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Introduction:RUNX1 is a major hematopoietic transcription factor that regulates megakaryopoiesis and platelet formation and function. Germline RUNX1haplodeficiency (RHD) is characterized by thrombocytopenia, impaired platelet function and granule deficiencies. Our previous studies in a patient with RUNX1mutation showed that platelet albumin and fibrinogen were decreased (Sun et al, Blood103: 948-54, 2004) .Human platelet α-granules contain numerous proteins, some synthesized (e.g., PF4 and VWF) and others (e.g., fibrinogen, albumin and IgG) are incorporated by endocytosis, a process poorly understood in platelets/megakaryocytes (MK).

RUNX1 is an essential transcription factor for hematopoiesis. Germline RUNX1haplodeficiency is associated with thrombocytopenia, platelet dysfunction and predisposition to myeloid malignancies. Three major RUNX1 isoforms (A, B and C) are recognized and share a DNA binding RUNT domain; RUNX1A lacks the transactivation domain. Two distinct promoters regulate RUNX1 expression: distal P1 regulates RUNX1C; proximal P2 regulates RUNX1B and RUNX1A. Little is known regarding the differential effects of isoforms in RUNX1 autoregulation, target-gene regulation and association with clinical events. We performed studies in megakaryocytic HEL cells, HeLa cells (which do not express RUNX1) and in platelets of healthy subjects (n=74) and provide evidence for isoform-specific differential autoregulation and target-gene regulation by RUNX1. We show an association between expression of specific RUNX1-regulated genes in whole blood with cardiovascular events in patients.

Background:Natural killer (NK) immune status in Acute Myeloid Leukemia (AML) could influence therapeutic results and natural history of the disease.

Acute Lymphoblastic Leukemia (ALL) is the most common cancer in children, with a second incidence peak in adults over 60 years old. Long-term survival with currently available therapy regimens is >90% in children, but <50% in adults, reflecting differences in disease biology and tolerance of aggressive multi-agent chemotherapy regimens. While CAR-T cell therapy provides effective salvage to patients with relapsed B-cell ALL (B-ALL), outcome in relapsed T-ALL is exceptionally poor. In addition, therapy-related chronic functional impairment in pediatric ALL survivors are common. Less toxic, and more effective therapies are needed to improve ALL survival, particularly in adults, and reduce toxicity and functional impairment in all patients.

Background

We investigated the impact of donor-recipient HLA-DPB1 matching on outcomes of allogeneic hematopoietic stem cell transplantation with in vivo T-cell depletion using antithymocyte globulin (ATG) for patients with hematological malignancies. All donor-recipient pairs had high-resolution typing for HLA-A, HLA-B, HLA-C, HLA-DRB1, HLA-DQB1, HLA-DPB1, and HLA-DRB3/4/5 and were matched at HLA-A, HLA-B, HLA-C, and HLA-DRB1. HLA-DPB1 mismatches were categorized by immunogenicity of the DPB1 matching using the DPB T-cell epitope tool. Of 1004 donor-recipient pairs, 210 (21%) were DPB1 matched, 443 (44%) had permissive mismatches, 184 (18%) had nonpermissive mismatches, in graft-versus-host (GVH) direction, and 167 (17%) had nonpermissive mismatches in host-versus-graft (HVG) direction. Compared with HLA-DPB1 permissive mismatched pairs, nonpermissive GVH mismatched pairs had the highest risk for grade II to IV acute graft-versus-host disease (aGVHD) (hazard ratio [HR], 1.4; P = .01) whereas matched pairs had the lowest risk (HR, 0.5; P < .001). Grade III to IV aGVHD was only increased with HLA-DPB1 nonpermissive GVH mismatched pairs (HR, 2.3; P = .005). The risk for disease progression was lower with any HLA-DPB1 mismatches, permissive or nonpermissive. However, the favorable prognosis of HLA-DPB1 mismatches on disease progression was observed only in peripheral blood stem cell recipients who were in the intermediate-risk group by the Disease Risk Index (HR, 0.4; P = .001) but no other risk groups. Our results suggest avoidance of nonpermissive GVH HLA-DPB1 mismatches for lowering the risk for grade II to IV and III to IV aGVHD. Permissive or nonpermissive HVG HLA-DPB1 mismatches may be preferred over HLA-DPB1 matches in the intermediate-risk patients to decrease the risk for disease progression.

