New insights into the expression and role of platelet FXIII-A

25 p.-6 fig.Background: The A subunit of factor XIII (FXIII-A) functions as an intracellular transglutaminase (TG) in the megakaryocyte/platelet lineage, where it probably participates in the cytoskeletal remodeling associated with cell activation. However, so far, the precise role of cellular FXIII (cFXIII) and the functional consequences of its absence in FXIII-A-deficient patients are unknown. Objectives and methods: In this study, we used platelets from four patients with congenital deficiency of FXIII-A to study the role of cFXIII in platelet functions. Results: We found that FXIII-A represents the only detectable source of TG activity in platelets and that the binding of fibrinogen in response to thrombin receptor agonist peptide (TRAP) stimulation was significantly reduced in platelets from the patients. In agreement with this, in control platelets, monodansyl-cadaverine (MDC), a competitive amino-donor for TGs, inhibited fibrinogen binding induced by TRAP in a dose-dependent manner. Moreover, upon adhesion to fibrinogen, normal platelets incubated with MDC as well as FXIII-A-deficient platelets showed a distinct extension pattern with reduced lamellipodia and increased filopodia formation, suggesting a delay in spreading. Conclusions: These findings provide evidence for the direct involvement of cFXIII-dependent TG activity in the regulation of platelet functionsThis work was supported by grants from the Dirección General de Investigación del Ministerio de Educación y Ciencia (BFU2006-00914) and Fundación Rodríguez Pascual. A. Jayo was recipient of a fellowship from the Ministerio de Educación y Ciencia. I. Conde holds a research contract from the Consejo Superior de Investigaciones Científica

Clinical trials and Haemophilia during the COVID-19 pandemic: Madrid's experience

This is the peer reviewed version of the following article: "Clinical trials and Haemophilia during the COVID‐19 pandemic: Madrid's experience". Haemophilia (2020): 16 May, which has been published in final form at https://doi.org/10.1111/hae.14055. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Version

Outcomes in children with hemophilia A with inhibitors: Results from a noninterventional study

Background: Data regarding management of pediatric persons with hemophilia A (PwHA) with factor VIII (FVIII) inhibitors are limited. This prospective noninterventional study (NCT02476942) evaluated annualized bleeding rates (ABRs), safety, and health-related quality of life (HRQoL) in pediatric PwHA with FVIII inhibitors. Procedure: PwHA aged <12 years with current FVIII inhibitors and high-titer inhibitor history were enrolled. Participants remained on usual treatment; no interventions were applied. Outcomes included ABR, safety, and HRQoL. Results: Twenty-four PwHA aged 2-11 years (median 7.5) were enrolled and monitored for 8.7-44.1 weeks (median 23.4). In the episodic (n = 10) and prophylactic (n = 14) groups, respectively, 121 of 185 (65.4%) and 101 of 186 (54.3%) bleeds were treated using activated prothrombin complex concentrate (aPCC) and/or recombinant activated FVII (rFVIIa). ABRs (95% confidence interval) were 19.4 (13.2-28.4) and 18.5 (14.2-24.0) for treated bleeds, and 32.7 (20.5-52.2) and 33.1 (22.4-48.9) for all bleeds, respectively. Most prophylactic group participants (92.9%) were prescribed aPCC; 50% adhered to their prescribed treatment regimen. Adherence to prophylactic rFVIIa was not assessed. Serious adverse events included hemarthrosis (12.5%) and mouth hemorrhage (12.5%); the most common nonserious adverse event was viral upper respiratory tract infection (12.5%). HRQoL showed functional impairment at baseline; scores remained stable throughout, with little intergroup variation. Conclusions: ABRs remained high in pediatric PwHA with inhibitors receiving standard treatment. This study demonstrates the need for more effective treatments, with reduced treatment burden, to prevent bleeds, increase prophylaxis adherence, and improve patient outcomes.Was funded by F. Hoffmann-La Roche Ltd

Challenges and key lessons from the design and implementation of an international haemophilia registry supported by a pharmaceutical company

