Karen Breen

The pathogenesis and management of the coagulopathy of acute promyelocytic leukaemia

Coagulopathy occurs in most patients with (APML) and is life‐threatening; therefore prompt diagnosis and recognition of any coagulation defect is imperative. Unfortunately haemorrhage remains a major cause of early death, preventing some from reaching treatment. The coagulopathy is caused directly or indirectly by the leukaemic cells through expression of activators of coagulation and fibrinolysis, proteases and cytokine generation, compounded by failure of platelet production due to marrow invasion. At presentation the predominant feature is usually hyperfibrinolysis. Since the introduction of all‐trans retinoic acid (ATRA), patient outcome has dramatically improved; yet, haemorrhagic complications remain the most frequent cause of mortality. Thrombotic complications occur but are less well recognized and potentially underreported. Supportive measures and prompt initiation of ATRA currently represent the mainstay of treatment of the coagulopathy in patients with suspected APML, but unanswered questions remain as to the optimal approach to further decrease the associated haemorrhagic and thrombotic risks. In particular, it is unclear how to best predict and monitor the coagulopathy; whether there is a role for the early use of antifibrinolytics; the most appropriate trigger for giving fibrinogen replacement and the value of low‐dose anticoagulation to suppress coagulation activation once fibrinolysis has been suppressed.

Rivaroxaban use in patients with antiphospholipid syndrome and previous venous thromboembolism.

Research Fellow in Thrombosis and Haemostasis, Guy’s and St Thomas’ Guy’s & St Thomas’ Hospital, London, UK, Centro di Ricerche di Immunologia Clinica ed Immunopatologia e Documentazione su Malattie Rare (CMID), Dipartimento di Scienze Cliniche e Biologiche, Università di Torino, Italy, Consultant in Thrombosis & Thrombophilia and Professor of Thrombosis & Haemostasis, Kings Health Partners & Consultant in Thrombosis & Thrombophilia, Guy’s & St Thomas’ NHS Foundation Trust, London, UK

Endothelial and platelet microparticles in patients with antiphospholipid antibodies

BACKGROUND The antiphospholipid syndrome (APS) is the association of thrombosis and recurrent pregnancy loss and/or pregnancy morbidity with persistent antiphospholipid antibodies (aPL). Previous studies of microparticles in patients with APS/aPL have mainly been small and findings, contradictory. OBJECTIVES To quantify endothelial and platelet microparticle levels in patients with isolated antiphospholipid antibodies or primary antiphospholipid syndrome (PAPS). PATIENTS/METHODS We measured endothelial and platelet microparticle levels by flow cytometry in 66 aPL/PAPS patients and 18 healthy controls. RESULTS Levels of circulating platelet (CD41 and CD61) and endothelial microparticles (CD51 and CD105) were significantly increased in patients with PAPS and aPL compared to healthy controls. There were correlations between platelet and endothelial microparticles levels in all patients with aPL. CONCLUSIONS Platelet and endothelial microparticles are increased in all patient groups within this cohort of patients aPL. Whether they may have a role in the pathogenesis of APS merits further study.

HYdroxychloroquine to Improve Pregnancy Outcome in Women with AnTIphospholipid Antibodies (HYPATIA) Protocol: A Multinational Randomized Controlled Trial of Hydroxychloroquine versus Placebo in Addition to Standard Treatment in Pregnant Women with Antiphospholipid Syndrome or Antibodies

Women with antiphospholipid antibodies (aPL) are at risk of adverse pregnancy outcomes, including recurrent first-trimester pregnancy loss and late pregnancy complications such as preeclampsia, HELLP (hemolysis, elevated liver enzyme levels, and low platelet levels) syndrome, premature delivery, intrauterine growth restriction, placental abruption, and intrauterine death. Current standard care in obstetric antiphospholipid syndrome includes aspirin and heparin and has resulted in live-birth rates of approximately 70%. However, 30% continue to have pregnancy complications. Hydroxychloroquine (HCQ) is suggested as a new treatment approach, but no randomized controlled trials (RCTs) have assessed its efficacy. This study aims to assess pregnancy outcome in women with aPL treated with HCQ versus placebo in addition to standard treatment. The HYdroxychloroquine to improve Pregnancy outcome in women with AnTIphospholipid Antibodies (HYPATIA) study is a phase IV multicenter RCT, in which pregnant women with persistent aPL will receive either HCQ or placebo in addition to their usual medication. The primary endpoint is a composite of aPL-related adverse pregnancy outcomes: one or more pregnancy loss(es) (either   10 weeks of gestation) and premature birth before 34 weeks due to any of the following preeclampsia, eclampsia, or recognized features of placental insufficiency. The HYPATIA study is expected to provide evidence on the effect of HCQ in pregnant women with persistent aPL.

