ALBERT

Description: Abstract 4216 Background: Increased complement activation has been implicated in the pathogenesis of APS. Most evidence to date comes from animal models of APS. Studies of murine APS models have demonstrated complement activation to be a mediator of thrombosis (Fischetti et al, 2005, Pierangeli 2007) and foetal loss (Girardi et al, 2003). Increased complement deposition was demonstrated in a study of placentae of APS pregnancies further supporting the findings in mice (Shamonki et al, 2007). Low levels of complement have been demonstrated in patients with APS which may be due to increased complement turnover (Oku et al, 2008). C3a-desArg is a stable product of C3a cleavage generated during complement activation; Bb is an activation fragment of Factor B, an alternative pathway component. Both have been evaluated as reliable markers of complement activation in patients. Objectives: To evaluate levels of complement activation products in patients with antiphospholipid syndrome by measuring the complement activation products Bb and C3a-desArg. Methods: Local ethics committee approval was obtained. Samples were obtained from patients attending clinics at our institution who had PAPS according to International Consensus statement criteria, or had persistent aPL without associated complications. Patients with systemic lupus erythematosus (SLE), intercurrent infection or malignancy were excluded. None of the patients were taking heparin. The control group were recruited from hospital staff who were not known to have aPL, were non smokers and not taking the oral contraceptive pill. Control samples were obtained from 18 healthy non-pregnant women (median age 37.5 (range 20–58) years). Patient blood samples were obtained from 39 women with apL and previous thrombosis, 5 of whom had previous pregnancy morbidity, 3 of whom were smokers and all of whom were on oral vitamin K antagonists (median 47 (23-61)), 15 women with obstetric APS and no history of thrombosis, 2 of whom were smokers (median 41 (32-54)), and 19 women with isolated aPL, 3 of whom were smokers (median 43.5 (19-73)). Blood was drawn by flawless venepuncture into tubes containing EDTA, immediately centrifuged at 3000 rpm for 15 min at 4°C and stored at -80°C until use. ELISA assays measuring complement fragments Bb and C3a-desArg levels were performed on plasma samples in one batch by one technician according to manufacturer's protocol (Quidel, Technoclone Dorking, UK). Intra-assay CV was 2.4% for Bb and 2.8% for C3a-desArg. Statistical analysis: The unpaired t-test was used to compare complement levels between groups. A p-value of

Description: Background Obstetric antiphospholipid (aPL) syndrome (APS) is defined by the presence of persisting aPL with previous unexplained recurrent first trimester pregnancy loss, &/or intrauterine death, &/or placental dysfunction (severe pre-eclampsia, intrauterine growth retardation or placental abruption). The placental anticoagulant protein Annexin A5 (AnxA5) is expressed on the surfaces of placental syncytiotrophoblasts where it has been postulated to play a thrombomodulatory role. aPL antibodies have been demonstrated to reduce the quantity of AnxA5 on these cells and accelerate plasma coagulation. Resistance to AnxA5 anticoagulant activity has previously been demonstrated in APS patients with thrombotic histories. We have investigated whether plasma samples from patients with the obstetric APS also interfere with AnxA5 anticoagulant activity and also whether this correlated with antibody recognition of domain I on β2GPI. Methods Plasmas were obtained from 30 healthy non-pregnant donors (median age 34, range 18–55) and 70 healthy non-pregnant women with previous obstetric APS (median age 39, range 24–58), and assayed for AnxA5 resistance and anti-β2GPI domain I antibodies, using previously published assays. Results Women with obstetric APS had significant reduction of AnxA5 anticoagulant ratios compared to controls (median 216%, range 130–282% vs 247%, range 217–283%, p

