pathway in APL following the recent demonstration by Amodeo et al (CellRep. 2017) that the PML protein induces neural stem/progenitor cells migration by inhibiting the SLIT2 gene, which was associated with an increased presence of H3K27me3 in the SLIT2 promotor region. Moreover, sensitivity towards the PML-targeting drug arsenic trioxide in primary glioblastoma cells was shown to be regulated by the PML/SLIT axis. Aims: Here, we quantified SLIT2 transcript levels in bone marrow (BM) samples from APL patients and healthy subjects and determined whether they are associated with clinical and laboratory features at diagnosis and treatment outcomes. In addition, we evaluated the effect of increased SLIT2 protein on leukemic cell survival, proliferation and clonogenecity. Methods: Cell cycle distribution, proliferation index (Ki-67/proliferation curve), colony formation and rate of apoptotic cells (annexin V/PI) were evaluated in both APL cell lines NB4 (ATRA-sensitive), NB4R2 (ATRA- resistant) and four primary APL samples following the treatment with the human recombinant SLIT2 protein (50 ng/ml) for 24 to 72 hours. In addition, 88 patients (age, 18-73y) with newly diagnosed APL enrolled in the International Consortium on Acute Leukemia (ICAL) study - ICAPL2006 were included. For comparison, BM mononuclear cells from five healthy volunteers (age, 18-60y) were also included. SLIT2 transcripts was determined by qPCR and expressed as comparative Ct method. Patients were dichotomized into "low" and "high" SLIT2 expression groups using a cut off value of 1.53 based on survival receiver operating characteristic (ROC) curve and the C index analyses. The following parameters were used to evaluate treatment outcome: complete hematological remission (CHR); 5-year Disease-Free Survival (DFS) and 5-year Overall Survival (OS) rates. Results: At the end of the sixth day, in vitro treatment with SLIT2 significantly reduced the proliferation rate (P=.01) and clonogenicity (P=.01) in primary APL samples, while significantly increasing the apoptotic rate after 72 hours treatment with SLIT2 (P=.03). In accordance, SLIT2 treatment decreased cell proliferation and clonogenicity (all P Disclosures Pagnano: EMS: Other: Financial support for participation in congress; Novartis: Consultancy; Shire: Other: Lecture; Abbvie: Consultancy. Tallman:Daiichi-Sankyo: Other: Advisory board; Cellerant: Research Funding; ADC Therapeutics: Research Funding; AROG: Research Funding; AbbVie: Research Funding; Orsenix: Other: Advisory board; BioSight: Other: Advisory board. Ganser:Novartis: Membership on an entity's Board of Directors or advisory committees. Lowenberg:Royal Academy of Sciences and Arts, The Netherlands: Membership on an entity's Board of Directors or advisory committees; Astex: Consultancy; Editorial Board "European Oncology & Haematology": Membership on an entity's Board of Directors or advisory committees; international Scientific Advisory Board, Institute Gustave Roussy, Paris: Membership on an entity's Board of Directors or advisory committees; Clear Creek Bio Ltd: Consultancy, Honoraria; Agios Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Editorial Board "The Netherlands Journal of Medicine": Membership on an entity's Board of Directors or advisory committees; Elected member, Royal Academy of Sciences and Arts, The Netherlands: Membership on an entity's Board of Directors or advisory committees; Editorial Board "International Journal of Hematology": Membership on an entity's Board of Directors or advisory committees; Supervisory Board, National Comprehensive Cancer Center (IKNL), Netherlands: Membership on an entity's Board of Directors or advisory committees; Chairman Scientific Committee and Member Executive Committee, European School of Hematology (ESH, Paris, France): Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Chairman, Leukemia Cooperative Trial Group HOVON (Netherlands): Membership on an entity's Board of Directors or advisory committees; "Up-to-Date", section editor leukemia: Membership on an entity's Board of Directors or advisory committees.

