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For several decades, therapeutic options for inherited deficiencies of factor VIII or IX (hemophilia A or B, respectively) have largely been the replacement of the missing clotting factor with plasma-derived or recombinant products. Hemostasis laboratories use standard activated partial thromboplastin time (aPTT)-based clotting or chromogenic assays to monitor plasma factor levels to guide therapy. The emergence in the past 10 years of extended half-life replacement products and other novel therapies for hemophilia has led to a reappraisal of assay suitability, with studies of product measurement showing some existing assay types or reagents to be unsuitable for some products. The hemostasis laboratory must adapt to the changing landscape by adding new assays or modifying existing assays to ensure accurate results for product measurement. These strategies include switching from a chromogenic assay to a clotting assay, or vice versa, changing an aPTT reagent brand, or introducing product specific calibrators. This article evaluates the effects of some of the newer treatment options on the laboratory testing of factor levels and related assays. [ABSTRACT FROM AUTHOR]

Background: To date, there is an ongoing debate regarding the ability to predict PVT development using markers of FVIII or FVIII/PC ratio. This study presents evidence-based medical findings on the influence of FVIII activity levels and FVIII/PC values in the formation of PVT in cirrhosis. Methods: The search for original studies on risk factors for portal vein thrombosis (PVT) associated with cirrhosis was conducted, which primarily focused on comparing circulating FVIII activity levels or FVIII/PC ratio in cirrhotic patients with and without PVT. The quality of evidence from each study was assessed using the Newcastle-Ottawa Scale. Results: The meta-analysis included a total of 10 original studies. In total, 2250 cirrhotic patients were included, with 414 having PVT and 1836 without PVT. The pooled analysis using a random-effects model showed no significant difference in standardized mean difference (SMD) for FVIII activity levels in cirrhotic patients with or without PVT (SMD = 0.12, 95% CI=-0.46 to 0.70, P = 0.68), but there was significant heterogeneity (I2 = 95.52%, P = 0.00). Meta-regression analysis indicated that differences in mean FVIII activity levels in the PVT group, the number of cases in the non-PVT group, and the study design methods partially contributed to the heterogeneity (P < 0.05). However, compared to the non-PVT group, the PVT group had higher FVIII/PC ratio with a statistically significant difference (SMD = 0.39, 95% CI: 0.15 to 0.63, P = 0.00), and there was no significant heterogeneity (I2 = 28.62%). Conclusion: In conclusion, the FVIII/PC ratio not only reflects the severity of liver disease, but also can be used as one of the predictors of PVT development. [ABSTRACT FROM AUTHOR]

Abstract Background To date, there is an ongoing debate regarding the ability to predict PVT development using markers of FVIII or FVIII/PC ratio. This study presents evidence-based medical findings on the influence of FVIII activity levels and FVIII/PC values in the formation of PVT in cirrhosis. Methods The search for original studies on risk factors for portal vein thrombosis (PVT) associated with cirrhosis was conducted, which primarily focused on comparing circulating FVIII activity levels or FVIII/PC ratio in cirrhotic patients with and without PVT. The quality of evidence from each study was assessed using the Newcastle-Ottawa Scale. Results The meta-analysis included a total of 10 original studies. In total, 2250 cirrhotic patients were included, with 414 having PVT and 1836 without PVT. The pooled analysis using a random-effects model showed no significant difference in standardized mean difference (SMD) for FVIII activity levels in cirrhotic patients with or without PVT (SMD = 0.12, 95% CI=-0.46 to 0.70, P = 0.68), but there was significant heterogeneity (I2 = 95.52%, P = 0.00). Meta-regression analysis indicated that differences in mean FVIII activity levels in the PVT group, the number of cases in the non-PVT group, and the study design methods partially contributed to the heterogeneity (P

Objective To observe the changes of coagulation factor activity and protein content of the thawed fresh frozen plasma (FFP) and fresh liquid plasma (FLP) during storage at 2-6℃, and to provide reference for exploring the appropriate storage time of FFP at 2-6℃ after thawing. Methods The small-thaw group and the large-thaw group were respectively detected for the activity of coagulation factor FⅤ (FⅤ∶C) and FⅧ(FⅧ∶C), and the levels of fibrinogen (Fib), total protein (TP) and albumin (Alb) in TTP at 1, 2, 3, 4, 5, 6 and 7 days after thawing. And the FLP was detected for FⅤ∶C, FⅧ∶C, Fib, TP and Alb at 1, 2, 3, 4, 5, 6, 7 days and 1, 6, 11, 16, 21, 26 and 31 days after preparation, respectively. Results In FFP group, FⅧ∶C decreased gradually with the prolongation of storage time after melting (P0.05). In FLP group, FⅧ∶C decreased gradually with the prolongation of storage time after melting (P0.05), but it decreased gradually in 31-day storage group (P0.05). Conclusion Although FⅧ∶C is decreased in thawed FFP stored at 2-6℃ for 7 days, it is still about 52.4%, which should be able to play a normal role in clinical practice.

Objective To observe and analyze the influence of the improved ultra-low temperature storage box on the quality of fresh frozen plasma (FFP). Methods A total of 80 qualified whole blood samples (400 mL, O type not included) collected from July to November in 2023 were selected, and were divided into 4 groups, with 20 samples in each group. Group A: quick-frozen in a traditional low temperature box for 1 hour and then stored in a -30℃ cold storage; Group B: quick-frozen in the flat freezer for 1 hour and then stored in a -30℃ cold storage; Group C: quick-frozen in a newly improved ultra-low temperature storage box for 1 hour and stored in a -30℃ cold storage; Group D: quick-frozen in a new improved ultra-low temperature storage box for 12 hours and stored in a -30℃ cold storage. The contents of FⅧ and fibrinogen (Fg) in four groups were detected. Results The contents of FⅧ in group B, C and D were significantly higher than those in group A, with statistical difference (P0.05), and no statistical difference in the contents of Fg was found among the four groups(P>0.05). Conclusion The improved ultra-low temperature storage box is superior to the traditional low temperature box in preparing FFP, and there is no obvious difference between the improved ultra-low temperature storage box and the flat-plate quick freezer. However, the improved ultra-low temperature storage box can make the process of preparing FFP more flexible and improve the efficiency of component preparation.

Hemophilia A is an X-linked disorder characterized by quantitative deficiency of coagulation factor VIII (FVIII) caused by pathogenic variants in the factor 8 (F8) gene. Our study's primary objective was to identify genetic variants within the exonic region of F8 in 50 Colombian male participants with severe hemophilia A (HA). Whole-exome sequencing and bioinformatics analyses were performed, and bivariate analysis was used to evaluate the relationship between identified variants, disease severity, and inhibitor risk formation. Out of the 50 participants, 21 were found to have 17 different pathogenic F8 variants (var). It was found that 70% (var = 12) of them were premature truncation variants (nonsense, frameshift), 17.6% (var = 3) were missense mutations, and 11.7% (var = 2) were splice-site variants. Interestingly, 35% (var = 6) of the identified variants have not been previously reported in the literature. All patients with a history of positive inhibitors (n = 4) were found to have high-impact genetic variants (nonsense and frameshift). When investigating the relationship between variant location (heavy versus light chain) and specific inhibitor risk, 75% (n = 3) of the inhibitor participants were found to have variants located in the F8 light chain (p = 0.075), suggesting that conserved domains are associated with higher inhibitor risk. In summary, we identified genetic variants within the F8 that can possibly influence inhibitor development in Colombian patients with severe HA. Our results provide a basis for future studies and the development of further personalized treatment strategies in this population. [ABSTRACT FROM AUTHOR]

Introduction: The safety and efficacy of the extended half‐life factor VIII (FVIII) product damoctocog alfa pegol (BAY 94‐9027, Jivi®) has been demonstrated in the PROTECT VIII Kids study (NCT01775618), where male previously‐treated patients (PTPs) aged <12 years old with severe haemophilia A and ≥ 50 exposure days (EDs) were treated prophylactically. The PROTECT VIII Kids extension study assessed the long‐term safety and efficacy of damoctocog alfa pegol in the same population. Aim: To evaluate the long‐term impact of damoctocog alfa pegol in a post hoc subgroup analysis of adolescent patients in the PROTECT VIII Kids study and its extension from 12th birthday onwards. Methods: The current analysis included PTPs aged ≥12 years old, who remained in the extension for ≥6 months following their 12th birthday. The observation period was defined as the time from 12th birthday to the end of the extension period; all data from this birthday were included whether in the main study or extension phase. The main efficacy variable was annualised bleeding rate (ABR) and the main safety variable was the frequency of inhibitor development. Results: This subgroup analysis comprised 25 patients. Median observation time after 12th birthday was 3.2 years. Median total/joint/spontaneous ABRs in the observation period were 1.7/0.7/0.3, respectively. Safety findings were consistent with those reported for the overall study population; no confirmed FVIII inhibitors or anti‐drug antibodies were reported. Conclusions: Damoctocog alfa pegol is efficacious with a favourable safety profile in adolescents with haemophilia A, supporting its long‐term use in children and adolescents. [ABSTRACT FROM AUTHOR]