Introduction: Real-world data are lacking regarding the relationship between prospectively collected patient-reported outcomes (PROs), clinical outcomes and treatment in people with haemophilia (PWH). The Expanding Communications on Hemophilia A Outcomes (ECHO) registry was designed to address this data gap, but a range of difficulties led to early study closure. Aim: To describe the challenges faced and lessons learned from implementing a multinational haemophilia registry. Methods: The Expanding Communications on Hemophilia A Outcomes was planned as a five-year observational cohort study to collect data from 2000 patients in nine countries. Based on direct observations, feedback from patients enrolled in ECHO, challenges of the study design and input from study-sponsor representatives, the ECHO Steering Committee systematically identified the challenges faced and developed recommendations for overcoming or avoiding them in future studies. Results: The study closed after two years because few countries were activated and patient recruitment was low. This was related to multiple challenges including delayed implementation, stringent pharmacovigilance requirements, objections of investigators and patients to the burden of multiple PROs, data collection issues, lack of resources at study sites, little engagement of patients and competing clinical trials, which further limited recruitment. At study closure, 269 patients had been enrolled in four of nine participating countries. Conclusions: Researchers planning studies similar to ECHO may want to consider the barriers identified in this global registry of PWH and suggestions to mitigate these limitations, such as greater patient involvement in design and analysis, clearer assessment and understanding of local infrastructure and potential changes to the administration of the study

International recommendations on the diagnosis and treatment of acquired hemophilia A

Acquired hemophilia A (AHA), a rare bleeding disorder caused by neutralizing autoantibodies against coagulation factor VIII (FVIII), occurs in both men and women without a previous history of bleeding. Patients typically present with an isolated prolonged activated partial thromboplastin time due to FVIII deficiency. Neutralizing antibodies (inhibitors) are detected using the Nijmegen-modified Bethesda assay. Approximately 10% of patients do not present with bleeding and, therefore, a prolonged activated partial thromboplastin time should never be ignored prior to invasive procedures. Control of acute bleeding and prevention of injuries that may provoke bleeding are top priorities in patients with AHA. We recommend treatment with bypassing agents, including recombinant activated factor VII, activated prothrombin complex concentrate, or recombinant porcine FVIII in bleeding patients. Autoantibody eradication can be achieved with immunosuppressive therapy, including corticosteroids, cyclophosphamide and rituximab, or combinations thereof. The median time to remission is 5 weeks, with considerable interindividual variation. FVIII activity at presentation, inhibitor titer and autoantibody isotype are prognostic markers for remission and survival. Comparative clinical studies to support treatment recommendations for AHA do not exist; therefore, we provide practical consensus guidance based on recent registry findings and the authors’ clinical experience in treating patients with AHA

Emicizumab prophylaxis in infants with hemophilia A (HAVEN 7): primary analysis of a phase 3b, open-label trial

Subcutaneous emicizumab enables prophylaxis for people with hemophilia A (HA) from birth, potentially reducing risk of bleeding and intracranial hemorrhage (ICH). HAVEN 7 (NCT04431726) is the first clinical trial of emicizumab dedicated to infants, designed to investigate the efficacy, safety, pharmacokinetics, and pharmacodynamics of emicizumab in those aged ≤12 months with severe HA without factor VIII (FVIII) inhibitors. Participants in this phase 3b trial received emicizumab 3 mg/kg maintenance dose every 2 weeks for 52 weeks and are continuing emicizumab during the 7-year long-term follow-up. Efficacy end points included annualized bleed rate (ABR): treated, all, treated spontaneous, and treated joint bleeds. Safety end points included adverse events (AEs), thromboembolic events (TEs), thrombotic microangiopathies (TMAs), and immunogenicity (anti-emicizumab antibodies [ADAs] and FVIII inhibitors). At primary analysis, 55 male participants had received emicizumab (median treatment duration: 100.3; range, 52-118 weeks). Median age at informed consent was 4.0 months (range, 9 days to 11 months 30 days). Model-based ABR for treated bleeds was 0.4 (95% confidence interval, 0.30–0.63), with 54.5% of participants (n = 30) having zero treated bleeds. No ICH occurred. All 42 treated bleeds in 25 participants (45.5%) were traumatic. Nine participants (16.4%) had ≥1 emicizumab-related AE (all grade 1 injection-site reactions). No AE led to treatment changes. No deaths, TEs, or TMAs occurred. No participant tested positive for ADAs. Two participants were confirmed positive for FVIII inhibitors. This primary analysis of HAVEN 7 indicates that emicizumab is efficacious and well tolerated in infants with severe HA without FVIII inhibitors

Type II Glanzmann thrombasthenia in a compound heterozygote for the [alpha]IIb gene. A novel missense mutation in exon 27 that results in enhanced skipping of exon 28

