Publications by authors named "Benoît Guillet"

22 Publications

  • Page 1 of 1

Simoctocog Alfa (Nuwiq) in Previously Untreated Patients with Severe Haemophilia A: Final Results of the NuProtect Study.

Thromb Haemost 2021 Feb 13. Epub 2021 Feb 13.

Octapharma AG, Lachen, Switzerland.

Introduction:  FVIII inhibitor development is the most serious contemporary treatment complication in haemophilia A, particularly in previously untreated patients (PUPs). No inhibitors developed in clinical trials in previously treated patients treated with simoctocog alfa (Nuwiq), a fourth-generation recombinant FVIII produced in a human cell line.

Methods:  The NuProtect study investigated the immunogenicity of simoctocog alfa in PUPs. NuProtect was a prospective, multinational, open-label, non-controlled, phase III study. PUPs with severe haemophilia A (FVIII:C <1%) of any age and ethnicity were treated with simoctocog alfa for 100 exposure days or a maximum of 5 years. Patients were true PUPs without prior exposure to FVIII concentrates or blood components. Inhibitor titres were measured with the Nijmegen-modified Bethesda assay; cut-off for positivity was 0.6 BU mL (≥0.6 to <5 low-titre, ≥5 high titre).

Results:  A total of 108 PUPs with a median age at first treatment of 12.0 months (interquartile range: 8.0-23.5) were treated with simoctocog alfa. mutation type was known for 102 patients (94.4%) of whom 90 (88.2%) had null mutations and 12 (11.8%) had non-null mutations. Of 105 PUPs evaluable for inhibitor development, 28 (26.7%) developed inhibitors; 17 high titre (16.2%) and 11 low titre (10.5%). No PUPs with non-null mutations developed inhibitors.

Conclusion:  In the NuProtect study, the rate of inhibitor development in PUPs with severe haemophilia A treated with simoctocog alfa was lower than the rate reported for hamster-cell-derived recombinant factor VIII products in other recent clinical trials. No inhibitors were reported in PUPs with non-null mutations.
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http://dx.doi.org/10.1055/s-0040-1722623DOI Listing
February 2021

Long-Term Antithrombotic Treatments Prescribed for Cardiovascular Diseases in Patients with Hemophilia: Results from the French Registry.

Thromb Haemost 2021 Mar 24;121(3):287-296. Epub 2020 Oct 24.

Centre Régional de Traitement des Hémophiles, Hôpital Saint-Eloi, CHRU de Montpellier, Montpellier, France.

Cardiovascular diseases (CVDs) are a major issue in aging patients with hemophilia (PWHs). Antithrombotic agents are widely used in the general population for CVD treatment, but this recommendation is not fully applicable to PWHs. To improve treatment strategies, a prospective case-control study (COCHE) that analyzed CVD management and follow-up (2 years/patient) in PWHs was performed in France from 2011 to 2018. In total, 68 PWHs (median age: 65 years [39-89]; 48 mild, 10 moderate, and 10 severe hemophilia) were included ( = 50 with acute coronary syndrome,  = 17 with atrial fibrillation,  = 1 with both). They were matched with 68 control PWHs without antithrombotic treatment. In our series, bleeding was significantly influenced by (1) hemophilia severity, with a mean annualized bleeding ratio significantly higher in COCHE patients than in controls with basal clotting factor level up to 20%, (2) antihemorrhagic regimen (on-demand vs. prophylaxis) in severe (hazard ratio [HR] = 16.69 [95% confidence interval, CI: 8.2-47.26];  0.0001) and moderate hemophilia (HR = 42.43 [95% CI: 1.86-966.1];  = 00028), (3) type of antithrombotic treatment in mild hemophilia, with a significantly higher risk of bleeding in COCHE patients than in controls for dual-pathway therapy (HR = 15.64 [95% CI: 1.57-115.8];  = 0019), anticoagulant drugs alone (HR = 9.91 [95% CI: 1.34-73.47];  = 00248), dual antiplatelet therapy (HR = 5.31 [95% CI: 1.23-22.92];  = 00252), and single antiplatelet therapy (HR = 3.76 [95% CI: 1.13-12.55];  = 00313); and (4) HAS-BLED score ≥3 (odds ratio [OR] = 33 [95% CI: 1.43-761.2];  = 00065). Gastrointestinal bleeding was also significantly higher in COCHE patients than in controls (OR = 15 [95% CI: 1.84-268];  = 00141). The COCHE study confirmed that antithrombotic treatments in PWHs are associated with increased bleeding rates in function of hemophilia-specific factors and also of known factors in the general population.
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http://dx.doi.org/10.1055/s-0040-1718410DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7895544PMC
March 2021