Background: The histone-lysine N-methyltransferase 2E (KMT2E) is a member of the KMT2 family that regulates terminal myeloid differentiation and hematopoietic stem cell self-renewal. However, unlike the other members of KMT2 family, KMT2E does not exhibit the intrinsic histone methyl transferase activity, but has been shown to indirectly interact with chromatin by regulating SET7/9 expression and directing the tri-methylation state of the histone H3K4 (H3K4me3). We previously reported that the low expression of KMT2E predicts poorer prognosis in acute promyelocytic leukemia (APL) and that the overexpression of KMT2E contributed to granulocytic differentiation of APL cells in response to all-trans retinoic acid (ATRA). ATRA as a single agent is not effective in cell differentiation of non-APL acute myeloid leukemia (AML) but changes in H3K4 methylation promotes ATRA sensitivity and upregulates myeloid-differentiation-associated genes in AML cells. Therefore, to better understand the role of KMT2E in leukemogenesis and to test whether ATRA was capable to epigenetically mediate the KMT2E function in non-APL AML blasts, we investigated the effect of KMT2E overexpression in the cell viability, tumor growth and signaling response to ATRA in vitro and in vivo. Methods: qPCR analyzes revealed that the AML cell lines OCI-AML3, U937 and THP-1 express low levels of KMT2E in relation to the APL cell line NB4 and then, they were selected for further experiments. OCIAML3, THP1, and U937 were transduced with the pMEG or the pMEG-KMT2E vector, and U937 cells were also submitted to KMT2E gene silencing by a specific shRNA. The transduced cells were subjected to ATRA (1µM) treatment to evaluate proliferation (Ki-67), clonogenicity, cell cycle and apoptosis (annexin V). For dose-response curves (MTT), cells were administrated graduated ATRA concentrations and the IC50 values were calculated. ATRA-induced granulocytic differentiation was determined by immunophenotyping analysis of myeloid markers: CD11b, CD11c, CD14, CD16, CD64, and HLA-DR. Genes (SETD7/9) and protein (H3K4me3) expressions were established by qPCR and Western blot analysis respectively. 8-10 week-old NSG mice received a dorsal s.c. injection of 5 x 106 U937 cells (transduced with empty/KMT2E/shKMT2E) and 7 days after initial tumor growth treatment was initiated by intraperitoneal injection of the vehicle (n=26) or ATRA (5 mg/kg, n=30) for another 7 days. Tumor volume (V) was obtained using the formula (V=W2 x L x 0.52), where W represents the smaller and L the large diameter. The tumor apoptotic index was determined by TUNEL assay. Results: KMT2E overexpression significantly increased cell proliferation and the proportion of G2/M cells in all cell lines (all P In NSG mice, ATRA significantly reduced the tumor burden in U937- KMT2E cells and increased the apoptotic index (P.05). Conclusion: Our results demonstrated that KMT2E increases the cellular proliferation and ATRA-induced granulocytic differentiation in non-APL AML cell lines. Furthermore, ATRA triggered epigenetic reprogramming resulting in increased levels of H3K4me3, which redirected the biological function of KMT2E. Disclosures No relevant conflicts of interest to declare.

Aims: The active methylation of histones plays an important role in regulation of gene expression. Nuclear SET Domain (NSD) Histone Lysine Methyltransferases family (KMT) is composed of three members: NSD1, 2 and 3 which regulates gene expression through methylation of H3K36. NSD2 overexpression, initially reported in multiple myeloma, was recently associate with EZH2 mRNA levels through interaction with H3K27me3 which suppresses the expression of miR-203, miR-26a and miR-31 leading to the up regulation of NSD2 mRNA levels. This correlation has been observed in various types of cancer, although there is no data in myeloid malignancies. Aim: To evaluate the gene expression profile of the NSD family in three de novo AML cohorts: one Brazilian cohort and two public databases addressing its applicability in prediction of treatment outcomes, retrospectively. Methods: As a learning set, samples from 146 subjects (age, 18-87y) were analyzed. Seventy (48%) patients were treated in a University Hospital that serves as reference for northeast of Brazil, while 76 patients were treated in a center of similar characteristics in the southeast of the country. The baseline features distribution was similar between centers. The treatment protocol was described elsewhere (Lima AS et al., Blood, 2015), but was based on anthracycline and cytarabine for induction and intermediate to high doses of cytarabine as consolidation. As controls, sixteen samples of CD34+ cells isolated from total bone marrow (BM) of healthy volunteers (age, 18-60y) were analyzed. The external validation cohort composed by 173 patients (age, 18-88y) were obtained from TCGA AML study available online on CBioPortal for Cancer Genomics (Gao et al. 2013). Patients were dichotomized into "low" and "high" NSD1, 2 and 3 expression groups based on survival receiver