-Presence of GFI1-36N impedes homologous recombination and MGMT-mediated DNA repair selectively in AML cells.-Use of temozolomide and olaparib allows selective targeting of GFI1-36Nleukemic cells.

A single mismatch in highly expressed HLA-A, -B, -C, and -DRB1 loci (HEL) is associated with worse outcomes in hematopoietic stem cell transplantation, while less is known about the cumulative impact of mismatches in the lesser expressed HLA loci DRB3/4/5, DQ, and DP (LEL). We studied whether accumulation of LEL mismatches is associated with deleterious effects in 3853 unrelated donor transplants stratified according to number of matches in the HEL. In the 8/8 matched HEL group, LEL mismatches were not associated with any adverse outcome. Mismatches at HLA-DRB1 were associated with occurrence of multiple LEL mismatches. In the 7/8 HEL group, patients with 3 or more LEL mismatches scored in the graft-versus-host vector had a significantly higher risk of mortality (1.45 and 1.43) and transplant-related mortality (1.68 and 1.54) than the subgroups with 0 or 1 LEL mismatches. No single LEL locus had a more pronounced effect on clinical outcome. Three or more LEL mismatches are associated with lower survival after 7/8 HEL matched transplantation. Prospective evaluation of matching for HLA-DRB3/4/5, -DQ, and -DP loci is warranted to reduce posttransplant risks in donor-recipient pairs matched for 7/8 HEL.

Anti-HLA donor-specific Abs (DSAs) have been reported to be associated with graft failure in mismatched hematopoietic stem cell transplantation; however, their role in the development of graft failure in matched unrelated donor (MUD) transplantation remains unclear. We hypothesize that DSAs against a mismatched HLA-DPB1 locus is associated with graft failure in this setting. The presence of anti-HLA Abs before transplantation was determined prospectively in 592 MUD transplantation recipients using mixed-screen beads in a solid-phase fluorescent assay. DSA identification was performed using single-Ag beads containing the corresponding donor's HLA-mismatched Ags. Anti-HLA Abs were detected in 116 patients (19.6%), including 20 patients (3.4%) with anti-DPB1 Abs. Overall, graft failure occurred in 19 of 592 patients (3.2%), including 16 of 584 (2.7%) patients without anti-HLA Abs compared with 3 of 8 (37.5%) patients with DSA (P= .0014). In multivariate analysis, DSAs were the only factor highly associated with graft failure (P= .0001; odds ratio = 21.3). Anti-HLA allosensitization was higher overall in women than in men (30.8% vs 12.1%; P< .0001) and higher in women with 1 (P= .008) and 2 or more pregnancies (P= .0003) than in men. We conclude that the presence of anti-DPB1 DSAs is associated with graft failure in MUD hematopoietic stem cell transplantation.

Fibrinolysis and pericellular proteolysis depend on molecular coassembly of plasminogen and its activator on cell, fibrin, or matrix surfaces. We report here the existence of a fibrinolytic cross-talk mechanism bypassing the requirement for their molecular coassembly on the same surface. First, we demonstrate that, despite impaired binding of Glu-plasminogen to the cell membrane by ϵ-aminocaproic acid (ϵ-ACA) or by a lysine-binding site–specific mAb, plasmin is unexpectedly formed by cell-associated urokinase (uPA). Second, we show that Glu-plasminogen bound to carboxy-terminal lysine residues in platelets, fibrin, or extracellular matrix components (fibronectin, laminin) is transformed into plasmin by uPA expressed on monocytes or endothelial cell–derived microparticles but not by tissue-type plasminogen activator (tPA) expressed on neurons. A 2-fold increase in plasmin formation was observed over activation on the same surface. Altogether, these data indicate that cellular uPA but not tPA expressed by distinct cells is specifically involved in the recognition of conformational changes and activation of Glu-plasminogen bound to other biologic surfaces via a lysine-dependent mechanism. This uPA-driven cross-talk mechanism generates plasmin in situ with a high efficiency, thus highlighting its potential physiologic relevance in fibrinolysis and matrix proteolysis induced by inflammatory cells or cell-derived microparticles.