Bleeding complications during pregnancy and delivery in haemophilia carriers and their neonates in Western France: An observational study.

Haemophilia 2020 Nov 25;26(6):1046-1055. Epub 2020 Aug 25.

EA3878, Université de Bretagne Occidentale, Brest, France.

Background: Pregnancy, delivery and the postpartum period expose haemophilia carriers, as well as their potentially affected neonates to a high risk of haemorrhagic complications.

Objectives: To describe bleeding complications in haemophilia carriers and their newborns throughout pregnancy and postpartum and to identify potential factors increasing the risk of bleeding in this population.

Patients/methods: The ECHANGE multicentre observational cohort study was conducted between January 2014 and February 2019 using the BERHLINGO database comprised of patients from seven French haemophilia centres.

Results: During the 5 years study period, a total of 104 haemophilia carriers and 119 neonates were included, representing 124 pregnancies and 117 deliveries. Thirty-five (30%) bleeding events were observed, most of them (83%) occurred during the postpartum period, and 37% were reported during the secondary postpartum. Neuraxial anaesthesia was not complicated by spinal haematoma. Three (2.5%) neonates experienced cerebral bleeding. Caesarean section was associated with an increased risk of maternal bleeding in primary and secondary postpartum periods. Basal factor level <0.4 IU/mL was also found to be associated with an increased risk of bleeding during secondary postpartum.

Conclusion: In our cohort, bleeding events occurred in more than a third of haemophilia carriers mainly in the postpartum period, and a significant portion of this bleeding occurred during the secondary postpartum. Haemophilia carriers warrant specific attention during primary and secondary postpartum, in particular in case of caesarean section and low basal factor level. The ECHANGE study is registered at clinicaltrials.gov identifier: NCT03360149.
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http://dx.doi.org/10.1111/hae.14117DOI Listing
November 2020

Postauthorization safety surveillance study of antihaemophilic factor (recombinant) reconstituted in 2 mL sterile water for injection in children with haemophilia A.

Haemophilia 2020 May 27;26(3):478-486. Epub 2020 Apr 27.

Baxalta US Inc., a member of the Takeda group of companies, Lexington, MA, USA.

Introduction: Antihaemophilic factor (recombinant) (rAHF; ADVATE ) is approved for prophylaxis and treatment of bleeding in children and adults with haemophilia A. Reconstitution in 2 mL sterile water for injection instead of 5 mL allows for a 60% reduction in infusion volume and administration time, but could increase the likelihood of hypersensitivity and infusion-related reactions, especially in children.

Aim: To assess local tolerability, safety and effectiveness of rAHF 2 mL during routine clinical practice factor VIII (FVIII) replacement (on-demand and prophylaxis) in children with severe (FVIII < 1%) or moderately severe (FVIII 1%-2%) haemophilia A.

Methods: This was a prospective, non-interventional, postauthorization safety surveillance study (NCT02093741). Eligible patients were previously treated with rAHF and had a negative inhibitor test result during ≤10 exposure days prior to study entry.

Results: Of 65 patients enrolled (0-11 years of age), 54 and 11 had severe and moderately severe haemophilia A, respectively; 56 patients received prophylaxis, and 11 had ≤50 exposure days, of which 4 had ≤4 exposure days. No patients reported local hypersensitivity reactions, treatment-related adverse events or developed inhibitors. Investigators rated overall effectiveness of rAHF 2 mL prophylaxis as excellent or good. Ninety-four bleeding events in 34 patients were treated. Haemostatic effectiveness was rated as excellent or good for 75.8% of bleeds; 86.2% of bleeds required 1 or 2 infusions.

