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Purpose: To evaluate efficacy for an on-demand treatment of acute bleeding events, pharmacokinetics, safety, and tolerability of HemoRel-A® in severe hemophilia A. Methods: A total of 44 male subjects with severe hemophilia A with an annualized bleed rate of 12 while on-demand treatment with factor VIII (FVIII) were enrolled in the study and received HemoRel-A® for bleed treatment. The efficacy of HemoRel-A® was evaluated based on a four-point scale (excellent, good, moderate, or none). Six-point pharmacokinetic (PK) assessment was performed following a single dose of 50 IU/kg in 12 subjects after a 7-day wash-out period. Safety evaluations were performed at each visit and inhibitor testing was performed in all patients at screening and end of study. Results: Forty-four male subjects received at least a single dose of the study medication and were included in the intent-to-treat (ITT) analysis and safety outcome. In 23 (7.52%) out of the 306 bleeding events, HemoRel-A® efficacy was rated as excellent, in 272 (88.89 %) bleeds it was rated as good, and in 11 (3.68%) bleeding events it was rated as moderate. No failure of efficacy was noted in any of the bleeding events. Thus overall out of 306 bleeding events, 295 (96.41%) showed excellent or good efficacy. Pharmacokinetic assessment based on plasma FVIII activity measured by the chromogenic assay in 12 patients showed comparative results similar to FVIII preparations. A total of 12 adverse events (AEs) were reported in this study. There was no inhibitor development in this previously treated patients (PTP) cohort. Conclusion: HemoRel-A® was established to be efficacious and safe in the treatment of acute bleeding events in subjects with severe hemophilia A. Trial registration number: CTRI/2018/05/013790. Registration date: 9th May 2018.

Purpose Hemophilia B is an X-linked congenital bleeding disorder caused by a deficiency of coagulation factor IX (FIX) clotting activity. This study evaluated safety and efficacy of nonacog alfa, a recombinant human blood coagulation FIX replacement product, in males aged 12–65 years with hemophilia B (FIX activity ≤ 2%) with or without inhibitors in India. Methods In this multicenter, open-label, post-approval phase 4 study, participants were treated for up to 8 weeks, with up to a 4-week screening period and a subsequent post-treatment 28-day safety observation period. Intravenous nonacog alfa 40 IU/kg (range 13–78 IU/kg) was administered at intervals of 3–4 days, in accordance with the approved local product document. Results A total of 25 participants were enrolled and completed the study. No participants developed FIX inhibitors during the study, experienced treatment-related adverse events (AEs) or serious AEs, or developed a thrombotic event and/or hypersensitivity reaction. No participants experienced bleeding events requiring on-demand treatment with nonacog alfa. Seventeen bleeding episodes (16 spontaneous and 1 traumatic) were reported in 10 participants; all occurred post treatment, with the exception of a minor gum-bleeding event, and were managed without treatment. The mean (SD) annualized total factor consumption (TFC) per patient was 224,582 (75,527) IU; the mean (SD) annualized TFC by weight per patient was 3639 (573) IU/kg. Conclusion Nonacog alfa was safe and effective for the prevention of hemorrhagic episodes in Indian males with congenital, severe hemophilia B. No participants developed FIX inhibitors, and no new safety signals were reported.

The development of inhibitors with factor VIII (FVIII) replacement therapy is one of the most common and challenging complications of haemophilia A (HA) treatment, jeopardising treatment efficacy and predisposing patients to high risks of morbidity and mortality. The management of patients with inhibitors is particularly challenging in countries where resources are limited.To provide a comprehensive summary of the management of HA with inhibitors while focusing on differences in practice between Western and non-Western countries and how resource scarcity can impact HA management, leading to suboptimal outcomes in patients with inhibitors.Summary of key evidence and regional expert opinion.We address, particularly, the diagnosis of and testing for inhibitors, as well as the epidemiology of inhibitors, including incidence, prevalence and disease burden. Secondly, we provide an overview of the current treatment landscape in HA with inhibitors regarding the eradication of inhibitors with immune tolerance induction and the treatment and prevention of bleeding with bypassing agents, non-factor replacement agents and other experimental therapies. This is complemented with insights from the authors around the applicability of, and challenges associated with, such therapies in their settings of practice.We conclude by proposing some key steps towards bridging the gaps in the management of HA with inhibitors in resource-limited countries, including: (1) the collection of quality data that can inform healthcare reforms and policies; (2) improving disease knowledge among healthcare practitioners and patients with the aim of standardising disease management across centres and (3) working towards promoting equal access to HA care and therapies for everyone.

Purpose Hemophilia A is an X-linked congenital disorder, characterized by factor VIII (FVIII) deficiency. Globally, India has the highest population of patients with hemophilia, and there is a clear unmet need for appropriate and effective treatment for this patient population. This multicenter, open-label, post-approval study evaluated the safety and efficacy of moroctocog alfa in patients with moderate or severe congenital hemophilia A in India. Methods Intravenous moroctocog alfa was administered 30 ± 5 IU/kg 3 times weekly for bleeding prophylaxis, according to the local product document. Participants were treated for up to 8 weeks, with an up to 4-week screening period and a subsequent post-treatment, 28-day safety observation period. Patients continued in the study until at least 24 exposure days or a period of up to 8 weeks on moroctocog alfa. Results A total of 50 participants were enrolled, and 48 (85.7%) completed the study. No participants developed FVIII inhibitors during the study. The mean (SD) annualized bleeding rate during moroctocog alfa prophylaxis was 0.79 (2.0) with a median (range) of 0.00 (0.0, 6.8). The mean (SD) annualized total factor consumption (TFC) per participant was 287,432 (93,866) IU; the mean (SD) annualized TFC by weight per participant was 4176 (858) IU/kg. Moroctocog alfa was well tolerated with no reported treatment-emergent adverse event-related dose reductions, discontinuations, or serious adverse events. Conclusion Moroctocog alfa was safe, effective, and well tolerated in Indian participants with congenital moderate to severe hemophilia A. No participant developed FVIII inhibitors during the study.

Adeno-associated virus (AAV)-based gene therapies can restore endogenous factor VIII (FVIII) expression in hemophilia A (HA). AAV vectors typically use a B-domain–deleted FVIII transgene, such as human FVIII-SQ in valoctocogene roxaparvovec (AAV5-FVIII-SQ). Surprisingly, the activity of transgene-produced FVIII-SQ was between 1.3 and 2.0 times higher in one-stage clot (OS) assays than in chromogenic-substrate (CS) assays, whereas recombinant FVIII-SQ products had lower OS than CS activity. Transgene-produced and recombinant FVIII-SQ showed comparable specific activity (international units per milligram) in the CS assay, demonstrating that the diverging activities arise in the OS assay. Higher OS activity for transgene-produced FVIII-SQ was observed across various assay kits and clinical laboratories, suggesting that intrinsic molecular features are potential root causes. Further experiments in 2 participants showed that transgene-produced FVIII-SQ accelerated early factor Xa and thrombin formation, which may explain the higher OS activity based on a kinetic bias between OS and CS assay readout times. Despite the faster onset of coagulation, global thrombin levels were unaffected. A correlation with joint bleeds suggested that both OS and CS assay remained clinically meaningful to distinguish hemophilic from nonhemophilic FVIII activity levels. During clinical development, the CS activity was chosen as a surrogate end point to conservatively assess hemostatic efficacy and enable comparison with recombinant FVIII-SQ products. Relevant trials are registered on clinicaltrials.gov as #NCT02576795 and #NCT03370913 and, respectively, on EudraCT (European Union Drug Regulating Authorities Clinical Trials Database; https://eudract.ema.europa.eu) as #2014-003880-38 and #2017-003215-19.

