Emicizumab for hemophilia A without inhibitors.

Introduction: Hemophilia A (HA) is an inherited bleeding disorder that, if not properly treated, is associated with debilitating joint damage due to recurrent hemarthroses as well as life-threatening bleeds including intracranial hemorrhage. For decades, the only method to prevent bleeding events was to infuse factor (F) VIII concentrates intravenously two to three times weekly. Although successful in reducing bleeding frequency, preventing a high proportion of joint disease, and extending life expectancy, standard continuous prophylaxis with FVIII is burdensome and insufficiently effective at preventing long-term joint dysfunction in some patients. In October 2018, the Federal Drug Administration approved a novel agent, emicizumab-kxwh, for the treatment of patients with HA without inhibitors. Areas covered: In this article, the preclinical and clinical development of emicizumab-kxwh will be reviewed. Data from licensure phase 3 clinical trials will be reviewed in detail discussing issues of both safety and efficacy. Expert opinion: As emicizumab-kxwh leads the way of a shift in treatment paradigm for patients with HA without inhibitors, a number of questions remain, including the impact of emicizumab-kxwh on joint and bone health, inhibitor development, and thrombotic risk. Ultimately, time and clinical investigation will be able to elucidate the influence of emicizumab-kxwh in these areas.

Terapia anticoagulante nas valvopatias / Anticoagulant therapy in valvulopathies

As valvopatias, especialmente na presença da fibrilação atrial (FA), aumentam o risco de eventos tromboembólicos que, além de modificar a história natural da doença, têm impacto significativo na sobrevida e na qualidade de vida dos pacientes. Além do envelhecimento da população mundial, com o consequente número crescente de pacientes com fibrilação atrial, há cada vez mais associações de valvopatias com a doença arterial coronariana (DAC). Nesse grupo de pacientes para os quais há indicação emergencial ou eletiva de intervenção coronariana percutânea (ICP) com implante de stents, serão prescritos antiplaquetários e anticoagulantes ao menos nos primeiros meses pós-ICP. A prevenção do tromboembolismo (TE) com anticoagulantes, como a varfarina ou com os anticoagulantes orais diretos (AOD), é recomendada na maioria das diretrizes. O emprego dos escores CHADS2-VASc e HAS-BLED são úteis para a quantificação dos riscos TE e hemorrágicos

Valvulopathies, especially in the presence of atrial fibrillation (AF), increase the risk of thromboembolic events, which in addition to modifying the natural history of the disease; have a significant impact on survival and quality of life of patients. In addition to the aging of the world's population, with a consequent increase in the number of patients with atrial fibrillation, there are increasing cases of associations of valvular diseases with coronary artery disease (CAD). In this group of patients, in whom there is an emergency or elective indication for percutaneous coronary intervention (PCI) with the implantation of stents, antiplatelet and anticoagulant therapies will be prescribed, at least in the first months after PCI. The prevention of thromboembolic events (TE) with anticoagulants, such as warfarin, or with direct oral anticoagulants (DAOCs), is recommended in most of the Guidelines. The use of the CHADS2-VASc and HAS-BLED scores are useful in the quantification of TE and hemorrhagic risks

Baby hamster kidney cell-derived recombinant factor VIII: a quarter century of learning and clinical experience.

INTRODUCTION: Management and care of individuals with hemophilia A advanced immensely with the introduction of recombinant factor VIII (rFVIII) replacement products. This review provides a historical overview of rFVIII development with a focus on Bayer's rFVIII (with albumin) and sucrose-formulated rFVIII (rFVIII-FS), the only rFVIII products cloned in baby hamster kidney (BHK) cells with >25 years of proven safety and efficacy. Areas covered: We review the advances in rFVIII technology and the efficacy and safety data for BHK-derived rFVIII/rFVIII-FS from clinical trials, investigator-initiated studies, and observational studies. Innovative products with new treatment potentials (eg, BAY 81-8973 and BAY 94-9027) built on this established safety and efficacy profile are also briefly discussed. The literature search strategy included targeted searches (PubMed) with manual article selection and other product-specific searches. Expert commentary: Development of rFVIII products and related improvements in viral safety and manufacturing efficiency have guaranteed an adequate supply of factor products worldwide and increased prophylaxis use. The net effects have been joint health preservation, reduction in morbidity and mortality, and quality-of-life enhancements. Current treatment challenges include lack of adherence to prophylaxis and inhibitor development; extended-half-life rFVIII products and non-FVIII replacement therapies in development may help overcome these challenges.

Pearls and pitfalls in factor inhibitor assays.

The proper performance and interpretation of factor inhibitor assays is a critical role for the hemostasis laboratory. Both false-positive and false-negative inhibitor assays may be reported, leading to serious patient mismanagement. Knowledge and recognition of common causes of both false-positive and negative-results can aid in the identification of these potential pitfalls. Safeguards to reporting accurate factor inhibitor assays include initial characterization of the sample, using the Nijmegen modification, properly performing and interpreting an incubated mixing test in conjunction, and performing two dilutions for each dependent dilution in the factor inhibitor assay.