Conclusion: In children with severe/moderately severe haemophilia A, no hypersensitivity reactions were reported with rAHF 2 mL treatment, and the safety and effectiveness are consistent with data previously reported for rAHF 5 mL.
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http://dx.doi.org/10.1111/hae.13997DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7383916PMC
May 2020

Real Life Population Pharmacokinetics Modelling of Eight Factors VIII in Patients with Severe Haemophilia A: Is It Always Relevant to Switch to an Extended Half-Life?

Pharmaceutics 2020 Apr 21;12(4). Epub 2020 Apr 21.

Department of Medical Pharmacology, University Hospital of Reims, EA3801, SFR Cap-Santé, University of Reims, 51100 Reims, France.

We retrospectively analysed the data files of 171 adults and 87 children/adolescents with severe haemophilia, except for 14 patients (moderate; minor) (1), to develop a global population pharmacokinetic (PK) model for eight factors VIII (FVIII) that could estimate individual PK parameters for targeting the desired level of FVIII activity (FVIII:C); and (2) to compare half-life (HL) in patients switching from a standard half-life (SHL) to an extended half-life (EHL) and evaluate the relevance of the switch. One-stage clotting assay for the measurement of FVIII activity (FVIII:C, IU/mL) was used for population PK modelling. The software, Monolix version 2019R1, was used for non-linear mixed-effects modelling. A linear two-compartment model best described FVIII:C. The estimated PK parameters (between-subject variability) were: 2640 mL (23.2%) for volume of central compartment (V1), 339 mL (46.8%) for volume of peripheral compartment (V2), 135 mL/h for Q (fixed random effect), and 204 mL/h (34.9%) for clearance (Cl). Weight, age, and categorical covariate EHL were found to influence Cl and only weight for V1. This model can be used for all of the FVIII cited in the study. Moreover, we demonstrated, in accordance with previous studies, that Elocta had longer half-life (EHL) than SHL (mean ratio: 1.48) as compared to Advate, Factane, Kogenate, Novoeight, and Refacto.
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http://dx.doi.org/10.3390/pharmaceutics12040380DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7238177PMC
April 2020

A Glanzmann thrombasthenia family associated with a TUBB1-related macrothrombocytopenia.

J Thromb Haemost 2019 12 29;17(12):2211-2215. Epub 2019 Sep 29.

Institut de Rhythmologie et de Modélisation Cardiaque, Hôpital Xavier Arnozan, Pessac, France.

Background: Macrothrombocytopenia (MTP) is a rare but enigmatic complication of Glanzmann thrombasthenia (GT), an inherited bleeding disorder caused by the absence of platelet aggregation due to deficiencies of the αIIbβ3 integrin.

Objectives: We report a family with type I GT and a prolonged bleeding time but unusually associated with congenital mild thrombocytopenia and platelet size heterogeneity with giant forms.

Methods And Results: Sanger sequencing of DNA from the propositus identified 2 heterozygous ITGB3 gene mutations: p.P189S and p.C210S both of which prevent αIIbβ3 expression and are causative of GT but without explaining the presence of enlarged platelets. High-throughput screening led to the detection of a predicted disease-causing heterozygous mutation in the TUBB1 gene: p.G146R, encoding β1-tubulin, a component of the platelet cytoskeleton and a gene where mutations are a known cause of MTP.

Conclusions: Family screening confirmed that this rare phenotype results from oligogenic inheritance while suggesting that the GT phenotype dominates clinically.
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http://dx.doi.org/10.1111/jth.14622DOI Listing
December 2019

Determinants of adherence and consequences of the transition from adolescence to adulthood among young people with severe haemophilia (TRANSHEMO): study protocol for a multicentric French national observational cross-sectional study.

BMJ Open 2018 07 25;8(7):e022409. Epub 2018 Jul 25.

Haemophilia Treatment Centre, Hospital Edouard Herriot, University Hospital of Lyon, Lyon, France.

