Background Denecimig (Mim8) is a fully human, activated FVIII mimetic bispecific antibody in development for subcutaneous prophylaxis to prevent bleeding in people with haemophilia A (HA). Objectives Report efficacy and safety of denecimig over 52 weeks in adolescents and adults from FRONTIER2 (NCT05053139). Methods Males and females (≥12 years) with HA (any severity), with/without inhibitors, were enrolled. In the 26-week main phase, patients previously treated on-demand were randomised to continued on-demand treatment (Arm 1), denecimig once-every-week (QW; Arm 2a) or once-every-month (QM; Arm 2b); patients previously receiving clotting factor concentrate prophylaxis were randomised to denecimig QW (Arm 3) or QM (Arm 4). In the 26-week extension, patients in Arm 1 switched to denecimig QW or QM; other arms followed the same dosing frequency. Annualised bleeding rate (ABR) of treated bleeds was estimated using a negative binomial model. Results In the main phase, 281 patients were randomised; 272 entered the extension. Estimated mean ABR in the extension for Arm 1 was 0.67 (QW) and 0.79 (QM). Mean ABR over 52 weeks was 0.37, 0.21, 2.02 and 1.65 in Arms 2a, 2b, 3 and 4, respectively. Most baseline target joints resolved. No hypersensitivity reactions, thromboembolic events or clinical evidence of neutralising anti-denecimig antibodies occurred. Injection-site reactions occurred in 1.81% and 1.34% of denecimig QW and QM injections administered, respectively. Patient-reported physical function improved; treatment burden and joint pain reduced. Conclusions Denecimig maintained low ABRs over 52 weeks, was well tolerated and improved patient-reported outcomes in adolescents and adults with HA with/without inhibitors.