The bispecific monoclonal antibody emicizumab bridges activated factor IX and factor X, mimicking the cofactor function of activated factor VIII (FVIII), restoring hemostasis.The Phase 3b STASEY study was designed to assess the safety of emicizumab prophylaxis in people with hemophilia A (HA) with FVIII inhibitors.People with HA received 3 mg/kg emicizumab once weekly (QW) for 4 weeks followed by 1.5 mg/kg QW for 2 years. The primary objective was the safety of emicizumab prophylaxis, including incidence and severity of adverse events (AEs) and AEs of special interest (thrombotic events [TEs] and thrombotic microangiopathies). Secondary objectives included efficacy (annualized bleed rates [ABRs]).Overall, 195 participants were enrolled; 193 received emicizumab. The median (range) duration of exposure was 103.1 (1.1-108.3) weeks. Seven (3.6%) participants discontinued emicizumab. The most common AEs were arthralgia (The safety profile of emicizumab prophylaxis was confirmed in a large population of people with HA with FVIII inhibitors and no new safety signals occurred. The majority of participants had zero treated bleeds.

There is convincing evidence to show that low-dose prophylaxis (LDP) results in reduction in annualized bleeding rate (ABR) and better health-related quality of life (HRQoL) compared with on-demand or episodic treatment (ET) in haemophilia patients. The aim is to review various LDP protocols practised for the treatment of haemophilia, specifically in resource-limited countries.A literature survey was made of articles published in English language in PubMed and EMBASE without any time limit using keywords 'low dose', 'prophylaxis' and 'haemophilia' in different combinations.A total of 19 reports involving LDP in patients with haemophilia were included in this review. Almost all studies reported reduction in ABR, improvement in joint function, pain and HRQoL compared with ET, but this did not fully translate into significant improvement in structural arthropathy already caused by earlier bleeds, suggesting that LDP may be less or ineffective in either stopping or reversing the damage. Individualized dose escalation protocols based on pharmacokinetic (PK) or clinical parameters were found to be superior to fixed LDP protocols and cost-effective compared with standard dose protocols.The developing countries can initiate LDP as the first step of prophylaxis, but certainly this should not be the final goal of the health care system in any country. Due to the complex pathophysiological mechanisms underlying haemophilic arthropathy, long-term data on LDP in haemophilia patients are warranted.

Gene and cell therapies for a variety of life-limiting illnesses are under investigation, and a small number of commercial products have successfully obtained regulatory approval. The cost of treatment is high, and clinical studies evaluating safety and efficacy are performed predominately in high-income countries. We reviewed the current status of gene and cell therapies in low- and middle-income countries and highlighted the need and current barriers to access. The state of product development in Brazil, South Africa, and India is discussed, including lessons learned from American Society of Gene and Cell Therapy (ASGCT)-sponsored virtual symposia in each of these countries.

Gene therapy shows promise as a potential "cure" for hemophilia A and B. Adeno-associated virus (AAV) vectors are the leading platform to deliver modified genetic code of factor VIII or IX to the liver effecting endogenous production. Patient exposure to wild-type AAV leads to the formation of neutralizing factors, which can prevent successful transduction. It is thus important to establish the seroprevalence of the AAV serotypes in people with hemophilia to aid prediction of successful gene transfer. The seroprevalence of AAV6 in UK people with hemophilia B is not yet reported.We studied the prevalence of anti-AAV6 neutralizing factors in UK people with hemophilia B (Serum samples and patient data were collected from 49 people with hemophilia B registered at UK hemophilia comprehensive care centers. The samples were tested for neutralizing factors to AAV6 using a cell-based transduction inhibition assay.Thirty-one percent of patients had serum neutralization against AAV6. There was no correlation between AAV6 seropositivity and previous treatment with plasma-derived FIX products or hepatitis C exposure.Based on limited data, there is no evidence of association between the presence of AAV6 neutralizing factors in people with hemophilia B and exposure to contaminated plasma derivatives. The frequency of AAV6 neutralizing factors in our hemophilia B cohort is similar to UK people with hemophilia A and non-hemophilia populations.

Background: the mortality of patients admitted to the intensive care unit (ICU) with COVID-19 remains significantly high. Severe COVID-19 pneumonia is characterised by refractory hypoxemia with significant shunting due to a combination of alveolar damage, vascular vasoconstriction, and occlusion due to microthrombi. Similar pathological features are seen in extra-pulmonary organs. However, the influence of thrombotic markers on the risk of mechanical ventilation (MV) and the development of acute kidney injury (AKI) is not fully defined.Methods: this was a cross-sectional evaluation of haemostatic and thrombotic markers of COVID-19 patients admitted to the ICU to determine their predictability for the development of thromboembolism and the need for non-invasive or invasive MV, development of AKI, and mortality.Results: an extended coagulation profile was obtained in 71 SARS-CoV-2 positive patients admitted to the ICU. All patients had acute severe hypoxic respiratory failure and required non-invasive or invasive MV. There were increases in peak D-dimer (3.0 mg/L), factor VIII levels (255 IU/dL) vWF antigen (471 IU/dL) with low ADAMTS13 activity (54.7 IU/dL) compared to the reference ranges. Peak D-dimer was consistently raised in patients who developed AKI and required invasive MV. ADAMTS13/vWF/platelet axis was associated with disease severity, multi-organ dysfunction, and mortality.Conclusions: haematological abnormalities are a common feature of severe COVID-19 pneumonia. We found peak D-dimer and vWF-ADAMTS13-platelet axis are associated with increased ICU severity and outcome in severe COVID-19 patients admitted to ICU. Larger studies are needed to evaluate this more comprehensively.

Background Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy for pseudomyxoma peritonei (PMP) is associated with excessive bleeding and acquired fibrinogen deficiency. Maintaining plasma fibrinogen may support hemostasis. Objectives To compare hemostatic efficacy and safety of human fibrinogen concentrate (HFC) vs cryoprecipitate as fibrinogen sources for bleeding patients with acquired fibrinogen deficiency undergoing PMP CRS. Methods FORMA‐05 was an off‐label single‐center, prospective, randomized, controlled phase 2 study. Patients undergoing PMP surgery with predicted intraoperative blood loss ≥2 L received human fibrinogen concentrate (HFC; 4 g) or cryoprecipitate (two pools of 5 units, containing approximately 4.0‐4.6 g fibrinogen), repeated as needed. The primary endpoint was a composite of intraoperative and postoperative efficacy, graded using objective 4‐point scales and adjudicated by an independent committee. Results One hundred percent of patients receiving HFC (95% confidence interval: 83.9‐100.0, n = 21) or cryoprecipitate (84.6‐100.0, n = 22) achieved hemostatic success. HFC demonstrated noninferior efficacy (P = .0095; post hoc) and arrived in the operating room 46 minutes faster. There were significantly greater mean increases with HFC vs cryoprecipitate in plasma fibrinogen (0.78 vs 0.35 g/L; P

Background Current treatment for severe hemophilia A is replacement of deficient factor. Although replacement therapy has improved life expectancy and quality, limitations include frequent infusions and high costs. Gene therapy is a potential alternative that utilizes an adeno‐associated virus (AAV) vector containing the human genetic code for factor 8 (FVIII) that transduces the liver, enabling endogenous production of FVIII. Individuals with preexisting immunity to AAV serotypes may be less likely to benefit from this treatment. Objectives This study measured seroprevalence of antibodies to AAV5 and 8 in an UK adult hemophilia A cohort. Patients/Methods Patients were recruited from seven hemophilia centres in the UK. Citrated plasma samples from 100 patients were tested for preexisting activities against AAV5 and 8 using AAV transduction inhibition and total antibodies assays. Results Twent‐one percent of patients had antibodies against AAV5 and 23% had antibodies against AAV8. Twenty‐five percent and 38% of patients exhibited inhibitors of AAV5 or AAV8 cellular transduction respectively. Overall seroprevalence using either assay against AAV5 was 30% and against AAV8 was 40% in this cohort of hemophilia A patients. Seropositivity for both AAV5 and AAV8 was seen in 24% of participants. Conclusions Screening for preexisting immunity may be important in identifying patients most likely to benefit from gene therapy. Clinical studies may be needed to evaluate the impact of preexisting immunity on the safety and efficacy of AAV mediated gene therapy.

