scholarly journals MAA868, a novel FXI antibody with a unique binding mode, shows durable effects on markers of anticoagulation in humans

Blood ◽  
2019 ◽  
Vol 133 (13) ◽  
pp. 1507-1516 ◽  
Author(s):  
Alexander W. Koch ◽  
Nikolaus Schiering ◽  
Samu Melkko ◽  
Stefan Ewert ◽  
Janeen Salter ◽  
...  

Abstract A large unmet medical need exists for safer antithrombotic drugs because all currently approved anticoagulant agents interfere with hemostasis, leading to an increased risk of bleeding. Genetic and pharmacologic evidence in humans and animals suggests that reducing factor XI (FXI) levels has the potential to effectively prevent and treat thrombosis with a minimal risk of bleeding. We generated a fully human antibody (MAA868) that binds the catalytic domain of both FXI (zymogen) and activated FXI. Our structural studies show that MAA868 traps FXI and activated FXI in an inactive, zymogen-like conformation, explaining its equally high binding affinity for both forms of the enzyme. This binding mode allows the enzyme to be neutralized before entering the coagulation process, revealing a particularly attractive anticoagulant profile of the antibody. MAA868 exhibited favorable anticoagulant activity in mice with a dose-dependent protection from carotid occlusion in a ferric chloride–induced thrombosis model. MAA868 also caused robust and sustained anticoagulant activity in cynomolgus monkeys as assessed by activated partial thromboplastin time without any evidence of bleeding. Based on these preclinical findings, we conducted a first-in-human study in healthy subjects and showed that single subcutaneous doses of MAA868 were safe and well tolerated. MAA868 resulted in dose- and time-dependent robust and sustained prolongation of activated partial thromboplastin time and FXI suppression for up to 4 weeks or longer, supporting further clinical investigation as a potential once-monthly subcutaneous anticoagulant therapy.

Author(s):  
Rania Khogli ELsidig Khogli ◽  
Abdel Rahim Mahmoud Muddathir ◽  
Alaa Eltayeb Omer ◽  
Lienda Bashier Eltayeb

Background: Repeated miscarriage can cause tissue injury can lead to the formation of antibodies to the phospholipids. Recurrent miscarriage (RM) is considering the one of the most common cause of sterility. Which has received more attention in recent years as a result of an increase in the number of reproductive-aged women. Materials and Methods: Plasma samples were tested for antiphospholipid antibodies using ELISA, and platelet count using Sysmex (KX21) Heamatology analyzer and Activated Partial Thromboplastin Time using semi-automated machine (STAGO PT31039352 (for coagulation). Results: The prevalence of Anti phospholipid antibodies (APL) was 30.5% in Sudanese patients with recurrent miscarriage, the prevalence of (Anti phospholipid Antibodies-IgM and IgG) was found to be 23.6% in patients with recurrent miscarriage compared to (Anti phospholipid Antibodies-IgG) was found to be 11.1% ((P value≤0.001), low platelets count (<50×109/l) observed in 10 (13.5%), as well as prolongation of activated partial thromboplastin time (APTT) among studied group were detected among 19 (26.1%). Conclusion: Higher prevalence of antiphospolidids antibodies, and acquired thrombophilia was detected among Sudanese women with recurrent abortion; The findings are concerning because they link an increased risk of thrombosis and a hypercoagulable state lead to recurrent miscarriage in pregnant women.


Author(s):  
Mouleeswaran Sundaram ◽  
Sonia Bansal ◽  
Rohini M. Surve

AbstractFactor XII deficiency is a rare disorder that can complicate the perioperative management of a patient. Factor XII plays an important role in the activation of intrinsic pathway of coagulation; the deficiency, therefore, results in prolongation of activated partial thromboplastin time (aPTT). This aPTT prolongation is expected to cause increased bleeding during surgery. However, on the contrary, in vivo isolated factor XII deficiency is associated with increased risk of thromboembolism (this risk being higher than the risk of bleeding). We report the perioperative management of a patient with factor XII deficiency who underwent cervical vertebral fusion (C1–C2) for atlantoaxial dislocation.


