Introduction
Congenital TTP (cTTP) is an ultra-rare disorder in which deficiency of a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) results in circulating ...ultra large Von Willebrand Factor (VWF) multimers and subsequent microthrombi formation. Regular prophylactic therapy aims to improve outcomes from long-term complications, but also ongoing symptoms, including lethargy, headaches and abdominal pain, despite normal blood counts. Existing methods of quantifying ADAMTS13 activity lack the sensitivity to enable their use for evaluating treatment response in patients with cTTP. We present a novel flow-based assay with the aim of assessing treatment response, novel therapeutic options and analyzing the impact of different mutations on disease severity.
Method
A VenaFlux semi-automated microfluidic system was used to provide shear flow to mimic in vivo flow rates. Using whole blood, we analyzed platelet adhesion, aggregation and thrombi formation on microchannels coated with type I collagen and mounted onto the stage of an inverted epifluorescence microscope. Fresh, citrated whole blood was treated with DiOC6 to achieve platelet fluorescence and a macro on Image-Pro Premier was designed for automated calculation of total surface coverage. Surface coverage represented increasing thrombus formation with total coverage by thrombus within 180 seconds quantified as 100% coverage.
Results were compared to a normal range developed using 43 normal controls (26=female, 17=male) with normal hemoglobin, platelet count and hematocrit. The surface coverage normal range was 6-39%.
cTTP samples were analyzed for complete blood count, ADAMTS13 activity, VWF antigen, VWF activity and percentage surface coverage. Samples were taken 30 minutes before and after prophylactic treatment, either plasma infusion or BPL-8Y. Recombinant ADAMTS13 was added in-vitro on all pre-treatment samples with 15 minutes incubation time. Further re-measurement was undertaken after initiation of aspirin for at least ten days.
Results
Eighteen patients with cTTP confirmed by genetic analysis and ADAMTS13 levels <5 IU/dl were included (16 = female, 2 = male) with a median age of 33 (range: 15-69 years). Median VWF antigen levels: 114% (range: 54% - 276%, NR: 50-160%) and median VWF activity levels: 173% (range: 83% - 338%, NR: 50-187%).
The median pre-treatment surface coverage was 90% (range 47% - 100%). There was no significant difference in surface coverage considering genetic mutation type (median coverage for homozygous patients 88%, heterozygous 67%, p=0.99), mutation location (pre-spacer mutation surface coverage 67%, post spacer mutation surface coverage 84%, p=0.84), or age of first symptom onset (childhood onset surface coverage 59%, adult onset 86%, p=0.19).
Plasma infusion improved surface coverage results with pre treatment coverage of 90% compared to 44% post plasma infusion (p=0.0003). In vivo recombinant ADAMTS13 administration on pre prophylaxis samples, resulted in normalization of surface coverage in all patients (p<0.0001)(median post rADAMTS13 coverage 28%, range 3-39%). In patients initiated on aspirin, surface coverage had improved both pre and post prophylaxis. The median pre treatment surface coverage for patients on aspirin was 51% (vs. 90% pre treatment and no aspirin, p=0.004). This improvement persisted after treatment with post treatment surface coverage of 18% (vs. 44% post treatment but not on aspirin, p=0.003). 100% of patients who received aspirin saw surface coverage return to the normal range post treatment compared to 82% with plasma infusion alone (p=0.0195).
Conclusion
Plasma infusion and aspirin synergistically reduce surface coverage by thrombus in patients with cTTP, demonstrated on peak and trough samples. Furthermore, in vitro addition of recombinant ADAMTS13 completely normalized thrombus formation. There were no major differences in surface coverage by genetic mutation. The newly developed flow-based assay presented can be used to assess treatment options and efficacy in cTTP in addition to demonstrating cTTP disease pathophysiology that has not previously been identified. In combination with clinical symptoms it offers potential to improve and personalize treatment for patients with cTTP.
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Liesner:Bayer: Consultancy, Research Funding; Sobi: Speakers Bureau; Roche: Research Funding; Baxalta: Consultancy, Research Funding; Novo Nordisk: Research Funding, Speakers Bureau; Octapharma: Consultancy, Other: Clinical study investigator for NuProtect Study (Octapharma sponsored), Research Funding, Speakers Bureau. Scully:Novartis: Honoraria, Other: Member of Advisory Board, Speakers Bureau.