The polymorphic products of major histocompatibility complex class I–related chain A (MICA) genes are important in solid organ transplantation rejection. MICA expression is limited to gut epithelium and may play a role in triggering acute graft-versus-host disease (aGVHD). A total of 236 recipients of unrelated donor transplantation were studied. Donor-recipient human leukocyte antigen (HLA) match was 10/10 human leukocyte antigen (HLA-A, -B, -C, -DRB1, -DQB1) in 73% and MICA mismatch in 8.4%. Because of physical vicinity of the loci, MICA mismatch was significantly associated with mismatch at HLA-B and HLA-C. A higher rate of grade II-IV aGVHD was seen in MICA-mismatched patients (80% vs 40%, P = .003) irrespective of degree of HLA matching (HLA 10/10 match: 75% vs 39%, P = .02) and HLA any mismatch (83% vs 46%, P = .003). The rate of grade II-IV gastrointestinal aGVHD was also higher in MICA-mismatched patients (35% vs 17%, P = .05). We conclude that MICA may represent novel a transplantation antigen recognized by human allogeneic T cells. This study was registered at ClinicalTrials.gov (Identifier NCT00506922).

The regulation of plasmin generation on cell surfaces is of critical importance in the control of vascular homeostasis. Cell-derived microparticles participate in the dissemination of biological activities. However, their capacity to promote plasmin generation has not been documented. In this study, we show that endothelial microparticles (EMPs) from tumor necrosis factor α (TNFα)–stimulated endothelial cells served as a surface for the generation of plasmin. The generation of plasmin involved expression of urokinase-type plasminogen activator (uPA) and its receptor (uPAR) at the surface of EMPs and was further increased by their ability to bind exogenous uPA on uPAR. Plasminogen was activated at the surface of EMPs in a dose-dependent, saturable, and specific manner as indicated by the inhibition of plasmin formation by ϵ-amino-caproic acid (ϵ-ACA) and carboxypeptidase B. EMP-induced plasmin generation affects tube formation mediated by endothelial progenitor cells. However, low amounts of EMPs increased tube formation, whereas higher concentrations inhibited it. Prevention of these effects by inhibitors of either uPA or plasmin underscore the key role of EMP-induced plasmin generation. In conclusion, we demonstrated that EMPs act as vectors supporting efficient plasmin generation and dissemination, a new pathway in the regulation of endothelial proteolytic activities with potential involvement in inflammation, angiogenesis, and atherosclerosis.

SARS-CoV-2 infection can impact survival of patients with acute myeloid leukemia (AML). International experts recommend considering delaying or stopping AML treatment, test patients who need intensive induction and s prioritizing outpatient treatment. However there is little published evidence in AML.

Hermans: Kedrion:Speakers Bureau;Octapharma:Consultancy, Speakers Bureau;Roche:Consultancy, Speakers Bureau;Pfizer:Consultancy, Research Funding, Speakers Bureau;Novo Nordisk:Consultancy, Speakers Bureau;LFB:Consultancy, Speakers Bureau;Shire, a Takeda company:Consultancy, Research Funding, Speakers Bureau;Sobi:Consultancy, Research Funding, Speakers Bureau;Bayer:Consultancy, Research Funding, Speakers Bureau;EAHAD:Other;WFH:Other;CSL Behring:Consultancy, Speakers Bureau;CAF-DCF:Consultancy, Speakers Bureau;Biogen:Consultancy, Speakers Bureau.Négrier:CSL Behring, Octapharma, Shire/Takeda, Sobi:Research Funding;CSL, F. Hoffmann-La Roche Ltd, Sobi:Other: Travel support;Bayer, Biomarin, CSL Behring, Freeline, LFB, Novo Nordisk, Octapharma, Pfizer, F. Hoffmann-La Roche Ltd, Sanofi, Shire/Takeda, Sobi, Spark:Consultancy.Holme:Sobi:Honoraria, Research Funding;Bayer:Honoraria, Research Funding;CSL Behring:Honoraria;Novo Nordisk:Honoraria;Octapharma:Research Funding;Pfizer:Honoraria, Research Funding;Shire, a Takeda company:Honoraria, Research Funding.Escuriola:Grifols:Honoraria;CSL Behring:Consultancy, Honoraria, Research Funding;Biotest:Honoraria, Research Funding;Biomarin:Honoraria;Bayer:Honoraria;Kedrion:Honoraria;Shire, a Takeda company:Honoraria;Octapharma:Consultancy, Honoraria, Research Funding;Novo Nordisk:Consultancy, Honoraria;Roche:Honoraria;Sobi:Honoraria, Research Funding.Cid:Roche:Consultancy, Honoraria;Sobi:Consultancy, Honoraria;Novo Nordisk:Honoraria;Shire, a Takeda company:Honoraria.Kemenyash:Takeda Pharmaceutical International AG:Current Employment, Current equity holder in publicly-traded company.Botha:Takeda Pharmaceutical International AG:Current Employment, Current equity holder in publicly-traded company.Cano-Garcia:Sanofi Genzyme:Current Employment, Current equity holder in publicly-traded company;Shire, a Takeda company:Divested equity in a private or publicly-traded company in the past 24 months, Ended employment in the past 24 months.Windyga:Sanofi:Honoraria, Research Funding;Alexion:Honoraria, Research Funding;Alnylam:Honoraria, Research Funding;Baxalta/Shire, a Takeda company:Honoraria, Research Funding;Bayer:Honoraria, Research Funding;Siemens:Honoraria, Research Funding;Sobi:Honoraria, Research Funding;Werfen:Honoraria, Research Funding;CSL Behring:Honoraria, Research Funding;Ferring Pharmaceuticals:Honoraria, Research Funding;Novo Nordisk:Honoraria, Research Funding;Octapharma:Honoraria, Research Funding;Rigel Pharmaceuticals:Honoraria, Research Funding;Roche:Honoraria, Research Funding.