Continuous infusion in haemophilia: current practice in Europe.

Summary. Continuous infusion (CI) of factor VIII (FVIII) is an effective method for replacement therapy in haemophilia. Recently, concerns have been raised regarding association of CI with the development of inhibitors. The aim of this study was to gain information on the current practices in Europe regarding CI and the true inhibitor incidence after this mode of therapy. In a cross sectional study performed in 22 Comprehensive Care Centres (CCCs), we evaluated CI techniques, treatment protocols, efficacy, safety and complications of CI including inhibitors. Thirteen (59%) CCCs reported a total of 1079 CI treatments, given peri-operatively or for major bleeds, in 742 patients. Most centres used 'adjusted dose' CI aimed at median target FVIII level of 0.8 IU mL(-1). CI was haemostatically very effective with a low incidence of complications: median incidence of postoperative bleeding was 1.8%, six centres observed phlebitis in 2-11% of CI treatments. Only nine (1.2%) patients developed inhibitors (0.45% of 659 severe and 7.2% of 83 mild haemophilia patients). Additional analysis of inhibitor patients revealed several confounding factors (low number of prior FVIII exposure days, high steady-state factor levels during CI, high-risk genotype). In this unprecedentedly large cohort, CI treatment appears to be an effective and safe treatment that does not increase the risk of inhibitor development in patients with severe haemophilia. Thus, previous small case series reports suggesting that CI may increase inhibitors cannot be confirmed. Inhibitor risk in mild haemophilia could not be evaluated as the influence of other, potentially confounding, risk factors could not be excluded.

Experience of four UK comprehensive care centres using FEIBA® for surgeries in patients with inhibitors.

Increasing evidence indicates that factor VIII (FVIII) inhibitor bypassing agents (FEIBA® and NovoSeven®) can provide effective peri-operative haemostasis in haemophilia patients with high-responding inhibitors. We report the collected experience of all major and minor surgeries, conducted between December 1998 and September 2008, at four UK haemophilia Comprehensive Care Centres with FEIBA® as the first-line bypassing agent in patients with inhibitors. A total of 26 surgical procedures were performed in 18 patients of ages 34-83 years including five patients with acquired FVIII inhibitors. A single pre-operative infusion of FEIBA was followed by 6-12 h interval dosing for major surgeries at the discretion of the physician to approximate a maximum of 200 U kg(-1) day(-1), with tapering when postoperative haemostasis and wound healing permitted. Haemostatic outcomes were retrospectively reviewed against European consensus thresholds for blood loss and duration of treatment compared with expectations for equivalent procedures in non-inhibitor patients. Peri-operative haemostatic outcome with FEIBA was rated excellent or good in 78% of 18 major surgeries in 12 patients, including 11 major orthopaedic procedures. Haemostatic outcome was rated excellent in all seven procedures in five patients with acquired FVIII inhibitors and in all eight minor surgical procedures in six patients. FEIBA was well tolerated with no intra-operative haemostatic complications. A single, transient postoperative thrombotic adverse event occurred in a patient with cerebrovascular disease. This case series adds significantly to existing evidence that FEIBA can provide adequate, well-tolerated, peri-operative haemostatic cover for a wide variety of major and minor surgical procedures.

Association of genetic variations with nonfatal venous thrombosis in postmenopausal women.

CONTEXT: Although the roles of clotting proteins and enzymes that activate or inhibit fibrin production and lysis are well characterized, the underlying contribution of genetic variation in these constituents to risk of venous thrombosis (VT) has not been fully investigated. OBJECTIVE: To describe the association of common genetic variation in 24 coagulation, anticoagulation, fibrinolysis, and antifibrinolysis candidate genes with risk of incident nonfatal VT in postmenopausal women. DESIGN, SETTING, AND PARTICIPANTS: Population-based case-control study conducted in a large integrated health care system in Washington State. Participants were perimenopausal and postmenopausal women aged 30 to 89 years who sustained a first VT event between January 1995 and December 2002 (n = 349) and 1680 controls matched on age, hypertension status, and calendar year (n = 1680). MAIN OUTCOME MEASURE: Risk of venous thrombosis associated with global variation within a gene as measured by common haplotypes and with individual haplotypes and single nucleotide polymorphisms (SNPs). Significance of the associations was assessed by a .20 threshold of the false-discovery rate q value, which accounts for multiple testing. RESULTS: Only the tissue factor pathway inhibitor gene demonstrated global association with risk (q = .13). Five significant SNP associations were identified across 3 of the candidate genes (factors V, XI, and protein C) in SNP analyses. Two associations have been previously reported. Another 22 variants across 15 genes had P values less than .05 but q values between .20 and .35. Five of these confirm previously reported associations (fibrinogen genes and protein C), 2 were inconsistent with earlier reports (thrombomodulin and plasminogen activator inhibitor 1), and 15 were new discoveries. CONCLUSIONS: After accounting for multiple testing, 5 SNPs associated with VT risk were identified, 3 of which have not been previously reported. Replication of these novel associations in other populations is necessary to corroborate these findings and identify which genetic factors may influence VT risk in postmenopausal women.