Acquired hemophilia A is a severe bleeding disorder caused by an autoantibody to factor VIII. Previous reports have focused on referral center patients and it is unclear whether these findings are ...generally applicable. To improve understanding of the disease, a 2-year observational study was established to identify and characterize the presenting features and outcome of all patients with acquired hemophilia A in the United Kingdom. This allowed a consecutive cohort of patients, unbiased by referral or reporting practice, to be studied. A total of 172 patients with a median age of 78 years were identified, an incidence of 1.48/million/y. The cohort was significantly older than previously reported series, but bleeding manifestations and underlying diseases were similar. Bleeding was the cause of death in 9% of the cohort and remained a risk until the inhibitor had been eradicated. There was no difference in inhibitor eradication or mortality between patients treated with steroids alone and a combination of steroids and cytotoxic agents. Relapse of the inhibitor was observed in 20% of the patients who had attained first complete remission. The data provide the most complete description of acquired hemophilia A available and are applicable to patients presenting to all centers.
Factor X deficiency is a rare coagulation disorder that can be hereditary or acquired. The typology and severity of the associated bleeding symptoms are highly heterogeneous, adding to the ...difficulties of diagnosis and management. Evidence-based guidelines and reviews on factor X deficiency are generally limited to publications covering a range of rare bleeding disorders. Here we provide a comprehensive review of the literature on factor X deficiency, focusing on the hereditary form, and discuss the evolution in disease management and the evidence associated with available treatment options. Current recommendations advise clinicians to use single-factor replacement therapy for hereditary disease rather than multifactor therapies such as fresh frozen plasma, cryoprecipitate, and prothrombin complex concentrates. Consensus in treatment guidelines is still urgently needed to ensure optimal management of patients with factor X deficiency across the spectrum of disease severity.
The objective was to examine the genotypic and phenotypic characteristics of individuals with hereditary factor X deficiency (FXD), a rare autosomal recessive bleeding disorder caused by mutations in ...the F10 gene located on chromosome 13q34-ter. To date, 149 F10 mutations have been identified as contributory to FXD. Three open-label phase 3 trials enrolled individuals with mild, moderate, or severe FXD. Individuals received plasma-derived factor X concentrate as routine prophylaxis, to treat bleeds, and/or during or after surgery. F10 genotyping was performed (studies 1 and 2) or genotype data was collected at screening (study 3), and identified F10 mutations were compared against the Human Gene Mutation Database to assess novelty. Genotype data were combined to evaluate the number, type, and novelty of the F10 mutations identified. Genotype data were available for 24 of 27 individuals with mild (n = 2), moderate (n = 2), or severe (n = 20) FXD. Analyses identified 22 separate mutations, including 15 missense mutations, 2 deletions, 4 splice site mutations, and 1 nonsense mutation. Sixteen individuals had homozygous mutations; 8 had compound heterozygous mutations. Eleven unique novel mutations (all compound heterozygous) were identified in seven individualssix missense mutations, three splice site mutations, one exon deletion, and one nonsense mutation. In silico analyses strongly supported the pathogenicity of all novel mutations. The identification of 11 novel F10 mutations provides a substantial contribution to the mutations known to cause FXD.
Introduction: Congenital factor X (FX) deficiency (FXD) is a rare bleeding disorder characterized by spontaneous joint and mucocutaneous bleeding and gastrointestinal or intracranial hemorrhage. A ...high-purity plasma-derived FX concentrate (pdFX; Coagadex®, Bio Products Laboratory, Elstree, UK) is licensed in the United States (US) and European Union to treat congenital FXD. This open-label, multicenter, international study collected retrospective data on compassionate use of pdFX in subjects with hereditary FXD.
Methods: This study included subjects of any age with hereditary FXD (irrespective of severity) who received pdFX on a compassionate use basis as routine prophylaxis (RP), on-demand (OD) treatment, short-term prevention, and/or perisurgical hemostatic cover. Dosing was set at the discretion of the investigator and tailored to each patient. Data collection lasted from date of first dose of compassionate use until data cutoff (31 December 2015). Retrospective efficacy assessments included number of bleeds/year/subject, total dose/year/subject, dose to treat a bleed, investigator's efficacy assessment in treating a bleed (effective, not effective, or unknown), and investigator's overall efficacy assessment during compassionate use (excellent, good, poor, or unassessable). All subjects (or a parent/guardian) provided written informed consent; the protocol was approved by appropriate independent ethics committees.
Results: All 15 enrolled subjects from 12 study centers in 5 countries (Germany, Spain, Turkey, the United Kingdom, and the US) received ≥1 pdFX dose for compassionate use. Of these, 13 subjects were aged ≥12 years (mean, 22.8 years) and 2 were aged <12 years, 8 (53.3%) were female, 12 (80.0%) were white, 3 (20.0%) were Asian, and all subjects had moderate or severe FXD (FX activity FX:C <5 IU/dL).
Of the 15 patients, 7 received only RP, 7 received only OD, and 1 patient alternated between OD and RP treatment. Of the 8 subjects on RP, 4 received pdFX once weekly (of whom 2 changed for a short period to dosing every 2 days), 3 received pdFX every 3 days, and 1 received pdFX every 15 days. Overall, these 8 subjects received a total of 1239 RP infusions (mean 154.9 infusions/subject, range 39-492), with a mean dose/infusion/subject of 32.5 IU/kg (range 21.9-53.6). The 2 subjects aged <12 years received larger RP doses than the 6 older subjects, with mean doses/infusion/subject of 51.1 vs 26.3 IU/kg, respectively.
