Etude phénotypique et génotypique de patients hémophiles A modérés ou atténués avec anomalie qualitative (rapports structure / fonction du facteur VIII)

Nous avons évalué l'activité du facteur VIII de la coagulation (FVIII:C) en utilisant 2 techniques différentes (méthode chronométrique en 1 temps et méthode chromogénique) chez 307 patients hémophiles A modérés/atténués issus de 173 familles. Il existe une discordance entre les 2 méthodes chez 36 patients appartenant à 17 (10%) familles. Dans 14 de ces familles où l'anomalie moléculaire a pu être recherchée, une mutation a été mise en évidence : 5 nouvelles mutations du gène du FVIII sont identifiées : p.Pro264Leu, p.His281Asn, p.Ile369Thr, p.Phe1785Leu et p.Phe2127Ser. Nous rapportons également les résultats de l analyse génétique de 130 autres familles : 29 nouvelles mutations sont décrites en étudiant les conséquences moléculaires de ces substitutions d acides aminés grâce à une modélisation 3D de la protéine du FVIII. Dans 2 familles (X et Y) avec des résultats de FVIII:C discordants selon la technique, nous étudié l'intérêt de la thrombinographie (TG) pour évaluer le risque hémorragique. Soixante et un patients hémophiles sans discordance dans les résultats de FVIII:C et 15 sujets normaux servirent de contrôles. La famille X ne présentait aucun antécédent hémorragique contrairement à la famille Y. Pour les membres de la famille X, les résultats étaient normaux ; ceux de la famille Y se sont comparables à ceux des patients hémophiles A sans discordance biologique. Ces résultats suggèrent que la TG peut avoir une pertinence clinique chez les patients hémophiles modérés/atténués, particulièrement en cas de discordance des taux de FVIII:C en fonction de la méthode.We measured factor VIII activity (FVIII:C) using 2 methods (one-stage chronometric and chromogenic assays) in 307 patients with moderate/mild hemophilia belonging to 173 families. Thirty-six patients from 17 (10%) families exhibited discrepancy between the two assays. Five novel FVIII mutations associated with discrepancy were described: p.Pro264Leu, p.His281Asn, p.Ile369Thr, p.Phe1785Leu and p.Phe2127Ser. Furthermore, we report on the spectrum of mutations in 130 other families with moderate/mild hemophilia A. Twenty-eight novel missense mutations and one single-residue deletion are described. We studied their putative involvement at known FVIII functional sites, their conservation status with cross-species FVIII proteins, and their spatial position within the FVIII 3D conformation. In 2 of these families (X and Y) with discrepant FVIII:C results, we examined whether thrombography (TG) could provide a better evaluation of the haemostatic status of these patients. Sixty-one moderate/mild haemophiliacs without discrepancy and 15 healthy subjects served as controls. Family X had no serious bleedings by contrast to family Y. For members of family X, the TG parameters were normal whereas for those of family Y they were diminished, similar to results of moderate/mild haemophiliacs without discrepancy. These results suggest that the haemostatic phenotype assessed by TG may be clinically relevant in moderate/mild hemophilic patients with discrepant FVIII:C results.NANTES-BU Médecine pharmacie (441092101) / SudocSudocFranceF

Évaluation d un nouveau score clinique dans l appréciation du risque hémorragique (étude monocentrique et prospective sur 324 patients en 2009)

L expression clinique des pathologies de l hémostase est très hétérogène et peut varier pour un même profil biologique. Cela rend très difficile l évaluation du risque hémorragique. Nous avons développé un score hémorragique permettant la standardisation du recueil des symptômes hémorragiques et l évaluation de la tendance hémorragique du patient (profil saigneur et non saigneur ) et améliorant le dialogue entre cliniciens. Il a été corrélé aux tests biologiques de référence et montre de bonnes performances en tant qu outil diagnostique. Ce score est un outil très prometteur dans l évaluation clinique des troubles de l hémostase primaire et des troubles de la coagulation.NANTES-BU Médecine pharmacie (441092101) / SudocSudocFranceF

Intérêt du suivi des D-dimères pour le diagnostic de thrombose au cours du traitement par L-asparaginase des LAL de l'enfant