8 páginas, 5 figuras -- PAGS nros. 1352-1359Background and Objectives. Glanzmann thrombasthenia is an autosomal recessive bleeding disorder characterized by a life-long hemorrhagic tendency and absent or severely reduced platelet aggregation in response to agonists, caused by quantitative or qualitative abnormalities in the platelet fibrinogen receptor, integrin αIIbβ3. The aim of this study was to identify the molecular genetic defect and determine its functional consequences in a patient with type II Glanzmann thrombasthenia. Design and Methods. The expression of platelet αIIbβ3 was determined by flow cytometry and western blotting. Mutations were identified by sequencing both cDNA and genomic DNA. Functional characterization was assessed by exontrap and transient transfection analysis. Results. Flow cytometry and western blot analysis revealed markedly reduced levels of platelet αIIbβ3, which may account for the residual fibrinogen binding detected upon platelet activation. Sequencing of genomic DNA revealed the presence of two mutations in the αIIb gene: a C1750T transition in the last codon of exon 17 changing Arg553 to STOP, and a C2829T transition in exon 27 that changes Pro912 to Leu. Sequence analysis of reversely transcribed αIIb mRNA did not detect cDNA from the C1750T mutant allele, and revealed a significant increase of the physiological splicing out of exon 28 in the cDNA carrying the C2829T mutation. Transient expression of [912Leu]αIIb in CHO-β3 cells showed a marked reduction in the rate of surface expression of αIIbβ3. Interpretation and Conclusions. The results suggest that the thrombasthenic phenotype is the result of reduced availability of αIIb-mRNA, enhanced expression of exon 28- deleted transcripts, and defective processing of [912Leu]αIIbFunding: this work was supported by a grant from the Dirección General de Investigación of the Ministerio de Educación y Ciencia (BMC2003-01409). A. Jayo is recipient of a fellowship from the Ministerio de Educación y CienciaPeer reviewe

Possible role for cellular FXIII in monocyte-derived dendritic cell motility

19 p.- 5 fig.The A subunit of plasma factor XIII (FXIII-A) is thought to function as an intracellular transglutaminase (TG) in the monocyte/macrophage lineage to regulate certain intracellular processes involving cytoskeleton remodeling, but its precise role and the functional consequences of its absence remain poorly understood. In the present study, we show that cellular FXIII (cFXIII) expression is largely upregulated during in vitro differentiation of monocytes into dendritic cells (DCs). Monodansyl-cadaverine, a competitive substrate of TG activity, inhibited basal and CCL19-stimulated migration of mature DCs. In agreement, FXIII-A-deficient DCs showed a reduced chemotactic response to CCL19. Consistent with these findings, CHO cells stably expressing human FXIII-A showed enhanced motility in transwell and scratch-wound assays. These cells displayed increased formation of membrane blebs, dynamic cell protrusions implicated in cell movement that were also observed in DCs. The results provide evidence suggesting that upregulation of cFXIII in DCs has a role in regulating cell motilityThis work was supported by grants from the Dirección General de Investigación del Ministerio de Educación y Ciencia (BFU2006-00914) and Fundación Rodríguez Pascual. A. Jayo was recipient of a fellowship from the Ministerio de Educación y Ciencia. I. Conde holds a research contract from the Consejo Superior de Investigaciones CientíficasPeer reviewe

Optimizing joint function : new knowledge and novel tools and treatments

Progressive joint destruction resulting from intra-articular bleeding is the major morbidity affecting patients with haemophilia (PWH), particularly those with inhibitors. Advances in understanding the detrimental processes set in motion by the exposure of joints to bleeding have shaped current management methods. However, to achieve optimal joint health in PWH, in addition to achieving haemostasis at the bleeding vessel, it may be appropriate to explore experimentally other conceptual frameworks. These include the possibilities that markers might help to identify individuals at the risk of more rapid joint deterioration, that clotting factors may have additional local action within tissues, and that outcomes might be improved with therapies that directly address wound healing and inflammation. Joint assessment tools are important. Conventional radiography is frequently used, but given the possibility of subclinical joint bleeds, accurate non-invasive imaging tools are required to detect soft tissue and cartilage changes. Magnetic resonance imaging and ultrasonography can prove valuable here. New imaging techniques should help to increase understanding of the biological basis of early events in haemophilic arthropathy. The optimal way to measure outcomes in haemophilia is to use several methods - in addition to imaging methods, a 360° approach will use physical, functional and quality-of-life instruments. In PWH, inhibitor development complicates treatment of joint bleeds and increases the risk of developing arthropathy. A new therapeutic approach for joint bleeds in inhibitor patients divides treatment into two phases: bleed control, with bypassing agent therapy until bleeding has definitely ceased, followed by regular dosing to prevent rebleeds until synovial recovery is complete