Background:Phase I clinical trial for oncology drugs have the highest clinical failure rate. Drug candidates may be discarded if they don´t show activity. Yet these drugs may have valuable activity in patient subgroups. Biomarkers attempt to identify these sensitive subpopulations, but are normally evaluated and validated in Phase II when good drugs may have been discarded.

Plasma Factor XIII, a transglutaminase, is a complex of two A (gene F13A1) chains with catalytic activity and two B chains (gene F13B). FXIII induces clot stabilization and retraction via cross-linking of fibrin monomers and other proteins. Factor XIII deficiency in plasma causes a major bleeding disorder with impaired clot retraction. FXIIIA is synthesized in megakaryocytes, and is abundant in platelets. It is expressed on activated platelets and cross-links proteins on platelet surface. Little is known regarding the regulation of F13A1in megakaryocytes and platelets.RUNX1 is a major hematopoietic transcription factor and regulates expression of numerous genes in megakaryocytes and platelets. Patients with RUNX1 haplodeficiency (RHD) with heterozygous mutations have thrombocytopenia, platelet dysfunction with impaired responses to activation, and predisposition to myeloid malignancies. Platelet expression profiling using Affymetrix microarrays of a patient (P1) with a heterozygous RUNX1mutation (c.969-323G>T) revealed decreased F13Aexpression, which encodes for subunit A of FXIII: fold-change 0.30; p=0.006; patient profiled twice 10 months apart and compared to 6 healthy subjects. These findings were confirmed by qPCRWith RT-PCR platelet F13AmRNA expression was decreased to ~ 20% of mean expression in 4 subjects. Platelet F13A protein expression was decreased by ~50% as assessed by corrected total cellular fluorescence imaging. Platelet F13AmRNA expression was also decreased (to less than 20% of expression in 5 controls) in two siblings (P2 and P3 ages 8 and 3 years) from an unrelated family with a heterozygous RUNX1mutation 508+1G>A). Plasma FXIII was normal in the patient P1. We studied the regulation of F13Aby RUNX1 in human erythroleukemia (HEL) cells treated with phorbol myristate acetate (PMA) to induce megakaryocytic transformation. In silicoanalyses of the 5’ upstream region of F13Ashowed 7 RUNX1 consensus sites within 545bp from ATG. Chromatin immunoprecipitation studies performed using HEL cells and RUNX1 antibody showed that that RUNX1 binds in the region encompassing site 4 and sites 5-7. In parallel, electrophoretic mobility shift assay (EMSA) studies showed binding of nuclear protein to labeled DNA probes with sites 1, 4, 5, 6, and 7. RUNX1 antibody produced a “supershift” with addition suggesting RUNX1 binding. Site-directed mutagenesis of the RUNX1 binding sites in F13A1promoter decreased promoter activity in luciferase reporter studies in HEL cells, providing evidence that the binding sites are functional. Further, overexpression of RUNX1 in HEL cells increased F13A1promoter activity and protein while siRNA RUNX1knockdown reduced F13A1 protein. We assessed clot retraction over 90 min at 37oC in the patient P1 and his daughter (also with RUNX1mutation) in citrated whole blood following addition of tissue factor (1 pM) and CaCl2(1 mM), and in washed platelets resuspended in platelet poor plasma from a healthy subject supplemented with added fibrinogen (0.5 mg/mL) and stimulated with 0.5 U/mL thrombin in the presence of CaCl2. These preliminary studies suggested that clot retraction was slower in the patient P1 compared to the controls, particularly in studies with platelet suspensions.