La chimiothérapie des LAL de l'enfant incluant la L-asparaginase, associée aux effets de la maladie, aux infections et éventuellement aux facteurs héréditaires entraîne un état d'hypercoagulabilité. Chez ces enfants à risque thromboembolique élevé, il n'existe à l'heure actuelle aucun marqueur biologique capable de prédire ou d'aider au diagnostic de thrombose. Dans le cadre du protocole FRALLE 2000, les D-dimères ont été dosés chez 26 enfants au cours de leur phase d'induction et d'intensification. Trois événements thrombotiques sont survenus chez trois enfants: deux thromboses veineuses et une thrombose artérielle. Nous avons évalué les D-dimères soit comme marqueur d'exclusion en déterminant des seuils à chaque injection de L-asparaginase, soit comme marqueur prédictif de survenue de thrombose en calculant un seuil pour chaque phase. Mais notre étude reste limitée par le nombre insuffisant d'événement thrombotique et comporte des biais comme l'existence possible de thromboses infra-cliniques. En pratique, les D-dimères ne peuvent être utilisés comme marqueur d'exclusion du fait de leur mauvaise spécificité, ni comme marqueur prédictif du fait de leur élévation transitoire en début de traitement et du délai non maîtrisé de survenue de l'accident.NANTES-BU Médecine pharmacie (441092101) / SudocSudocFranceF

Use of clinical biological tests of haemostasis to evaluate topical haemostatics

International audienceIntroductionIn addition to traditional means, topical haemostatics are currently used to avoid haemorrhage during surgery. Although they have been reported to be effective, there is a low level of proof of their clinical efficacy, which is at odds with their levels of use. This study used two methods to better understand their in vitro mechanism of action.MethodsTwo clinical biology assays were used to measure the action of topical haemostatics on primary and secondary haemostasis. Calibrated samples of collagen sponges and polypropylene non-woven gauze were tested. Platelet aggregation was assessed using a multichannel aggregometer. A thrombin generation assay (TGA) was used with a fluorogenic readout. Tissue factor solutions were used to activate coagulation.ResultsIn terms of primary haemostasis, collagen sponges stimulated platelet aggregation, in particular between 2 and 5 min after incubation with platelet-rich plasma and with no dose effect. In regard to coagulation, the kinetics of thrombin generation was enhanced. Polypropylene non-woven gauze did not exhibit any effect on platelet aggregation, although it did have a weak effect on the kinetics of thrombin generation.ConclusionCollagen is well known to exert a haemostatic effect due to its action on platelet aggregation. By contrast, polypropylene non-woven gauze has not been shown to have any effect on platelet aggregation other than a minor impact on thrombin generation. The results obtained with the devices tested are in agreement with the literature. Platelet aggregation biological assays and TGA measurements appear to be suitable for evaluation of these medical products

An observational study of haemophilia A patients without inhibitors using the French national claims (SNDS) database

To describe clinical characteristics, factor consumption, and events of interest in patients with haemophilia A without inhibitors receiving prophylaxis in France, and the clinical impact of switching to Elocta® in this population. This retrospective, observational study using the Système National des Données de Santé database, analysed data from patients with haemophilia A without inhibitors using prophylactic factor VIII (FVIII) replacement therapy during 2016–2019. Clinical characteristics, treatment patterns and switches, factor consumption, and rate of events of interest were determined. In a sub-cohort of patients treated with Elocta®, clinical characteristics, factor consumption, and rate of events of interest before and after switching to Elocta® were compared. For 545 patients, with mean age (standard deviation [SD]) 25.4 (17.8) years, Elocta® was the most used treatment. Bleeding events and articular non-bleeding events leading to hospitalization occurred in 15.4% and 13.9% of patients, respectively, and 9.9% of patients had surgeries or procedures related to haemophilic arthropathy. The mean (SD) FVIII product consumption was 344 (93) IU/kg/month for extended half-life treatment, and 331 (98) IU/kg/month for standard half-life products. For the sub-cohort of 146 patients, bleeding events (SD) decreased from 0.32 (2.2) to 0.09 (0.42) events/patient/year (p = 0.227) after switching to Elocta®. There was no statistically significant difference in rates of factor consumption or articular non-bleeding events before and after initiation of Elocta®. This study provides real-world insights that advance the understanding of treatment patterns and events of interest in patients with haemophilia A on prophylactic regimens in France.</p