Description: Abstract 5244 Background: Microparticles are membrane fragments from cells and microparticles derived from platelets, monocytes and endothelial cells have been implicated in prothrombotic states. Their procoagulant activity is thought to be through exposure of procoagulant phospholipids. Elevated microparticle levels have been found in artherosclerosis, inflammatory states and pregnancy loss. More recently, elevated levels of both endothelial and platelet microparticles have been implicated in APS and thrombosis and in APS and recurrent miscarriage. Microparticles may play a role in the pathogenesis of APS. Aims: The aim of this study was to assess levels of circulating endothelial and platelet microparticles and to measure microparticle procoagulant activity in patients with aPL. Materials & Methods: We obtained samples from 69 patients (69 females, median age 45 (range 19–73) years) who had PAPS according to International Consensus statement criteria, or had persistent aPL without associated complications. 18 healthy controls (18 females, median age 37.5 (range 20–58) years) were recruited and were not known to have antiphospholipid antibodies. Patients with PAPS included 38 with thrombotic complications, 12 with obstetric complications and 19 with isolated aPL. 37/69 patients with thrombotic complications of APS were receiving vitamin K antagonists and 9/19 of those with isolated aPL were receiving aspirin. Blood was drawn by flawless venepuncture into tubes containing citrate. Samples were centrifuged at 3000 rpm for 15 min at 4°C and stored at −80°C until use. A functional ELISA assay of microparticle procoagulant activity (based on prothrombinase activity stimulated by microparticle phospholipid exposure on binding to annexin V immobilised on the ELISA plates) was performed on platelet depleted plasma samples according to manufacturer's protocol (Hyphen Biomed, UK). Intra-assay CV was 3–8%. Endothelial and platelet derived microparticles were detected by flow cytometry, specific surface markers were used to identify platelet microparticles (CD41&CD61, Beckman Coulter, UK) and endothelial microparticles (CD51&CD105, Beckman Coulter, UK). Samples were thawed at room temperature and incubated with CD41-PC, CD61-PC, CD51-FITC and CD105-PE. Enumeration beads were added prior to analysis by flow cytometry for quantification of microparticle levels. The unpaired t-test was used to compare platelet microparticle levels between groups and a p-value of

Description: Multiple factors are likely to contribute to the pathogenesis of thrombosis in Essential thrombocythaemia (ET) including platelet number, activation of platelets and leukocytes; the formation of platelet leucocyte aggregates, and circulating prothrombotic and endothelial factors. The normal functional activity of platelets depends on the presence of platelet glycoprotein complexes, which play an important role in platelet adhesion and aggregation. A number of polymorphisms in platelet glycoproteins have been correlated with thrombotic events in hematologically normal patients. Particular polymorphisms of interest include three within the glycoprotein Ibα gene: −5T/C (affecting a Kozak sequence), 1018C/T (T145M, encoding Human Platelet Antigen − 2), a variable number of tandem repeats (VNTR) in a region encoding the macroglycopeptide and one polymorphism C807T, within the glycoprotein Ia gene. To date whether there is a relationship between these platelet glycoprotein polymorphisms and the clinical features of ET has not been determined. In this study samples obtained from 797 ET patients recruited to the 3 large prospective PT–1 trials were genotyped for the polymorphisms of interest and the results were correlated with clinical events including haemorrhagic and arterial or venous thrombotic events in the year prior to diagnosis and following trial entry (median 30 months). The VNTR data were analysed using the sum of the number of repeats of both alleles and treated as a continuous variable using logistic regression for retrospective and a Cox survival model for prospective analyses; other polymorphisms were analysed using the Chi-squared test for the retrospective clinical events, and log-rank survival analysis for the prospective clinical events. Neither the C807T, −5T/C Kozak nor the T145M polymorphism was associated with clinical events in the ET patient cohort. Interestingly the number of VNTR repeats was inversely associated with (p=0.02) rate of arterial events after trial entry in this patient cohort, but not for events in the year prior to diagnosis or post trial entry venous thrombotic or haemorrhagic events. This analysis suggested that a decreasing sum of VNTR were associated with an increased risk of arterial thrombosis, the degree of increase in risk was 75% per repeat (95% confidence interval 1.0–2.9). After multivariate analysis of this data with correction for age, sex, JAK2V617F and MPLW515L/K status the effect of the number of VNTR repeats remained significant (p=0.048). These results suggest that the C807T, T145M and −5T/C Kozak polymorphisms do not correlate with clinical events in ET. However a reduction in the number of VNTR within the glycoprotein Ibα gene was progressively associated with arterial events post trial entry (p=0.024) and remained significant on multivariate analysis (p=0.048).