Introduction: Severe haemophilia is a rare disease characterised by spontaneous bleeding from early childhood, which may lead to various complications, especially in joints. It is nowadays possible to avoid these complications thanks to substitutive therapies for which the issue of adherence is major. The transition from adolescence to adulthood in young people with severe haemophilia is a critical period as it is associated with a high risk of lack of adherence to healthcare, which might have serious consequences on daily activities and on quality of life.

Methods And Analysis: We present the protocol for a cross-sectional, observational, multicentric study to assess the differences between adolescents and young adults with severe haemophilia in France through the transition process, especially on adherence to healthcare. This study is based on a mixed methods design, with two complementary and consecutive phases, comparing data from a group of adolescents (aged 14-17 years) with those from a group of young adults (aged 20-29 years). The quantitative phase focuses on the determinants (medical, organisational, sociodemographic and social and psychosocial and behavioural factors) of adherence to healthcare (considered as a marker of the success of transition). The qualitative phase explores participants' views in more depth to explain and refine the results from the quantitative phase. Eligible patients are contacted by the various Haemophilia Treatment Centres participating in the French national registry FranceCoag.

Ethics And Dissemination: The study was approved by the French Ethics Committee and by the French National Agency for Medicines and Health Products Safety (number: 2016-A01034-47). Study findings will be disseminated to the scientific and medical community in peer-reviewed journals and presented at scientific meetings. Results will be popularised to be communicated via the French association for people with haemophilia to participants and to the general public.

Trial Registration Number: NCT02866526; Pre-results.
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http://dx.doi.org/10.1136/bmjopen-2018-022409DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6067371PMC
July 2018

Choice of factor VIII/IX regimen in adolescents and young adults with severe or moderately severe haemophilia. A French national observational study (ORTHem 15-25).

Thromb Res 2017 Mar 28;151:17-22. Epub 2016 Dec 28.

Haemophilia Treatment Centre, Pontchaillou Hospital, CHU Rennes and Inserm IRSET U1085, Rennes University 1, Rennes, France.

Introduction: The value and challenges of long-term prophylaxis (LTP) in adolescents and young adults need further characterisation.

Aim: To determine the proportions of adolescents and young adults with severe or moderately severe haemophilia in France under LTP and treatment on demand (OD).

Methods: Patients 15 to 25years old with haemophilia A or B, factor VIII/IX ≤2% and no current inhibitor could be included if they had been under factor VIII/IX treatment at least 12months and kept a treatment and bleeding diary.

Results: LTP was administered to 169/212 patients (79.7%) and OD treatment to 40/212 patients (18.9%). The most frequent reasons for initiating LTP were joint bleeding, target joints and frequent bleeds; whereas OD treatment was most often selected on the basis of mild bleeding phenotype or because of constraints on LTP. The mean annual bleed rate (ABR) in the OD group (6.33) was higher than in the LTP group (3.07, p<0.001). Mean ABR did not differ significantly between age strata (15-18, >18-21 and >21-25years), but was significantly higher for patients with severe haemophilia (4.02) as compared to those with moderate haemophilia (1.97, p=0.002). No significant difference was observed in mean ABR for joint bleeds between the LTP and OD groups. Physician reported LTP compliance was good or excellent in 97.0% of patients.

Conclusion: LTP is the predominant factor VIII/IX treatment among adolescents and young adults with severe or moderately severe haemophilia in France. LTP was associated with low ABR and high compliance.
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http://dx.doi.org/10.1016/j.thromres.2016.12.023DOI Listing
March 2017

Recombinant factor VIII products and inhibitor development in previously untreated boys with severe hemophilia A.

Blood 2014 Nov 24;124(23):3398-408. Epub 2014 Sep 24.

Service d'Hématologie et de Transfusion, Centre Hospitalier Universitaire de Lille, Université Lille 2, Equipe d'Accueil 2693, Faculté de Médecine, Lille, France.