Introduction Valoctocogene roxaparvovec is an investigational AAV5-based factor VIII (FVIII) gene therapy that has demonstrated sustained clinical benefit in people with severe haemophilia A. Aim To report safety, tolerability, efficacy, and quality of life (QOL) among participants who received valoctocogene roxaparvovec in a phase 1/2 clinical study (NCT02576795). Methods Men ≥18 years of age with severe haemophilia A (FVIII ≤1 IU/dl) without history of FVIII inhibitors or anti-AAV5 antibodies received a single infusion of valoctocogene roxaparvovec and were followed for 5 years (6 × 1013 vg/kg dose, n = 7) and 4 years (4 × 1013 vg/kg dose, n = 6). Results Over the past 2 years, few adverse events and no FVIII inhibitors were reported. Per chromogenic substrate (CSA) assay at years 5 and 4, four of seven and three of six participants in the 6 × 1013 and 4 × 1013 vg/kg cohorts, respectively, maintained median FVIII levels >5 IU/dl, corresponding to mild haemophilia. By regression analysis, rate of change in FVIII activity was -0.14 (95% confidence interval [CI]: -.32 to .03) IU/dl/wk in the 6 × 1013 vg/kg cohort in year 5 and -.06 (95% CI: -.14 to .01) IU/dl/wk in the 4 × 1013 vg/kg cohort in year 4. No participants resumed FVIII prophylaxis, and eight of 13 participants reported zero bleeds in the past 2 years. Improved QOL from baseline persisted in the 6 × 1013 vg/kg cohort; all six Haemo-QOL-A domain scores increased. For the 4 × 1013 vg/kg cohort, high baseline Haemo-QOL-A scores persisted. Conclusion These results demonstrate transgene expression and haemostatic response for up to 5 years in individuals with haemophilia A.

Thrombosis affecting the pulmonary and systemic vasculature is common during severe COVID-19 and causes adverse outcomes. Although thrombosis likely results from inflammatory activation of vascular cells, the mediators of thrombosis remain unconfirmed. In a cross-sectional cohort of 36 severe COVID-19 patients, we show that markedly increased plasma von Willebrand factor (VWF) levels were accompanied by a partial reduction in the VWF regulatory protease ADAMTS13. In all patients we find this VWF/ADAMTS13 imbalance to be associated with persistence of ultra-high-molecular-weight (UHMW) VWF multimers that are highly thrombogenic in some disease settings. Incubation of plasma samples from patients with severe COVID-19 with recombinant ADAMTS13 (rADAMTS13) substantially reduced the abnormally high VWF activity, reduced overall multimer size and depleted UHMW VWF multimers in a time and concentration dependent manner. Our data implicate disruption of normal VWF/ADAMTS13 homeostasis in the pathogenesis of severe COVID-19 and indicate that this can be reversed ex vivo by correction of low plasma ADAMTS13 levels. These findings suggest a potential therapeutic role for rADAMTS13 in helping restore haemostatic balance in COVID-19 patients.

Factor VIII gene transfer with a single intravenous infusion of valoctocogene roxaparvovec (AAV5-hFVIII-SQ) has demonstrated clinical benefits lasting 5 years to date in people with severe hemophilia A. Molecular mechanisms underlying sustained AAV5-hFVIII-SQ-derived FVIII expression have not been studied in humans. In a substudy of the phase 1/2 clinical trial (NCT02576795), liver biopsy samples were collected 2.6–4.1 years after gene transfer from five participants. Primary objectives were to examine effects on liver histopathology, determine the transduction pattern and percentage of hepatocytes transduced with AAV5-hFVIII-SQ genomes, characterize and quantify episomal forms of vector DNA and quantify transgene expression (hFVIII-SQ RNA and hFVIII-SQ protein). Histopathology revealed no dysplasia, architectural distortion, fibrosis or chronic inflammation, and no endoplasmic reticulum stress was detected in hepatocytes expressing hFVIII-SQ protein. Hepatocytes stained positive for vector genomes, showing a trend for more cells transduced with higher doses. Molecular analysis demonstrated the presence of full-length, inverted terminal repeat-fused, circular episomal genomes, which are associated with long-term expression. Interindividual differences in transgene expression were noted despite similar successful transduction, possibly influenced by host-mediated post-transduction mechanisms of vector transcription, hFVIII-SQ protein translation and secretion. Overall, these results demonstrate persistent episomal vector structures following AAV5-hFVIII-SQ administration and begin to elucidate potential mechanisms mediating interindividual variability.

Introduction Hemophilia A and B are rare bleeding disorders characterized by ineffective clot formation due to impaired thrombin generation as a result of deficiency of FVIII or FIX, respectively. Fitusiran is a subcutaneously (SC) administered investigational siRNA therapeutic targeting antithrombin to restore thrombin generation and rebalance hemostasis in people with hemophilia A or B, with or without inhibitors. Here, we present the safety and efficacy of fitusiran prophylaxis for PwHI in a phase 3 study (ATLAS-INH; NCT03417102). Methods The ATLAS-INH study is a randomized, open-label Phase 3 study designed to evaluate the efficacy and safety of fitusiran in PwHI. Eligible males ≥12 years receiving on-demand treatment with bypassing agents (BPA) were randomized in a 2:1 ratio to receive once monthly 80 mg SC fitusiran prophylaxis or continue with on-demand BPA. The primary endpoint is annualized bleeding rate (ABR) in PwHI on fitusiran prophylaxis compared to those on BPA on-demand in the efficacy period. The secondary endpoints include spontaneous ABR, joint ABR, and quality of life (QoL) measured by Haem-A-QoL. Results 57 subjects were randomized into the study. Mean (range) age of the study participants at screening was 28.4 (13-63) yrs. Statistical significance was achieved for primary and all secondary endpoints with significant reduction in ABRs of treated bleeds: all, spontaneous and joint bleeds for fitusiran vs on-demand BPA arm (Table 1). A total of 25 patients in fitusiran arm (65.8%) had zero treated bleeding events. Efficacy of fitusiran prophylaxis treatment was seen in both hemophilia A and hemophilia B patients with inhibitors. Statistical significance was also achieved for improvement in physical health domain score, with a difference (95% CI) of -28.72 (-39.07 to -18.37, p-value Overall, 38 patients (92.7%) in the fitusiran arm and 11 patients (57.9%) in the on-demand BPA arm experienced at least 1 treatment emergent adverse event (TEAE). A total of 13 treatment emergent serious adverse events (TESAEs) were reported in 7 patients (17.1%) in the fitusiran arm and 8 TESAEs were reported in 5 patients (26.3%) in the on-demand BPA arm. All TESAEs were reported in 1 patient each; in the fitusiran prophylaxis arm these included events of device related infection, hematuria, spinal vascular disorder, subclavian vein thrombosis, thrombosis, acute cholecystitis, chronic cholecystitis and asymptomatic COVID-19. One patient (2.4%) in the fitusiran arm experienced TEAEs that resulted in study drug discontinuation (spinal vascular disorder and thrombosis). There were no fatal TEAEs reported. Conclusions This Phase 3 study demonstrated the efficacy of the 80 mg monthly subcutaneous prophylaxis dose of fitusiran in people with hemophilia A or B with inhibitors. Specifically, fitusiran significantly reduced bleeding with a median ABR of zero and significant proportion of people with zero bleeds, resulting in a meaningful improvement in health-related quality of life. Reported TESAEs were generally consistent with what is anticipated in an adult and adolescent population with severe hemophilia A or B with inhibitors, or with the previously identified risks of fitusiran. A revised fitusiran dosing regimen with reduced dose and dose frequency is currently being evaluated in ongoing clinical studies. Figure 1 Figure 1. Disclosures Young: Genentech/Roche, Grifols, and Takeda: Research Funding; Apcintex, BioMarin, Genentech/Roche, Grifols, Novo Nordisk, Pfizer, Rani, Sanofi Genzyme, Spark, Takeda, and UniQure: Consultancy. Kavakli: Roche: Consultancy, Other: Clinical Trial Support; Novo Nordisk A/S: Consultancy, Other: Clinical Trial Support; Takeda: Consultancy, Other: Clinical Trial Support. Poloskey: Sanofi: Current Employment, Current equity holder in publicly-traded company. Qui: Sanofi: Current Employment, Current equity holder in publicly-traded company. Kichou: Sanofi: Current Employment, Current equity holder in publicly-traded company. Andersson: Sanofi: Current Employment, Current equity holder in publicly-traded company; WEST advisory committee member: Membership on an entity's Board of Directors or advisory committees. Mei: Sanofi: Current Employment, Current equity holder in publicly-traded company. Rangarajan: Sanofi: Other: Advisory Board; Pfizer: Other: Advisory Board; Reliance Life Sciences: Consultancy; Takeda: Other: Advisory Board, Conference Support, Speakers Bureau.