The effect of hydroxychloroquine on haemostasis, complement, inflammation and angiogenesis in patients with antiphospholipid antibodies

Objectives HCQ has been described as having a beneficial effect in patients with APS but its mechanism of action is unclear. We hypothesized that HCQ may have effects on subnormal angiogenesis, inflammation and haemostatic biomarkers seen in APS. The aim of our study was to assess laboratory markers [annexin A5 (AnxA5) anticoagulant activity, tissue factor (TF) levels, thromboelastography (TEG), CRP, Bb, C3a and VEGF] in HCQ-naïve patients with aPL at baseline and after commencing HCQ. Methods Twenty-two patients with aPL [20 female, 2 male, median age 55 (range 18-70) years] had blood taken pre- and 3 months after starting HCQ 200 mg daily. Results Soluble TF levels were significantly reduced comparing baseline and 3 months after HCQ commencement [401.8 (152.8) vs 300.9 (108) pg/ml (P = 0.010)]. No significant changes were found in the following [reported as pre- and post-HCQ commencement, mean (s.d.)]: AnxA5 anticoagulant ratio [187.1 (29.5) vs 193 (31) (P = 0.157)], anti-domain1 β2 glycoprotein1 IgG activity [1.8 (2) vs 1.2 (1.4) μg/ml (P = 0.105)], complement C3a-des-Arg [147.8 (84.5) vs 154.4 (88.1) ng/ml (P = 0.905)], complement Bb [1.3 (0.7) vs 1.1 (0.7) μg/ml (P = 0.422)], VEGF [68.8 (40) vs 59.4 (19.6) pg/ml (P = 0.454)] and CRP [7 (3.5) vs 7 (3.9) μg/ml (P = 0.917)]. TEG results including TEG reaction time, achievement of clot firmness, TEG maximum amplitude and TEG percentage lysis 30 and 60 min after maximum amplitude showed no significant difference. Conclusion HCQ significantly reduced soluble TF levels in patients with aPL. No significant change was observed in AnxA5 activity, anti-domain 1 IgG activity, TEG, CRP, complement Bb and C3a-des-Arg, and VEGF. Further studies of a larger patient cohort are needed.

Taipan snake venom time coupled with ecarin time enhances lupus anticoagulant detection in nonanticoagulated patients.

A study is presented which assesses the diagnostic impact of incorporating Taipan snake venom time (TSVT) with ecarin time confirmatory test into an existing dilute Russells viper venom time (dRVVT) and activated partial thromboplastin time (APTT) repertoire when testing nonanticoagulated patients for lupus anticoagulants. A total of 387 plasma samples from nonanticoagulated patients being investigated for antiphospholipid antibodies were tested for lupus anticoagulant by dRVVT and dilute APTT with confirmatory and mixing tests, and TSVT with ecarin time, with commercially available reagents. All were analyzed on a Sysmex CS2000i automated analyzer. Lupus anticoagulant was not detected by dRVVT, dilute APTT or TSVT screening in 265 of 387 (68.5%) samples. A lupus anticoagulant was detected in 60 (15.5%) samples in dRVVT and/or dilute APTT analysis, but gave normal TSVT ratios. Thirty-nine (10.1%) were positive by TSVT and ecarin time and one or both of dRVVT and dilute APTT testing, whereas a further 23 (5.9%) were only positive in TSVT/ecarin time testing. Most of the lupus anticoagulants manifested in dRVVT and/or APTT analysis, as might be anticipated for this reagent pairing. The samples positive by TSVT/ecarin time only, as has been previously demonstrated, emphasize that the many variables that impact lupus anticoagulant testing mean that even a well established dRVVT and APTT pairing cannot deliver diagnostic certainty. Interference by direct factor Xa inhibitors in dRVVT testing could pave the way for wider adoption of TSVT screening as we gain more evidence of its diagnostic performance.