Introduction Mim8 is a new-generation, bispecific antibody, activated factor VIII mimetic in clinical development for subcutaneous prophylaxis (PPX) in hemophilia A (HA) with or without factor VIII inhibitors. The phase 3 FRONTIER2 study (NCT05053139) demonstrated that Mim8 once every week (QW) or once every month (QM) significantly reduced the annualized bleeding rate for treated bleeds compared with continued on-demand treatment or previous clotting factor concentrate (CFC) PPX. Improvements in patient-reported outcomes (PROs) were observed during the 26-week main phase.Objective Assess PROs with Mim8 PPX over 52 weeks.Methods FRONTIER2 is an open-label, randomized trial in patients aged ≥12 years with HA, with or without inhibitors. Participants receiving on-demand treatment before the study were randomized to Mim8 PPX QW (Arm 2a) or QM (Arm 2b) for 52 weeks (main + extension), or to continue on-demand treatment (Arm 1) for 26 weeks (main) then switch to Mim8 QW or QM for another 26 weeks (extension). Participants on prior CFC PPX were randomized to Mim8 QW (Arm 3) or QM (Arm 4) for 52 weeks (main + extension). PROs were assessed at baseline, Week 26, and Week 52 using three instruments: the Hemophilia Treatment Experience Measure (Hemo-TEM; range 0–100; lower scores indicate lower burden, ≥8-point reduction defined as clinically meaningful improvement), the physical functioning domain of the Pediatric Quality of Life Inventory (PedsQL; range 0–100; higher scores indicate better functioning), and the Joint Pain Rating Scale (JPRS; range 0–10; lower scores indicate less pain). Additionally, the Patient Global Impression of Change (PGI-C) for pain and physical function and the Hemophilia Patient Preference Questionnaire (HPPQ) were assessed at Week 26 and Week 52. Changes were calculated from the start of Mim8 PPX (Week 0 for Arms 2a/2b/3/4; Week 26 for Arm 1).Results Comparable PRO results were observed across QW and QM dosing; therefore, results were pooled by previous treatment (Arm 1, Arms 2a/2b, Arms 3/4). A total of 281 participants were included in the full analysis set. Mean age was 32 (Arm 1), 32 (Arm 2a/2b), and 31 years (Arms 3/4). Most participants were male (99%) and weighed ≥45 kg (94%). This report includes 27 patients from China (Arm 1, n=1; Arms 2a/2b, n=2; Arms 3/4, n=24) absent from the prior 26-week abstract (Mancuso et al. ISTH 2024; LB01.5). At Week 52, mean changes in Hemo-TEM total scores from baseline were –16.0 in Arm 1 (n=13), –12.7 in Arms 2a/2b (n=29), and –9.7 in Arms 3/4 (n=182). Clinically meaningful improvement was achieved by 8/13 (62%), 16/29 (55%), and 84/182 (46%) respectively. At Week 52, a fairly strong or very strong preference for Mim8 over previous treatment was reported by 15/17 (88%) of participants in Arm 1, 39/40 (98%) in Arms 2a/2b, and 175/192 (91%) in Arms 3/4 as assessed by HPPQ. Mean changes in PedsQL physical function scores were +13.0 in Arm 1 (n=13), +17.6 in Arms 2a/2b (n=29), and +4.0 in Arms 3/4 (n=167). Improvements in PGI-C physical function were reported by 17/17 (100%) of participants in Arm 1, 36/40 (90%) in Arms 2a/2b, and 138/192 (72%) in Arms 3/4. Mean changes in JPRS joint pain scores were –1.8 in Arm 1 (n=13), –1.5 in Arms 2a/2b (n=29), and –0.4 in Arms 3/4 (n=184). Improvements in PGI-C pain intensity were reported by 15/17 (88%) of participants in Arm 1, 38/40 (95%) in Arms 2a/2b, and 115/192 (60%) in Arms 3/4.Discussion/Conclusion Mim8 PPX was associated with improvements across all assessed PROs over 52 weeks, including reduced treatment burden, improved physical function, decreased joint pain, and strong treatment preference. These findings are consistent with Week 26 results, indicating sustained patient-perceived benefits with continued Mim8 use. PROs were comparable between QW and QM dosing, supporting the flexibility of Mim8 tiered dosing. In Arms 3/4, the smaller magnitude of change may reflect a ceiling effect among participants on PPX at baseline. Patient preference data were highly favorable, including among participants already receiving PPX. These results support the long-term benefit of Mim8 in HA treatment, extending beyond bleed control. Consistent PRO improvements and strong patient preference highlight the potential for Mim8 to enhance the treatment experience and quality of life.

Background: Hemophilia A (HA) is predominantly associated with males due to Xlinked inheritance. Males and females with HA have shared unmet medical needs, highlighting the necessity for comprehensive care irrespective of sex.Objectives: This analysis investigated the efficacy and safety of emicizumab prophylaxis in 3 females with HA.Methods: HAVEN 6 (NCT04158648) is a phase III study of emicizumab in people with non-severe HA without factor (F)VIII inhibitors warranting prophylaxis per investigator assessment, and the study methodology has been reported previously. Female-specific endpoints included menstruation-related quality of life and menstruation heaviness. Results: HAVEN 6 enrolled 3 females aged >= 18 years and within reproductive age (n = 2 mild HA; n = 1 moderate HA; n = 2 receiving prior FVIII prophylaxis; n = 1 receiving prior episodic FVIII). Participants presented with diverse bleeding phenotypes at baseline: 2 had no bleeds in the 24 weeks prior to enrollment, while 1 had an annualized bleed rate for all bleeds of 208.6. On-study annualized bleed rates for all bleeds were 0, 2.8, and 11.6, respectively. The 2 evaluable participants indicated improved menstruation-related quality of life vs baseline. Two participants experienced 3 grade 1/2 treatment-related adverse events; no new safety signals were identified. All 3 participants preferred emicizumab over their previous treatment and reported a better score for treatment burden and preoccupation domains of the Comprehensive Assessment Tool of Challenges in Hemophilia questionnaire.Conclusion: Overall, results were consistent with those reported in the male population enrolled in the HAVEN 6 study, suggesting efficacy and a favorable safety profile for emicizumab in females with non-severe HA warranting prophylaxis.