BAY 94-9027 (damoctocog alfa pegol, Jivi) is an extended-half-life recombinant factor VIII (rFVIII) shown to be well-tolerated and efficacious in bleeding prevention in previously treated patients with severe hemophilia A. During the PROTECT VIII study, prophylaxis patients received BAY 94-9027 at intervals determined based on their bleeding phenotype, observed during a 10-week run-in treatment period with twice-weekly dosing. Those with ≤ 1 spontaneous joint or muscle bleed were randomized to either 45 to 60 IU/kg every 5 days or 60 IU/kg every 7 days; patients could increase dosing frequency to every 5 days or twice weekly in the case of bleeds. Those enrolled after the randomization arms were full, and those with ≥ 2 bleeds in the run-in period, received 30 to 40 IU/kg twice weekly. Patients completing the main study could receive open-label BAY 94-9027 in the extension phase. Dosing regimen, total, and joint annualized bleeding rates were analyzed over three periods: prestudy, main study, and extension. A total of 80 patients who were on prophylaxis treatment prior to and during the study and had prior bleed data available were evaluated in this post hoc analysis of PROTECT VIII. Most patients (> 80%) required fewer infusions with BAY 94-9027 prophylaxis versus their previous standard-half-life (SHL) rFVIII product. Lower bleeding and joint bleeding rates were observed over time from the prestudy to the extension study period in all treatment regimens. Compared with SHL FVIII, BAY 94-9027 prophylaxis allows patients to reduce infusion frequency with maintained or improved protection from bleeds.

Background Hemophilia is a rare bleeding disorder characterized by deficiency of FVIII or FIX resulting in ineffective clot formation due to impaired thrombin generation. Fitusiran is a subcutaneously (SC) administered investigational siRNA therapeutic agent which targets antithrombin to enhance thrombin generation potential and rebalance hemostasis in people with hemophilia (PwH), irrespective of inhibitor status. Here, we present results from a Phase 3 study of the efficacy and safety of fitusiran prophylaxis compared with on-demand (OD) treatment with factor concentrates in PwH A or B without inhibitors (ATLAS-A/B; NCT03417245). Methods This Phase 3, multicenter, multinational, randomized, open-label study evaluated the efficacy and safety of fitusiran in males aged ≥12 years with severe hemophilia A or B without inhibitors, previously treated OD. Eligible participants (pts) were randomized 2:1 to receive either once-monthly 80 mg SC fitusiran prophylaxis (fitusiran arm) or OD factor concentrates for treatment of bleeding episodes (OD arm) for a treatment period of 9 months. The primary endpoint was annualized bleeding rate (ABR) in the efficacy period (Day 29 post-first fitusiran dose up to Day 246). Secondary endpoints included annualized spontaneous bleeding rate (AsBR) and annualized joint bleeding rate (AJBR) in the efficacy period and health-related quality of life (HRQoL) in the treatment period, measured by Haem-A-QoL. Safety and tolerability were assessed throughout the study. Results Overall, 120 pts were randomized (fitusiran arm n=80; OD arm n=40); 79 pts (98.8%) in the fitusiran arm and 37 pts (92.5%) in the OD arm completed the study. A total of 93 pts had hemophilia A (fitusiran arm n=62, OD arm n=31) and 27 pts had hemophilia B (fitusiran arm n=18, OD arm n=9). Baseline demographics and characteristics were similar in both arms. Median observed ABR was 0.0 (IQR, 0.0 to 3.4) in the fitusiran arm and 21.8 (IQR, 8.4 to 41.0) in the OD arm; 40 pts (50.6%) in the fitusiran arm experienced no bleeds that required treatment with OD factor concentrates. A significant reduction in estimated ABR was achieved in the fitusiran arm vs the OD arm (89.9% reduction [95% CI, 84.1% to 93.6%], p Seventy-nine pts received at least 1 dose of fitusiran and 40 patients were randomized to the OD arm and included in the safety analysis. Overall, 62 pts (78.5%) in the fitusiran arm and 18 pts (45%) in the OD arm experienced ≥1 treatment emergent adverse event (TEAE). A total of 5 treatment emergent serious adverse events (TESAEs) were reported in 5 pts (6.3%) in the fitusiran arm and 9 TESAEs were reported in 5 pts (12.5%) in the OD arm. TESAEs in the fitusiran arm included cholelithiasis (2 pts, 2.5%), cholecystitis, lower respiratory tract infection, and asthma (1 pt each, 1.3%). In the fitusiran arm, 2 pts (2.5%) experienced TEAEs that resulted in fitusiran discontinuation (cholecystitis and increased alanine aminotransferase). No TEAEs of thrombosis and no fatal TEAEs were reported. Conclusions All key primary and secondary endpoints were met in this Phase 3 study. Specifically, once-monthly 80 mg SC fitusiran prophylaxis demonstrated a significant reduction in ABR, AsBR and AJBR (all ~90%) in people with severe hemophilia A or B without inhibitors compared with OD treatment. This reduction in bleeding was associated with a meaningful improvement in HRQoL. Reported TESAEs were generally consistent with previously identified risks of fitusiran. With the aim of further enhancing the benefit-risk profile of fitusiran, a revised regimen with reduced dose and frequency is currently being evaluated in ongoing clinical studies. Figure 1 Figure 1. Disclosures Srivastava: Roche: Other: Advisory Board, Research Funding; Novo Nordisk: Other: Advisory Board, Research Funding; Sanofi: Other: Advisory Board, Research Funding; Pfizer: Other: Advisory Board, Research Funding; Takeda: Other: Advisory Board, Research Funding; Bayer Healthcare: Other: Grant Review & Awards Committee. Rangarajan: Sanofi: Other: Advisory Board; Pfizer: Other: Advisory Board; Reliance Life Sciences: Consultancy; Takeda: Other: Advisory Board, Conference Support, Speakers Bureau. Kavakli: Pfizer, Bayer, Takeda, Roche, Novo Nordisk: Honoraria; Pfizer, Bayer, Roche, Novo Nordisk, Takeda: Speakers Bureau; Roche, Bayer, Pfizer, Novo Nordisk, Takeda: Membership on an entity's Board of Directors or advisory committees. Klamroth: Bayer, Leo: Research Funding; Bayer, Biotest, Biomarin, BMS, CSL Behring, Daiichi Sankyo, Leo, Novo Nordisk, Octapharma, Pfizer, Roche, Sanofi, SOBI, Takeda: Honoraria; Bayer, Biotest, Biomarin, BMS, CSL Behring, Daiichi Sankyo, Novo Nordisk, Octapharma, Pfizer, Roche, Sanofi, SOBI, Takeda: Speakers Bureau. Kenet: Alnylam: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Opko Biologics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Shire: Research Funding, Speakers Bureau; Novo Nordisk: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Takeda: Consultancy, Honoraria, Research Funding; Nat'l Hemophilia Ctr and Coagulation Unit and Amalia Biron Res Inst of Thromb & Hemost, Sheba Medical Ctr, Tel Hashomer, Israel: Current Employment; BioMarin Pharmaceutical: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; CSL: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Uniquore: Honoraria, Membership on an entity's Board of Directors or advisory committees; BPL: Research Funding. Khoo: NSW Health Pathology: Current Employment; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novo Nordisk: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Speakers Bureau. You: Eulji University Hospital: Current Employment. Malan: PHOENIX Pharma (Pty) Ltd, Qgeberha, South Africa: Current Employment, Research Funding; St Francis Hospital, Qgeberha, South Africa: Membership on an entity's Board of Directors or advisory committees. Frenzel: Pfizer: Research Funding; Roche: Research Funding; SOBI: Research Funding; CSL Behring: Research Funding. Stasyshyn: CSL Behring: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novo Nordisk: Consultancy, Research Funding, Speakers Bureau; Octapharma: Consultancy, Research Funding, Speakers Bureau; Pfizer: Consultancy, Research Funding, Speakers Bureau; Takeda: Consultancy, Research Funding, Speakers Bureau; Grifols: Consultancy, Speakers Bureau; Shire: Consultancy, Honoraria, Research Funding; Institute of Blood Pathology and Transfusion Medicine of National Academy of Medical Sciences of Ukraine: Current Employment; Sanofi: Honoraria, Research Funding; Roche: Speakers Bureau; LFB: Honoraria, Research Funding. Poloskey: Sanofi: Current Employment, Current equity holder in publicly-traded company. Andersson: Sanofi: Current Employment, Current equity holder in publicly-traded company; WEST advisory committee member: Membership on an entity's Board of Directors or advisory committees. Mei: Sanofi: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months, Patents & Royalties. Pipe: Sangamo Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Scientific Advisory Board; ASC Therapeutics: Consultancy, Other: Scientific Advisory Board; Apcintex: Consultancy; Bayer: Consultancy; Biomarin: Consultancy; Catalyst Biosciences: Consultancy; CSL Behring: Consultancy; Freeline: Consultancy; Grifols: Consultancy; HEMA Biologics: Consultancy; Novo Nordisk: Consultancy; Octapharma: Consultancy; Pfizer: Consultancy; Roche/Genentech: Consultancy; Sanofi: Consultancy; Takeda: Consultancy; Spark Therapeutics: Consultancy; uniQure: Consultancy; GeneVentiv: Consultancy, Membership on an entity's Board of Directors or advisory committees; YewSavin: Research Funding; Siemens: Research Funding.