Key clinical message: Acquired hemophilia A is a rare bleeding disorder. Rapid diagnosis with prolonged aPTT and low FVIII, and immediate use of bypassing agents and steroids are crucial for better outcomes, highlighting the importance of early recognition and management. [ABSTRACT FROM AUTHOR]

Tolerance to self‐proteins involves multiple mechanisms, including conventional CD4+ T‐cell (Tconv) deletion in the thymus and the recruitment of natural regulatory T cells (nTregs). The significant incidence of autoantibodies specific for the blood coagulation factor VIII (FVIII) in healthy donors illustrates that tolerance to self‐proteins is not always complete. In contrast to FVIII‐specific Tconvs, FVIII‐specific nTregs have never been revealed and characterized. To determine the frequency of FVIII‐specific Tregs in human peripheral blood, we assessed the specificity of in vitro expanded Tregs by the membrane expression of the CD137 activation marker. Amplified Tregs maintain high levels of FOXP3 expression and exhibit almost complete demethylation of the FOXP3 Treg‐specific demethylated region. The cells retained FOXP3 expression after long‐term culture in vitro, strongly suggesting that FVIII‐specific Tregs are derived from the thymus. From eleven healthy donors, we estimated the frequencies of FVIII‐specific Tregs at 0.17 cells per million, which is about 10‐fold lower than the frequency of FVIII‐specific CD4+ T cells we previously published. Our results shed light on the mechanisms of FVIII tolerance by a renewed approach that could be extended to other self‐ or non‐self‐antigens. [ABSTRACT FROM AUTHOR]

Objectives: The objective of this study was twofold: to determine the prevalence of arterial and venous thromboembolic events in the Norwegian Hereditary Hemorrhagic Telangiectasia (HHT) population, and to explore potential factors linked to such events, with particular emphasis on FVIII. Methods: Patients with an HHT diagnosis attending the Otorhinolaryngology Department at Oslo University Hospital—Rikshospitalet were included consecutively between April 2021 and November 2022. We recorded the participants' medical history with an emphasis on thromboembolic events. Measurements of blood constituents, including FVIII, FIX, vWF, hemoglobin, iron, ferritin, and CRP were performed. Results: One hundred and thirty‐four patients were included in the study. The total prevalence of thromboembolic events among the participants was 23.1%. FVIII levels were high (>150 IU/dL) in the majority of HHT patients (n = 84) (68.3%) and were significantly associated with thromboembolic events (p <.001), as was age. Of the patients with high FVIII levels, 28 (33%) had experienced a thromboembolic event. Furthermore, FVIII levels were measured consecutively in 51 patients and were found to fluctuate above or below 150 IU/dL in 25% of these cases. Conclusion: Thromboembolic events are highly prevalent in the Norwegian HHT population and are significantly associated with FVIII levels. FVIII levels can fluctuate, and measurements should be repeated in HHT patients to assess the risk of thromboembolic events. Level of Evidence: 4. [ABSTRACT FROM AUTHOR]

To explore the feasibility, safety and cost effectiveness of the use of peripherally inserted central catheter (PICC) in children with hemophilia A and inhibitors who underwent ITI treatment. This retrospective cohort study evaluated the effect of PICC placement and ITI on bleeding rates, costs, and parents' satisfaction before and within 6 months after PICC placement in children with hemophilia A and inhibitors. A total of 20 children with hemophilia A and high-titer inhibitors were included, with a success rate for PICC placement of 100%, at a cost of ¥6730.50. Parents' satisfaction with PICC was 100%, and the total length of catheter indwelling was 6055 days. In terms of curative effect, the success rate of ITI treatment was 75%, and the annualized bleeding rate was decreased from 10.90 ± 12.16 times before placement to 2.10 ± 3.32 times (p < 0.05). The transportation expense for children and their parents to the clinic decreased from ¥20,920 ± 32,274.57 before catheter placement to ¥2915 ± 2195.99 (p < 0.05). Time of children missed school and their parents missed work decreased from 10.85 ± 22.36 days to 1.90 ± 3.58 (p < 0.05) days and 40.33 ± 46.11 days to 3.83 ± 7.11 days (p < 0.05), respectively. The use of PICC for ITI treatment in children with hemophilia A and accompanying inhibitors in developing countries (e.g. China) can ensure the effect of ITI, reducing expense and improving the quality of life without obvious side effects. [ABSTRACT FROM AUTHOR]

Prophylaxis with emicizumab, a bispecific monoclonal antibody that mimics FVIII function, has shown encouraging results in clinical trials in terms of efficacy and safety. However, current experience is limited, and many areas of concern to clinicians have yet to be reviewed. This paper reviews the experience of hemophilia A patients treated with emicizumab based on the results of clinical trials and real-life studies. The authors place special emphasis on issues such as the management of these patients in situations of hemorrhage and/or surgical interventions, joint health or laboratory monitoring. Treatment with emicizumab has been shown to improve joint health and reduce bleeding, of particular interest to patients with inhibitors and high bleeding rates. However, there are still concerns about its administration in neonates and previously untreated patients due to limited reported experience. Laboratory monitoring is not strictly necessary due to the stable pharmacokinetics emicizumab has been shown to exhibit, however, tests that globally assess hemostasis may be useful especially in cases of bleeding or surgery. The authors are also of the opinion that prophylaxis before minor surgery is not necessary and that major surgeries can be safely performed with additional prophylactic coagulation factor. [ABSTRACT FROM AUTHOR]

Key clinical message Acquired hemophilia A is a rare bleeding disorder. Rapid diagnosis with prolonged aPTT and low FVIII, and immediate use of bypassing agents and steroids are crucial for better outcomes, highlighting the importance of early recognition and management.

Hemophilia A is an X-linked disorder characterized by quantitative deficiency of coagulation factor VIII (FVIII) caused by pathogenic variants in the factor 8 (F8) gene. Our study’s primary objective was to identify genetic variants within the exonic region of F8 in 50 Colombian male participants with severe hemophilia A (HA). Whole-exome sequencing and bioinformatics analyses were performed, and bivariate analysis was used to evaluate the relationship between identified variants, disease severity, and inhibitor risk formation. Out of the 50 participants, 21 were found to have 17 different pathogenic F8 variants (var). It was found that 70% (var = 12) of them were premature truncation variants (nonsense, frameshift), 17.6% (var = 3) were missense mutations, and 11.7% (var = 2) were splice-site variants. Interestingly, 35% (var = 6) of the identified variants have not been previously reported in the literature. All patients with a history of positive inhibitors (n = 4) were found to have high-impact genetic variants (nonsense and frameshift). When investigating the relationship between variant location (heavy versus light chain) and specific inhibitor risk, 75% (n = 3) of the inhibitor participants were found to have variants located in the F8 light chain (p = 0.075), suggesting that conserved domains are associated with higher inhibitor risk. In summary, we identified genetic variants within the F8 that can possibly influence inhibitor development in Colombian patients with severe HA. Our results provide a basis for future studies and the development of further personalized treatment strategies in this population.