Patients with a bleeding tendency with normal laboratory tests have been described as having an unclassified bleeding disorder or bleeding disorder of unknown cause (BDUC). There are very little data available on how to manage pregnancy.

Background Bleeding of unknown cause (BUC) and unclassified bleeding disorders (UBD) are increasingly recognized. There is no guidance on diagnosis and management. Objectives To examine UK haemophilia centre registration patterns and current practice for UBD patients. Methods In a two-step process, the UK National Haemophilia Database (NHD) was reviewed for registration patterns of UBD patients and a survey of UK haemophilia centers was conducted (January/February 2021) to capture current practice for diagnosis and management of patients with UBD. Results/discussion Overall, registrations with the NHD for UBD patients has sharply risen from 2012 to 2020 and in 2019 accounted for 2.65% of registered patients. For the survey, the response rate was 52/67 (78%). Practice was widely variable; 35/52 (67%) centers register UBD; among these 35 centers, terminology included UBD (28 centers), undiagnosed bleeding disorder (four centers), and BUC (three centers); 34/52 (65%) centers use a formal bleeding assessment tool. For management of dental extraction and high bleeding risk surgery in a fictional UBD patient we found that tranexamic acid was widely used; however, beyond this a variety of hemostatic products were advised including blood products, recombinant factor VIIa/prothrombin complex concentrate, and desmopressin. There was general consensus (approximate to 90%) on avoiding regional anesthesia in pregnancy, but no agreement on the need for fetal precautions to avoid bleeding at delivery (50% would advise these). There was a disparity of opinion on chemical thromboprophylaxis, and management of patients without prior hemostatic challenges and offspring of these patients. Conclusion This study provides a snapshot of current practice and real-world data in this area. Future studies need to address the gaps in evidence.

Unclassified bleeding disorders account for 2.6% of all new bleeding disorder registrations in the UK. The management of the bleeding phenotype associated with these disorders is poorly described. Systematic review and meta-analysis to determine the bleeding rates associated with tranexamic acid, desmopressin, platelet transfusion, plasma transfusion and recombinant activated factor VII, for patients with unclassified bleeding disorders undergoing surgery, childbirth or with menorrhagia. We searched for randomized controlled trials in MEDLINE, Embase, The Cochrane Central Register of Controlled Trials, PubMed, ISI Web of Science and the Transfusion Evidence Library from inception to 24 February 2020. Wherever appropriate, data were pooled using the metaprop function of STATA. Two studies with 157 participants with unclassified bleeding disorders were identified. The pooled risk of minor bleeding for patients undergoing surgery treated with peri-operative tranexamic acid was 11% (95% confidence interval 3--20%; n = 52; I-2 = 0%); the risk for desmopressin and tranexamic acid in combination was 3% (95% confidence interval 0--7%; n = 71; I-2 = 0%). There were no instances of major bleeding. In one procedure, 1 of 71 (1.4%), treated with a combination of desmopressin and tranexamic acid, the patient had a line-related deep vein thrombosis. There were too few patients treated to prevent postpartum haemorrhage or for menorrhagia to draw conclusions. The GRADE quality of evidence was very low suggesting considerable uncertainty over the results. However, both tranexamic acid, and the combination of tranexamic and desmopressin have high rates of haemostatic efficacy and have few adverse events. Protocol registration PROSPERO CRD42020169727.