Introduction Haemophilia A patients are at a high risk of excess bleeding during surgeries. The aim of haemostatic therapy during the perioperative period is to normalize FVIII level perioperatively and postoperatively to maintain normal haemostasis until wound healing is complete. Aims/Methods To examine the efficacy of Nuwiq® (simoctocog alfa, human-cl rhFVIII), a 4th generation recombinant FVIII produced in a human cell line, for surgical prophylaxis in patients with severe haemophilia A. This analysis assessed the efficacy of Nuwiq® during surgical procedures and in the postoperative period in seven clinical studies of previously treated patients (PTPs) with severe haemophilia A. Results Thirty-six patients, aged 3-55 years, received surgical prophylaxis with Nuwiq® for 60 surgeries (28 major and 32 minor). Efficacy was evaluated for 52 surgeries (25 major and 27 minor). The success rate of Nuwiq® treatment was 98.1% (51 of 52 evaluated surgeries); haemostatic efficacy was assessed as “excellent” or “good” in all but one major surgery (assessed as “moderate”). The number of infusions ranged from 1 to 19 for minor surgeries and from 3 to 76 for major surgeries. The median (range) daily doses were 42.0 (28.2-100.9) IU kg−1 for minor surgeries and 69.3 (43.3-135.6) IU kg−1 for major surgeries. There were no serious treatment-related adverse events, and none of the patients developed FVIII inhibitors. Conclusions The results of this pooled analysis show that Nuwiq® was efficacious in maintaining haemostasis during and after major and minor surgical procedures in PTPs with severe haemophilia A.

Summary Inhibitor formation in non-severe haemophilia A is a life-long risk and associated with morbidity and mortality. There is a paucity of data to understand real-world inhibitor screening practice. We evaluated the treatment burden, haemostatic strategies, F8 genotyping and inhibitor screening practices in non-severe haemophilia A in seven London haemophilia centres. In the 2-year study period, 44% (377/853) patients received at least one haemostatic treatment. Seventy-nine percent of those treated (296/377) received factor VIII (FVIII) concentrate. F8 genotype was known in 88% (331/377) of individuals. Eighteen per cent (58/331) had ‘high-risk’ F8 genotypes. In patients with ‘standard-risk’ F8 genotypes treated on-demand with FVIII concentrate, 51·3% episodes (243/474) were screened within 1 year. However, poor screening compliance was observed after ‘high-risk’ treatment episodes. In patients with ‘standard-risk’ F8 genotypes, 12·3% (28/227) of treatment episodes were screened in the subsequent 6 weeks after surgery or a bleed requiring ≥5 exposure days. Similarly, in the context of ‘high-risk’ F8 genotypes after any FVIII exposure, only 13·6% (12/88) of episodes were screened within 6 weeks. Further study is required to assess optimal practice of inhibitor screening in non-severe haemophilia A to inform subsequent clinical decisions and provide more robust prevalence data to further understand the underlying immunological mechanism.