Twelve subjects (8 OD, 4 RP; all aged ≥12 years) reported 88 bleeds, of which 34 were rated as minor (epistaxis, gum bleed, mild menorrhagia, or superficial hematoma), 7 as major (severe gastrointestinal bleeding, intracerebral hemorrhage, severe hemarthrosis, major menorrhagia, or large/complicated muscle hematoma), and 47 were not rated for severity; 37 bleeds were menorrhagic, 28 were traumatic, 17 were spontaneous, 4 were other, and 2 had unknown cause. pdFX efficacy was rated as effective for the 79 bleeds (including 1 subdural hematoma) that received on-demand pdFX treatment. Mean pdFX dose was 22.2 IU/kg/infusion/subject, with a mean number of 9.5 infusions/subject to treat a bleed. Subjects in the OD population experienced more bleeds than subjects in the RP population.
Two subjects underwent 1 dental procedure each, each of which required only 1 presurgical pdFX dose (27.1 and 28.5 IU/kg); the third surgery, a portacath insertion, required 6 infusions to prevent postoperative bleeding (1 presurgical dose of 72.8 IU/kg + 5 doses of 48.5 IU/kg at days 1, 2, 3, 5, and 15 post surgery). Two successful pregnancies/childbirths were also reported, with no abnormal bleeding complications and no efficacy or safety concerns reported.
The mean duration of compassionate use was 87.6 weeks for the 15 subjects, with a range of 15-211 weeks (0.3 to 4.0 years). Over the 1373 infusions administered across 25.2 subject-years in this study, investigators rated overall pdFX efficacy use as excellent in 14 (93.3%) subjects and good in 1 (6.7%) subject. No adverse drug reactions, safety concerns, infusion site reactions, tolerability issues, or inhibitor development were reported during pdFX compassionate use.
Conclusion: The higher bleed rate in OD versus RP use and the duration of treatment (up to 4 years) support the efficacy and safety of pdFX demonstrated in prospective clinical studies and its continued use in the treatment of subjects with hereditary FXD.
Funding: BPL
Huang:Baxter: Research Funding; Biogen: Research Funding; Bio Products Laboratory: Other: Study investigator; Novartis: Other: support to attend meeting. Liesner:SOBI/Bioverativ: Research Funding, Speakers Bureau; Bayer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; NovoNordisk: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Baxalta: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; SOBI: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Octapharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bio Products Laboratory: Consultancy, Membership on an entity's Board of Directors or advisory committees. Akenezi:Bio Products Laboratory: Employment. Austin:Baxalta: Consultancy, Other: Advisory board member and educational support; SOBI: Consultancy, Other: Advisory board member and educational support; Bayer: Consultancy, Other: Advisory board member and educational support; Pfizer: Consultancy, Other: Advisory board member and educational support; Bio Products Laboratory: Consultancy, Other: Advisory board member and educational support; Novo Nordisk: Consultancy, Other: Advisory board member and educational support; CSL Behring: Consultancy, Other: Advisory board member and educational support. Kavakli:Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Shire: Honoraria, Membership on an entity's Board of Directors or advisory committees.
Summary
The discussion of prophylactic therapy in haemophilia is largely focused on joint outcomes. The impact of prophylactic therapy on intracranial haemorrhage (ICH) is less known. This study ...aimed to analyse ICH in children with haemophilia, with a focus on different prophylaxis regimens and sequelae of ICH. We conducted a multicentre retrospective and prospective study that included 33 haemophilia centres from 20 countries. Inclusion criteria were children and adolescents born between 1993 and 2014, with severe haemophilia A or B without inhibitors. Participants were categorized by prophylaxis regimen: full, partial or none, based on dose and dose frequency of regular infusions. The cohort study included 1515 children: 29 cases of ICH over 8038 patient years were reported. The incidence of ICH in the prophylaxis group, 0·00033 cases of ICH/patient year, was significantly lower compared to the no prophylaxis group, 0·017 cases of ICH/patient year (RR 50·06; P < 0·001) and the partial prophylaxis group, 0·0050 cases of ICH/patient year (RR 14·92; P = 0·007). In the on‐demand‐group, 8% (2/24) children with ICH died and 33% had long‐term sequelae, including intellectual and behavioural problems, paresis and epilepsy. Children on regular, frequent prophylaxis have a low risk of ICH compared to those using non‐frequent or no prophylaxis.