Introduction One of the most often stated tenets of haemophilia care is that prophylaxis converts a person from a severe to a moderate phenotype. In this review, we argue that this is not an accurate assumption and that people on prophylaxis predominantly have factor VIII/IX levels in the mild range. Moderate haemophilia and prophylaxis People with moderate haemophilia, who are treating with on-demand regimens, experience joint bleeds and often develop significant arthropathy. This is especially true for people with a baseline level of 1-3 IU/dl, as first reported 55 years ago, and confirmed in more recent studies. Evidence is emerging suggesting that people with severe haemophilia who are using prophylaxis have better musculoskeletal outcomes than people with moderate haemophilia treated episodically. Trough levels The debate around the optimum trough level whilst on prophylaxis is ongoing. It is not appropriate to extrapolate information about baseline levels to recommendations about target trough levels on prophylaxis because these are different situations. Studies are emerging that support higher target trough levels than previously used, but in spite of this, the aim of achieving zero bleeds remains elusive with both factor replacement and non-replacement therapies. Conclusions We recommend that people with moderate haemophilia, especially those with a baseline of 1-3 IU/dl, should be offered prophylaxis based on the same criteria as people with severe haemophilia. Trough levels should be maintained above 3 IU/dl or higher if a level of 3 IU/dl does not control breakthrough bleeding and prophylaxis should be tailored to the bleeding phenotype. This advice is in line with recently published guidelines from the World Federation of Haemophilia and the UK Haemophilia Centre Doctors' Organisation.

HaemophiliaVolume 26, Issue 4 p. e209-e210 LETTER TO THE EDITOR Diagnostic work up of patients with increased bleeding tendency: Comment Will Thomas, Corresponding Author Will Thomas w.thomas1@nhs.net orcid.org/0000-0001-8740-0194 Department of Haematology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK Correspondence Will Thomas, Department of Haematology, Cambridge University Hospitals NHS Foundation Trust, Hills Road, Cambridge CB2 0QQ, UK. Email: w.thomas1@nhs.netSearch for more papers by this authorDanielle White, Danielle White Department of Haematology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UKSearch for more papers by this authorStephen MacDonald, Stephen MacDonald Department of Haematology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UKSearch for more papers by this authorKate Downes, Kate Downes Department of Haematology, University of Cambridge, Cambridge, UK East Midlands and East of England Genomic Laboratory Hub, Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, Cambridge, UKSearch for more papers by this authorSamya Obaji, Samya Obaji Cardiff Haemophilia Centre, University Hospital of Wales, Cardiff, UKSearch for more papers by this authorMichael Desborough, Michael Desborough orcid.org/0000-0002-1951-5616 Haemostasis and Thrombosis Centre, St Thomas' Hospital, London, UKSearch for more papers by this author Will Thomas, Corresponding Author Will Thomas w.thomas1@nhs.net orcid.org/0000-0001-8740-0194 Department of Haematology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK Correspondence Will Thomas, Department of Haematology, Cambridge University Hospitals NHS Foundation Trust, Hills Road, Cambridge CB2 0QQ, UK. Email: w.thomas1@nhs.netSearch for more papers by this authorDanielle White, Danielle White Department of Haematology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UKSearch for more papers by this authorStephen MacDonald, Stephen MacDonald Department of Haematology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UKSearch for more papers by this authorKate Downes, Kate Downes Department of Haematology, University of Cambridge, Cambridge, UK East Midlands and East of England Genomic Laboratory Hub, Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, Cambridge, UKSearch for more papers by this authorSamya Obaji, Samya Obaji Cardiff Haemophilia Centre, University Hospital of Wales, Cardiff, UKSearch for more papers by this authorMichael Desborough, Michael Desborough orcid.org/0000-0002-1951-5616 Haemostasis and Thrombosis Centre, St Thomas' Hospital, London, UKSearch for more papers by this author First published: 20 April 2020 https://doi.org/10.1111/hae.13989Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume26, Issue4July 2020Pages e209-e210 RelatedInformation