Introduction: Thrombin plays a central role in hemostasis: in the initiation, amplification, and propagation phases of coagulation and in the formation of a stable fibrin clot. Normal hemostatic function requires a balance between procoagulant and anticoagulant proteins that regulate thrombin generation (Negrier et al. Blood Reviews. 2019). Co-inheritance of antithrombin deficiency in people with hemophilia is associated with a milder bleeding phenotype (Shetty et al. Br J Haematol. 2007; Bolliger et al. Thromb Haemost. 2010), supporting the hypothesis that a reduction in antithrombin levels will increase thrombin generation and thus normalize hemostasis in people with hemophilia. Fitusiran is a subcutaneously administered investigational RNA interference therapeutic targeting antithrombin for prophylactic treatment of patients with hemophilia A and B, with or without inhibitors. In a completed Phase I study, monthly subcutaneous administration of fitusiran was found to lower antithrombin levels, increase thrombin generation, and was generally well tolerated (Pasi et al. Blood. 2016; Pasi et al. New Engl J Med. 2017). The aim of this abstract is to describe the longitudinal assessment of thrombin generation with fitusiran in the Phase I/II open-label extension study (NCT02554773). Methods: The fitusiran Phase I dose-escalation study (NCT02035605) was followed by the Phase II open-label extension study (NCT02554773), which included male patients, >18 years of age, with moderate or severe hemophilia A and B, with or without inhibitors, who were eligible to continue dosing with monthly subcutaneous fixed doses of fitusiran 50 mg or 80 mg. Thrombin generation was assessed monthly for the first 2 years and every 6 months thereafter using the calibrated automated thrombogram (CAT) assay. Results: Thirty-four patients aged 19-61 with hemophilia A (n=27; 13 with inhibitors and 14 without inhibitors) or hemophilia B (n=7; 2 with inhibitors and 5 without inhibitors) were treated for up to 4.7 years with a median exposure of approximately 2.6 years at the time of the data cut (March 10, 2020). Peak thrombin generation was assessed over the length of the study for each patient. Once-monthly subcutaneous dosing of 50 mg or 80 mg fitusiran prophylaxis over a period of 48 months resulted in sustained antithrombin lowering (a reduction of between 85% to 72% from baseline), which led to peak thrombin levels and an endogenous thrombin potential approaching the normal range seen in healthy volunteers (see figure). Additional subgroup analyses (hemophilia A and B, with or without inhibitor) will be conducted for presentation at the congress. Conclusions: Monthly fitusiran prophylaxis resulted in consistent peak thrombin generation levels in patients with hemophilia A and B, with or without inhibitors over an extended period of time. With the thrombin generation levels in people with hemophilia on fitusiran approaching that of normal healthy adults, this sustained lowering of thrombin has the potential to provide consistent bleed protection in patients over time. Disclosures Négrier: CSL, F. Hoffmann-La Roche Ltd, Sobi: Other: Travel support; CSL Behring, Octapharma, Shire/Takeda, Sobi: Research Funding; Bayer, Biomarin, CSL Behring, Freeline, LFB, Novo Nordisk, Octapharma, Pfizer, F. Hoffmann-La Roche Ltd, Sanofi, Shire/Takeda, Sobi, Spark: Consultancy. Ragni:Alnylam Pharmaceuticals Inc., Baxalta/Takeda, BioMarin, Bioverativ, and Spark Therapeutics: Membership on an entity's Board of Directors or advisory committees; Sangamo: Consultancy, Research Funding; Takeda: Research Funding; Bioverativ: Consultancy, Research Funding; Spark: Consultancy, Research Funding; BioMarin: Consultancy, Research Funding; Alnylam/Sanofi, ATHN, BioMarin, Bioverativ, Sangamo, Spark: Research Funding; Alnylam/Sanofi, BioMarin, Bioverativ, Spark: Consultancy; American Thrombosis Hemostasis Network: Other: Committee work; Baxalta/Takeda, CSL Behring, Genentech, a member of the Roche Group, OPKO Biologics, and Vascular Medicine Institute: Research Funding. Pasi:BioMarin: Consultancy, Honoraria, Other: Grants, personal fees, and nonfinancial support; honoraria as member of scientific advisory boards and symposia; Sanofi: Honoraria, Other: Personal fees and nonfinancial support; honoraria as member of scientific advisory boards and symposia, Research Funding; Roche: Honoraria, Other; Pfizer: Other; Octapharma: Honoraria, Other: Personal fees and nonfinancial support; honoraria as member of scientific advisory boards and symposia , Speakers Bureau; Novo Nordisk: Honoraria, Other: Personal fees and nonfinancial support; honoraria as member of scientific advisory boards and symposia ; Catalyst Biosciences: Consultancy, Other: Personal fees and nonfinancial support; honoraria as member of scientific advisory boards and symposia; Biotest: Consultancy, Honoraria, Other: Personal fees and nonfinancial support; honoraria as member of scientific advisory boards and symposia; Alnylam (Sanofi): Other: Personal fees and nonfinancial support ; Takeda: Consultancy, Honoraria, Other: Personal fees; honoraria as member of scientific advisory boards and symposia ; ApcinteX: Consultancy, Other: Personal fees ; uniQure: Other: Grants and nonfinancial support , Research Funding; Sigilon: Research Funding; Tremeau: Research Funding; Sobi: Consultancy, Honoraria, Other. Pipe:Apcintex, Bayer, BioMarin, Catalyst Biosciences, CSL Behring, HEMA Biologics, Freeline, Novo Nordisk, Pfizer, F. Hoffmann-La Roche Ltd/Genentech, Inc., Sangamo Therapeutics, Sanofi, Takeda, Spark Therapeutics, uniQure: Consultancy; Siemens: Research Funding; Medical and Scientific Advisory Council to the National Hemophilia Foundation; Medical Advisory Board to World Federation of Hemophilia: Membership on an entity's Board of Directors or advisory committees. Kenet:PI Healthcare, CSL Behring: Honoraria; Bayer, Pfizer, Takeda, BioMarin, Novo Nordisk: Speakers Bureau; Bayer, Pfizer, Roche, Alnylam (Sanofi), Shire: Research Funding; Bayer, Pfizer, BioMarin, Takeda, Roche, Novo Nordisk, Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Rangarajan:Sangamo: Research Funding; Takeda, Grifols, Roche, Reliance Life Sciences: Other: Conference support, Speakers Bureau. Kichou:Sanofi: Current Employment. Mei:Sanofi: Current Employment, Current equity holder in publicly-traded company. Andersson:Sanofi: Current Employment, Current equity holder in publicly-traded company.

BACKGROUND: Adeno-associated virus (AAV)-mediated gene therapy is under investigation as a therapeutic option for persons with hemophilia A. Efficacy and safety data include 3 years of follow-up after a single administration of AAV5-hFVIII-SQ. METHODS: We report durable efficacy, long-term safety, and clinical and biologic results in 15 adults with severe hemophilia A (factor VIII level, ≤1 IU per deciliter) who had received a single infusion of AAV5-hFVIII-SQ at various dose levels. We evaluated the factor VIII level, annualized rate of bleeding events, use of factor VIII, safety, expression kinetics, and biologic markers of AAV transduction for up to 3 years. RESULTS: Three years after infusion, two participants (one who had received 6×1012 vector genomes [vg] per kilogram of body weight and one who had received 2×1013 vg per kilogram) had factor VIII expression of less than 1 IU per deciliter, as assessed on chromogenic assay. Seven participants (who had received 6×1013 vg per kilogram) had a median factor VIII expression of 20 IU per deciliter; the median number of annualized treated bleeding events was 0, and the median use of exogenous factor VIII was reduced from 138.5 infusions to 0 infusions per year. Bleeding in all target joints (major joints with ≥3 bleeding events within 6 months) in this cohort resolved (≤2 bleeding events within 12 months). Two years after infusion, six participants (who had received 4×1013 vg per kilogram) had a median factor VIII expression of 13 IU per deciliter; the median annualized rate of bleeding events was 0, and the median use of factor VIII was reduced from 155.5 infusions to 0.5 infusions per year. Bleeding in target joints resolved in five of six participants. The factor VIII pharmacodynamic profiles reflected cellular turnover in the blood and molecular events leading to episomal DNA stabilization for persistent expression, findings that are consistent with previous observations in two model systems. Transgene-derived human factor VIII (hFVIII) protein activity mirrored native hFVIII in hemostatic ability. No inhibitor development, thromboses, deaths, or persistent changes in liver-function tests were observed. CONCLUSIONS: Gene therapy with AAV5-hFVIII-SQ vector in participants with hemophilia A resulted in sustained, clinically relevant benefit, as measured by a substantial reduction in annualized rates of bleeding events and complete cessation of prophylactic factor VIII use in all participants who had received 4×1013 vg per kilogram or 6×1013 vg per kilogram of the gene therapy. (Funded by BioMarin Pharmaceutical; ClinicalTrials.gov number, NCT02576795; EudraCT number, 2014-003880-38.).

The objective of this scoping review is to summarize the current use of pharmacokinetics for tailoring prophylaxis in hemophilia patients switching between clotting factor products. Patients with hemophilia may require switching of clotting factor concentrates due to a variety of factors, but there have been perceived risks associated with switching, such as inhibitor development or suboptimal protection due to inadequate dosing while titrating treatment. Studies that look at patients switching from one clotting factor concentrate to another are categorized in terms of their primary and/or secondary objectives, notably biosimilarity and comparative pharmacokinetic studies and inhibitor development studies. Research on how best to switch concentrates with respect to dosing regimen are lacking, and currently a trial-and-error approach is used for dosing the new factor concentrate. In the future, studies looking at the predictability of pharmacokinetics (PK) of a new factor concentrate based on individual PK knowledge of the original factor concentrate may offer clinical benefit by providing a safer switching approach and protocol.

Introduction Immune tolerance induction (ITI) is a standard intervention to eradicate inhibitors in haemophilic patients. However, information on the long-term condition of patients who eradicated the inhibitor totally or partially after ITI is scarce. Aim To perform a long-term follow-up to describe the status of patients reported as ITI success in the G-ITI study. Methods This was an international, multicentre, observational, retrospective study of the 57 haemophilic patients who were reported as ITI success in the G-ITI study. Demographics and post-ITI clinical data recorded until January 2015 were extracted from the medical records. A descriptive analysis was undertaken. Results Forty-four patients were evaluable. Post-ITI follow-up was 9.1 years in average. Thirty-seven target joints were affected in 21 patients; 38 patients presented bleeding with a mean of 1.0 ± 1.2 episodes year−1, most of them (271/330) treated with Fanhdi® (Grifols). Around half of the patients underwent at least one surgical procedure. Most venous access complications were of expected nature, requiring hospital stay in practically all cases. Fanhdi was used in 42 patients as the regular haemophilia treatment after ITI, mainly prophylactically. Three patients (6.8%) who were being treated with Fanhdi (prophylaxis), Kogenate (prophylaxis) and Emoclot (on demand), respectively, showed inhibitor relapse (at 29, 53 and 13 months after ITI, with 0.9, 3.65 and 12.5 BU respectively). All of them were successfully tolerized after rescue ITI. Conclusion After ITI success, all patients continued with regular successful FVIII treatment for haemophilia for more than 9 years. The few inhibitor relapses were successfully overcome after rescue ITI.