Description: The management of post-operative bleeding in paediatric cardiac surgery is difficult because the underlying haemostatic changes have been poorly studied. The thromboelastogram (TEG) provides a real-time, functional measure of haemostasis, quantifying clot formation, strength and lysis. We investigated the use of serial intra-operative TEG to assess perioperative haemostatic changes and as an adjunct to demographic and laboratory variables for the prediction of bleeding following cardiopulmonary bypass (CPB) surgery. Ethical committee approval was obtained to study fifty-one children, median (interquartile) age 6.8 months (0.5 to 10.5) prospectively through CPB and for the first 24 hours after intensive care unit admission. Significant post-operative blood loss was defined as more than 10ml/kg in the first four post-operative hours. TEG readings and traditional coagulation parameters were measured throughout CPB. Forward stepwise logistic regression analysis was used to predict bleeding. The incidence of bleeding was 37% (19/51), with a mean 4-hour blood loss of 24 ml/kg. Both groups showed abnormalities in all TEG parameters (apart from lysis) at the end of CPB, which were more marked among those who bled (all p

Description: Objectives Evaluate early outcomes following endoluminal stenting using first-generation dedicated venous stents. Methods Patients undergoing deep venous reconstruction using venous stents between 2012-2015 were identified. Duplex ultrasonography was used to assess sent patency at 1d, 2wks, 3mths, 6mths and yearly following intervention. Venous Disability Scores (VDS) and Villalta Scores (VS) taken before and after intervention (6wks, 6mths, yearly) were calculated. Results 347stents were inserted in 140pts (median age 39yrs, 80 female) with median follow-up 16mths (1-38mths). Overall 1yr primary, primary-assisted and secondary patency rates were 67%, 80% and 82% respectively. The 1yr re-intervention rate was 30% with 16% occurring within two-weeks. 57pts had stenting of residual stenoses after catheter-directed-thrombolysis for acute iliofemoral DVT. Median post-operative VDS and VS were 0 (P

Description: Introduction Myeloproliferative neoplasms (MPN) are associated with an increased rate of venous thromboembolism (VTE), which can be a major cause of morbidity and mortality especially in the more indolent diseases of polycythaemia rubra vera (PV) and essential thrombocythaemia (ET). Splanchnic vein thromboses are common in MPN and may have high recurrence rates between 15-20% over 10 years1. Traditionally, vitamin K antagonists (VKA) have been the mainstay of anticoagulation for MPN-associated VTE and recent data suggests a high rate of recurrent VTE on their discontinuation in MPN patients2. In the last 5 years, there has been a significant change to the use of direct oral anticoagulants (DOAC) in non-MPN associated VTE and limited data is available in the MPN setting due to the exclusion of malignancies from initial Phase III studies. Methods A retrospective review of patients treated at a single tertiary centre for MPN was performed. Clinical details were obtained from electronic clinical notes, imaging and prescriptions. Results A total of 102 patients were identified as having a MPN-associated VTE with 24 of these receiving DOACs. The median age at VTE was 48 years (range 27.4-92.2 years) with 10 males (41.7%), primary diagnosis: 10 PV, 5 ET, 7 myelofibrosis (MF) and 2 MPN/myelodysplasia overlap. 18 patients were JAK2 V617F positive, 1 pt had MPL mutation and 5 pts were triple negative. In total 29 thrombotic events were recorded - 10 splanchnic (34.4%), 10 pulmonary embolism (34.4%), 5 deep vein thrombosis (17.2%), 2 cerebral venous sinus thrombosis (6.9%), 1 superficial thrombophlebitis (3.4%). The median follow-up period was 2.2 years (range 0.7-7.5 years) with 16 patients initiated on DOAC (12 rivaroxaban and 4 apixaban) and 8 patients changed from VKA or heparin (3 rivaroxaban, 3 apixaban and 1 edoxaban). Two patients used more than one DOAC in this period. 21 patients were receiving long-term anticoagulation and 3 had defined courses of anticoagulation due to provocation. 21 patients were receiving cytoreductive agents or regular venesection along with anticoagulation. During the total follow-up period of patients receiving DOACs, amounting to 66 pt years, there were no VTE recurrences in 23 patients and indeterminate imaging for 1. There were no episodes of major bleeding but 2 patients (8.3%) had clinically relevant non-major bleeding both of which were taking aspirin in addition to DOAC. Conclusions These results suggest that there were very low/no recurrence rates of VTE and no major bleeding in patients with MPN-associated VTE who are receiving DOACs. These include heterogeneous sites of VTE including splanchnic vein thromboses and cerebral venous sinus thrombosis. Of note, cytoreductive measures were also used in a majority of these patients. We suggest that DOACs could be safely used in this group in appropriately selected patients with MPN. References: 1. Finazzi G, De Stefano V, Barbui T. Splanchnic vein thrombosis in myeloproliferative neoplasms: treatment algorithm. Blood Cancer J. 2018; 8(7): 64. 2. De Stefano V, Ruggeri M, Cervantes F et al. High rate of recurrent venous thromboembolism in patients with myeloproliferative neoplasms and effect of prophylaxis with vitamin K antagonists. Leukemia. 2016; 30(10): 2032-38. Table Disclosures McLornan: Jazz Pharmaceuticals: Honoraria, Speakers Bureau; Novartis: Honoraria. Radia:Blueprint Medicines: Consultancy; Novartis: Consultancy, Speakers Bureau. Harrison:AOP: Honoraria; Promedior: Honoraria; Gilead: Speakers Bureau; Roche: Honoraria; Janssen: Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Sierra Oncology: Honoraria; CTI: Speakers Bureau; Novartis: Honoraria, Research Funding, Speakers Bureau; Shire: Speakers Bureau; Incyte: Speakers Bureau.