Tissue factor (TF) is critical for the activation of blood coagulation. TF function is regulated by the amount of externalised phosphatidylserine (PS) and phosphatidylethanolamine (PE) on the surface of the cell in which it is expressed. We investigated the role PS and PE in fibroblast TF function. Fibroblasts expressed 6-9 x 104 TF molecules/cell but had low specific activity for FXa generation. We confirmed that this was associated with minimal externalized PS and PE and characterised for the first time the molecular species of PS/PE demonstrating that these differed from those found in platelets. Mechanical damage of fibroblasts, used to simulate vascular injury, increased externalized PS/PE and led to a 7-fold increase in FXa generation that was inhibited by annexin V and an anti-TF antibody. Platelet-derived extracellular vesicles (EVs), that did not express TF, supported minimal FVIIa-dependent FXa generation but substantially increased fibroblast TF activity. This enhancement in fibroblast TF activity could also be achieved using synthetic liposomes comprising 10% PS without TF. In conclusion, despite high levels of surface TF expression, healthy fibroblasts express low levels of external-facing PS and PE limiting their ability to generate FXa. Addition of platelet-derived TF-negative EVs or artificial liposomes enhanced fibroblast TF activity in a PS dependent manner. These findings contribute information about the mechanisms that control TF function in the fibroblast membrane.

Approximately 2.4% of the human mitochondrial DNA (mtDNA) genome exhibits common homoplasmic genetic variation. We analyzed 12,975 whole-genome sequences to show that 45.1% of individuals from 1526 mother-offspring pairs harbor a mixed population of mtDNA (heteroplasmy), but the propensity for maternal transmission differs across the mitochondrial genome. Over one generation, we observed selection both for and against variants in specific genomic regions; known variants were more likely to be transmitted than previously unknown variants. However, new heteroplasmies were more likely to match the nuclear genetic ancestry as opposed to the ancestry of the mitochondrial genome on which the mutations occurred, validating our findings in 40,325 individuals. Thus, human mtDNA at the population level is shaped by selective forces within the female germ line under nuclear genetic control, which ensures consistency between the two independent genetic lineages.

HaemophiliaVolume 25, Issue 1 p. e59-e65 LETTER TO THE EDITOR Mycophenolate mofetil as adjunctive therapy in acquired haemophilia A Samya Obaji, orcid.org/0000-0002-8195-9621 Department of Haematology, University Hospital of Wales and Cardiff University, Cardiff, UKSearch for more papers by this authorRachel Rayment, Arthur Bloom Haemophilia Centre, University Hospital of Wales, Cardiff, UKSearch for more papers by this authorPeter W. Collins, Corresponding Author Peter.Collins@wales.nhs.uk orcid.org/0000-0002-6410-1324 Arthur Bloom Haemophilia Centre, University Hospital of Wales, Cardiff, UK Correspondence Peter Collins, Arthur Bloom Haemophilia Centre, University Hospital of Wales, Cardiff, UK. Email: Peter.Collins@wales.nhs.ukSearch for more papers by this author Samya Obaji, orcid.org/0000-0002-8195-9621 Department of Haematology, University Hospital of Wales and Cardiff University, Cardiff, UKSearch for more papers by this authorRachel Rayment, Arthur Bloom Haemophilia Centre, University Hospital of Wales, Cardiff, UKSearch for more papers by this authorPeter W. Collins, Corresponding Author Peter.Collins@wales.nhs.uk orcid.org/0000-0002-6410-1324 Arthur Bloom Haemophilia Centre, University Hospital of Wales, Cardiff, UK Correspondence Peter Collins, Arthur Bloom Haemophilia Centre, University Hospital of Wales, Cardiff, UK. Email: Peter.Collins@wales.nhs.ukSearch for more papers by this author First published: 18 December 2018 https://doi.org/10.1111/hae.13658Citations: 3Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat Citing Literature Volume25, Issue1January 2019Pages e59-e65 RelatedInformation