operating characteristic (ROC) curve and the C index analyses. To validate our data, NSD transcript levels from an independent cohort was used (525 patients from Amazonia! - NSD1 Probe #219084_at; NSD2 Probe #209052_s_at; NSD3 Probe #218173_s_at - and five normal CD34+ samples included in the same databank). The following parameters were used to evaluate treatment outcome: complete hematological remission (CHR); 5-year Disease-Free Survival (DFS) and 5-year Overall Survival (OS) rates. Results: The median age of the learning set was 46y with 70 males (48%). NSD1, 2 and 3 expression levels are lower in de novo AML samples compared to CD34+ cells (P0.96) albeit only NSD2 and 3 had a correlation in the validation cohort (r=0.6). Baseline characteristics (sex, age, leukocyte count, cytogenetic risk, FLT3 and NPM1 mutations)were similar between the cohort of patients with NSDs low and high expression, except for higher blast count in BM, but not in peripheral blood, in high expression group for NSD1 and 2 (P=.021 and P=.033, respectively). Overall, 78/146 (57%) patients achieved CHR. Patients with a high NSD1 expression had a lower CHR rate (44%) compared with those a low expression (56%) (OR: 0.5; 95%CI: 0.2-0.9; P=.04). With a median follow up of 21 months (1-61 months) the estimated 5y DFS rate was 49% (95%CI: 30-65%). The group with high NSD1 expression presented a lower 5y DFS rate (13%; 95%CI: 1-42%) than those with low NSD1 expression (72%; 95%CI: 47-87%) (P=.003). This result was consistent with the multivariable proportional hazards analysis (HR: 7.3; 95%CI: 1.3-38; P=.02). The estimated 5y OS rate was 24% (95%CI: 14-35%) which patients with high NSD1 expression exhibiting lower 5y OS rate (13%; 95%CI: 4-29%). The median age of the external validation cohort was 58y with 107 males (62%). Only NSD2 levels had a association with higher diagnosis age (P=.008). With a median follow up of 40 months (1-118 months) the NSD expression may predict only a higher 5y OS rate in patients with high NSD2 expression (30%; 95%CI: 26-49%) retained the result in a multivariable model (HR: 0.53; 95%CI: 0.3-0.9; P=.02). Conclusions: In summary, NSD1 and 2 transcript levels were independent factors associated with treatment outcomes in two AML cohorts treated with standard protocols based on anthracyclines and cytarabine. Disclosures No relevant conflicts of interest to declare.

To the editor: Despite its undeniable importance, standard cytogenetic analysis is still not a routine practice for most reference centers in developing countries, and its accomplishment is practically limited to university research centers. Particularly in Brazil, little is known about the

The Nuclear SET Domain (NSD) Protein Lysine Methyltransferases (KMT) family is composed of three members: NSD1/KMT3B, NSD2/WHSC1/MMSET and NSD3/WHSC1L1 which regulate gene expression through methylation of lysine 36 of histone H3 (H3K36). NSD2 overexpression was reported in multiple myeloma with t(4;14)/IgH-MMSET. NSDs gene expression profile is unknown in acute leukemias, however NSD1 and NSD3 were described to be fused with the nucleoporin 98 gene (NUP98) in rare AML and myelodysplastic syndrome cases and, both fusion proteins were associated with poor prognosis. The aims of the present study were to characterize the expression of NSD-KMTs in patients with AML and healthy controls, to determine if this expression is associated with specific genetic abnormalities and/or with treatment outcome.A total of four healthy donors and 45 AML patients (27♀, 18♂) at diagnosis were included in the study. Our cohort included 8 patients with acute promyelocytic leukemia (APL), 8 with core binding factor (CBF) leukemias [4 with t(8;21) and 4 with inv(16)], and 29 patients with non-APL non-CBF AML. NSD family gene expression was evaluated by qPCR using the comparative Ct method for analysis. A higher expression of the NSD1 gene was observed in AML cells compared to normal bone marrow (BM) samples {median [range] = 3.202 [0.6804-0.096] vs. 1.003 [:0.7956-1.265], p=0.0243}. Similarly, the expression of NSD3 was higher in AML, but the difference was significant only for the comparison between healthy BM and CBF-AML groups {median [range] = 1.070 [0.6360-1.410] vs. 2.719 [1.238-8.830], p=0.0265}. No significant differences were detected in the analysis of NSD2 expression. Considering the three groups of AML patients, no correlation was found between NSD1, NSD2 or NSD3 expression levels and age, gender, leukocyte counts at diagnosis, karyotype (normal vs. abnormal), frequency of specific genetic abnormalities (t(15;17)/PML-RARA; t(8;21)/RUNX1-RUNX1T1; inv(16)/CBFB-MYH11) or percentage of blasts in bone marrow. NPM1 mutations and FLT3 internal tandem duplications (FLT3-ITD) were detected in 29.6% (13/44) and 21% (9/43) of the patients with AML, respectively. We observed a significant increase in NSD1, NSD2 and NSD3 expression in blasts from patients with FLT3-ITD (p=0.0177), but not in those with NPM1 mutations. These differences remained significant when APL