Six recombinant factor VIII (rFVIII) products have been marketed worldwide. In 2013, the Research of Determinants of Inhibitor Development (RODIN) study group reported an unexpectedly high risk of inhibitor development with a second-generation full-length rFVIII (Product D) in previously untreated patients (PUPs) with severe hemophilia A (HA). In 1994, French public health authorities established a prospective cohort to monitor hemophilia treatment safety. A PUP subgroup was designed to investigate inhibitor risk factors. We analyzed this subcohort in view of the RODIN findings. After excluding 50 patients who participated in the RODIN study, the primary analysis focused on 303 boys with severe HA first treated with a rFVIII product. A clinically significant inhibitor was detected in 114 boys (37.6%). The inhibitor incidence was higher with Product D vs the most widely used rFVIII product (adjusted hazard ratio [aHR], 1.55; 95% confidence interval [CI], 0.97-2.49). Similar results were found for high-titer inhibitors and in 10 sensitivity analyses. No heterogeneity was observed between RODIN and our results. Combined aHRs were 1.58 (95% CI, 1.17-2.14) for all inhibitors and 1.70 (95% CI, 1.15-2.52) for high-titer inhibitors. Our results confirm the higher immunogenicity of Product D vs other rFVIII products in PUPs with severe HA.
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http://dx.doi.org/10.1182/blood-2014-07-586347DOI Listing
November 2014

Development of inhibitory antibodies to therapeutic factor VIII in severe hemophilia A is associated with microsatellite polymorphisms in the HMOX1 promoter.

Haematologica 2013 Oct 28;98(10):1650-5. Epub 2013 May 28.

Induction of heme oxygenase-1, a stress-inducible enzyme with anti-inflammatory activity, reduces the immunogenicity of therapeutic factor VIII in experimental hemophilia A. In humans, heme oxygenase-1 expression is modulated by polymorphisms in the promoter of the heme oxygenase-1-encoding gene (HMOX1). We investigated the relationship between polymorphisms in the HMOX1 promoter and factor VIII inhibitor development in severe hemophilia A. We performed a case-control study on 99 inhibitor-positive patients and 263 patients who did not develop inhibitors within the first 150 cumulative days of exposure to therapeutic factor VIII. Direct sequencing and DNA fragment analysis were used to study (GT)n polymorphism and single nucleotide polymorphisms located at -1135 and -413 in the promoter of HMOX1. We assessed associations between the individual allele frequencies or genotypes, and inhibitor development. Our results demonstrate that inhibitor-positive patients had a higher frequency of alleles with large (GT)n repeats (L: n≥30), which are associated with lesser heme oxygenase-1 expression (odds ratio 2.31; 95% confidence interval 1.46-3.66; P<0.001]. Six genotypes (L/L, L/M, L/S, M/M, M/S and S/S) of (GT)n repeats were identified (S: n<21; M: 21≤n<30). The genotype group including L alleles (L/L, L/M and L/S) was statistically more frequent among inhibitor-positive than inhibitor-negative patients, as compared to the other genotypes (33.3% versus 17.1%) (odds ratio 2.21, 95% confidence interval 1.30-3.76; P<0.01). To our knowledge, this is the first association identified between HMOX1 promoter polymorphism and development of anti-drug antibodies. Our study paves the way towards modulation of the endogenous anti-inflammatory machinery of hemophilia patients to reduce the risk of inhibitor development.
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http://dx.doi.org/10.3324/haematol.2013.084665DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3789472PMC
October 2013

Bioactive lipids lysophosphatidic acid and sphingosine 1-phosphate mediate breast cancer cell biological functions through distinct mechanisms.

Oncol Res 2009 ;18(4):173-84

Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.

Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are structurally related bioactive lipids with growth factor-like activities. LPA and S1P are naturally produced in vivo by blood platelets upon platelet aggregation and at least in vitro by fibroblasts, adipocytes, and multiple types of tumor cells. Breast cancer cells respond to LPA and S1P. However, their specific actions on breast cancer cell biological functions remain unclear. We therefore conducted an in vitro side-by-side study of these two lipids on breast cancer cells. LPA mediates human breast cancer MDA-BO2 cell proliferation, migration, and invasion through activation of a G(alpha i)/ERK1/2-dependent signaling pathway, whereas activation of G(alpha i)/PI3K predominates upon S1P stimulation. In MDA-BO2 cells, LPA but not S1P activities were dependent on active type 1 insulin-like growth factor and epithelial growth factor receptors. LPA and S1P act directly on endothelial cells to induce angiogenesis. We demonstrate that LPA and S1P have indirect angiogenic properties as judged by induced secretion of angiogenic factors by breast cancer cells primed with these lysophospholipids. S1P, but not LPA, controlled the expression of VEGF-A by breast cancer cells, while LPA, but not S1P, controlled the expression of GM-CSF, Gro-alpha, MCP-1, and IL-6. According to the secretion of these paracrine osteoclastic factors, LPA, but not S1P, stimulates breast cancer cell-induced osteoclastogenesis. These findings suggest that, in vivo, LPA and S1P can coordinate their action on tumor and surrounding cells to induce breast cancer progression both at primary and bone metastatic sites.
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http://dx.doi.org/10.3727/096504009790217399DOI Listing
March 2010

Detection of 28 novel mutations in the Wiskott-Aldrich syndrome and X-linked thrombocytopenia based on multiplex PCR.

Blood Cells Mol Dis 2007 Jul-Aug;39(1):102-6. Epub 2007 Apr 2.

Service d'Hématologie, d'Immunologie et de Cytogénétique, Hôpital de Bicêtre, AP-HP, 78 rue du Général-Leclerc, 94275, Le Kremlin-Bicêtre, France.

The Wiskott-Aldrich syndrome (WAS) is an X-linked disorder including microthrombocytopenia, eczema and immunodeficiency. A mild form is known as the X-linked thrombocytopenia (XLT). We screened 150 individuals or families based on a multiplex PCR method. We found 28 novel mutations (7 missense, 1 nonsense, 1 nonstop change, 5 splice site mutations and 14 deletions or insertions). The method relied on the co-synthesis of 5 amplicons and direct sequencing, optimizing the novel protocol proposed by Jones et al. [L.N. Jones, M.I. Lutskiy, J. Cooley, et al. A novel protocol to identify mutations in patients with Wiskott-Aldrich syndrome, Blood Cells Mol. Dis. 28 (2002) 392-398]. It was thus possible to identify faster and at a lower cost the mutations in newly diagnosed patients. The mutation distribution, according to the type, was in keeping with the distribution reported previously. No clear-cut genotype-phenotype correlation was observed.
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http://dx.doi.org/10.1016/j.bcmd.2007.02.007DOI Listing
September 2007

Detection of 95 novel mutations in coagulation factor VIII gene F8 responsible for hemophilia A: results from a single institution.

Hum Mutat 2006 Jul;27(7):676-85

Centre de traitement des hémophiles, Laboratoire d'Hématologie, Hôpital Bicêtre, Assistance Publique-Hôpitaux de Paris (AP-HP), Le Kremlin-Bicêtre, France.

Hemophilia A (HA) is an X-linked hereditary bleeding disorder defined by a qualitative and/or quantitative factor VIII (FVIII) deficiency. The molecular diagnosis of HA is challenging because of the high number of different causative mutations that are distributed throughout the large F8 gene. The putative role of the novel mutations, especially missense mutations, may be difficult to interpret as causing HA. We identified 95 novel mutations out of 180 different mutations responsible for HA in 515 patients from 406 unrelated families followed up at a single hemophilia treatment center of the Bicêtre university hospital (Assistance Publique-Hôpitaux de Paris [AP-HP], Le Kremlin-Bicêtre). These 95 novel mutations comprised 55 missense mutations, 12 nonsense mutations, 11 splice site mutations, and 17 small insertions/deletions. We therefore developed a mutation analysis based on a body of proof that combines the familial segregation of the mutation, the resulting biological and clinical HA phenotype, and the molecular consequences of the amino acid (AA) substitution. For the latter, we studied the putative biochemical modifications: its conservation status with cross-species FVIII and homologous proteins, its putative location in known FVIII functional regions, and its spatial position in the available FVIII 3D structures. The usefulness of such a strategy in interpreting the causality of novel F8 mutations is emphasized.
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http://dx.doi.org/10.1002/humu.20345DOI Listing
July 2006

Circulating microparticles are elevated in haemophiliacs and non-haemophilic individuals aged <18 years.

