A randomized trial of safety, pharmacokinetics and pharmacodynamics of concizumab in people with hemophilia A.

Essentials explorer™3 was a double-blinded, multiple-dose escalation trial of subcutaneous concizumab. A pharmacodynamic relationship for unbound TFPI and thrombin generation was confirmed. No serious adverse events and no anti-drug antibodies were observed. explorer™3 data support further clinical development of concizumab in people with hemophilia. SUMMARY: Background Concizumab is a humanized mAb targeting tissue factor pathway inhibitor (TFPI), leading to enhanced thrombin generation (TG) potential. explorer™3 (NCT02490787) was a phase 1b, double-blind, multiple-dose escalation trial of subcutaneous concizumab in people with severe hemophilia A without inhibitors. Objectives The primary objective was to evaluate safety. Assessments of pharmacokinetics, pharmacodynamics and subcutaneous concizumab immunogenicity were secondary objectives. Patients/Methods Adverse events (AEs), clinical assessments and bleeding episodes were recorded. Plasma concizumab levels and unbound TFPI levels were measured with ELISAs; residual TFPI activity was measured with a chromogenic assay. Standardized assays were used to assess TG, D-dimer and prothrombin fragment 1 + 2 (F1 + 2 ) levels. explorer™3 was completed after investigation of three dose cohorts (0.25, 0.5 and 0.8 mg kg-1 , once every 4 days) had been completed. Twenty-four patients received 12 doses of concizumab or placebo in a 3 : 1 randomization over a 42-day period. Results No serious AEs and no anti-drug antibodies were observed. Fifty-four mild and two moderate AEs were observed in 19 patients. Concizumab exposure increased with dose in a non-linear manner, confirming target-mediated drug disposition. D-dimer and F1 + 2 levels were increased mostly in the highest dose cohort, in line with previous observations. The level of unbound TFPI decreased in a dose-dependent manner, and was accompanied by a residual TFPI activity decrease and an increase in peak TG. Although the trial was not powered to evaluate efficacy, a trend towards lower bleeding rates was observed in patients in the highest dose cohort. Conclusion explorer™3 data support further clinical development of concizumab for use in people with hemophilia, with or without inhibitors.

International Society on Thrombosis and Haemostasis core curriculum project: core competencies in clinical thrombosis and hemostasis.

UNLABELLED: Essentials The priority of ISTH was to establish a global core curriculum in thrombosis and hemostasis. International survey to determine competencies required for clinical specialists was carried out in the field. Competency framework provides a reference point for mapping and developing regional curricula. Core curriculum informs and links to a variety of ISTH educational materials. SUMMARY: Background The International Society on Thrombosis and Haemostasis (ISTH) identified the need for an international core curriculum on thrombosis and hemostasis for its society members and the larger thrombosis and hemostasis community. Aims The current research sought consensus on the core competencies required by medical doctors who are ready to practise as independent clinical specialists in thrombosis and hemostasis with the aim of developing a core clinical curriculum for specialists in the field. Method A draft list of competencies was developed by the Working Group and formed the basis of an online survey. ISTH members and the larger thrombosis and hemostasis community were asked to rate the importance of each competency, on a Likert scale, for clinical specialists in thrombosis and hemostasis. Results There were a total of 644 responses to the online survey with broad geographical representation. There was general agreement on what level of competency would be required for clinical specialists in thrombosis and hemostasis at the specified level of training. Conclusions Using the survey to gain consensus on the level of competency required by clinical specialists in the field of thrombosis and hemostasis enabled the development of a core clinical curriculum that has been endorsed by the ISTH Council. The curriculum will offer a framework and international reference that will be used by the society, by national and regional organizations, and for further research.

Safety and pharmacokinetics of anti-TFPI antibody (concizumab) in healthy volunteers and patients with hemophilia: a randomized first human dose trial.