Contemporary management of acute and chronic deep venous thrombosis

INTRODUCTION This review aims to provide an update on the management of deep vein thrombosis (DVT). SOURCES OF DATA A systematic search of PubMed, Google Scholar and Cochrane databases was carried out. AREAS OF AGREEMENT Direct oral anticoagulants (DOACs) are as effective and easier to use than vitamin K antagonists for the treatment of DVT. Catheter-directed thrombolysis can reduce post thrombotic syndrome in patients with iliofemoral DVT. Compression bandaging can help heal a venous ulcer. AREAS OF CONTROVERSY Compression hosiery to prevent post thrombotic syndrome. Long-term evidence to show clinical benefit of using endovenous therapies to restore deep vein patency. GROWING POINTS Developing imaging methods to identify patients who would benefit from venous thrombolysis. The evolution of dedicated venous stents. AREAS TIMELY FOR DEVELOPING RESEARCH Understanding the mechanisms that lead to stent occlusion and investigation into the appropriate treatments that could prevent in-stent thrombosis is required.

Lack of association of serum mannose/mannan binding lectin or ficolins with complement activation in patients with antiphospholipid antibodies.

The antiphospholipid syndrome (APS) is an autoimmune disorder characterized by either thrombotic and/or obstetric complications associated with the presence of persistent antiphospholipid antibodies (aPL) [1]. Complement activation has been proposed to play a role in the pathogenesis of both thrombotic and obstetric complications of APS with most evidence for this demonstrated in murine models of APS [2,3]. Recently, we demonstrated increased levels of complement activation products, Factor Bb and C3aDesArg, in a large group of patients with primary APS (PAPS) or isolated

AB0147 The effect of treatment with hydroxychloroquine on soluble tissue factor levels in patients with antiphospholipid antibodies and antiphospholipid syndrome with and without underlying systemic lupus erythematosus

Background Antiphospholipid syndrome (APS) is characterized by venous, microvascular and/or arterial and/or obstetric morbidity (obstetric APS) in patients who are persistently positive for antiphospholipid antibodies (aPL)[1]. The mainstay of treatment is based on anticoagulation therapy; however, increasing interest is currently received by the antimalarial hydroxychloroquine (HCQ). The use of HCQ has been associated with a reduced risk of thrombosis but HCQs antithrombotic mechanism of action is unclear particularly in patients with aPL and APS. Objectives The aim of our study was to assess soluble tissue factor (TF) levels in HCQ naïve-patients with persistent aPL or APS at baseline and 12 weeks after commencing HCQ. We hypothesise that HCQ lowers levels of soluble TF. Methods Twenty- two individuals with APS with or without other associated autoimmune disease (20 females, two males, median age 55 (range 18–70) years) had blood samples taken before and 12 weeks after starting HCQ 200mg. Plasma was stored at -80oC and thawed to measure TF using Imubind TF kit (Invitech Ltd, Cambridgeshire, UK). The assay was performed according to the manufacturers instructions. Patient characteristics are outlined in table 1. Statistical analysis was performed using SPSS Version 22. For continuous normally distributed data a two-tailed students paired t-test was performed. A value of p=0.05 was considered as significant. There are no previous data in this area, so we were unable to do a power calculation to work out study size. Our study is therefore a pilot study. Results Soluble TF levels were above our normal range (40–300 pg/ml) prior to the commencement of HCQ and were significantly reduced (pre level mean (SD) 401.8 (152.8) pg/ml versus post 300.9 (108) pg/ml (p=0.010). Conclusions There was a significant reduction in soluble TF levels in this patient cohort of patients with apL and APS after commencing HCQ. Our previous work has shown that HCQ has not affected complement turnover, VEGF levels, thromboelastometry findings or CRP levels. Our findings of a reduction of soluble TF levels in aPL positive patients after the commencement of HCQ maybe a key mechanism by which HCQ reduces thrombotic risk. Further studies of a larger patient cohort are required to confirm our observation. References Miyakis, S., et al., International consensus statement on an update of the classification criteria for definite antiphospholipid syndrome (APS). J Thromb Haemost, 2006. 4(2): p. 295–306. Disclosure of Interest K. Schreiber Shareholder of: Novo Nordisk, Grant/research support from: educational support from Daiichi Sankyo, K. Breen: None declared, K. Parmar: None declared, B. Hunt: None declared