Enhanced half-life factor VIII and IX products are being introduced into routine clinical practice. Published data report on clinical trials and there are limited data available on how to use these products in routine clinical practice. Many patients, for example, those with a past history of an inhibitor, have been excluded from clinical trials and there are limited data published on children. This guidance document is a consensus statement from the UK Haemophilia Centres Doctors' Organisation and aims to give pragmatic advice on the use of these products in routine practice.

Hemophilia A (HA) arises from pathogenic variants in the F8 gene, affecting ~ 1/5000 males. Current factor replacement therapies have limitations, including treatment burden, kinetics (peaks/troughs), morbidity and mortality from breakthrough bleeds, including chronic joint disease, inhibitor development, as well as risk of thrombotic events and coagulation test interference with novel non-factor therapies. Cell therapies with genetically modified human cells expressing hFVIII have been tested as a new potential therapeutic approach. To avoid host cytotoxic immune response, allogeneic cells either need to be physically shielded and/or the host immunosuppressed. Various biomaterials, which can provide a physical barrier from the host immune cells, activate a foreign body response, resulting in pericapsular fibrotic overgrowth (PFO) that significantly limits efficacy and durability of these cell-based therapies. Sigilon utilized a library of proprietary small molecules that avoid PFO when conjugated to alginate biomaterials (Bochenek Nat Biomed Eng 2018) to create a modular, cell-based platform with potential for utilization across a range of chronic diseases, including rare blood disorders. The platform consists of genetically modified allogeneic human cells engineered to produce the therapeutic protein of interest, encapsulated in a two-compartment sphere which supports the function of cells (inner compartment) and shields the cells from the host's immune system and PFO (outer layer) (Barney ASGCT 2020). SIG-001 is a buffered suspension of 1.5 mm alginate spheres encapsulating hFVIII-expressing human cells. SIG-001 can produce functionally active hFVIII in a dose-dependent manner, correct the bleeding phenotype in HA mice, and produce sustained long-lasting hFVIII levels in NSG mice sacrificed at 6 months (Carmona ASH 2019). In preparation for entry into the clinic, SIG-001 was evaluated in mice and non-human primates (NHP). The studies showed no concerning signals in the safety/toxicology profile of SIG-001 (Carmona ISTH 2020). The first-in-human phase 1/2 trial in HA (SIG-001-121, EudraCT 2019-004210-33) will assess the safety, tolerability and preliminary efficacy of SIG-001. This multi-center, open-label study with sequential, dose escalating cohorts, will enroll up to 18 participants (pts), including up to 3 initial pts per cohort and 3 additional pts if cohort expansion is warranted at any dose. A sentinel pt in each cohort will receive a single administration of SIG-001 and be evaluated for at least 4 weeks prior to enrollment of subsequent pts. The next dose level will be initiated following safety review of all pts from the previous dose level(s). The study will include adult males (≥18), with severe or moderately-severe HA (≤2% FVIII activity) who have had ≥150 exposure days to FVIII product(s). The key exclusion criteria include pts with current or past history of FVIII inhibitors. SIG-001 will be administered into the peritoneal cavity using a short laparoscopic procedure, and pts will be followed for 5 years after SIG-001 administration. Primary endpoint of the study is safety, including clinically significant changes in vital signs, clinical laboratory tests, and treatment emergent adverse events compared to baseline. Secondary endpoints include FVIII one-stage and chromogenic activity levels, FVIII inhibitor titers, annualized bleeding rate, and annualized FVIII concentrate use. Exploratory endpoints include QoL metrics, and joint health and physical activity assessments. Results will be analyzed using descriptive statistics. The study will be conducted at sites located in the UK, US and Germany. In conclusion, Sigilon has developed an innovative, modular, scalable, cell-based platform of candidate products for the treatment of chronic diseases, including rare bleeding disorders. The platform was designed to overcome the significant challenges of allogeneic cell therapy, namely immune rejection and PFO. SIG-001 produces hFVIII with in vitro and in vivo functionality. SIG-001-121, first-in-human clinical trial of SIG-001 in HA, is targeted to open in 2020. Disclosures Shapiro: Agios: Research Funding; BioMarin: Research Funding; Bioverativ: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Catalyst BioSciences: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Research Funding; Genentech/Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Glover Blood Therapeutics: Research Funding; Kedrion Biopharma: Research Funding; Novartis: Research Funding; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; OPKO: Research Funding; Octapharma: Research Funding; Pfizer: Research Funding; ProMetic Bio Therapeutics: Consultancy, Research Funding; Sangamo: Research Funding; Sigilon: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novo Nordisk Hemophilia Foundation: Membership on an entity's Board of Directors or advisory committees. Konkle:Sigilon: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; BioMarin: Consultancy; Takeda: Research Funding; Spark: Consultancy, Research Funding; Sanofi: Consultancy, Research Funding; CSL Behring: Consultancy; Uniquire: Research Funding; Roche: Consultancy; Baxalta: Research Funding. Croteau:Bayer: Consultancy; Genentech: Consultancy; Pfizer: Consultancy; Novo Nordisk: Research Funding; CSL-Behring: Consultancy; Spark Therapeutics: Research Funding; ATHN: Research Funding; Sigilon Therapeutics: Consultancy; National Hemophilia Foundation: Honoraria; Hemophilia Federation of America: Honoraria. Miesbach:Ablynx: Consultancy; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Aventis: Consultancy; Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Biomarin: Consultancy, Membership on an entity's Board of Directors or advisory committees; Freeline: Consultancy, Membership on an entity's Board of Directors or advisory committees; LEO: Consultancy, Membership on an entity's Board of Directors or advisory committees; LFB: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Octapharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sobi: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novo Nordisk: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Consultancy; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sigilon: Consultancy; UniQure: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Biotest: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Alexion: Membership on an entity's Board of Directors or advisory committees. Mihova:Sigilon Therapeutics: Current Employment. Rangarajan:Takeda: Other: Conference support, Speakers Bureau; Grifols: Speakers Bureau; Roche: Speakers Bureau; Reliance Life Sciences: Other: Conference support; Sangamo: Research Funding. Pasi:Roche: Honoraria, Other; Sobi: Consultancy, Honoraria, Other; Tremeau: Research Funding; Pfizer: Other; Octapharma: Honoraria, Other: Personal fees and nonfinancial support; honoraria as member of scientific advisory boards and symposia , Speakers Bureau; Novo Nordisk: Honoraria, Other: Personal fees and nonfinancial support; honoraria as member of scientific advisory boards and symposia ; Catalyst Biosciences: Consultancy, Other: Personal fees and nonfinancial support; honoraria as member of scientific advisory boards and symposia; Biotest: Consultancy, Honoraria, Other: Personal fees and nonfinancial support; honoraria as member of scientific advisory boards and symposia; Alnylam (Sanofi): Other: Personal fees and nonfinancial support ; Takeda: Consultancy, Honoraria, Other: Personal fees; honoraria as member of scientific advisory boards and symposia ; ApcinteX: Consultancy, Other: Personal fees ; uniQure: Other: Grants and nonfinancial support , Research Funding; BioMarin: Consultancy, Honoraria, Other: Grants, personal fees, and nonfinancial support; honoraria as member of scientific advisory boards and symposia; Sanofi: Honoraria, Other: Personal fees and nonfinancial support; honoraria as member of scientific advisory boards and symposia, Research Funding; Sigilon: Research Funding.