BACKGROUND: Prophylaxis with either intravenous (i.v.) factor VIII (FVIII) or FIX is the gold standard of care for patients with severe hemophilia. A monoclonal antibody (concizumab) targeting tissue factor pathway inhibitor (TFPI) that can be administered subcutaneously (s.c.) has the potential to alter current concepts of prophylaxis in hemophilia. OBJECTIVES: To evaluate the safety and describe the pharmacokinetics and pharmacodynamics of single-dose concizumab in healthy volunteers and patients with hemophilia A or B. METHODS: In this first human dose, phase 1, multicenter, randomized, double-blind, placebo-controlled trial escalating single i.v. (0.5-9000 µg kg(-1) ) or s.c. (50-3000 µg kg(-1) ) doses of concizumab were administered to healthy volunteers (n = 28) and hemophilia patients (n = 24). RESULTS: Concizumab had a favorable safety profile after single i.v. or s.c. administration. There were no serious adverse events and no anti-concizumab antibodies. No clinically relevant changes in platelets, prothrombin time, activated partial thromboplastin time, fibrinogen, or antithrombin were found. A dose-dependent procoagulant effect of concizumab was seen as increased levels of D-dimers and prothrombin fragment 1 + 2. Nonlinear pharmacokinetics of concizumab was observed due to target-mediated clearance. A maximum mean AUC0-∞ of 33 960 h µg mL(-1) and a maximum mean concentration of 247 µg mL(-1) was measured at the highest dose. CONCLUSIONS: Concizumab showed a favorable safety profile after i.v. or s.c. administration and nonlinear pharmacokinetics was observed due to target-mediated clearance. A concentration-dependent procoagulant effect of concizumab was observed, supporting further study into the potential use of s.c. concizumab for hemophilia treatment.

Thrombosis: a major contributor to global disease burden.

BACKGROUND: Thrombosis is the common pathology underlying ischemic heart disease, ischemic stroke, and venous thromboembolism (VTE). The Global Burden of Disease Study 2010 (GBD 2010) documented that ischemic heart disease and stroke collectively caused 1 in 4 deaths worldwide. GBD 2010 did not report data for VTE as a cause of death and disability. OBJECTIVE: To review the literature on the global burden of disease caused by VTE. APPROACH AND RESULTS: We performed a systematic review of the literature on the global disease burden because of VTE in low-, middle-, and high-income countries. Studies from Western Europe, North America, Australia, and Southern Latin America (Argentina) yielded consistent results with annual incidences ranging from 0.75 to 2.69 per 1000 individuals in the population. The incidence increased to between 2 and 7 per 1000 among those aged ≥70 years. Although the incidence is lower in individuals of Chinese and Korean ethnicity, their disease burden is not low because of population aging. VTE associated with hospitalization was the leading cause of disability-adjusted life-years lost in low- and middle-income countries, and second in high-income countries, responsible for more disability-adjusted life-years lost than nosocomial pneumonia, catheter-related blood stream infections, and adverse drug events. CONCLUSIONS: VTE causes a major burden of disease across low-, middle-, and high-income countries. More detailed data on the global burden of VTE should be obtained to inform policy and resource allocation in health systems and to evaluate whether improved use of preventive measures will reduce the burden.

Integration of genetic, clinical, and INR data to refine warfarin dosing.

Well-characterized genes that affect warfarin metabolism (cytochrome P450 (CYP) 2C9) and sensitivity (vitamin K epoxide reductase complex 1 (VKORC1)) explain one-third of the variability in therapeutic dose before the international normalized ratio (INR) is measured. To determine genotypic relevance after INR becomes available, we derived clinical and pharmacogenetic refinement algorithms on the basis of INR values (on day 4 or 5 of therapy), clinical factors, and genotype. After adjusting for INR, CYP2C9 and VKORC1 genotypes remained significant predictors (P < 0.001) of warfarin dose. The clinical algorithm had an R(2) of 48% (median absolute error (MAE): 7.0 mg/week) and the pharmacogenetic algorithm had an R(2) of 63% (MAE: 5.5 mg/week) in the derivation set (N = 969). In independent validation sets, the R(2) was 26-43% with the clinical algorithm and 42-58% when genotype was added (P = 0.002). After several days of therapy, a pharmacogenetic algorithm estimates the therapeutic warfarin dose more accurately than one using clinical factors and INR response alone.