Br J Haematol 2005 Nov;131(4):487-9

Service d'Hématologie Biologique, AP-HP, Hôpital Bicêtre, Faculté de Médecine Paris XI, Le Kremlin Bicêtre, France.

Platelet and cell stimulation lead to plasma membrane remodelling, resulting in phosphatidylserine (PS) externalisation in the outer leaflet of the membrane, associated with the shedding of PS-rich microparticles (MPs), and contributes to thrombin generation by promoting the assembly of coagulation enzyme complexes. A previous study assessed MP levels in haemophiliacs after haemostatic treatment. To further investigate in vivo membrane remodelling, MP levels and characteristics were studied in 79 haemophiliacs and in 62 non-haemophiliacs. Both groups showed heterogeneity in MP levels, with higher values in individuals <18 years. This finding should be considered when studying MP levels in individuals <18 years.
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http://dx.doi.org/10.1111/j.1365-2141.2005.05792.xDOI Listing
November 2005

Factor XI deficiency: identification of six novel missense mutations (P23L, P69T, C92G, E243D, W497C and E547K).

Haematologica 2005 Aug;90(8):1149-50

Factor XI (FXI) deficiency is a rare coagulation disorder associated with bleeding of variable severity but without a clear relationship between bleeding and FXI levels. This study reports the molecular genetic analysis of FXI deficiencies in thirteen patients. Six novel missense mutations were identified: P23L, P69T, C92G, E243D, W497C and E547K.
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August 2005

Recurrent V75M mutation within the Wiskott-Aldrich syndrome protein: description of a homozygous female patient.

Eur J Haematol 2005 Jul;75(1):54-9

Service d'Hématologie, d'Immunologie et de Cytogénétique, Hôpital de Bicêtre, AP-HP, Faculte de Medecine Paris-Sud, 78 rue du Général Leclerc, 94275 Le Kremlin-Bicêtre, France.

The Wiskott-Aldrich syndrome is a rare genetic disorder due to mutations in the WAS gene situated on chromosome X. It is comprised of microthrombocytopenia, eczema and immunodeficiency. However, the phenotypical presentation may vary as to the number and intensity of its manifestations. A milder form of Wiskott-Aldrich syndrome is known as the X-linked thrombocytopenia. We independently found eight individual or familial cases with the V75M substitution (9.76%). This high incidence was partly accounted for by the fact that three cases turned out to be related. The V75M mutation is recurrent, however, due to a CpG island. A genuine homozygous female patient was found. She showed microthrombocytopenia and infections to the same degree as her hemizygous father and brother. The WAS protein was decreased in a comparable fashion in the hemizygotes and the homozygote as well. Its amount was about 10% and 15% of normal in platelets and mononucleated white cells, respectively. In all patients was the picture consistent with XLT.
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http://dx.doi.org/10.1111/j.1600-0609.2005.00415.xDOI Listing
July 2005

B-domain deleted factor VIII is aggregated and degraded through proteasomal and lysosomal pathways.

Thromb Haemost 2005 May;93(5):824-32

Laboratoire d'Hémobiologie, Faculté de Médecine RTH Laennec, Lyon, France.