cases were excluded from the analysis. Next, patients were grouped according to NSD1 or NSD2 expression. Patients with NSD1 or NSD2 expression higher or lower than the median value (3.25 and 3.16, respectively), showed no significant differences regarding age distribution, leukocyte counts or percentage of blasts in bone marrow at diagnosis, or presence of genetic abnormalities. Regarding the analysis of treatment outcome, patients with non-APL AML were stratified into high and low NSD1 or NSD2 expression subgroups using the criteria above. The median overall survival of patients in the low NSD2 expression subgroup was of 333,023 days [95% CI:158,541-507,505 days] whereas patients in the high NSD2 expression subgroup was of 817,629 days [95% CI:238,702-1396,555 days] (p=0,633). No significant difference observed between the overall survival of patients in the high and low NSD1 expression subgroups. In order to determine if NSD-KMT levels were associated with changes at histone H3 lysine 4 (H4K4) and H3K36 (known to activate gene transcription), as well at histone H3 lysine 9 (H3K9), H3K27, H3K79 and H4K29, associated to regulatory repression, we ran an experiment using Illumina Infinium Methylation 450k arrays. The comparison between normal and leukemic cells revealed specific histone methylation profiles. There is experimental evidence that histone methylation is a prerequisite for DNA methylation and transcriptional regulation, suggesting interplay between histone and DNA methylation. Our data correlate overexpression levels of NSD-KMT with histone modifications, suggesting that this modification and not only DNA methylation can contribute for epigenomic changes associated to AML pathogenesis. Disclosures No relevant conflicts of interest to declare.

Chemokine receptors mediate the migration of lymphocytes through the binding of soluble ligands, and their expression is differentially regulated in lymphocyte subsets. The pattern of chemokine receptor expression in T-cell non-Hodgkin lymphoma has not been previously studied. Using a panel of mouse monoclonal antibodies, we studied the immunohistochemical expression of the Th1-associated chemokine receptor CXCR3 in 141 patients with T-cell lymphoma, and we studied the receptors CCR4 and CCR5 and some of their ligands in a subset of these tumors. Expression of CXCR3 was typical of the smaller T cells in angioimmunoblastic lymphoma (15 of 18 patients), angiocentric lymphoma (3 of 3 patients), histiocyte-rich tumors (4 of 5 patients), and unspecified T-cell lymphomas (17 of 39 patients). CXCR3 expression was seen in only 1 of 15 patients with anaplastic lymphoma kinase (ALK)-positive anaplastic large-cell lymphoma. In contrast, all ALK-positive tumors showed diffuse reactivity for the Th2-associated receptor CCR4 (5 of 5 patients). CCR4 expression was also a consistent feature of the large-cell transformation of mycosis fungoides. CCR5 expression showed no consistent association with any T-cell tumor type. The chemokines Mig (CXCR3 ligand), TARC (CCR4 ligand), and MCP-2 (CCR5 ligand) were detected in intratumoral blood vessels and histiocytes. Mig was also coexpressed by a subset of CXCR3-positive tumor cells in 6 of 20 lymphomas. MCP-2 was highly expressed in stromal cells in 3 patients with nodal involvement by cutaneous T-cell lymphoma. As with normal T-cell subsets, we demonstrated that there is frequent differential expression of chemokine receptors in T-cell tumors, which may explain, in part, the distinctive patterns of spread in different tumor subtypes.

The updated Sapporo classification criteria for antiphospholipid syndrome (APS) only include thrombosis or pregnancy morbidity as clinical criteria. To test this notion, we studied 55 patients (80% women) with hematologic manifestations. All fulfilled the laboratory criteria for primary APS. Thirty-five patients (64%) had thrombocytopenia, 14 (25%) had autoimmune hemolytic anemia, and 6 (11%) had both. Twenty-five patients (22 women, 88%) also fulfilled one clinical criterion for APS after a median follow-up of 13.2 years (range, 1.45-37 years), whereas the remaining 30 patients (22 women, 73%) have not had any thrombotic event nor pregnancy morbidity after a median follow-up of 5.4 years (range, 0.12-24 years). No patient developed systemic lupus erythematosus during follow-up. The hematologic manifestation was asynchronous with the APS onset in 84% of patients. The response to treatment was similar regardless of the APS status. Patients with definite APS were more frequently positive for the lupus anticoagulant (63%) than lupus anticoagulant-positive patients without APS (30%; odds ratio, 3.5; 95% confidence interval, 1.07-11.4; P < .02). Anticardiolipin or anti–β2-glycoprotein-I antibodies were highly prevalent among the study groups. Our study suggests that, depending upon their antiphospholipid profile, patients with hemocytopenias appear to comprise a peculiar subset of patients with APS; some develop thrombotic and/or obstetric APS whereas others continue with hematologic APS.