Gili Kenet,1,2 Thomas Moulton,3 Brian M Wicklund,4 Sanjay P Ahuja,5 Miguel Escobar,6 Johnny Mahlangu7 1National Hemophilia Center, Sheba Medical Center, Tel HaShomer, Israel; 2The Amalia Biron Thrombosis Research Institute, Tel Aviv University, Tel Aviv, Israel; 3Bayer, Whippany, NJ, USA; 4Children’s Mercy-Kansas City, Kansas City, MO, USA; 5Rainbow Babies & Children’s Hospital, Cleveland, OH, USA; 6University of Texas Health Science Center, Houston, TX, USA; 7Hemophilia Comprehensive Care Center, Faculty of Health Sciences, Charlotte Maxeke Johannesburg Academic Hospital, University of the Witwatersrand, and National Health Laboratory Service, Johannesburg, South AfricaCorrespondence: Gili Kenet, Amalia Biron Thrombosis Research Institute, Tel Aviv University, Tel HaShomer, 52621, Israel, Tel +972-3-5307356, Fax +972-3-5351806, Email Gili.kenet@sheba.health.gov.ilIntroduction: Previous clinical trials established the efficacy and safety of sucrose-formulated recombinant factor (F) VIII (rFVIII-FS/Kogenate FS®/Helixate FS®) and octocog alfa (BAY 81– 8973/Kovaltry®; LEOPOLD trials).Aim: To report the results of a post hoc subgroup analysis assessing efficacy and safety outcomes in patients with hemophilia A who were receiving rFVIII-FS prior to enrolling into the LEOPOLD I Part B and LEOPOLD Kids Part A clinical trials and switching to octocog alfa.Methods: LEOPOLD I Part B (NCT01029340) and LEOPOLD Kids Part A (NCT01311648) were octocog alfa Phase 3, multinational, open-label studies in patients with severe hemophilia A aged 12– 65 years and ≤ 12 years, respectively. Annualized bleeding rate (ABR) was the efficacy endpoint for both studies. Safety endpoints included adverse events (AEs) and development of FVIII inhibitors.Results: Of the 113 patients in both LEOPOLD trials, 40 (35.4%) patients received rFVIII-FS prophylaxis pre-study and had data available for pre-study total ABR. In LEOPOLD I Part B (n = 22, 35.5%), median (Q1; Q3) total ABR decreased from 2.5 (0.0; 9.0) pre-study to 1.0 (0.0; 6.8), and from 1.0 (0.0; 6.0) pre-study to 0.0 (0.0; 6.02) in LEOPOLD Kids Part A (n = 18, 35.3%). Octocog alfa was well tolerated, and no patients had drug-related serious AEs or inhibitors.Conclusion: Treatment with octocog alfa prophylaxis appeared to have a favorable risk–benefit profile compared with rFVIII-FS and thus could be an effective and improved alternative strategy for individualized treatment for children, adolescent and adult patients with severe hemophilia A currently on rFVIII-FS treatment.Keywords: FVIII, hemophilia A, prophylaxis, recombinant proteins, octocog alfa

Abstract Objectives The objective of this study was twofold: to determine the prevalence of arterial and venous thromboembolic events in the Norwegian Hereditary Hemorrhagic Telangiectasia (HHT) population, and to explore potential factors linked to such events, with particular emphasis on FVIII. Methods Patients with an HHT diagnosis attending the Otorhinolaryngology Department at Oslo University Hospital—Rikshospitalet were included consecutively between April 2021 and November 2022. We recorded the participants' medical history with an emphasis on thromboembolic events. Measurements of blood constituents, including FVIII, FIX, vWF, hemoglobin, iron, ferritin, and CRP were performed. Results One hundred and thirty‐four patients were included in the study. The total prevalence of thromboembolic events among the participants was 23.1%. FVIII levels were high (>150 IU/dL) in the majority of HHT patients (n = 84) (68.3%) and were significantly associated with thromboembolic events (p

ABSTRACTIntroduction Prophylaxis with emicizumab, a bispecific monoclonal antibody that mimics FVIII function, has shown encouraging results in clinical trials in terms of efficacy and safety. However, current experience is limited, and many areas of concern to clinicians have yet to be reviewed.Areas covered This paper reviews the experience of hemophilia A patients treated with emicizumab based on the results of clinical trials and real-life studies. The authors place special emphasis on issues such as the management of these patients in situations of hemorrhage and/or surgical interventions, joint health or laboratory monitoring.Expert opinion Treatment with emicizumab has been shown to improve joint health and reduce bleeding, of particular interest to patients with inhibitors and high bleeding rates. However, there are still concerns about its administration in neonates and previously untreated patients due to limited reported experience. Laboratory monitoring is not strictly necessary due to the stable pharmacokinetics emicizumab has been shown to exhibit, however, tests that globally assess hemostasis may be useful especially in cases of bleeding or surgery. The authors are also of the opinion that prophylaxis before minor surgery is not necessary and that major surgeries can be safely performed with additional prophylactic coagulation factor.

Introduction: Turoctocog alfa pegol (N8‐GP) is a glycoPEGylated, extended half‐life (EHL), human recombinant factor VIII (FVIII) approved for the treatment and prevention of bleeding episodes in patients with haemophilia A. Since its launch in August 2019, > 800 patients have been treated worldwide. Aim: To present data from identified post‐marketing cases of less‐than‐expected FVIII activity in previously treated patients (PTPs) without inhibitors after switching to N8‐GP. Methods: The post‐marketing safety database was searched using keywords such as 'coagulation FVIII level decreased'. Identified cases reported prior to 13 October 2021 were included in this report. Cases in which patients had FVIII inhibitors were excluded. Results: Here we report 14 cases of less‐than‐expected FVIII activity. Details varied greatly amongst the cases. At presentation, FVIII activity ranged from 1% (15 min post‐dose) to 51% (2 days post‐dose). Seven patients experienced bleeding episodes after switching to N8‐GP with heterogeneity in bleeding presentations. Six out of seven patients who were tested for anti‐PEG IgG and/or IgM antibodies were positive. In all known cases, FVIII activity returned to the expected range when switched to an alternative FVIII replacement product. Conclusion: In conclusion, the 14 reported cases of less‐than‐expected FVIII activity, without presence of detectable FVIII inhibitors, presented with heterogenous characteristics, and wide variations in FVIII activity and anti‐PEG antibody titre. FVIII activity returned to the expected range after switching to alternative FVIII products. In line with WFH guidelines, monitoring of FVIII activity can ensure FVIII activity in the expected range. The safety surveillance of N8‐GP continues. [ABSTRACT FROM AUTHOR]

Background: Regular prophylactic therapy has become an increasingly common treatment for severe hemophilia. Therefore, hypercoagulability—a potential risk factor of thrombosis—is a cause for concern in hemophilic patients treated with a high dose of FVIII concentrate. In clot waveform analysis (CWA)-thrombin time (TT), a small amount of thrombin activates clotting factor VIII (FVIII) instead of fibrinogen, resulting in FVIII measurements using CWA-TT with a small amount of thrombin. Methods: The coagulation ability of patients treated with FVIII concentrate or emicizumab was evaluated using activated partial thromboplastin time (APTT), TT and a small amount of tissue factor-induced FIX activation assay (sTF/FIXa) using CWA. Results: The FVIII activity based on CWA-TT was significantly greater than that based on the CWA-APTT or chromogenic assay. FVIII or FVIII-like activities based on the three assays in plasma without emicizumab were closely correlated; those in plasma with emicizumab based on CWA-TT and chromogenic assays were also closely correlated. CWA-APTT and CWA-TT showed different patterns in patients treated with FVIII concentrates compared to those treated with emicizumab. In particular, CWA-TT in patients treated with FVIII concentrate showed markedly higher peaks in platelet-rich plasma than in platelet-poor plasma. CWA-APTT showed lower coagulability in hemophilic patients treated with FVIII concentrate than in healthy volunteers, whereas CWA-sTF/FIXa did not. In contrast, CWA-TT showed hypercoagulability in hemophilic patients treated with FVIII concentrate. Conclusions: CWA-TT can be used to evaluate the thrombin bursts that cause hypercoagulability in patients treated with emicizumab. Although routine APTT evaluations demonstrated low coagulation ability in patients treated with FVIII concentrate, CWA-TT showed hypercoagulability in these patients, suggesting that the evaluation of coagulation ability may be useful when using multiple assays. [ABSTRACT FROM AUTHOR]

Introduction: In recent years, there has been increased focus on individualizing treatment for persons with hemophilia including pharmacokinetic‐guided (PK) dosing. Aims: In this retrospective study clinical outcomes before and after PK‐guided prophylaxis were examined. Materials and methods: Eight Haemophilia Treatment Centres from the United States participated in the study and included 132 patients classified into two cohorts: those undergoing a PK‐assessment for product switch (switchers) or to optimize treatment (non‐switchers). Subset analyses for the two most common products and patients with dosing per prescription label were included for annual bleeding rates (ABR), mean weekly consumption outcomes, and annualized cost of prophylaxis. Results: The most common products before and after index date were octocog alfa, rurioctocog alfa pegol, and efmoroctocog alfa. Seventy‐four (56%) patients were identified as switchers and 58 (44%) patients were classified as non‐switchers. The majority of patients (78.0%) experienced either a decrease in ABR post‐index or maintained 0 ABR during pre‐ and post‐index time periods, with similar proportions identified in both switchers (77.0%) and non‐switchers (79.3%) populations. Non‐switchers were identified as having no significant change in cost of therapy, while switchers experienced increased cost of therapy driven by higher price of extended half‐life products. Within subset analyses, patients receiving rurioctocog alfa pegol and efmoroctocog alfa had mean ABR under 1 after index date. Conclusion: PK‐guided prophylaxis has the potential to improve clinical outcomes without increase in cost of therapy for patients maintaining product and can aid in maintaining effective protection against bleeds in those switching product. [ABSTRACT FROM AUTHOR]