ADAMTS13 activity assays are sometimes useful in confirming the clinical diagnosis or to distinguish different thrombotic microangiopathies (TMA). We investigated the commonly used clinical assays ...for ADAMTS13 activity. 159 samples from normal subjects or acquired TMA patients were studied in collagen binding (CBA), Fret and chromogenic peptide substrate assays. Frozen aliquots of pooled normal plasma gave similar values by CBA, Fret-VWF73 peptide, Fret-VWF86 and chromogenic VWF73 ELISA (chr-VWF73). Two lyophilised commercial calibrants gave lower ADAMTS13 activity by CBA than peptide substrate assays. The addition of solid HEPES to normal plasma caused a significant fall in CBA, but not Fret-VWF73 activity and might partly explain the differences, since lyophilised plasmas are often HEPES buffered. Normal plasmas showed good agreement between CBA and Fret assays, although chr-VWF73 gave slightly higher values. In acquired TMA, there was reasonable agreement between assays for samples with
ABSTRACT
Introduction
European regulatory authorities request postmarketing safety and efficacy data for factor IX (FIX) products.
Aim
Collect additional clinical data from routine nonacog alfa use ...in children aged <6 years with haemophilia B.
Methods
The EUREKIX registry included retrospective and prospective data collection phases. Safety was assessed via adverse drug reactions (ADRs)/adverse events (AEs) and events of special interest (ESIs) as the primary objective; efficacy was evaluated via annualised bleeding rates (ABRs).
Results
The retrospective phase comprised 37 subjects. Of these, 25 had severe haemophilia B. One subject experienced 2 ADRs; another experienced 4 ESIs of hypersensitivity. Median ABR in subjects receiving a predominantly on‐demand regimen (prophylaxis <50% of time; n = 11) was 2.0; median ABR was 3.8 in those receiving predominantly prophylactic treatment (prophylaxis ≥50% of time; n = 24). Joint bleeding was infrequent (median ABR, 0.4; n = 35). The prospective phase included 26 subjects, with 17 continuing from the retrospective phase. A total of 20 subjects had severe haemophilia B. Three subjects experienced 7 treatment‐related AEs; 3 experienced 4 ESIs. Median ABR was 4.5 and 1.1 in subjects who received predominantly on‐demand (n = 5) or prophylactic treatment (n = 19), respectively; the overall median ABR for joint bleeding events was 0.0.
Conclusions
Overall, nonacog alfa treatment effectively controlled bleeding events, with no new safety signals identified. These data support the safety and efficacy of nonacog alfa in routine clinical settings in children aged <6 years.
Introduction
In good risk patients (historic inhibitor peak < 200BU), the International Immune Tolerance Study demonstrated equal efficacy to induce tolerance between high (200iu/kg/day) and low dose ...(50iu/kg ×3 times/week) immune tolerance induction (ITI) regimens. However, the trial stopped early on account of the excessive bleed rate in the low dose ITI arm.
Methods
United Kingdom Haemophilia Centre Doctors’ Organization (UKHCDO) Paediatric and Inhibitor working parties considered available ITI data alongside the bi‐phenotypic antibody emicizumab (Hemlibra®) efficacy and safety data to develop a consensus guideline for the future UK ITI guideline.
Results
This revision of UKHCDO ITI guidance incorporates the recommendation to use emicizumab as a prophylaxis haemostatic agent to reduce bleeding rates and to facilitate low dose and reduced frequency of FVIII CFC for ITI in the majority of children.
Conclusion
This consensus protocol will facilitate future evaluation of ITI outcomes in the evolving landscape of haemophilia therapeutics and ITI strategies.
The quantification of residual plasmatic ADAMTS13 activity in congenital thrombotic thrombocytopenic purpura (TTP) patients is constrained by limitations in sensitivity and reproducibility of ...commonly used assays at low levels of ADAMTS13 activity, blunting efforts to establish genotype-phenotype correlations. In the present study, the residual plasmatic activity of ADAMTS13 was measured centrally by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (limit of detection = 0.5%) in 29 congenital TTP patients. The results were used to study correlations among ADAMTS13 genotype, residual plasmatic activity, and clinical phenotype severity. An ADAMTS13 activity above 0.5% was measured in 26 (90%) patients and lower levels of activity were associated with earlier age at first TTP episode requiring plasma infusion, more frequent recurrences, and prescription of fresh-frozen plasma prophylaxis. Receiver operating characteristic curve analysis showed that activity levels of less than 2.74% and 1.61% were discriminative of age at first TTP episode requiring plasma infusion < 18 years, annual rate of TTP episodes > 1, and use of prophylaxis. Mutations affecting the highly conserved N-terminal domains of the protein were associated with lower residual ADAMTS13 activity and a more severe phenotype in an allelic-dose dependent manner. The results of the present study show that residual ADAMTS13 activity is associated with the severity of clinical phenotype in congenital TTP and provide insights into genotype-phenotype correlations.
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