Lambert: Dova: Consultancy, Membership on an entity's Board of Directors or advisory committees; Principia: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Shionogi: Consultancy; Educational Concepts in Medicine: Consultancy; Octapharma: Consultancy, Research Funding; Bayer: Consultancy; Platelet Disorder Support Association (PDSA): Consultancy; 22qSociety: Consultancy; ITP Australia: Consultancy; CdLS Foundation: Consultancy; RDMD ITP study: Consultancy; Sysmex: Research Funding; AstraZeneca: Research Funding; Argenix: Consultancy; ClinGen: Honoraria.

Hematopoietic stem cell transplantation from unrelated donors is an effective treatment for myeloid malignancies, but its use is usually restricted to young patients without comorbidities. The development of reduced-intensity preparative regimens has allowed the extension of this form of treatment to older and medically infirm patients. We assessed the outcomes of patients older than 54 years who received unrelated donor transplants for the treatment of myeloid malignancies in our institution. There were 29 patients (median age, 59 years) with advanced acute myeloid leukemia (n = 13), myelodysplastic syndrome (n = 7), and chronic myeloid leukemia (n = 9) included. With a median follow-up of 27 months, the probability of overall and event-free survival, and nonrelapse mortality at one year were 44%, 37%, and 55%, respectively. Grades II to IV acute graft-versus-host disease (GVHD) occurred in 41% of patients and chronic GVHD developed in 63% of patients surviving more than 100 days. Of the 11 survivors, 9 were interviewed and reported good quality of life after transplantation using the Functional Assessment of Cancer Therapy–Bone Marrow Transplant Scale (FACT-BMT) questionnaire, with high scores in all dimensions. Unrelated donor transplantation is a treatment option for older patients with myeloid malignancies. The results in this cohort of patients are comparable with those reported in younger patients with similarly advanced disease.

Introduction:Acute Myeloid Leukemia (AML) is an aggressive hematological malignancy. Elderly patients were historically treated with chemotherapy, with ORRs below 30%. Despite treatment improvements with the recent approval of the combination venetoclax plus azacitidine, with 64% of ORR and overall survival of 14.7 months, 25% of patients continue to be refractory and 50% are estimated to relapse. The management of AML, especially in elderly or unfit patients, remains a major challenge.

Introduction

Background and objective. The combination of HyperCVAD and ponatinib resulted in a high molecular response rate and survival in adults with Ph+ ALL, suggesting improved outcome compared with combinations of chemotherapy with first- or second-generation tyrosine kinase inhibitors (TKI) (Jabbour E, et al, Lancet Haematol. 2018;5:e618-e627). The Spanish PETHEMA group conducted the phase 2 PONALFIL trial, which incorporates ponatinib to the same chemotherapy as that of the ALL Ph08 trial that used imatinib as TKI (Ribera JM et al. Cancer 2019;125:2810-17). Final results of this trial are reported.

BACKGROUND

Ribera: AMGEN: Consultancy, Research Funding, Speakers Bureau; NOVARTIS: Consultancy, Speakers Bureau; TAKEDA: Consultancy, Research Funding, Speakers Bureau; ARIAD: Consultancy, Research Funding, Speakers Bureau; SHIRE: Consultancy, Speakers Bureau; Pfizer: Consultancy, Research Funding, Speakers Bureau. Esteve: Novartis: Consultancy, Research Funding; Pfizer: Consultancy; Abbvie: Consultancy; Bristol Myers Squibb/Celgene: Consultancy; Novartis: Research Funding; Jazz: Consultancy; Astellas: Consultancy. Mercadal: Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead Sciences, Inc.: Honoraria, Speakers Bureau. Martínez-López: Roche, Novartis, Incyte, Astellas, BMS: Research Funding; Janssen, BMS, Novartis, Incyte, Roche, GSK, Pfizer: Consultancy.This trial includes Ponatinib in off-label indication.