Background Phospholipids on the surface of platelets play a key role in supporting coagulation in both health and disease. Alterations to phospholipid composition in platelets can contribute to thrombotic and bleeding disorders. We recently identified pro-coagulant enzymatically oxidized phospholipids (eoxPL) generated by platelets in response to thrombin activation via cyclooxygenase-1 (COX) and 12-lipoxygenase (LOX). It is not known how these lipids vary in relation to aspirin (a COX inhibitor) supplementation and/or gender. Methods Twenty-eight healthy volunteers (14 males, 14 females) donated blood for platelet isolation at baseline (following a 14-day NSAID washout) and after 7-day supplementation with 75 mg aspirin. Repeat sampling took place 2 months and 4 months later to account for variations over time. Lipids were extracted from platelets either basally or following 30 min thrombin activation then analysed using liquid chromatography with tandem mass-spectrometry (LC-MS/MS) for the 49 most abundant eoxPL molecular species. Results The majority (96%) of eoxPL increased in response to thrombin activation of platelets. Gender differences were observed with a trend towards higher levels generated by females. Correlation analysis highlighted clustering of eoxPL by enzymatic origin (12-LOX versus COX-1). Aspirin supplementation decreased eoxPL generated via COX-1 in both genders, but in males it increased levels of those generated by 12-LOX (p<0.05). Importantly, elevated levels of 12-hydroxyeicosatetraenoic acid (12-HETE)-containing eoxPL, which are known to be procoagulant, were observed. In contrast, generation of free 12-HETE was not affected by aspirin. Conclusion In this study, we found an influence of both gender and aspirin supplementation on the generation of eoxPL in thrombin-activated platelets from healthy volunteers. Further characterisation of the gender influence may reveal novel mechanisms that contribute to the risk of arterial thrombosis in human populations. Conflict of interest None declared

Significance Abdominal aortic aneurysm (AAA) is a disease of the abdominal aorta where inflammation causes damage and can ultimately lead to rupture. When this happens, uncontrolled internal bleeding can lead to death within minutes. Many aneurysms are not detected until they rupture, and for those that are, treatments to stop them progressing are limited. Here we used biophysics and genetically modified mice to show that a new family of lipids (fats) made by circulating blood cells promote AAA formation in the vessel wall because they directly regulate blood clotting. An approach that prevents AAA development was identified, based on intravenous administration of lipids. The studies provide insights into how AAA develops and may lead to novel therapies for this disease.

Key Points DIAPH1-related disorder has a bilineage hematological phenotype of macrothrombocytopenia and neutropenia associated with hearing loss. Eltrombopag increased proplatelet formation from cultured DIAPH1-related disorder megakaryocytes and improved platelet counts in vivo.

Platelets are anuclear cells that are essential for blood clotting. They are produced by large polyploid precursor cells called megakaryocytes. Previous genome-wide association studies in nearly 70,000 individuals indicated that single nucleotide variants (SNVs) in the gene encoding the actin cytoskeletal regulator tropomyosin 4 (TPM4) exert an effect on the count and volume of platelets. Platelet number and volume are independent risk factors for heart attack and stroke. Here, we have identified 2 unrelated families in the BRIDGE Bleeding and Platelet Disorders (BPD) collection who carry a TPM4 variant that causes truncation of the TPM4 protein and segregates with macrothrombocytopenia, a disorder characterized by low platelet count. N-Ethyl-N-nitrosourea-induced (ENU-induced) missense mutations in Tpm4 or targeted inactivation of the Tpm4 locus led to gene dosage-dependent macrothrombocytopenia in mice. All other blood cell counts in Tpm4-deficient mice were normal. Insufficient TPM4 expression in human and mouse megakaryocytes resulted in a defect in the terminal stages of platelet production and had a mild effect on platelet function. Together, our findings demonstrate a nonredundant role for TPM4 in platelet biogenesis in humans and mice and reveal that truncating variants in TPM4 cause a previously undescribed dominant Mendelian platelet disorder.