Immune tolerance induction with highly purified plasma-derived factor VIII containing von Willebrand factor in hemophilia A patients with high-responding inhibitors.

International audienceWe retrospectively evaluated the efficacy of immune tolerance induction (ITI) in a homogenous cohort of eight patients with constitutive severe hemophilia A with high-responding factor VIII (FVIII) inhibitors using Facteur VIII-LFB/Factane, a highly purified FVIII concentrate containing von Willebrand factor (VWF)

rFVIII-Fc in severe haemophilia A: The incentive switch in case of high risk of joint bleedings

International audienceBackground Efmoroctocog alfa, the first recombinant factor VIII fusion protein with extended half-life (rFVIII-Fc), has been hypothesized to lower FVIII consumption in patients with severe Haemophilia A (pwSHA), without reducing clinical efficacy. What about real life? Method MOTHIF-II was a noninterventional, multicentre, before/after study, via the collection of retrospective data from July 2015 to June 2016 (called T1), and from July 2017 to June 2018 (called T2), in 7 French haemophilia treatment centres. We examined the prescriptions and dispensations of factor VIII and the Annual Bleeding Rate (ABR), in pwSHA without current inhibitors on prophylaxis, before and after the introduction of rFVIII-Fc. The data gathered from the BERHLINGO research database and from the French Healthcare claims database with a determinist pairing process based on the national unique identification number. Results A total of 156 pwSHA were included in the prescription cohort and 83 in the ABR cohort. For switched patients, the mean amounts of prescribed FVIII were significantly higher during T1 compared to T2 (4333 (2052) vs. 3921 (2029) IU/kg/year/patient, p: 0.028); a significant decrease in their ABR was also observed between T1 and T2 (6.3 (6.0) vs. 4.4 (5.4), p: 0.047). These patients had a more severe bleeding profile centred on haemarthrosis. Conclusion The results are related to those of the pivotal clinical trials for the reduction in FVIII consumption following the switch to rFVIII-Fc, with a significant improvement in the haemorrhagic phenotype for pwSHA

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<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>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

A focus on dominant negative variants in a series of 170 heterozygous FXI-deficient patients

International audienceINTRODUCTION: Dominant-negative effects have been described for 10 F11 variants in the literature. AIM: The current study aimed at identifying putative dominant-negative F11 variants. MATERIAL AND METHODS: This research consisted in a retrospective analysis of routine laboratory data. RESULTS: In a series of 170 patients with moderate/mild factor XI (FXI) deficiencies, we identified heterozygous carriers of previously reported dominant-negative variants (p.Ser243Phe, p.Cys416Tyr, and p.Gly418Val) with FXI activities inconsistent with a dominant-negative effect. Our findings also do not support a dominant-negative effect of p.Gly418Ala. We also identified a set of patients carrying heterozygous variants, among which five out of 11 are novel, with FXI activities suggesting a dominant-negative effect (p.His53Tyr, p.Cys110Gly, p.Cys140Tyr, p.Glu245Lys, p.Trp246Cys, p.Glu315Lys, p.Ile421Thr, p.Trp425Cys, p.Glu565Lys, p.Thr593Met, and p.Trp617Ter). However, for all but two of these variants, individuals with close to half normal FXI coagulant activity (FXI:C) were identified, indicating an inconstant dominant effect. CONCLUSION: Our data show that for some F11 variants recognized has having dominant-negative effects, such effects actually do not occur in many individuals. The present data suggest that for these patients, the intracellular quality control mechanisms eliminate the variant monomeric polypeptide before homodimer assembly, thereby allowing only the wild-type homodimer to assemble and resulting in half normal activities. In contrast, in patients with markedly decreased activities, some mutant polypeptides might escape this first quality control. In turn, assembly of heterodimeric molecules as well as mutant homodimers would result in activities closer to 1:4 of FXI:C normal range

Influence of advancing age on clinical presentation, treatment efficacy and safety, and long-term outcome of pre-excitation syndromes: a retrospective cohort study of 961 patients included over a 25-year period

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Gynecological and obstetric outcome in the French cohort of women with factor XIII deficiency

International audienceIntroduction: Congenital factor XIII deficiency is a very rare bleeding disorder affecting 33 patients in France. Besides its role in fibrin clot stabilization, factor XIII is involved in placental attachment. Fetal miscarriages represent a frequent and concerning issue for these patients. The aim of the present study was to describe clinical characteristics of women presenting severe congenital FXIII deficiency in France, to focus on gynecological and obstetrical events, and to report the management of these rare situations. Methods: We conducted a retrospective study in the French Hemophilia Comprehensive Care and Clinical Hemostasis Centers. Women between 15 and 65 years with factor XIII activity < 10 IU dL(-1) were included. Biological, clinical and therapeutic events that occurred to these patients during their gynecological and obstetrical period were recorded.Results: Among 31 centers, eleven patients were included. The median age at diagnosis was 1.5 years (range: 0-35), and at inclusion it was 30 years (range: 15-63). Fetal miscarriage was the primary manifestations in 2 (18%) patients, the remaining were diagnosed during hemorrhage. Menorrhagias were reported by 2 women (27%), 13 pregnancies were reported by 9 women including one abortion. Every pregnancy was conducted under factor XIII substitution, no hemorrhagic episode was reported. Four patients (36%) experienced at least one fetal miscarriage with a total amount of 30 miscarriages with 6 occurring during substitution.Conclusion: Altogether, our data confirmed the high incidence of miscarriage in women with factor XIII deficiency. Good outcome of pregnancies required prophylaxis in accordance with international guidelines

LAMP5 Fine-Tunes GABAergic Synaptic Transmission in Defined Circuits of the Mouse Brain

International audienceLAMP5 is member of the LAMP family of membrane proteins. In contrast to the canonical members of this protein family, LAMP1 and LAMP2, which show widespread expression in many tissues, LAMP 5 is brain specific in mice. In C. elegans, the LAMP5 ortholog UNC-46 has been suggested to act a trafficking chaperone, essential for the correct targeting of the nematode vesicular GABA-transporter UNC-47. We show here that in the mouse brain LAMP5 is expressed in subpopulations of GABAergic forebrain neurons in the striato-nigral system and the olfactory bulb. The protein was present at synaptic terminals, overlapping with the mammalian vesicular GABA-transporter VGAT. In LAMP5-deficient mice localization of the transporter was unaffected arguing against a conserved role in VGAT trafficking. Electrophysiological analyses in mutants showed alterations in short term synaptic plasticity suggesting that LAMP5 is involved in controlling the dynamics of evoked GABAergic transmission. At the behavioral level, LAMP5 mutant mice showed decreased anxiety and deficits in olfactory discrimination. Altogether, this work implicates LAMP5 function in GABAergic neurotransmission in defined neuronal subpopulations