Acquired bleeding disorders: the impact of health problems in the developing world.

Several acquired bleeding disorders in the developing world have impacts on health, including late vitamin K deficiency bleeding (VKDB) in infants, dengue haemorrhagic fever (DHF), and malaria. This paper describes their clinical manifestations, mechanisms involved, and treatment.

Survival analysis of patients with haemophilia at the International Haemophilia Training Centre, Bangkok, Thailand.

Haemophiliac treatment in less developed countries is limited to locally prepared fresh frozen plasma, cryoprecipitate, cryo-removed plasma and lyophilized products as replacement therapy. Factor concentrate is seldom used because of the high price. The present study reports the survival analysis of 164 patients comprising 138 haemophilia A and 26 haemophilia B cases from 134 families registered at the International Haemophilia Training Centre-Bangkok, Faculty of Medicine, Ramathibodi Hospital, Mahidol University from 1971 to 2000. The duration of follow-up ranged from 1 to 27 years and 8 months with a median of 9 years and 1 month. They received treatment on demand of bleedings, and 85 patients received additional home treatment for early bleedings. The proportion of death was 15.2%. The Kaplan-Meier survival curves revealed the median (95% CI) survival time of patients with severe and moderate degrees of 35 years and 6 months (21.4-49.7), and 38 years and 1 month (28.8-47.3), respectively. To compare the progressive achievement of haemophilia care services, the treatment period was divided into three decades: 1971-1980, 1981-1990 and 1991-2000. The patients with unaided proper walking increased from 62.8% in the first decade to 84.5% in the third decade. However, one-third of the patients developed one to four chronic haemarthrosis determined by clinical evaluation, especially patients with severe degree. Moreover, the estimated probability of a survival time beyond 13 years of age among patients with severe degree increased from 0.85 in the first decade to 0.94 and 1 in the second and third decades, respectively. Thus, established haemophilia care, even with limited resources, has significantly decreased the risk of death and increased the survival time among patients with haemophilia.

Nursing roles in orthopaedic joint correction in haemophiliac patients.

The roles of nurses in 16 orthopaedic joint corrections of 14 haemophilia A patients (eight severe, six moderate) are described. The patients' ages ranged from 10 to 37 years with a mean age of 17 years and 4 months. The nursing tasks could be divided into three stages. The first is preoperation, the nurse acting as care provider on a team of experts involved in planning the corrective surgery for the affected joints; and as a counsellor for preparing the patients and family members to cope with the challenging operation. The second is intraoperation, the nurse having the role of care provider, giving factor concentrate either by bolus injection (seven episodes) or continuous infusion (nine episodes). The third is postoperation, as a comprehensive care provider, giving cryoprecipitate and/or factor concentrate and monitoring bleeding doses, and as a trainer, teaching the patients how to dissolve blood components and self-venepuncture with aseptic technique. Home treatment for early bleeding was given for 11 episodes, while 6-month prophylaxis was given for five. The accomplishment of these different roles required good communication and nurturing skills, a well-adjusted personality and a warm and positive attitude. The successful performance of nursing roles allows the haemophiliac patients to have a near-normal quality of life.

Prevalence of the C677T methylenetetra- hydrofolate reductase mutation in Thai patients with deep vein thrombosis.