Introduction: Conventional genetic investigation fails to identify the F8 causal variant in 2.5%‐10% of haemophilia A (HA) patients with non‐severe phenotypes. In these cases, F8 deep intronic variants could be causal. Aim: To identify pathogenic F8 deep intronic variants in genetically unresolved families with non‐severe HA analysed in the haematology laboratory of the Hospices Civils de Lyon. Methods: The whole F8 was analysed by next generation sequencing. The pathogenic impact of candidate variants identified was assessed using both in silico analysis (MaxEntScan and spliceAI) and functional analysis (RNA or minigene assay). Results: Sequencing was performed in 49/55 families included for which a DNA sample from a male propositus was available. In total, 33 candidate variants from 43 propositi were identified. These variants corresponded to 31 single nucleotide substitutions, one 173‐bp deletion, and an 869‐bp tandem triplication. No candidate variant was found in six propositi. The most frequent variants found were the association of [c.2113+1154G>C and c.5374‐304C>T], identified in five propositi, and the c.2114‐6529C>G identified in nine propositi. Four variants had been previously described as HA‐causing. Splicing functional assay found a deleterious impact for 11 substitutions (c.671‐94G>A, c.788‐312A>G, c.2113+1154G>C, c.2114‐6529C>G, c.5999‐820A>T, c.5999‐786C>A, c.5999‐669G>T, c.5999‐669G>A, c.5999‐669G>C, c.6900+4104A>C, and c.6901‐2992A>G). The HA‐causing variant was identified in 33/49 (67%) cases. In total, F8 deep intronic variants caused 8.8% of the non‐severe HA among the 1643 families analysed in our laboratory. Conclusion: The results emphasise the value of whole F8 gene sequencing combined with splicing functional analyses to improve the diagnosis yield for non‐severe HA. [ABSTRACT FROM AUTHOR]

• Plasma VWF antigen and FVIII:C levels are raised in patients with active multiple myeloma (MM), irrespective of therapy • High VWF propeptide and reduced propeptide/antigen ratios suggest endothelial activation and impaired VWF clearance in MM • Increased VWF propeptide is seen in precursor MM, strengthening the hypothesis of hypercoagulability in MGUS/smouldering MM • VWF multimer distribution is not altered in MM disease and accordingly, ADAMTS13 activity is not impaired [ABSTRACT FROM AUTHOR]

Hemophilia A (HA) is a bleeding disorder characterized by spontaneous and prolonged hemorrhage. The disease is caused by mutations in the coagulation factor 8 gene (F8) leading to factor VIII (FVIII) deficiency. Since FVIII is primarily produced in endothelial cells (ECs) in a non-diseased human being, ECs hold great potential for development as a cell therapy for HA. We showed that HA patient-specific induced pluripotent stem cells (HA-iPSCs) could provide a renewable supply of ECs. The HA-iPSC-derived ECs were transduced with lentiviral vectors to stably express the functional B domain deleted F8 gene, the luciferase gene, and the enhanced green fluorescent protein gene (GFP). When transplanted intramuscularly into neonatal and adult immune deficient mice, the HA-iPSC-derived ECs were retained in the animals for at least 10-16 weeks and maintained their expression of FVIII, GFP, and the endothelial marker CD31, as demonstrated by bioluminescence imaging and immunostaining, respectively. When transplanted into HA mice, these transduced HA-iPSC-derived ECs significantly reduced blood loss in a tail-clip bleeding test and produced therapeutic plasma levels (11.2%-369.2%) of FVIII. Thus, our studies provide proof-of-concept that HA-iPSC-derived ECs can serve as a factory to deliver FVIII for the treatment of HA not only in adults but also in newborns.

Abstract Background Thrombotic complications are synergistic and associated with orthopedic procedures, trauma, and malignancy. Because cancer enhances coagulation activity and vice versa, we assessed preoperative biomarkers for survival and complications after treatment of pathologic fractures in non-spinal skeletal metastases. Patients/methods Our study population comprised 113 actual or impending pathologic fractures in 100 patients admitted to two referral centers. Laboratory variables were collected retrospectively from patient records and analyzed related to incidence of pulmonary embolism (PE) and mortality (Kaplan-Meier and Cox regression analyses and biomarker quartiles). Results Preoperative coagulation variables were high without exceptions. PE occurred in 12 patients at 36 post-operative days at incidence of 11% in the lower and 13% in the upper extremity fractures. Patients with fibrinogen exceeding 5 g/l (log-rank 0.022) developed PE earlier (5 to 15 days postoperatively) than others. Also, mean patient survival with normal fibrinogen range (2–4 g/l) was 34 months, whereas it halved upon elevated fibrinogen (log-rank p = 0.009). Survival in patients with FVIII levels under 326 IU/dl (Q3) was 22 months, but only 7 months if FVIII exceeded 326 IU/dl (log-rank p = 0.002). Combined elevated fibrinogen and FVIII predicted survival: for patients with levels below threshold limits was 22 months versus only 7 months when both variables exceeded the ranges (log-rank p

Factor VIII (FVIII) replacement and emicizumab are effective at preventing bleeds in patients with hemophilia A (HA). Though benefits of emicizumab among inhibitor patients with HA (PwHA) are well established, more real-world evidence among non-inhibitor patients is needed. Using a United States healthcare claims database, we compared billed annualized bleed rates (ABRb) and the total cost of care (TCC) before and after switching from FVIII prophylaxis to emicizumab among non-inhibitor male PwHA. Bayesian inferences were used to assess the difference in ABRb and TCC per patient per year (PPPY) pre- versus post-prophylaxis switch. We included 101 non-inhibitor male PwHA aged between 3 and 63 years old who switched from FVIII prophylaxis to emicizumab prophylaxis in 2018 or 2019. The ABRb increased from 0.52 to 0.62 (p = 0.83) after switch. The posterior probability of the mean ABRb increasing after the switch was 75.54%. The TCC PPPY increased from $517,143 to $627,005 (p < 0.0001) after switch and the posterior probability of mean costs increasing after the switch was 99.80%. Personalization of care through the identification of the most appropriate therapy for each patient can optimize clinical and economic outcomes. Future real-world evidence research could help establish the value of prophylactic options in targeted populations such as the non-inhibitor male PwHA. [ABSTRACT FROM AUTHOR]

Hemophilia A (HA) is a rare bleeding disorder caused by deficiency/dysfunction of the FVIII protein. As current therapies based on frequent FVIII infusions are not a definitive cure, long-term expression of FVIII in endothelial cells through lentiviral vector (LV)-mediated gene transfer holds the promise of a one-time treatment. Thus, here we sought to determine whether LV-corrected blood outgrowth endothelial cells (BOECs) implanted through a prevascularized medical device (Cell Pouch) would rescue the bleeding phenotype of HA mice. To this end, BOECs from HA patients and healthy donors were isolated, expanded, and transduced with an LV carrying FVIII driven by an endothelial-specific promoter employing GMP-like procedures. FVIII-corrected HA BOECs were either directly transplanted into the peritoneal cavity or injected into a Cell Pouch implanted subcutaneously in NSG-HA mice. In both cases, FVIII secretion was sufficient to improve the mouse bleeding phenotype. Indeed, FVIII-corrected HA BOECs reached a relatively short-term clinically relevant engraftment being detected up to 16 weeks after transplantation, and their genomic integration profile did not show enrichment for oncogenes, confirming the process safety. Overall, this is the first preclinical study showing the safety and feasibility of transplantation of GMP-like produced LV-corrected BOECs within an implantable device for the long-term treatment of HA.