Description: Abstract 3179 Introduction: Antiphospholipid syndrome (APS) is an immune disorder characterised by recurrent thrombosis and/or complications during pregnancy associated with the presence of persistent antiphospholipid antibodies (aPL). Several mechanisms have been proposed to underlie the pathogenic mechanisms of aPL but studies of markers of coagulation activity and thrombin generation suggest healthy individuals with aPL do not usually have a hypercoagulable state. Thromboelastography (TEG) is a global measure of haemostasis and has been shown to demonstrate hypercoagulable states. Also, studies have shown women with recurrent first trimester loss have hyercoagulable TEG parameters. There have been no studies to date assessing the use of TEG in patients with aPL/PAPS. Objective: The aim of this study was to assess the potential role of TEG to assess hypercoagulability of individuals with antiphospholipid antibodies or PAPS. Methods: Local ethical committee approval was obtained. Samples were obtained from patients attending clinics at our institution who had PAPS according to International Consensus statement criteria, or had persistent aPL without associated complications. The control group were recruited from hospital staff who were not known to have aPL, were non smokers and not taking the oral contraceptive pill. Control blood samples were obtained from 17 healthy non-pregnant women (median age 37.5 (range 20–58) years). Patient blood samples were obtained from 39 women with apL and previous thrombosis, 5 of whom had previous pregnancy morbidity, 3 of whom were smokers and all of whom were on oral vitamin K antagonists (median 47 (23-61)), 14 women with obstetric APS and no history of thrombosis, 2 of whom were smokers (median 41 (32-54)), and 17 women with isolated aPL, 2 of whom were smokers (median 43.5 (19-73)). Fresh whole blood was drawn by flawless venepuncture into tubes containing citrate 0.105M and stored at room temperature for 30 minutes prior to analysis. 500μl of whole blood was activated with 12.5μl of Kaolin and thromboelastography was performed by the same technician on 340μl of activated blood using a TEG® analyzer according to the manufacturer's protocol. Statistical analysis of all TEG parameters was performed using the unpaired t-test. A P-value of

Description: Previously published guidelines for the diagnosis and management of primary immune thrombocytopenia (ITP) require updating largely due to the introduction of new classes of therapeutic agents, and a greater understanding of the disease pathophysiology. However, treatment-related decisions still remain principally dependent on clinical expertise or patient preference rather than high-quality clinical trial evidence. This consensus document aims to report on new data and provide consensus-based recommendations relating to diagnosis and treatment of ITP in adults, in children, and during pregnancy. The inclusion of summary tables within this document, supported by information tables in the online appendices, is intended to aid in clinical decision making.

Description: The safety and efficacy of weekly rituximab 375 mg/m2 (×4), given within 3 days of acute TTP admission, with standard therapy (PEX and steroids) was evaluated. Clinical outcomes were compared to historical controls (n = 40) who had not received rituximab. Within the trial group, 15 of 40 required ICU admission and 15% of all cases with the highest troponin T levels on admission were ventilated. Before the second rituximab infusion, 68% of cases had a platelet count 〉 50 × 109/L and 38% 〉 150 × 109/L. Fewer PEX were required in whites compared to nonwhite in the rituximab group (mean 14 vs 21, P = .0095). Inpatient stay was reduced by 7 days in the non-ICU trial cases compared to historical controls (P = .04), especially in whites, with a mean reduction of 7 days (P = .05). Ten percent of trial cases relapsed, median, 27 months (17-31 months), compared to 57% in historical controls, median 18 months (3-60 months; P = .0011). There were no excess infections or serious adverse events with rituximab. In conclusion, rituximab appears a safe and effective therapy. Inpatient stay and relapse are significantly reduced in the rituximab cohort. Rituximab should be considered in conjunction with standard therapy on acute presentation of TTP. This study was registered at www.clinicaltrials.gov as NCT009-3713.