We investigated the prevalence of a genetic variation in the 5, 10-methylenetetrahydrofolate reductase (MTHFR) gene (C677T) using polymerase chain reaction techniques in a sample of 500 general Thai population and among 40 unselected Thai patients with an objectively confirmed history of deep vein thrombosis (DVT). The prevalence of the mutated homozygous and heterozygous C677T MTHFR genotype in the group of 500 healthy Thai population was 1.4 and 25.6%, respectively (allele frequency of 14.2%). Of the 40 patients studied, none were homozygotes and 15% were heterozygotes for the C677T MTHFR gene mutation (allele frequency of 7.5%). There was no significant difference in genotype frequency between patients and control groups (p = 0.09). Odds ratios for the probability of the C677T MTHFR gene mutation in the patient versus control group were 0.49 (95% CI 0. 21-1.12). These data indicated that the C677T MTHF gene mutation was not associated with DVT in the Thai population. The lower frequency of the C677T MTHFR gene mutation in our Thai population compared with reports from other studies suggests a wide heterogeneity in the 677T MTHFR genotype frequencies of the different ethnic populations even among Asians.

Prevalence of the G1691A mutation in the factor V gene (factor V Leiden) and the G20210A prothrombin gene mutation in the Thai population.

We investigated the prevalence of a genetic variation in the factor V gene (G1691A Leiden mutation) and the prothrombin gene (G20210A) using polymerase chain reaction techniques in samples from 500 normal Thai population and among 50 unselected Thai patients with an objectively confirmed history of deep venous thrombosis. The prevalence of factor V Leiden and the prothrombin G20210A gene mutation in a group of 500 healthy controls was 0.2% in both groups (allele frequency of 0.1%). Of the 50 adult patients studied, none was a carrier of factor V Leiden or the prothrombin G20210A gene mutation. Our findings confirm that the prevalence of factor V Leiden and prothrombin G20210A gene mutation is lower among Asians than Caucasians and that the distribution of factor V Leiden is similar to that of the prothrombin G20210A variant. The low prevalence of these two mutations can, at least in part, account for the lower frequency of deep venous thrombosis reported in the Thai population. Screening for factor V Leiden and prothrombin gene mutation is of limited benefit and may not be cost-effective in Thai patients with the first episode of deep venous thrombosis.

Etiology and incidence of thrombotic and hemorrhagic disorders in Thai patients with extreme thrombocytosis.

A retrospective study of 126 patients with extreme thrombocytosis (defined as a platelet count > or = 1,000 x 10(9)/L) was performed during a five-year period (June 1994-June 1999). The aim of this study was to determine the etiology and to evaluate the clinical consequences of extreme thrombocytosis. Seventy patients (55.5%) had reactive thrombocytosis (RT) with an age range of 43 +/- 2.2 years, 56 (44.5%) had chronic myeloproliferative disorders (MPD) with an age range of 53 +/- 2.4 years. Underlying causes of RT were malignancy (25/70 or 35.7%), infection (16/70 or 22.9%), postsplenectomized beta-thalassemia/Hb E (11/70 or 15.7%), inflammation (12/70 or 17.1%), iron deficiency anemia (6/70 or 8.6%). Duration post splenectomy in our beta-thalassemia/Hb E patients ranged from 4 months to 21 years, with a median of 10 years. Subtypes of our MPD cases were chronic myeloid leukemia (30/56 or 53.6%), essential thrombocytosis (18/56 or 32.1%), polycythemia vera (4/56 or 7.1%), agnogenic myeloid metaplasia (3/56 or 5.4%) and unclassified MPD (1/56 or 1.8%). Bleeding and thrombotic tendency were respectively noted in 7 (12.5%) and 2 (3.6%) of MPD patients. Two patients of the MPD group (3.6%) experienced both bleeding and thrombotic episodes. One patient (1.4%) of the RT group developed vasculitis-associated thrombosis. However, none of the patients in the RT group had bleeding complications. Extreme thrombocytosis was not a rare condition in a university hospital population, and bleeding and/or thrombotic complication was more common in the MPD group.

Controlling acute bleeding episodes with recombinant factor VIIa in haemophiliacs with inhibitor: continuous infusion and bolus injection.