IntroductionPlacenta-derived mesenchymal cells (PLCs) endogenously produce FVIII, which makes them ideally suited for cell-based fVIII gene delivery. We have previously reported that human PLCs can be efficiently modified with a lentiviral vector encoding a bioengineered, expression/secretion-optimized fVIII transgene (ET3) and durably produce clinically relevant levels of functionally active FVIII. The objective of the present study was to investigate whether CRISPR/Cas9 can be used to achieve location-specific insertion of a fVIII transgene into a genomic safe harbor, thereby eliminating the potential risks arising from the semi-random genomic integration inherent to lentiviral vectors. We hypothesized this approach would improve the safety of the PLC-based gene delivery platform and might also enhance the therapeutic effect by eliminating chromatin-related transgene silencing.MethodsWe used CRISPR/Cas9 to attempt to insert the bioengineered fVIII transgene “lcoET3” into the AAVS1 site of PLCs (CRISPR-lcoET3) and determined their subsequent levels of FVIII production, comparing results with this approach to those achieved using lentivector transduction (LV-lcoET3) and plasmid transfection (Plasmid-lcoET3). In addition, since liver-derived sinusoidal endothelial cells (LSECs) are the native site of FVIII production in the body, we also performed parallel studies in human (h)LSECs).ResultsPLCs and hLSECs can both be transduced (LV-lcoET3) with very high efficiency and produce high levels of biologically active FVIII. Surprisingly, both cell types were largely refractory to CRISPR/Cas9-mediated knockin of the lcoET3 fVIII transgene in the AAVS1 genome locus. However, successful insertion of an RFP reporter into this locus using an identical procedure suggests the failure to achieve knockin of the lcoET3 expression cassette at this site is likely a function of its large size. Importantly, using plasmids, alone or to introduce the CRISPR/Cas9 “machinery”, resulted in dramatic upregulation of TLR 3, TLR 7, and BiP in PLCs, compromising their unique immune-inertness.DiscussionAlthough we did not achieve our primary objective, our results validate the utility of both PLCs and hLSECs as cell-based delivery vehicles for a fVIII transgene, and they highlight the hurdles that remain to be overcome before primary human cells can be gene-edited with sufficient efficiency for use in cell-based gene therapy to treat HA.

Background: Thrombotic complications are synergistic and associated with orthopedic procedures, trauma, and malignancy. Because cancer enhances coagulation activity and vice versa, we assessed preoperative biomarkers for survival and complications after treatment of pathologic fractures in non-spinal skeletal metastases. Patients/methods: Our study population comprised 113 actual or impending pathologic fractures in 100 patients admitted to two referral centers. Laboratory variables were collected retrospectively from patient records and analyzed related to incidence of pulmonary embolism (PE) and mortality (Kaplan-Meier and Cox regression analyses and biomarker quartiles). Results: Preoperative coagulation variables were high without exceptions. PE occurred in 12 patients at 36 post-operative days at incidence of 11% in the lower and 13% in the upper extremity fractures. Patients with fibrinogen exceeding 5 g/l (log-rank 0.022) developed PE earlier (5 to 15 days postoperatively) than others. Also, mean patient survival with normal fibrinogen range (2–4 g/l) was 34 months, whereas it halved upon elevated fibrinogen (log-rank p = 0.009). Survival in patients with FVIII levels under 326 IU/dl (Q3) was 22 months, but only 7 months if FVIII exceeded 326 IU/dl (log-rank p = 0.002). Combined elevated fibrinogen and FVIII predicted survival: for patients with levels below threshold limits was 22 months versus only 7 months when both variables exceeded the ranges (log-rank p < 0.001). Multivariate analysis to control confounders supported an independent role of fibrinogen and FVIII for survival. Conclusions: Our study has established fibrinogen and FVIII as potential preoperative contributors of survival and complications after treatment of metastatic fractures. These results highlight the need for novel anticoagulation and thromboprophylaxis strategies among these patients. [ABSTRACT FROM AUTHOR]

Background: Mild haemophilia (MH) is mainly characterized by haemorrhages secondary to surgery/invasive procedures or trauma. Haemostatic treatment in MH ranges from on demand to short prophylaxis according to the type of bleeding events and the basal clotting factor level. Oral surgery and dental extractions can represent a frequent haemostatic challenge in MH requiring appropriate treatment. However, only few studies on limited numbers of patients are available in the literature regarding the implications of dental management in patients with MH. Objectives: The purpose of the study was to evaluate the impact of dental care on the burden of haemostatic treatment in patients affected by MH. Methods: We conducted a retrospective multicentre study evaluating adult patients with MH regularly examined at the Haemophilia Treatment Centres (HTCs) of the Saint‐Luc University Hospital, Brussels (Belgium) and of Paolo Giaccone Hospital, Palermo (Italy). The population consisted of 107 male patients with MH, with a mean age of 39 years (range 18–81 years). Results: The majority of patients (86/107, 79%) needed at least one treatment within the study period, and 44% (38/86) of them received haemostatic therapy for dental care. Haemostatic therapy in our study varied from antifibrinolytic therapy alone and perioperative factor replacement to the absence of treatment at all. The great majority of oral interventions (27/42, 64%) were managed with clotting factor concentrate. Conclusion: This study demonstrates that dental care currently represents a major reason for haemostatic treatments in patients with MH. Maintaining good oral health appears as a priority to minimize avoidable replacement therapy and optimize resources. [ABSTRACT FROM AUTHOR]

Hemophilia A is treated with human plasma coagulation factor VIII (FVIII) replacement therapy and Hemophilia B with coagulation factor IX, which is purified from prothrombin complex concentrate (PCC). In this paper we evaluated the separation of FVIII and PCC by directly loading raw thawed plasma to an anion exchange resin (AEX). Under this relatively high ionic strength, most of the plasma proteins such as albumin, immunoglobulins and others were not adsorbed. Five resins commonly used in protein purification (plasma fractionation) were tested. With all resins, PCC was eluted by pseudoaffinity in a calcium gradient step. Afterwards, FVIII could be recovered with a good yield and high purification factor in the salt gradient step with 400–500 mM NaCl. Using ANX Sepharose FF and Q Sepharose FF, the CaCl2 elution step was introduced after the intermediate wash with 200 mM NaCl, whereas using DEAE Sepharose FF, Fractogel EMD TMAE and Fractogel EMD DEAD, PCC eluted after the wash of the unbound proteins. Our results indicate that three important fractions: (1) albumin, immunoglobulin etc.; (2) PCC; and (3) FVIII can be separated in one chromatographic AEX column and the delicate and troublesome cryoprecipitation can be eliminated, making the purification of blood products faster and cheaper. [ABSTRACT FROM AUTHOR]

Factor VIII (FVIII) replacement and emicizumab have demonstrated efficacy for prevention of bleeds among patients with hemophilia A (PwHA) compared to on-demand (OD) use. Evidence investigating clinical outcomes and healthcare costs of non-inhibitor PwHA switching from prophylaxis with FVIII concentrates to emicizumab has not been well-established within large real-world datasets. This study aimed to investigate billed annualized bleed rates (ABRb) and total cost of care (TCC) among non-inhibitor PwHA switching from FVIII-prophylaxis to emicizumab-prophylaxis. This retrospective, observational study was conducted using IQVIA PharMetrics Plus, a US administrative claims database. The date of first claim for emicizumab was defined as the index date. OD patients and inhibitor patients were excluded. Bleeds were identified using a list of 535 diagnosis codes. Bayesian models were developed to estimate the probability ABRb worsens and TCC increases after switching to emicizumab. Wilcoxon rank-sum tests were used to test statistical significance of changes in ABRb and TCC after switch. Among the 121 identified patients, the difference in mean ABRb between FVIII-prophylaxis (0.68 [SD = 1.28]) and emicizumab (0.55 [SD = 1.48]) was insignificant (p =.142). The mean annual TCC significantly increased for patients switching from FVIII-prophylaxis ($518,151 [SD = $289,934]) to emicizumab ($652,679 [SD = $340,126]; p <.0001). The Bayesian models estimated a 21.0% probability of the ABRb worsening and a 99.9% probability of increasing TCC after switch. This study found that in male non-inhibitor PwHA, switching from FVIII prophylaxis to emicizumab incurs substantial cost increase with no significant benefit in ABRb. This evidence may help guide providers, payers, and patients in shared decision-making conversations around best treatment options. [ABSTRACT FROM AUTHOR]

Background: Pharmacokinetic (PK) studies of low‐dose prophylaxis (LDP) of coagulation factor VIII (FVIII) in children with severe haemophilia A (SHA) are scarce. Objective: This study aims to investigate the PK profile of children with SHA receiving LDP of FVIII. Methods: Paediatric patients receiving FVIII infusions (10 IU/kg twice weekly) were included. PK profiles were estimated using the Web Accessible Population Pharmacokinetic Service for Haemophilia (WAPPS‐Haemo). The primary outcomes were the terminal half‐life (t1/2), concentration–time profile, and time to reach an FVIII level of < 1%. The secondary outcome was the suggested dosing interval of FVIII prophylaxis based on the individual PK profile. Results: Twenty‐five patients were recruited; their mean age was 12.3 ± 3.0 years. The t1/2 differed among patients receiving LDP of FVIII twice weekly, with a median of t1/2 was 14.8 h (IQR 12.6–16). The median time to reach an FVIII level of < 1% was 73.8 h (IQR 58.8–80.3). Most patients could maintain a trough level of FVIII > 1% longer than 48 h. At 72–96 h, patients needed a second dose of FVIII infusion because the FVIII level was < 1%. The suggested dosing interval of FVIII prophylaxis ranged from daily to every 96 h, depending on the individual PK profile. Conclusion: Our study identified inter‐individual differences in the PK parameters using LDP of FVIII twice weekly. The inter‐individual results in different dosing intervals advise the timing of LDP. Estimating individual PK parameters enables the identification of the optimal prophylaxis frequency to prevent bleedings. [ABSTRACT FROM AUTHOR]