Monoclonal antibodies (MAbs) to vascular plasminogen activator (vPA), the tissue-type plasminogen activator (tPA) in human plasma, were produced to be used as probes for immunochemical analysis. Human tissue sections and one of these MAbs were used to demonstrate the endothelial origin of plasma-tPA by immunohistochemistry. To produce MAbs, mice were immunized with semipurified vPA isolated from postocclusion human venous blood. Primed spleen cells were fused with the mouse myeloma cell line NS-1. Screening for MAb-producing hybridomas was performed with postocclusion euglobulins as a source of antigen by means of a solid-phase fibrin-vPA immunoassay. The selective and high-affinity binding of vPA for fibrin ensures the specificity and sensitivity of this test. Thus, eight hybridomas secreting MAbs to vPA were selected, cloned, and established as permanent hybridoma cell lines. Immunohistochemical analysis of cryostat sections of human tissues was performed with EA-delta 12D, a MAb having no inhibitory effect against vPA activity but binding to vPA with a high affinity. Thus, the only structures immunostained were endothelial cells of venules, capillaries, and arterioles. The EA-delta 12D monoclonal localization of plasma vPA in the endothelial lining of blood vessels provides evidence that tPA in plasma originates from the vascular wall and validates its designation as vascular plasminogen activator, ie, vPA. Also, our results are consistent with the fact that vPA in blood and tPA in tissues are immunologically identical and have a common endothelial origin.

High plasma levels of lipoprotein(a) [Lp(a)] are considered to be an independent risk factor for premature cardiovascular disease and are inversely associated with apolipoprotein(a) [apo(a)] isoform sizes. The contribution of apo(a) polymorphism to the inhibition of fibrinolysis, a mechanism that may favor thrombus development, was therefore evaluated by measuring the ability of Lp(a) particles of distinct apo(a) isoform content to compete with plasminogen for fibrin binding during plasminogen activation by fibrin-bound tissue-type plasminogen activator. The rate of plasmin generation was most efficiently inhibited by an isoform with a molecular weight (M(r)) of approximately 540 Kd. An isoform with M(r) approximately 590 Kd produced a less pronounced effect, whereas the isoform with M(r) approximately 610 Kd failed to inhibit plasminogen activation. These effects were directly proportional to the amount of Lp(a) bound to the carboxy-terminal lysine residues of degraded fibrin. The relative affinity of the binding (kd range, 16 to 180 nmol/L) reflected the ability of individual Lp(a) isoforms to inhibit the binding of plasminogen (kd, 600 nmol/L). The question of the influence of kringle sequence variability on the binding to fibrin was not addressed by the present work. These data suggest that apo(a) isoform types with high affinity for fibrin may influence the ability of Lp(a) to interfere with fibrinolysis and contribute thereby to the association of elevated levels of Lp(a) with atherosclerotic and thrombotic risks.

We have studied the coagulation status of eight patients with the Chediak-Higashi syndrome (CHS), both in the chronic and the accelerated phase of the disease. It has been shown that during the accelerated phase there are coagulation abnormalities. These abnormalities include a peripheral thrombocytopenia, minor alterations of liver clotting factors, and mainly a profound hypofibrinogenemia and hypoplasminogenemia, which cause life-threatening bleedings. These disorders are of complex origin, but a fibrinolytic process, possibly primary, appears to play a significant role, since the present evidence for intravascular coagulation is not definitive. The accelerated phase of the CHS is characterized by a visceral infiltration by macrophages and lymphocytes. Therefore, we have investigated the possible role of the macrophages in the fibrinolytic process. We have found an excessive plasminogen activator (PA) production by CHS mononuclear cells in the accelerated phase and to a lesser extent in the chronic phase, except in one patient in whom no anomaly was found. Single-cell studies revealed an increased number of PA-producing cells among the monocyte- macrophage lineage rather than a higher level of production per cell. Polymorphonuclear cells (PMN) from patients with CHS were also shown to contain more PA. Slight but significant abnormalities in PA production were observed in obligatory heterozygotes (five out of nine), indicating the inherited nature of the excessive PA production. Finally, an enhanced PA production was similarly demonstrated using beige mice macrophages. The exacerbated production of PA by macrophages in the accelerated phase of the CHS can account to some extent for the coagulation abnormalities that have been observed.