The efficacy of recombinant activated factor VII (rFVIIa, NovoSeven) in five Haemophiliacs (four Haemophilia A, one Haemophilia B), with high inhibitors ranging from 70 to 1900 Bethesda units, was evaluated. The treatment regimen was divided into two groups: group I, continuous infusion of 16.5 microg h-1 kg-1 body weight (bw) after the initial bolus of 90 microg kg-1 bw in three episodes of severe bleeding and group II, bolus injection 80-150 microg kg-1 bw every 3 hours for a maximum of four doses in six haemarthroses. The bleeding was effectively controlled within 1 to 48 h in five of nine bleeding episodes. One patient in group I, who had active arterial bleeding requiring sutures, had an ineffective response and three patients in group II had partially effective responses because the rFVIIa was given after the onset of bleeding at 36, 44 and 72 h, respectively. The prothrombin time was shortened and the FVII:C levels were successfully achieved at approximately 10 U mL-1. The continuous infusion reduced the total dose of rFVIIa by 50%. Recurrent bleeding episodes were found in three patients; two occurred at the same site after ceasing rFVIIa for 51 h and while receiving rFVIIa at 144 h and one occurred at a new site after ceasing rFVIIa for 12 h. Our experience would suggest that rFVIIa is effective in controlling acute bleeding episodes in Haemophiliacs with high inhibitors either by continuous infusion or bolus injection.

Use of plasma exchange in hereditary deficiency of factor V and factor VIII.

Combined hereditary deficiency of coagulation factors V and VIII is a very rare bleeding disorder. The severity of bleeding is determined by the level of these factors, although in general, this is less striking than the severe deficiency of either factor alone. We describe in this article a patient with this congenital defect, and the preoperative management for major surgery.

Effects of recombinant human thrombopoietin on megakaryocyte colony formation and megakaryocyte ploidy by human CD34+ cells in a serum-free system.

In serum-free cultures of human CD34 cells, recombinant human thrombopoietin (TPO) induced megakaryocyte colony formation a dose-dependent fashion that was further enhanced by the presence of interleukin-3 (IL-3) and stem cell factor (SCF), but not by IL-6, IL-11 or erythropoietin. TPO gave rise to much smaller colonies and at an earlier time than IL_3, indicating that TPO affects predominantly more mature megakaryocytic progenitors. In liquid cultures. TPO increased the percentage and the absolute number of > or = 8N megakaryocytes, but it did not shift their modal ploidy from 2N. TPO-induced endomitosis was totally inhibited by the presence of or previous exposure of cells to, IL-3 and /or SCF. The mechanism by which TPO overcomes in vivo the negative effects of IL-3 and SCF on megakaryocyte ploidy remains unknown.

Replication and endoreplication in developing megakaryocytes in vitro.

To study the relation in time between replication and endoreplication and the relation between appearance of platelet-specific proteins and endoreplication in maturing megakaryocytes, peripheral blood mononuclear cells highly enriched in hematopoietic progenitors were cultured in liquid cultures and plasma clots in the presence of either interleukin-3 (IL-3) and stem cell factor (SCF) or medium conditioned by blood mononuclear cells stimulated by phytohemagglutinin (PHA). In plasma clots, megakaryocytic (MK) colonies appeared first on day 5 and reached a maximum by day 8, whereas the number of cells per colony increased until day 10, indicating that there was a single wave of MK colony formation. In liquid cultures, the first immunologically recognizable megakaryocytes appeared on day 5 and expressed GPIIb/IIIa and thrombospondin only, but all other platelet-specific protein markers appeared within 24 hours. Replating cells from liquid medium into plasma clots showed that 92 +/- 8% of day 6 GPIIb/IIIa-positive cells are capable of replicating. Their replicative potential decreased with age, however, so that between days 6 and 11, a linear correlation was noted between the logarithm of the percentage of megakaryocytes with replicative capacity and their age in culture. Replication ceased completely after day 10. In the presence of IL-3, polyploid megakaryocytes appeared at the same time that GPIIb/IIIa was expressed, and the megakaryocyte distribution into ploidy classes remained unchanged until day 20. In the presence of PHA-leukocyte conditioned medium (PHA-LCM), ploidy of megakaryocytes was shifted toward higher classes after day 6, and the process of endoreplication was completed by day 10. No changes in ploidy distribution were noted between days 10 and 20. These findings indicate that in the cohort of megakaryocytes derived from colony-forming units-megakaryocyte (CFU-MK), endoreplication can occur at an early stage of development, proceeds synchronously with replication, and is completed before the megakaryocytes exhaust their replicative potential.