Introduction: Hemophilia A is managed with coagulation clotting factor VIII (FVIII) therapy that poses significant challenges, such as a high treatment burden, immunogenicity, inconsistent hemostatic cover, poor treatment outcomes, and musculoskeletal progression despite adequate prophylactic treatment. Various non-factor therapies, such as several natural anticoagulant inhibitors and factor FVIII mimetics, have been developed to address these unmet needs. However, the role of emicizumab in addressing these unmet needs remains underexplored., Areas Covered: This review delves into the evolution of hemophilia A replacement clotting therapy from plasma-derived products to recombinant products and, more recently, nonfactor therapies. It underscores the unmet needs of replacement therapy and explores the nonfactor therapies developed to address them. The review then comprehensively summarizes the clinical trial and real-world experience data, demonstrating how emicizumab tackles these unsatisfied demands., Expert Opinion: Replacement clotting factor therapies as the standard of care has exposed several needs that have yet to be addressed. However, data from numerous emicizumab clinical trials and real-world experience offer a promising outlook, suggesting that it may effectively address many unmet needs. As hemophilia treatment goals continue to evolve, the role of currently developed nonfactor therapies in hemophilia management is yet to be fully defined.

Abstract Background COVID-19 infection is associated with a hypercoagulable state. Severe COVID-19 patients present with high plasma fibrinogen levels, continuous deposition of fibrin and the presence of microthrombi in their lungs, accompanied by significant fibrinolysis, resulting in high D-dimer levels. Due to the role of FXIII in fibrin crosslinking and clot stabilization, we analyzed its activity levels and dynamics in COVID-19 patients hospitalized in the intensive care unit (ICU). Methods FXIII levels were measured in thirty four COVID-19 patients hospitalized in the ICU and in fourteen non-severe COVID-19 patients. FVIII levels were measured for comparison. Laboratory data and clinical variables were recorded. Results The average FXIII activity level in 34 ICU hospitalized COVID-19 patients was 69.9±33 %, significantly lower compared to an average of 120±20.9 % FXIII activity in 14 non-severe COVID-19 patients. FXIII activity levels were below the low normal value (< 79 % FXIII activity) in 74 % of the ICU hospitalized COVID-19 patients. In contrast, high FVIII activity was measured among all severe COVID-19 patients. Consecutive measurements, performed in fourteen ICU hospitalized COVID-19 patients, pointed to a significant decrease in FXIII activity from the average of 85.7±28.2 %, (which is in the normal range), to an average of 68.0±20.4 %, below the low normal range, within 6.4±3.4 days of ICU hospitalization. Liver functions did not differentiate between patients with low and normal FXIII activity. No inhibitor to FXIII activity was found in the plasma of severe COVID-19 patients. Levels of FXIII-A antigen correlated with FXIII activity, and were low in severe COVID-19 patients. Conclusions Low FXIII activity levels were found in COVID-19 patients hospitalized in the ICU, with gradual decline during their hospitalization. A mechanism of consumption may account for the low FXIII activity in these patients.

Sreenivas P Veeranki,1 Priti Pednekar,1 Marlon Graf,1 Rifat Tuly,1 Michael Recht,2,3 Katharine Batt1 1PRECISIONheor, Los Angeles, CA, USA; 2American Thrombosis and Hemostasis Network, Rochester, NY, USA; 3The Hemophilia Center, Oregon Health & Science University, Portland, OR, USACorrespondence: Priti PednekarPRECISIONheor, 11100 Santa Monica Blvd, Ste 500, Los Angeles, CA, 90025, USATel +1 267 438 3588Email Priti.Pednekar@precisionvh.comIntroduction: Over the past decade, there has been an increase in novel therapeutic options to treat hemophilia A. It is still unclear how these novel treatments are used in the management of patients with hemophilia A, particularly those with challenging clinical scenarios who are typically excluded in clinical trials.Purpose: This study aimed to understand the areas of consensus and disagreement among hematologists regarding the preferences toward therapeutic approaches for difficult-to-treat patients with severe hemophilia A without inhibitors.Patients and Methods: During February–June 2020, a three-round modified Delphi study was conducted to generate consensus among 13 US experts in the field of hemophilia. Experts were asked about their preferences toward therapeutic options for patients with challenging clinical situations, including age-related morbidities (eg, myocardial infarction, joint arthropathy), increasing demand for high-impact physical activities, early onset osteoporosis, and newborns with hemophilia A. Consensus was defined as ≥ 75% agreement between the panelists.Results: Consensus was reached on many, but not all cases, leaving uncertainty about appropriateness of therapeutic approaches for some patients where clinical evidence is not available or driven by physicians’ or patients’ preferences toward therapeutic options. A majority of panelists preferred FVIII replacement therapy rather than emicizumab prophylaxis for the challenging cases presented due to established evidence on safety, efficacy, and level of bleed protection for FVIII treatment.Conclusion: Recommendations emerging from this study may help guide practicing hematologists in the management of challenging hemophilia A cases. Future studies are needed to address treatment options in the clinical cases where no consensus was reached.Keywords: emicizumab, expert elicitation, FVIII, treatment, management

Featured Application: The computational approaches hereby shown can be used in the rational design of biologic drugs. Factor VIII belongs to the coagulation cascade and is expressed as a long pre-protein (mature form, 2351 amino acids long). FVIII is deficient or defective in hemophilic A patients, who need to be treated with hemoderivatives or recombinant FVIII substitutes, i.e., biologic drugs. The interaction between FVIII and von Willebrand factor (VWF) influences the pharmacokinetics of FVIII medications. In vivo, full-length FVIII (FL-FVIII) is secreted in a plasma-inactive form, which includes the B domain, which is then proteolyzed by thrombin protease activity, leading to an inactive plasma intermediate. In this work, we analyzed through a computational approach the binding of VWF with two structure models of FVIII (secreted full-length with B domain, and B domain-deleted FVIII). We included in our analysis the atomic model of efanesoctocog alfa, a novel and investigational recombinant FVIII medication, in which the VWF is covalently linked to FVIII. We carried out a structural analysis of VWF/FVIII interfaces by means of protein–protein docking, PISA (Proteins, Interfaces, Structures and Assemblies), and protein contact networks (PCN) analyses. Accordingly, our computational approaches to previously published experimental data demonstrated that the domains A3-C1 of B domain-deleted FVIII (BDD-FVIII) is the preferential binding site for VWF. Overall, our computational approach applied to topological analysis of protein–protein interface can be aimed at the rational design of biologic drugs other than FVIII medications. [ABSTRACT FROM AUTHOR]

Introduction: Immunogenicity causing development of anti‐drug antibodies (ADAs) are major challenges in the treatment of haemophilia, as well as other diseases where proteins are used for treatment. Furthermore, it is a complication for preclinical testing of such therapies in animal models. Aim: To investigate if the immunosuppressive drug CTLA4 immunoglobulin (CTLA4‐Ig) can induce tolerance in haemophilia A (HA) rats receiving recombinant human coagulation factor VIII (rhFVIII) treatment. Methods: Two different prophylactic rhFVIII compounds were given intravenously to HA rats for 4 weeks. Both rhFVIII compounds were co‐administered with commercially available CTLA4‐Ig or human IgG subclass 4 (hIgG4) as control, and blood samples were collected. To functionally test if pharmacological efficacy was retained, rats were subjected to a bleeding experiment under anaesthesia at end of study. Results: The mean inhibitory level after 4 weeks in rats receiving rhFVIII and hIgG4 was 85.7 BU for octocog alfa and 37.4 BU for rurioctocog alfa pegol. In contrast, co‐administration with CTLA4‐Ig during rhFVIII therapy prevented the formation of ADAs (both binding and inhibitory) in 14/14 rats receiving octocog alfa and in 7/7 rats receiving rurioctocog alfa pegol. Moreover, we were able to show that the pharmacological efficacy of rhFVIII was preserved. Conclusion: In a rat model with spontaneous bleeding, co‐administration of CTLA4‐Ig with rhFVIII prevented antibody formation. No FVIII antibodies were detected, demonstrating that CTLA4‐Ig co‐administration can be applicable as a method to prevent immunogenicity, when evaluating human proteins in preclinical systems permitting continuous pharmacokinetic and pharmacodynamic assessment. [ABSTRACT FROM AUTHOR]