Blood ◽  
1988 ◽  
Vol 72 (2) ◽  
pp. 512-519 ◽  
Author(s):  
RA Fleck ◽  
SI Rapaport ◽  
LV Rao

Abstract The investigators have evaluated the frequency and manifestations of anti-prothrombin antibodies in patients with the lupus anticoagulant. Thirty-one of 42 patients with lupus anticoagulants associated with a variety of underlying conditions (74%) had evidence on crossed immunoelectrophoresis of anti-prothrombin antibodies. Twenty-four of 25 patients with an activated partial thromboplastin time exceeding 50 seconds and 14 of 15 patients with a prothrombin time exceeding control by more than two seconds had demonstrable anti-prothrombin antibodies. Three of the 31 patients with anti-prothrombin antibodies had essentially no measurable plasma prothrombin, a presumed result of accelerated clearance of prothrombin/prothrombin antibody complexes. Each of these patients had bled abnormally. The remaining patients with anti-prothrombin antibodies had neither substantial hypoprothrombinemia nor hemorrhagic manifestations, which confirms the non-neutralizing property of anti-prothrombin antibodies associated with the lupus anticoagulant. Since lupus anticoagulant immunoglobulins are known to react with phospholipids, the high prevalence of antibodies binding prothrombin led us to test the hypothesis of antibody polyreactivity. Adsorption of three lupus anticoagulant plasmas with insolubilized prothrombin markedly diminished evidence of both prothrombin/prothrombin antibody complexes and anticoagulant activity. Eluates of the insolubilized prothrombin contained IgG that not only bound prothrombin but possessed lupus anticoagulant activity.


Author(s):  
М.С. Успенская ◽  
М.Г. Ляпина ◽  
М.Д. Калугина

Введение. Актуальность темы исследования обусловлена проблемой борьбы с тромбозами и тромбоэмболиями безопасными для организма методами. Во многих растениях обнаружены антикоагулянты разной природы (гепариноподобные, пептиды). Цель исследования - изучение возможности проявления синергических эффектов на антикоагулянтную и фибринолитическую активность крови и процессы полимеризации фибрина экстракта из корней пиона «Иван Горожанкин» в сравнительном аспекте с действием экстракта из корней пиона «молочноцветковый». Методика. Объектом исследования служили корни пионов «Иван Горожанкин» и «молочноцветковый», произрастающих в Ботаническом саду МГУ. Пион «Иван Горожанкин» был создан скрещиванием пиона «молочноцветкового» и «лекарственного» Разработаны методы получения экстрактов из корней различных пионов. При различных разведениях экстрактов (0.1, 1, 5%) определены антикоагулянтная активность по тестам, характеризующим внутренний, внешний и общий пути свертывания крови, а также степень полимеризации фибрина плазмы крови крыс. Для сравнения был использован стандартный препарат низкомолекулярного гепарина (LMWH) животного происхождения фирмы «Celsus» (США). Проведены выделение и очистка активного начала (гепариноидов) из сухих препаратов и измерены их активности. Pезультаты. Показано, что экстракты из обоих препаратов пионов обладали антикоагулянтной и суммарной фибринолитической активностью на нестабилизированном фибрине, но в разной степени. В экстрактах из корней пиона «Иван Горожанкин» отмечались преимущественные синергические эффекты, а именно превышение антикоагулянтной активности на 20-30%, суммарной фибринолитической - на 18% по сравнению с таковыми, отмечаемыми в экстрактах из корней пиона «молочноцветковый». Подобные результаты выявлены и при изучении степени полимеризации фибрина под влиянием очищенных препаратов из пионов. Рассмотрены возможные механизмы активирующего действия экстракта из пиона «Иван Горожанкин» на антикоагулянтные свойства плазмы, суммарную фибринолитическую активность и степень полимеризации фибрина. Это связано с блокадой активности тромбина и факторов внутреннего механизма свертывания крови. При этом антикоагулянтный эффект от применения экстракта из пиона «Иван Горожанкин» по тесту APTT (activated partial thromboplastin time) превышал на 20-30% ту же активность, выявленную у пиона «молочноцветковый», которая соответствовала антикоагулянтной активности препарата сравнения LMWH. В экстракте из пиона «Иван Горожанкин» впервые обнаружено наличие антикоагулянтного гепариноподобного вещества. Заключение. Впервые установлена способность экстракта из корней пиона «Иван Горожанкин» проявлять синергические антикоагулянтные и фибриндеполимеризационные эффекты, превышающие таковые у экстракта из пиона «молочноветковый». На основе полученных данных возникает необходимость исследования пиона «Иван Горожанкин» в качестве антитромботического, а возможно, и антиатеросклеротического агента. Introduction. The research topic is relevant due to the problem of safely combating thrombosis and thromboembolism. Anticoagulants of various kinds, e.g., heparin-like and peptides, have been found in many plants. Aim. To investigate the possibility of synergistic effects on the blood anticoagulant and fibrinolytic activity and on processes of fibrin polymerization by an extract from the roots of the «Ivan Gorozhankin» peony compared with the root extract from «Paeonia lactiflora». Methods. The focus of the study was the roots of the “Ivan Gorozhankin” peony and the Paeonia lactiflora growing in the Botanical Garden of the Moscow State University. The “Ivan Gorozhankin” peony was created by crossing P. lactiflora and the “medicinal” peony. Methods for obtaining extracts from the roots of various peonies have been developed. In 1%, 3%, and 5% dilutions of the extracts, the anticoagulant activity was determined according to tests characterizing the internal, external and general blood coagulation pathways, as well as by the degree of polymerization of rat blood plasma fibrin. For comparison, we used a standard preparation of low molecular weight heparin (LMWH) of animal origin (Celsus, USA). Isolation and purification of the active substances, heparinoids, were isolated from dry preparations and purified, and their activities were measured. Results. Extracts from both peony preparations had anticoagulant and total fibrinolytic activity on unstabilized fibrin, but to different extents. In the extracts from the roots of the “Ivan Gorozhankin” peony, preferential synergistic effects were noted, namely, the anticoagulant activity was higher by 20-30%, and the total fibrinolytic activity was higher by 18% compared to those of extracts from Paeonia lactiflora roots. Similar results were obtained when studying the degree of fibrin polymerization as influenced by purified peony preparations. Possible mechanisms of the activating action of the «Ivan Gorozhankin» peony extract on the anticoagulant properties of plasma, the total fibrinolytic activity, and the degree of fibrin polymerization are considered. This action is due to the inhibition of thrombin activity and factors of the internal mechanism of blood coagulation. According to the activated partial thromboplastin time (APTT) test, the anticoagulant effect of extracts from the «Ivan Gorozhankin» peony exceeded by 20-30% the activity of Paeonia lactiflora extract, which corresponded to the anticoagulant activity of the LMWH comparator drug. Using the described biochemical methods, the presence of an anticoagulant heparin-like substance in an extract from the peony «Ivan Gorozhankin» has been discovered. Conclusion. For the first time, the ability of an extract from the roots of the «Ivan Gorozhankin» peony to exhibit synergistic anticoagulant and fibrin-depolymerization effects was demonstrated. These effects exceeded those of the Paeonia lactiflora extract. Based on these data, it appears necessary to study the «Ivan Gorozhankin» peony as an antithrombotic, and possibly as an anti-atherosclerotic agent.