HIV infection after autologous bone marrow transplantation despite HIV-antibody and HIV-antigen screening.

We report a 41-year-old woman who underwent ABMT for non-Hodgkin's lymphoma during her third CR. Her post-transplant course was complicated by interstitial pneumonitis, hemorrhagic cystitis, cytopenia and episodes of infection from herpes zoster virus and Staphylococcus aureus. She required prolonged blood product support and was later found to be seropositive for anti-HIV on day +191 despite HIV-antibody and HIV-antigen screening of blood donors.

Experience with factor VIII: C inhibitors and acquired von Willebrand's disease in an adult at Ramathibodi Hospital.

Eleven cases of acquired inhibitors against factor VIII: C and von Willebrand's factor (vWF) seen at the Department of Medicine, Ramathibodi Hospital from 1979 to 1991 were reviewed. Factor VIII: C inhibitor was found in 6 of 36 patients (17%) with hemophilia A (median age 18 years). Three patients each were weak (titer < 10 Bethesda units/ml), and strong antibody producers. Two cases of weak antibody producers had spontaneous disappearance of inhibitor, while all 3 strong antibody producers required specific treatment (corticosteroids, immunosuppressive drugs, and plasmapheresis). The inhibitor level temporarily declined in 2 patients, and disappeared in one. Spontaneous acquired inhibitor to factor VIII: C was seen in 3 patients. One each respectively had pemphigus vulgaris and bullous pemphigoid, autoimmune disease, and NIDDM. They were characterized by older age (median age 54 years), frequent skin and soft-tissue hematoma, but less hemarthroses. Inhibitor titer ranged from 15-280 Bethesda units/ml. Disappearance of the inhibitor after treatment with corticosteroids and immunosuppressive drugs were observed in all patients. Acquired von Willebrand's disease developed in 2 previously healthy patients. One patient was in the postpartum period, while the other had simultaneous acute viral hepatitis A infection. Both presented with the recent onset of spontaneous severe gingival bleeding, and demonstrated a prolonged bleeding time, reduced vWF:Ag (F VIIIR:Ag), and ristocetin cofactor (F VIIIR:vWF). Treatment with cryoprecipitate and corticosteroid resulted in remission of bleeding symptoms. Despite the rarity of these disorders, the recognition and proper management are of importance.

Clinical features of acute lymphoblastic leukemia subclasses in 28 Thai children--a preliminary study.

Twenty-eight Thai children with newly diagnosed acute lymphoblastic leukemia were evaluated for pretreatment characteristic, including immunophenotype of lymphoblast, outcome of treatment, and the correlation among them. By APAAP technique using a panel of eight monoclonal antibodies (HLA-DR, CD 19, CALLA (CD 10), IgM, CD 7, CD 3, CD 4, and CD 8), five subclasses were identified: 67.9, 17.9, 7.1, 3.6, and 3.6 per cent were respectively shown to be common-, null-, mature thymocyte T-, pre B-, and B-ALLs. Clinical features in each subclass conformed to previous reports. All of the 27 evaluable patients attained initial complete remission, but subsequent relapses were noted in 7 patients (25.9%). Three of the 19 cases in the common ALL group relapsed at 6-12 months, whereas, 4 of the 8 cases in the non-common ALL group relapsed at 2-15 months. Probability of relapse at 12 months in the common and non-common ALL groups were 19 and 49 per cent respectively. Disease-free survival from time of remission was shorter in the non-common ALL group. Multivariate analysis of the 6 factors predicting disease-free survival showed that the only strong factor was the immunophenotype of lymphoblast.