In patients with Cerebral Venous Thrombosis (CVT), inherited and acquired thrombophilic conditions have been studied either individually or as subset of a comprehensive evaluation. None of the studies have included a comprehensive evaluation of all the known associations. The associations for various conditions have been found to differ significantly between the Indian and the Western population. We defined a Comprehensive Thrombophilia panel (inherited and acquired) comprising of 13 thrombophilic conditions to include all the relevant known associations in CVT. All patients in this cross-sectional study were evaluated as per the defined protocol during the three-year study period. We evaluated 42 patients of CVT for presence of inherited and acquired thrombophilic conditions. The mean age of the study population was 38.4 yrs. An inherited or an acquired thrombophilic condition was diagnosed in 76% patients. Hyperhomocysteinemia and raised factor VIII levels were the most common conditions, seen in 38% and 35.7% patients respectively. MTHFR mutation was seen in 21% patients. Protein S deficiency was seen in 7% patients. Factor V Leiden and JAK2 positive MPN were seen in 2.3% cases. We did not detect any patients with Protein C deficiency, APLA syndrome, anti-thrombin deficiency, PG20210A mutation or PNH. PAI-1 polymorphism was not included in the protocol as its role is controversial and it has not been established in Indian studies. There is an urgent need for Comprehensive Thrombophilia testing in a larger population of CVT patients to better delineate the spectrum of associated thrombophilic conditions. Such a study is bound to impact therapy and prognosis of CVT. [ABSTRACT FROM AUTHOR]

Hemophilia A (HA) is a rare bleeding disorder caused by factor VIII (FVIII) deficiency due to various genetic mutations in the F8 gene. The disease severity inversely correlates with the plasma levels of functional FVIII. The treatment of HA patients is based on FVIII replacement therapy, either following a prophylactic or on-demand regime, depending on the severity of the disease at diagnosis and the patient's clinical manifestations. The hemorrhagic manifestations are widely variable amongst HA patients, who may require monitoring and treatment re-adjustment to minimize bleeding symptoms. Notably, laboratory monitoring of the FVIII activity is difficult due to a lack of sensitivity to various FVIII-related molecules, including non-factor replacement therapies. Hence, patient management is determined mainly based on clinical manifestations and patient–clinician history. Our goal was to validate the ST Genesia® automated thrombin generation analyzer to quantify the relative hemostatic status in HA patients. We recruited a cohort of HA patients from the Principality of Asturias (Spain), following treatment and at a stable non-bleeding phase. The entire cohort (57 patients) had been comprehensively studied at diagnosis, including FVIII and VWF activity assays and F8 genetic screening, and then clinically monitored until the Thrombin Generation Test (TGT) was performed. All patients were recruited prior to treatment administration, at the maximum time-window following the previous dose. Interestingly, the severe/moderate patients had a similar TGT compared to the mild patients, reflecting the non-bleeding phase of our patient cohort, regardless of the initial diagnosis (i.e., the severity of the disease), treatment regime, and FVIII activity measured at the time of the TGT. Thus, TGT parameters, especially the peak height (Peak), may reflect the actual hemostatic status of a patient more accurately compared to FVIII activity assays, which may be compromised by non-factor replacement therapies. Furthermore, our data supports the utilization of combined TGT variables, together with the severity of patient symptoms, along with the F8 mutation type to augment the prognostic capacity of TGT. The results from this observational study suggest that TGT parameters measured with ST Genesia® may represent a suitable tool to monitor the hemostatic status of patients requiring a closer follow-up and a tailored therapeutic adjustment, including other hemophilia subtypes or bleeding disorders. [ABSTRACT FROM AUTHOR]

BACKGROUND: Corona virus disease 2019 (COVID-19) is a coronavirus that can produce a variety of symptoms, ranging from asymptomatic carrier status to severe respiratory failure, multiple organ dysfunction, and death, it might be associated with hypercoagulability as increase in coagulation factor 8 (FVIII). OBJECTIVES: This study was carried out to investigate markers of hypercoaguablility (factor VIII activity, D-Dimer) in hospitalized adult patients with COVID-19, evaluation of certain markers of inflammation (S. ferritin, lactate dehydrogenase [LDH], C-reactive protein [CRP], and erythrocyte sedimentation rate [ESR]) and correlate those markers with each other. PATIENTS AND METHODS: This cross-sectional study included 70 adult hospitalized patients with COVID-19. Blood samples were obtained for FVIII, D. dimer, and ESR. Statistical analysis was performed using Statistical Package for Social Sciences (SPSS) version 23 and Microsoft Office Excel 2010. RESULTS: The mean age of enrolled 70 patients was 60.22 ± 14.43 years. 44 (62.9%) of patients had neutrophilia and lymphopenia was seen in 41 (58.6%). High ratio of N/L was seen in 66 (94.3%). Low count of eosinophil was seen in 44 (62.9%), high LDH level was seen at 57 (81.4%). Regarding serum ferritin, high level was seen 64 (91.4%) and high level of CRP was seen in 56 (80%). High level of ESR was seen in 64 (91.4%) and high level of D. dimer was seen in 55 (78.6%), while the high level of FVIII was seen in 30 (42.9%) and low FVIII level was seen in 4 (5.7%). CONCLUSIONS: The majority of patients had neutrophilia, lymphopenia, high N/L ratio, and eosinopenia. Markers of inflammation (S. ferritin, LDH, CRP, and ESR), which were elevated. FVIII level and D. dimer were elevated in the majority of patients with COVID-19. Few of the patients were had a low level of FVIII, which might be related to abnormal function of the liver or might be attributed to autoantibodies directed against FVIII.

Summary: Liver sinusoidal endothelial cells (LSECs) form the predominant microvasculature in the liver where they carry out many functions including the secretion of coagulation factor VIII (FVIII). To investigate the early origins of this lineage, we develop an efficient and scalable protocol to produce human pluripotent stem cell (hPSC)-derived LSEC progenitors characterized as venous endothelial cells (VECs) from different mesoderm subpopulations. Using a sensitive and quantitative vascular competitive transplantation assay, we demonstrate that VECs generated from BMP4 and activin A-induced KDR+CD235a/b+ mesoderm are 50-fold more efficient at LSEC engraftment than venous cells from BMP4 and WNT-induced KDR+CD235a/b− mesoderm. When transplanted into immunocompromised hemophilia A mice (NSG-HA), these VECs engraft the liver, proliferate, and mature to functional LSECs that secrete bioactive FVIII capable of correcting the bleeding phenotype. Together, these findings highlight the importance of appropriate mesoderm induction for generating hPSC-derived LSECs capable of functioning in a preclinical model of hemophilia A.

Background: Hemophilia A (HA) is an X-linked bleeding disorder diagnosed by a deficiency in factor VIII (FVIII). For severe HA (SHA), prophylaxis clotting factor concentrates (CFC) has become the standard of care; however, it imparts a high treatment burden and typically results in an annualized bleeding rate (ABR) of 2-6. Emicizumab, a subcutaneously administered FVIII substitute, has become the de facto standard-of-care prophylaxis for children with SHA in many countries. Previous clinical trials of emicizumab have assessed ABR in patients greater than 12 years without inhibitors, and in children less than 12 years with inhibitors; however, there is little information published regarding the ABR of emicizumab compared to CFC in non-inhibitor SHA children., Methods: Using a retrospective electronic medical record chart review, we conducted a self-control analysis of 15 patients less than 12 years of age during equivalent periods of CFC versus emicizumab prophylaxis., Results: The mean ABR on CFC and emicizumab was 1.79 and 1.13 (p = .092), respectively, with a substantially decreased rate of joint bleeds (CFC 0.94; emicizumab 0.33; p = .001) and spontaneous bleeds (CFC 0.79; emicizumab 0.23; p = .008). No safety events were recorded for patients while administering emicizumab. The mean annual cost of CFC prophylaxis was $515,340 (SD $199,540), compared to $328,410 (SD $137,230) for emicizumab prophylaxis (p < .001)., Conclusion: Emicizumab resulted in an improved ABR compared to CFC, especially for joint and spontaneous bleeds, had fewer administration complications, and was substantially less expensive compared to CFC prophylaxis; however, more research is necessary for a complete understanding of the effect of emicizumab on joint health and muscle bleeds., (© 2024 The Author(s). Pediatric Blood & Cancer published by Wiley Periodicals LLC.)