2014 ◽  
Vol 121 (5) ◽  
pp. 969-977 ◽  
Author(s):  
Niels Rahe-Meyer ◽  
Hein Fennema ◽  
Sam Schulman ◽  
Walter Klimscha ◽  
Michael Przemeck ◽  
...  

Abstract Background: Previous studies show a prolongation of activated partial thromboplastin time and prothrombin time in healthy volunteers after treatment with sugammadex. The authors investigated the effect of sugammadex on postsurgical bleeding and coagulation variables. Methods: This randomized, double-blind trial enrolled patients receiving thromboprophylaxis and undergoing hip or knee joint replacement or hip fracture surgery. Patients received sugammadex 4 mg/kg or usual care (neostigmine or spontaneous recovery) for reversal of rocuronium- or vecuronium-induced neuromuscular blockade. The Cochran–Mantel–Haenszel method, stratified by thromboprophylaxis and renal status, was used to estimate relative risk and 95% confidence interval (CI) of bleeding events with sugammadex versus usual care. Safety was further evaluated by prespecified endpoints and adverse event reporting. Results: Of 1,198 patients randomized, 1,184 were treated (sugammadex n = 596, usual care n = 588). Bleeding events within 24 h (classified by an independent, blinded Adjudication Committee) were reported in 17 (2.9%) sugammadex and 24 (4.1%) usual care patients (relative risk [95% CI], 0.70 [0.38 to 1.29]). Compared with usual care, increases of 5.5% in activated partial thromboplastin time (P &lt; 0.001) and 3.0% in prothrombin time (P &lt; 0.001) from baseline with sugammadex occurred 10 min after administration and resolved within 60 min. There were no significant differences between sugammadex and usual care for other blood loss measures (transfusion, 24-h drain volume, drop in hemoglobin, and anemia), or risk of venous thromboembolism, and no cases of anaphylaxis. Conclusion: Sugammadex produced limited, transient (&lt;1 h) increases in activated partial thromboplastin time and prothrombin time but was not associated with increased risk of bleeding versus usual care.