We have studied the coagulation status of eight patients with the Chediak-Higashi syndrome (CHS), both in the chronic and the accelerated phase of the disease. It has been shown that during the accelerated phase there are coagulation abnormalities. These abnormalities include a peripheral thrombocytopenia, minor alterations of liver clotting factors, and mainly a profound hypofibrinogenemia and hypoplasminogenemia, which cause life-threatening bleedings. These disorders are of complex origin, but a fibrinolytic process, possibly primary, appears to play a significant role, since the present evidence for intravascular coagulation is not definitive. The accelerated phase of the CHS is characterized by a visceral infiltration by macrophages and lymphocytes. Therefore, we have investigated the possible role of the macrophages in the fibrinolytic process. We have found an excessive plasminogen activator (PA) production by CHS mononuclear cells in the accelerated phase and to a lesser extent in the chronic phase, except in one patient in whom no anomaly was found. Single-cell studies revealed an increased number of PA-producing cells among the monocyte-macrophage lineage rather than a higher level of production per cell. Polymorphonuclear cells (PMN) from patients with CHS were also shown to contain more PA. Slight but significant abnormalities in PA production were observed in obligatory heterozygotes (five out of nine), indicating the inherited nature of the excessive PA production. Finally, an enhanced PA production was similarly demonstrated using beige mice macrophages. The exacerbated production of PA by macrophages in the accelerated phase of the CHS can account to some extent for the coagulation abnormalities that have been observed.

Salamero: Daichii Sankyo: Honoraria; Pfizer: Consultancy; Celgene: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Jazz Pharmaceuticals: Consultancy, Honoraria. Somervaille:Novartis: Consultancy, Honoraria; Imago Bioscience: Research Funding. Gutierrez:Oryzon Genomics: Current Employment. Bullock:Oryzon Genomics: Current Employment. Buesa:Oryzon Genomics: Current Employment, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Bosch:Roche: Honoraria; Takeda: Honoraria; Celgene: Honoraria; Astra Zeneca: Honoraria; Novartis: Honoraria; Abbvie: Honoraria; Jansen: Honoraria. Montesinos:Pfizer, Abbvie, Daiichi Sankyo: Research Funding; Astellas, Novartis, Janssen: Speakers Bureau; Celgene, Pfizer, Abbvie: Consultancy.

Windyga: Rigel Pharmaceuticals: Honoraria, Research Funding; Werfen: Honoraria, Research Funding; Baxalta/Shire (a Takeda company): Honoraria, Research Funding; Ferring Pharmaceuticals: Honoraria, Research Funding; CSL Behring: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; Alexion: Honoraria, Research Funding; Novo Nordisk: Honoraria, Research Funding; Roche: Honoraria, Research Funding; Bayer: Honoraria, Research Funding; Octapharma: Honoraria, Research Funding; Alnylam: Honoraria, Research Funding; Siemens: Honoraria, Research Funding; Sobi: Honoraria, Research Funding. Holme:Sobi: Honoraria, Research Funding; Shire, a Takeda company: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; CSL Behring: Honoraria; Bayer: Honoraria, Research Funding; Octapharma: Research Funding; Novo Nordisk: Honoraria. Hermans:Shire, a Takeda company: Consultancy; Novo Nordisk: Consultancy. Cid:Novo Nordisk: Honoraria; Shire, a Takeda company: Honoraria. Chatterjee:Baxalta US Inc., a Takeda company: Employment, Equity Ownership. Jiang:Baxalta US Inc., a Takeda company: Employment, Equity Ownership. Cano-Garcia:Shire, a Takeda company: Employment, Equity Ownership. Escuriola:Octapharma: Consultancy, Honoraria, Research Funding; Bayer: Consultancy, Honoraria, Research Funding; Sobi: Consultancy, Honoraria, Research Funding; Kedrion: Consultancy, Honoraria, Research Funding; Novo Nordisk: Consultancy, Honoraria, Research Funding; Grifols: Consultancy, Honoraria, Research Funding; Biotest: Consultancy, Honoraria, Research Funding; Shire, a Takeda company: Consultancy, Honoraria, Research Funding; CSL Behring: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Honoraria, Research Funding.