Factor VIII (FVIII) processing within mammalian cells is demonstrated to be much less efficient than proteins of similar size. The deletion of the B-domain from FVIII improves the level of production, due partly to the increase in mRNA synthesis. We aimed to characterise the cellular fate and the intracellular processing of the FVIII molecule devoid of B-domain. A B-domain deleted factor VIII (BDD-FVIII) possessing a furin consensus cleavage site in the connecting segment between the heavy and the light chain, was produced in CHO cell line. In such cells, FVIII was retained as two single chain products from which a majority was aggregated. The two species were located in Triton X-100 soluble (for 60-80%) and insoluble fractions (for 20-40%). The incubation of the expressing cells with tunicamycin (5 mug/ml) and the treatment of the intracellular species with a mixture of Neuraminidase and N-glycosidase-F revealed that both intracellular species were N-glycosylated. Furin over-expression neither diminished the intracellular FVIII contents nor improved its extracellular production. Intracellular FVIII was degraded through both lysosomal and proteasomal pathways as evidenced by inhibitor treatments (e.g. NH(4)Cl, leupeptin, clasto-Lactacystin beta-lactone and MG-132), pulse-chase analysis and confocal observations. This study demonstrates that a BDD-FVIII expressed in CHO cells is inefficiently processed consecutively to intracellular aggregation, proteasomal degradation, and routage to lysosomes.
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http://dx.doi.org/10.1160/TH04-09-0579DOI Listing
May 2005

Injection of recombinant activated factor VII can induce transient increase in circulating procoagulant microparticles.

Thromb Haemost 2004 May;91(5):873-8

INSERM Unit 143, Hôpital Bicêtre, Le Kremlin Bicêtre, France.

Recombinant activated factor VII (rFVIIa) is an effective haemostatic treatment in haemophiliacs with inhibitors. In vitro, FVIIa concentrations corresponding to those obtained with therapeutic doses of rFVIIa have been shown to induce normal thrombin generation and platelet activation in the absence of factors VIII or IX. To further study the in vivo haemostatic changes induced by rFVIIa, circulating procoagulant microparticles (MP) were measured in patients treated with discontinuous injections of Novoseven. In 6 out of 15 patients, a transient peak of procoagulant MP was observed after injection, occurring 15 min to 2 h after infusion. It was composed primarily of platelet-derived MP and was of very short duration. This peak was not observed in haemophiliacs without inhibitor, who were treated with conventional replacement therapies. Our results provide further in vivo evidence that rFVIIa specifically activates platelets, either directly or as a consequence of a burst of thrombin generation that could account for its haemostatic efficacy.
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http://dx.doi.org/10.1160/TH03-05-0301DOI Listing
May 2004

Protein A Sepharose immunoadsorption can restore the efficacy of platelet concentrates in patients with Glanzmann's thrombasthenia and anti-glycoprotein IIb-IIIa antibodies.

Br J Haematol 2002 Dec;119(4):991-7

Laboratoire d'Hématologie, Centre de Traitement de l'Hémophilie, Assistance Publique-Hôpitaux de Paris and Faculté de Médecine Paris XI, Le Kremlin-Bicêtre, Paris, France.

Type I Glanzmann's thrombasthenia is a rare congenital platelet function disorder, characterized by undetectable platelet membrane glycoprotein IIb-IIIa (GPIIb-IIIa). Severe bleeding is controlled by transfusion of normal platelets, leading in some cases to the occurrence of anti-GPIIb-IIIa isoantibodies, which induces a loss of transfused platelet efficacy. We used immunoadsorption on protein A Sepharose (IA-PA), which has been shown to be efficient in decreasing the titre of antibodies in several immune diseases, in three patients with Glanzmann's thrombasthenia and anti-GPIIb-IIIa isoantibodies on five different occasions. IA-PA was well tolerated with no deleterious side-effects reported. It induced a dramatic decrease of total immunoglobulin (Ig)G, including anti-GPIIb-IIIa isoantibody levels, as assessed by the monoclonal antibody-specific immobilization of platelet antigens test and the ex vivo inhibition of normal platelet aggregation induced by the patient's platelet-rich or platelet-poor plasma. Elimination of the antibody was associated with a correction of the bleeding time following platelet transfusion. IA-PA combined with platelet transfusion made it possible to control two life-threatening haemorrhages, and allowed two surgical procedures and one bone marrow transplantation to be performed safely. Our experience suggests that IA-PA, which restores the haemostatic efficacy of platelet transfusion, is a valuable therapeutic strategy in patients with Glanzmann's thrombasthenia and anti-GPIIb-IIIa isoantibodies.
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http://dx.doi.org/10.1046/j.1365-2141.2002.03936.xDOI Listing
December 2002