Blood ◽  
1988 ◽  
Vol 72 (2) ◽  
pp. 512-519
Author(s):  
RA Fleck ◽  
SI Rapaport ◽  
LV Rao

The investigators have evaluated the frequency and manifestations of anti-prothrombin antibodies in patients with the lupus anticoagulant. Thirty-one of 42 patients with lupus anticoagulants associated with a variety of underlying conditions (74%) had evidence on crossed immunoelectrophoresis of anti-prothrombin antibodies. Twenty-four of 25 patients with an activated partial thromboplastin time exceeding 50 seconds and 14 of 15 patients with a prothrombin time exceeding control by more than two seconds had demonstrable anti-prothrombin antibodies. Three of the 31 patients with anti-prothrombin antibodies had essentially no measurable plasma prothrombin, a presumed result of accelerated clearance of prothrombin/prothrombin antibody complexes. Each of these patients had bled abnormally. The remaining patients with anti-prothrombin antibodies had neither substantial hypoprothrombinemia nor hemorrhagic manifestations, which confirms the non-neutralizing property of anti-prothrombin antibodies associated with the lupus anticoagulant. Since lupus anticoagulant immunoglobulins are known to react with phospholipids, the high prevalence of antibodies binding prothrombin led us to test the hypothesis of antibody polyreactivity. Adsorption of three lupus anticoagulant plasmas with insolubilized prothrombin markedly diminished evidence of both prothrombin/prothrombin antibody complexes and anticoagulant activity. Eluates of the insolubilized prothrombin contained IgG that not only bound prothrombin but possessed lupus anticoagulant activity.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2255-2255 ◽  
Author(s):  
Husam Younis ◽  
Jeff R. Crosby ◽  
Chenguang Zhao ◽  
Robert MacLeod ◽  
Brett P. Monia ◽  
...  

Abstract Abstract 2255 Complications associated with increased bleeding risk are the main limitations with current anticoagulant therapy. Inhibition of factor XI (FXI), a component of the intrinsic coagulation pathway, has received considerable interest because of the potential to produce sufficient anticoagulant activity without bleeding. The objective of these studies were to characterize the efficacy and safety of ISIS-FXrx and to assess the bleeding risk associated with FXI depletion under experimental surgical settings in cynomolgus monkeys. ISIS-FXIRx was selected from a series of 2nd-generation (2'-O-methoxyethyl) antisense oligonucleotides (ASOs) targeted to FXI which were evaluated for both tolerability and efficacy in cynomolgus monkeys (25 mg/kg twice per week for 13 weeks, SC). ISIS-FXIRx emerged as the most efficacious among the FXI ASOs evaluated, producing marked reductions of FXI RNA in liver, and FXI protein and activity levelsin plasma with a good tolerability profile. A more extensive dose-response evaluation of ISIS-FXrx (4,8,12 and 40 mg/kg/wk, SC) was conducted over a 13-week treatment period in cynomolgus monkeys to further assess tolerability and activity. ISIS-FXIRx produced a dose-dependent reduction in plasma FXI activity (>80% at 4 weeks of treatment at 40 mg/kg) with a concomitant increase in aPTT (33%). No effects on PT, platelets and no evidence of bleeding were observed after 13 weeks of treatment with ISIS-FXrx. ASO treatment was well tolerated at all doses tested and only produced changes typical for this chemical class of ASOs (e.g., basophilic granules in multiple tissues due do drug accumulation). ISIS-FXIRx (20 mg/kg, SC for 6 weeks) was also evaluated for bleeding risk in two experimental surgical models in cynomolgus monkeys; a tail amputation model and gum laceration model. Enoxaparin (2 mg/kg), known to increase the risk of bleeding, produced a statistically significant (p<0.05) increase in bleeding time and blood volume loss compared to saline control animals in both the tail amputation and the gum laceration models. Animals treated with ISIS-FXIRx displayed no increase in bleeding parameters compared to control animals. These results further support the conclusion that targeting FXI is an effective and safe strategy for development of novel antithrombotic agents with minimal increase in bleeding risk. ISIS-FXIRx is currently under evaluation in Phase 1 studies. Disclosures: Younis: Isis Pharmaceuticals, Inc.: Employment. Crosby:Isis Pharmaceuticals: Employment. Zhao:Isis Pharmaceuticals: Employment. MacLeod:Isis Pharmaceuticals: Employment. Monia:Isis Pharmaceuticals: Employment. Henry:Isis Pharmaceuticals, Inc.: Employment.