Chemosensitization using plerixafor combined with FLAG-IDA (PLERIFLAG regimen) showed promising results (48% CR/CRi) in a phase 2 trial for primary refractory and early relapsed (duration of first CR <12 months) Adult AML patients. We aim to compare retrospectively results of the PLERIFLAG cohort versus historical cohorts of patients salvaged with FLAG-IDA (Fludarabine, Idarubicine, Cytarabine, G-CSF as priming agent), or FLAGO-IDA (Gemtuzumab plus FLAG-IDA) registered in the PETHEMA epidemiologic AML registry (NCT02006004). To match different cohorts, we used two risk-score classifications: EPI/HOVON (De Breems, JCO 2005) and SALFLAGE (Bergua, BJH 2016). The purpose is to analyse the complete remission (CR+CRi) rate, the rate of patients who underwent allogeneic hematopoietic stem cell transplantation (HSCT). The disease-free survival (DFS) and overall survival (OS) were adjusted using established risk factors (time to relapse (TTR), karyotype, FLT3-ITD, previous stem cell transplant (SCT)) using propensity score analysis.

Olive: ImCheck Therapeutics: Consultancy, Equity Ownership, Patents & Royalties; GlaxoSmithKline: Patents & Royalties.

No relevant conflicts of interest to declare.

Bell: Takeda Pharmaceuticals: Employment, Equity Ownership. Pompilus:Modus Outcomes: Employment; Takeda Pharmaceuticals: Research Funding. Christian:Modus Outcomes: Employment; Takeda Pharmaceuticals: Research Funding. Mazerolle:Modus Outcomes: Employment; Takeda Pharmaceuticals: Research Funding. Scipione:Takeda Pharmaceuticals: Employment. Bejar:Takeda: Research Funding; Celgene: Consultancy, Honoraria; Foundation Medicine: Consultancy; Modus Outcomes: Consultancy; Genoptix: Consultancy; AbbVie/Genentech: Consultancy, Honoraria; Astex/Otsuka: Consultancy, Honoraria. Galaznik:Takeda Pharmaceuticals International Co.: Employment. Fram:Takeda Pharmaceuticals: Consultancy; BeyondSpring Pharmaceuticals, Inc.: Consultancy. Faller:Takeda Pharmaceuticals: Employment, Equity Ownership. Cano:Modus Outcomes: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Takeda Pharmaceuticals: Research Funding. Regnault:Modus Outcomes: Employment, Membership on an entity's Board of Directors or advisory committees; Takeda Pharmaceuticals: Research Funding.

Background- According to recommendations, AML patients with intermediate- or adverse-risk genetics are candidates for allogeneic SCT in first complete remission (CR1). In practice, only a minority of them undergoes SCT because of older age, comorbidities, poor tolerance of prior therapy, inability to achieve CR, or early relapse. The benefit associated with RIC-SCT is particularly difficult to assess in older patients, due to lower SCT numbers and strong selection biases.

No relevant conflicts of interest to declare.

No relevant conflicts of interest to declare.

Transcription factor (TF) mutations are increasingly recognized to play a major role in inherited platelet abnormalities. RUNX1, a major hematopoietic TF, acts in a combinatorial manner with other TFs to regulate numerous megakaryocyte (MK)/platelet genes. Human RUNX1haplodeficiency is associated with thrombocytopenia, platelet function defects, and increased leukemia risk. We have described a patient with multiple abnormalities in platelet aggregation and secretion responses with a heterozygous RUNX1nonsense mutation (Sun et al Blood2004; 103; 948-54). Transcript expression profiling of patient platelets (Sun et al J Thromb Haemost2007; 5:146-54)showed several genes were significantly downregulated, including myosin light chain (MYL9), platelet factor 4 (PF4), protein kinase C-θ (PRCKQ), and 12-lipoxygenase (ALOX12); these have been shown by us to be regulated by RUNX1. The profiling data also showed 10-fold downregulation of phosphatidylcholine transfer protein (PCTP) gene (fold change ratio 0.09, p=0.02) in the patient compared with normal controls. PCTP regulates the intermembrane transfer of phosphatidylcholine (PC), a major plasma membrane phospholipid. Platelet PCTP expression is associated with increased platelet aggregation and calcium mobilization upon activation of protease-activated receptor 4 (PAR4) thrombin receptors in black subjects as compared to white subjects (Edelstein et al Nat Med2013; 19:1609-16). Pharmacologic inhibition of PCTP decreased platelet aggregation in response to PAR4 agonist and siRNA knockdown of PCTPin megakaryocytic cells blunted calcium mobilization induced by PAR4 (Edelstein et al Nat Med2013; 19:1609-16). Little is known regarding the regulation of PCTPin MKs/platelets and its role in cardiovascular events.

HEMOSTASIS, THROMBOSIS, AND VASCULAR BIOLOGY

No relevant conflicts of interest to declare.

No relevant conflicts of interest to declare.