• Hemophilia A is a bleeding disorder related to the deficiency of coagulation FVIII. • FVIII deficiency is associated with osteoporosis. • A dysregulation of the inflammatory processes is observed in FVIII deficiency. • FVIII deficiency leads to the neoformation of abnormal blood vessels. • In addition to VWF, FVIII interacts with numerous cell membrane proteins. Hemophilia A is an X-linked hereditary disorder that results from deficient coagulation factor VIII (FVIII) activity, leading to spontaneous bleeding episodes, particularly in joints and muscles. FVIII deficiency has been associated with altered bone remodeling, dysregulated macrophage polarization, and inflammatory processes that are associated with the neoformation of abnormal blood vessels. Treatment based on FVIII replacement can lead to the development of inhibitors that render FVIII concentrate infusion ineffective. In this context, hemophilia has entered a new therapeutic era with the development of new drugs, such as emicizumab, that seek to restore the hemostatic balance by bypassing pathologically acquired antibodies. We discuss the potential extrahemostatic functions of FVIII that may be crucial for defining future therapies in hemophilia. [ABSTRACT FROM AUTHOR]

Abstract Hemophilia A (HA) is a bleeding disorder characterized by spontaneous and prolonged hemorrhage. The disease is caused by mutations in the coagulation factor 8 gene (F8) leading to factor VIII (FVIII) deficiency. Since FVIII is primarily produced in endothelial cells (ECs) in a non‐diseased human being, ECs hold great potential for development as a cell therapy for HA. We showed that HA patient‐specific induced pluripotent stem cells (HA‐iPSCs) could provide a renewable supply of ECs. The HA‐iPSC‐derived ECs were transduced with lentiviral vectors to stably express the functional B domain deleted F8 gene, the luciferase gene, and the enhanced green fluorescent protein gene (GFP). When transplanted intramuscularly into neonatal and adult immune deficient mice, the HA‐iPSC‐derived ECs were retained in the animals for at least 10‐16 weeks and maintained their expression of FVIII, GFP, and the endothelial marker CD31, as demonstrated by bioluminescence imaging and immunostaining, respectively. When transplanted into HA mice, these transduced HA‐iPSC‐derived ECs significantly reduced blood loss in a tail‐clip bleeding test and produced therapeutic plasma levels (11.2%‐369.2%) of FVIII. Thus, our studies provide proof‐of‐concept that HA‐iPSC‐derived ECs can serve as a factory to deliver FVIII for the treatment of HA not only in adults but also in newborns.

Detection of factor VIII (FVIII) in cells by flow cytometry is controversial, and no monoclonal fluorescent antibody is commercially available. In this study, we optimized such an assay and successfully used it as a platform to study the functional properties of phosphoglycerate kinase (PGK)-FVIII lentiviral vector-transduced cells by directly visualizing FVIII in cells after different gene transfer conditions. We could measure cellular stress parameters after transduction by correlating gene expression and protein accumulation data. Flow cytometry performed on transduced cell lines showed that increasing MOI rates resulted in increased protein levels, plateauing after an MOI of 30. We speculated that, at higher MOI, FVIII production could be impaired by a limiting factor required for proper folding. To test this hypothesis, we interfered with the unfolded protein response by blocking proteasomal degradation and measured the accumulation of intracellular misfolded protein. Interestingly, at higher MOIs the cells displayed signs of toxicity with reactive oxygen species accumulation. This suggests the need for identifying a safe window of transduction dose to avoid consequent cell toxicity. Herein, we show that our flow cytometry platform for intracytoplasmic FVIII protein detection is a reliable method for optimizing gene therapy protocols in hemophilia A by shedding light on the functional status of cells after gene transfer.

The delivery of factor VIII (FVIII) through gene and/or cellular platforms has emerged as a promising hemophilia A treatment. Herein, we investigated the suitability of human placental cells (PLCs) as delivery vehicles for FVIII and determined an optimal FVIII transgene to produce/secrete therapeutic FVIII levels from these cells. Using three PLC cell banks we demonstrated that PLCs constitutively secreted low levels of FVIII, suggesting their suitability as a transgenic FVIII production platform. Furthermore, PLCs significantly increased FVIII secretion after transduction with a lentiviral vector (LV) encoding a myeloid codon-optimized bioengineered FVIII containing high-expression elements from porcine FVIII. Importantly, transduced PLCs did not upregulate cellular stress or innate immunity molecules, demonstrating that after transduction and FVIII production/secretion, PLCs retained low immunogenicity and cell stress. When LV encoding five different bioengineered FVIII transgenes were compared for transduction efficiency, FVIII production, and secretion, data showed that PLCs transduced with LV encoding hybrid human/porcine FVIII transgenes secreted substantially higher levels of FVIII than did LV encoding B domain-deleted human FVIII. In addition, data showed that in PLCs, myeloid codon optimization is needed to increase FVIII secretion to therapeutic levels. These studies have identified an optimal combination of FVIII transgene and cell source to achieve clinically meaningful levels of secreted FVIII.

Objective: Deleterious substitutions of the F8 gene are responsible for causing hemophilia A, which is an inherited bleeding disorder resulting from reduced or absent activity of the coagulant protein factor VIII (FVIII). The most important complication in treatment is inhibitor development toward therapeutic factor VIII. In this study, we aimed to analyze the effects of deleterious substitutions in the F8 gene upon protein structure and function. Materials and Methods: All tests were conducted by computational methods from the CHAMP (CDC Hemophilia A Mutation Project) database. We performed an in silico analysis of deleterious variations using five software programs, Sift, PolyPhen-2, Align-GVGD, KD4v, and MutationTaster, in order to analyze the correlation between variation and the disease. We also studied the correlation between these variations and inhibitor formation. Results: Our analysis showed that these in silico tools are coherent and that there are more variations in the A than the C domains. Moreover, we noticed that there are more deleterious variations than neutral variations in each of the A and C domains. We also found that 13.51% of the patients suffered from a severe form of hemophilia A and that carriers of missense variations developed inhibitors. Also, for the first time, we determined that variation nature is not associated with inhibitor formation. Furthermore, this analysis showed that the risk of developing inhibitors increases when the variation causes a change of amino acid class. Conclusion: This study will help to correctly associate variations with inhibitor development and aid in early characterization of novel variants.

In type 3 von Willebrand disease (VWD3), the most severe form with absent von Willebrand factor (VWF), the bleeding phenotype is variable. Platelet contribution to the hemostatic defect in VWD3 calls upon further studies. We investigated the contribution of platelets to in vitro thrombin generation (TG) and platelet procoagulant activity in VWD3. TG was assessed by calibrated automated thrombogram (CAT) in platelet-poor (PPP) and –rich plasma (PRP) from 9 patients before and in 6 patients also 30 min after receiving their regular VWF therapy. Responsiveness of PPP to FVIII and protein S was also investigated. TG data were compared with routine laboratory variables, rotational thromboelastometry (ROTEM) and platelet expression of P-selectin and phosphatidylserine in flow cytometry. Compared with healthy controls, TG was markedly decreased in VWD3 PPP (peak thrombin was 16% of normal median), but not in PRP (77% of normal median) (p = 0.002). Six out of nine patients (67%) were high responders in their platelet P-selectin, and 5/9 (56%) in phosphatidylserine expression. Replacement therapy improved TG in PPP, while in PRP TG only modestly increased or was unaffected. In PPP, FVIII levels associated with TG and in vitro FVIII-supplemented TG inclined up to threefold. Conversely, a FVIII inhibitory antibody reduced plasma TG in all, but especially in patients with remnant FVIII levels. Inhibition of protein S improved plasma TG, particularly at low FVIII levels. ROTEM failed to detect VWD3. In VWD3, TG is reduced in PPP and regulated by FVIII and protein S, but TG is close to normal in PRP. VWD3 platelets seem to compensate for the FVIII-associated reduction in TG by their exposure of P-selectin and phosphatidylserine.

Background/Objectives : FVIII reagent activity varies across different assays, as well as activated partial thromboplastin time (APTT) reagents. The hemostatic ability of various FVIII reagents was examined via clot waveform analysis (CWA). Methods : APTT was measured using 12 APTT reagents, a small amount of tissue factor-induced FIX activation (sTF/FIXa) and a small amount of thrombin time (sTT) in order to examine 10 FVIII reagents and reference plasma (RP) using CWA. FVIII activity was measured using CWA-APTT, a chromogenic assay, or CWA-sTT. Results : Although the peak time (PT) and peak height (PH) of the CWA-APTT were markedly different in different FVIII reagents using several APTT reagents, the PTs of CWA-APTT were generally normal or shortened and the PHs of CWA-APTT were generally lower than those of RP. The FVIII activity varied, as evaluated using APTT, and was higher when using the CWA-sTT method than the APTT or chromogenic methods. CWA-sTT showed an elevated second peak of first DPH in all FVIII reagents, and both CWA-sTF/FIXa and CWA-sTT were enhanced using APTT reagents. Conclusions: Our evaluation of the hemostatic ability of FVIII reagents varied among APTT reagents. CWA-sTT can be used to further evaluate the hemostatic ability of an FVIII concentrate based on thrombin burst.