2007 ◽  
Vol 13 (2) ◽  
pp. 137-145 ◽  
Author(s):  
Walter P. Jeske ◽  
Meredith K. McDonald ◽  
Debra A. Hoppensteadt ◽  
Elaine C. Bau ◽  
Aline Mendes ◽  
...  

This study characterized heparin isolated from tuna skins. Glycosaminoglycans were isolated from tuna skin after digestion using anion exchange resin. Heparin was eluted from the resin by sodium chloride gradient and was further fractionated by acetone fractionation. Anticoagulant activity was determined using the activated partial thromboplastin time and Heptest assays. Potency was determined using amidolytic antifactor IIa and antifactor Xa assays. The presence of heparin in the extracted tuna skin glycosaminoglycans was confirmed using 13C-nuclear magnetic resonance. The activated partial thromboplastin time and Heptest clotting times were doubled at concentrations of about 4 and 1 µg/mL, respectively. The clotting time prolongation and antiprotease activity induced by tuna heparin was readily neutralized by 25 µg/mL protamine sulfate. These results demonstrate that biologically active heparin with properties similar to clinical grade heparin can be derived from tuna skin, a raw material with otherwise relatively little economic value.


e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Dilyana Paneva ◽  
Olya Stoilova ◽  
Nevena Manolova ◽  
Dobri Danchev ◽  
Zdravko Lazarov ◽  
...  

Abstract Copolymers of 2-acryloylamido-2-methylpropanesulfonic acid (AMPS) and acrylic acid (AA), as well as the corresponding homopolymers PAMPS and PAA, were studied in vitro on human pool plasma for their anticoagulant activity. The values of the haemostatic parameters - prothrombin time, activated partial thromboplastin time and thrombin time - depend on the composition and the concentration of the (co)polymers. Reptilase time remains unchanged on adding the (co)polymers. A broad concentration range from 16 μg/ml to 3 mg/ml was studied. The copolymers possess anticoagulant activity, which is higher at higher content of AMPS units. It was found that, at certain concentrations, the haemostatic parameters of PAMPS are close to that of heparin. PAA has the lowest anticoagulant activity.


1995 ◽  
Vol 6 (4) ◽  
pp. 1250-1255
Author(s):  
C L Davis ◽  
W L Chandler

The ability of prebiopsy coagulation assays to predict mild postbiopsy bleeding was evaluated in renal transplant patients undergoing renal allograft biopsy (N = 120). The coagulation assays studied included the bleeding time, prothrombin time, partial thromboplastin time, platelet count, and thromboelastograph (TEG). Coagulation results were defined as abnormal if they fell outside the established normal reference range. Bleeding was defined as a drop in the hematocrit equal to or more than 4 points 6 h after the procedure or ultrasound evidence of a new perirenal hematoma. Overall, 21% of patients showed evidence of mild bleeding. Of those who bled, 78% had normal results on all coagulation tests, indicating that most mild bleeding was not associated with coagulation abnormalities. Of the assays tested, only abnormal TEG:angle (P < 0.01) and TEG:k (P < 0.04) values were associated with an increased risk of bleeding. Bleeding times were not predictive of an increased risk of postbiopsy bleeding; five patients had abnormal bleeding times ranging from 10 to 20 min of whom only one bled. All prothrombin time, partial thromboplastin time, and platelet count abnormalities were mild (e.g., no prothrombin times longer than 15 s, no platelet counts below 129,000/microL); none of these assays predicted postbiopsy bleeding. Other clinical characteristics, including patient age, sex, serum creatinine, blood pressure (if less than 160/90 mm Hg), number of biopsy passes, or renal pathology, did not appear to influence bleeding after biopsy. It was concluded that most bleeding after transplant renal biopsy was not associated with coagulation abnormalities and that the TEG was the best assay for detecting mild coagulation abnormalities associated with an increased risk of bleeding.


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