Design, synthesis and biological activity of selective and orally available TF/FVIIa complex inhibitors containing non-amidine P1 ligands.

We found the novel selective and orally available non-amidine TF/FVIIa complex inhibitor 21e, 4-({[(1S)-(aminocarbonyl)-3-methylbutyl]amino}carbonyl)-2'-({[4- (aminomethyl)phenyl]amino}carbonyl)-4'-(methylamino)biphenyl-2- carboxylic acid. The derivatives were synthesized by conversions of the isobutyl moiety and the introduction of alkylamino groups to 4'-position of the central phenyl ring of compounds 2a and 2b reported previously. Some compounds show increased in vitro anti-TF/FVIIa and PT prolongation activities. Among them, compound 21e reached and sustained micromolar plasma concentration levels of up to 2h after oral administration in mice. Moreover, compound 21e did not prolong the bleeding time even at the highest dose level in cynomolgus monkeys, while PT was prolonged 3.7-fold increases at this dose.

Current European practice in immune tolerance induction therapy in patients with haemophilia and inhibitors.

The management of patients with inhibitors is an important challenge in haemophilia care. The lack of randomized controlled trials means that clinical decisions are generally based on subjective opinions, and purchasers' attention is likely to focus on the costs of treatment. In order to assess the current management of inhibitor patients and use of immune tolerance induction therapy (ITI) in Europe, we performed a survey within a European network of 21 comprehensive care centres from 14 countries (the European Haemophilia Therapy Standardisation Board). The survey identified a total of 381 patients with inhibitors attending the centres, 211 (55.4%) of whom had never been exposed to ITI. Between 1998 and 2003, the centres performed 233 procedures and 114 (48.9%) were successful. The survey demonstrated that dosing, which is the time to start and stop the ITI, the type of concentrate to use and the definition of success varied among the centres. Well-designed trials are warranted to guide decision-making, but in the absence of these studies we have developed consensus guidance for the management of inhibitor patients based on current clinical practice, as identified by the survey, and review of the literature.

Dose-dependent antithrombotic activity of an orally active tissue factor/factor VIIa inhibitor without concomitant enhancement of bleeding propensity.

The discovery of a highly potent and selective tissue factor/factor VIIa inhibitor is described. Upon oral administration of its double prodrug in the guinea pig, a dose-dependent antithrombotic effect is observed in an established model of arterial thrombosis without prolonging bleeding time. The pharmacodynamic properties of this selective inhibitor are compared to the behaviour of a mixed factor VIIa/factor Xa inhibitor.

Discovery and pre-clinical development of antithrombotics from hematophagous invertebrates.

Bloodfeeding (hematophagous) parasites have evolved effective means of inhibiting mammalian thrombosis, thereby facilitating the acquisition and digestion of a bloodmeal. To date, specific inhibitors of coagulation and platelet function have been identified from numerous invertebrate species, representing an impressive array of convergent functional strategies. These parasite antithrombotics, in addition to playing a critical role in the diseases caused or transmitted by bloodfeeding invertebrates, may also serve as potentially useful therapeutic agents for the treatment of a variety of conditions associated with activation of thrombosis. A number of naturally occurring anticoagulants and platelet inhibitors have been evaluated in vivo, with some currently in varying stages of preclinical and clinical development. Because of the unique specificity and potency of parasite antithrombotics, these invertebrate natural products hold great promise for improving the treatment of a variety of human illnesses, including heart disease, stroke, and cancer.

Acquired protein S deficiency caused by estrogen treatment of tall stature.

OBJECTIVE: To evaluate the potential thrombogenic changes in the coagulation and fibrinolytic system related to treatment with ethinyl estradiol (200 and 300 microg). SUBJECTS AND METHODS: Twenty-five healthy girls with expected final height exceeding 185 cm, as calculated by the method of Bayley and Pinneau, were treated with 200 microg or 300 microg of ethinyl estradiol. Coagulation and fibrinolytic parameters were determined before and during estrogen treatment and 2 and 4 weeks after estrogen withdrawal. RESULTS: No difference in the effects on hemostasis was found between the 2 treatment groups. All 25 patients developed protein S deficiency during estrogen treatment, which in most girls lasted for 4 weeks after cessation of estrogen administration. During therapy, protein C activity increased, whereas antithrombin did not change. Plasminogen and plasmin-alpha(2) antiplasmin complexes significantly increased. Protein S deficiency was accompanied by significantly increased prothrombin fragment 1+2 and fibrinopeptide A. In contrast, thrombin-antithrombin complexes did not change. CONCLUSION: High-dose estrogen treatment to reduce the final height in tall girls is associated with a reversible acquired protein S deficiency with indications of a pre-thrombotic state. Risk of venous thrombo-embolism may be enhanced, especially when additional risk factors for thrombosis are present.