Genotype-dependent response to desmopressin in hemophilia A and proposal of a predictive response score

International audienceDesmopressin (DDAVP) is used in patients with moderate/mild hemophilia A (PWMH) to increase their factor VIII (FVIII) level and, if possible, normalize it. However, its effectiveness varies between individuals. The GIDEMHA study aims to investigate the influence of F8 gene variants. The study collected the evolution of FVIII levels from therapeutic intravenous DDAVP tests in 4 French hemophilia treatment centers. A pharmacological analysis was performed associated with efficacy scores according to F8 variants: absolute and relative responses, as well as new scores: absolute duration (based on duration with FVIII ≥0.50 IU.mL-1) and relative duration (based on half-life). From enrolled 439 PWMH, 327 had a hot-spot F8 variant (with ≥5 PWMH). For these, the median (min-max) basal and peak FVIII were 0.20 (0.02-0.040) and 0.74 (0.14-2.18) IU.mL-1 respectively, with FVIII recovery being 3.80 IU.ml-1 (1.15-14.75). The median FVIII half-life was 3.9h (0.7-15.9h). FVIII was normalized (≥0.50 IU.mL-1) in 224/327 PWMH (69%) and the median time with normalized FVIII was 3.9h (0.0-54.1h). Following the response profiles to DDAVP defined by the 4 efficacy scores, 4 groups of F8 variants were isolated then compared into survival curves with normalized FVIII (p&amp;lt;0.0001): “long lastingly effective” [p.(Glu739Lys), p.(Ser2030Asn), p.(Arg2178His), p.(Gln2208Glu) and T-stretch deletion in intron 13]; “moderately effective” [p.(Ser112Phe), p.(Ala219Thr), p.(Thr2105Ile), p.Phe2146Ser) and p.(Asp2150Asn)]; “moderately ineffective” [p.Ala81Asp), p.(Gln324Pro), p.(Tyr492His), p.(Arg612Cys), p.(Met701Val), p.(Val2035Asn) and p.(Arg2178Cys)]; and “frequently ineffective” [c.-219C&amp;gt;T, p.(Cys2040Tyr), p.(Tyr2169His), p.(Pro2319Leu) and p.(Arg2326Gln)]. In view of our data, we propose indications for DDAVP-use in PWMH based on F8 variants for minor and major invasive procedures.Clinical Trial: Registration number (trial ID): NCT05628558, Trial registry: ClinicalTrials.gov (http://www.clinicaltrials.gov/), Type of Study: Multicenter stud

Prostate interventions in patients with mild haemophilia: Safe and feasible

International audienceIntroduction: To date, there is no specific recommendation or evaluation of the morbidity of prostate surgery in patients with haemophilia (PWH) although this surgery is common and at high risk of bleeding.Aim: To assess the post-operative morbidity of benign prostate hyperplasia (BPH) surgeries and of oncological prostate interventions in patients with mild haemophilia A or B.Methods: We performed a monocentre, epidemiological, in real life study. Data were collected between 1 January, 1997 and 1 September, 2020 and focused on prostate biopsy, radical prostatectomy, prostate radiotherapy, simple prostatectomy, transurethral resection of prostate (TURP) and laser-vaporisation in patients with mild haemophilia A or B.Results: Between 1 January, 1997 and 1 September, 2020, 51 interventions were performed on 30 patients with mild haemophilia. Haemophilia A represented 93.33% of the population and haemophilia B 6.67%. For prostate biopsies (n = 24), median length of hospitalisation was 4 days and only one patient needed a blood transfusion. No patient needed re-admission. For prostatectomy (n = 10), one patient presented with intra-operative and post-operative bleeding. Two patients required re-admission. The other patients did not present any significant haemorrhagic symptoms. For radiotherapy (n = 4), two patients presented a grade II complication (radiocystitis and radiorectitis). For BPH surgeries, during hospitalisation, laser-vaporisation (n = 5) was less haemorrhagic than TURP (n = 5) but after hospital discharge, 60% of patients presented a haemorrhagic complication with two readmissions and one surgical re-explorations.Conclusion: Performed in a specialised centre, prostate surgeries and interventions in patients with mild haemophilia is feasible with acceptable morbidity

A Thrombin-Activatable Factor X Variant Corrects Hemostasis in a Mouse Model for Hemophilia A

International audienc