EssentialsCongenital afibrinogenemia causes a potentially life‐threatening bleeding and clotting tendency.Two human fibrinogen concentrates (HFCs) were compared in a randomized pharmacokinetic study.Bioequivalence was not shown for AUCnorm, which was significantly larger for the new HFC.Increases in clot strength were comparable, and no thromboses or deaths occurred in the study.SummaryBackgroundHuman fibrinogen concentrate (HFC) corrects fibrinogen deficiency in congenital a‐/hypofibrinogenemia.ObjectivesTo assess pharmacokinetics (PK), effects on thromboelastometry maximum clot firmness (MCF), and safety of a new double virus‐inactivated/eliminated, highly purified HFC vs. active control.Patients/MethodsIn this multinational, randomized, phase II, open‐label, crossover study in 22 congenital afibrinogenemia patients aged ≥ 12 years, 70 mg kg−1 of new HFC (FIBRYGA, Octapharma AG) or control (Haemocomplettan® P/RiaSTAP™, CSL Behring GmbH) were administered, followed by crossover to the other concentrate. Fibrinogen activity, PK and MCF in plasma were assessed.ResultsThe concentrates were not bioequivalent for the primary endpoint, AUCnorm (mean ratio, 1.196; 90% confidence interval [CI], 1.117, 1.281). Remaining PK parameters (Cmaxnorm, IVR, t1/2, MRT) reflected bioequivalence between concentrates, except for clearance (mean ratio, 0.836; 90% CI, 0.781, 0.895) and Vss (mean ratio, 0.886; 90% CI, 0.791, 0.994). Mean AUCnorm was significantly larger for the new HFC (1.62 ± 0.45 vs. 1.38 ± 0.47 h kg g L−1 mg−1, P = 0.0001) and mean clearance was significantly slower (0.665 ± 0.197 vs. 0.804 ± 0.255 mL h−1 kg−1, P = 0.0002). Mean MCF increased from 0 mm to 9.68 mm (new HFC) and 10.00 mm (control) 1‐hour post‐infusion (mean difference, −0.32 mm; 95% CI, −1.70, 1.07, n.s.). No deaths, thromboses, viral seroconversions or serious related adverse events occurred.ConclusionsBioequivalence was not demonstrated for AUCnorm, clearance and Vss. Larger AUCnorm and slower clearance were observed for the new HFC. Remaining pharmacokinetic parameters reflected bioequivalence to control. Safety profiles and increases in clot strength were comparable between concentrates.

Introduction Nuwiq® [human cell line-derived recombinant factor VIII (human-cl rhFVIII)] is a new generation rFVIII protein, without chemical modification or fusion to any other protein, produced in a human cell line. Aim/methods This prospective, open-label, multinational phase III study assessed the efficacy and safety of human-cl rhFVIII in 32 adult previously treated patients (PTPs) with severe haemophilia A during standard prophylaxis for ≥6 months and ≥50 exposure days. Efficacy in treating bleeds and during surgical prophylaxis was also assessed. Results Prophylactic efficacy, based on mean monthly bleeding rate, was rated as ‘excellent’ or ‘good’ in 97% of patients for all bleeds and in 100% of patients for spontaneous bleeds. Mean (SD) annualized bleeding rate was 2.28 (3.73) [median = 0.9] for all bleeds, 1.16 (2.57) [median = 0] for spontaneous bleeds and 1.00 (1.79) [median = 0] for traumatic bleeds. There were no bleeds in 50% of patients and there were no major, life-threatening bleeds. Efficacy was ‘excellent’ or ‘good’ in treating 28 (100%) of 28 bleeds. Overall efficacy was rated as ‘excellent’ during four surgical procedures (three major, one minor) and ‘moderate’ during one major surgery. Incremental in vivo recovery (IVR) data were comparable with the one-stage and chromogenic assays. IVR was >2.0% per IU kg−1 for all measurements and stable over 6 months. No patients developed FVIII inhibitors and there were no treatment-related serious or severe adverse events. Conclusion These results in adult PTPs indicate that human-cl rhFVIII is effective for the prevention and treatment of bleeds in adults with severe haemophilia A.

Introduction The safety, efficacy and prolonged half-life of recombinant factor VIII Fc fusion protein (rFVIIIFc) in previously treated patients with severe haemophilia A was demonstrated in the phase 3 A-LONG and Kids A-LONG studies. Here, we report interim safety and efficacy data from the rFVIIIFc extension study, ASPIRE (ClinicalTrials.gov #NCT01454739). Methods Eligible subjects could enrol in ASPIRE upon completing A-LONG or Kids A-LONG. There were four treatment groups: individualized prophylaxis; weekly prophylaxis; modified prophylaxis (for subjects in whom optimal treatment could not be achieved with individualized or weekly prophylaxis); and episodic treatment. The primary endpoint was development of inhibitors. Results A total of 150 A-LONG subjects and 61 Kids A-LONG subjects enrolled in ASPIRE. As of the interim data cut (6 January 2014), the median time on study was 80.9 (A-LONG) and 23.9 (Kids A-LONG) weeks. The majority of subjects (A-LONG, 92.0%; Kids A-LONG, 57.4%) had ≥100 cumulative rFVIIIFc exposure days. No inhibitors were observed. Adverse events were generally consistent with those expected in the general haemophilia A population. Median annualized bleeding rates (ABRs) were low with individualized [A-LONG: 0.66; Kids A-LONG: 0.00 (

SummaryAntibody formation to factor VIII (FVIII) remains the greatest clinical and diagnostic challenge to the haemophilia-treating physician. Current guidance for testing for inhibitory FVIII antibodies (inhibitors) recommends the functional Nijmegen-Bethesda assay (NBA). A FVIII ELISA offers a complementary, immunological approach for FVIII antibody testing. It was the aim of this study to retrospectively evaluate the performance of a FVIII ELISA (index) for detection of FVIII antibodies, compared with the NBA (reference). All samples sent for routine FVIII antibody testing at two haemophilia Comprehensive Care Centres, were tested in parallel using the NBA and a solid-phase, indirect FVIII ELISA kit (Immucor). A total of 497 samples from 239 patients (severe haemophilia A=140, non-severe haemophilia A=85, acquired haemophilia A=14) were available for analysis. Sixty-THree samples tested positive by the NBA (prevalence 12.7 %, 95 % confidence interval [CI], 9.9–15.9 %), with a median inhibitor titre of 1.2 BU/ml (range 0.7–978.0). The FVIII ELISA demonstrated a specificity of 94.0 % (95 %CI, 91.3–96.0), sensitivity of 77.8 % (95 %CI, 65.5–87.3), negative predictive value of 96.7 % (95 %CI, 94.5–98.2), positive predictive value 65.3 % (95 %CI, 53.5–76.0), negative likelihood ratio 0.2 (95 %CI, 0.1–0.4), positive likelihood ratio 13.0 (95 %CI, 8.7–19.3) and a diagnostic odds ratio of 54.9 (95 %CI, 27.0–112.0). Strong positive correlation (r=0.77, p< 0.001) was seen between the results of the NBA (log adjusted) and FVIII ELISA optical density. In conclusion, FVIII ELISA offers a simple, specific, surveillance method enabling batch testing of non-urgent samples for the presence of FVIII antibodies.

Background Patients with hemophilia A rely on exogenous factor VIII to prevent bleeding in joints, soft tissue, and the central nervous system. Although successful gene transfer has been reported in patients with hemophilia B, the large size of the factor VIII coding region has precluded improved outcomes with gene therapy in patients with hemophilia A. Methods We infused a single intravenous dose of a codon-optimized adeno-associated virus serotype 5 (AAV5) vector encoding a B-domain–deleted human factor VIII (AAV5-hFVIII-SQ) in nine men with severe hemophilia A. Participants were enrolled sequentially into one of three dose cohorts (low dose [one participant], intermediate dose [one participant], and high dose [seven participants]) and were followed through 52 weeks. Results Factor VIII activity levels remained at 3 IU or less per deciliter in the recipients of the low or intermediate dose. In the high-dose cohort, the factor VIII activity level was more than 5 IU per deciliter between weeks 2 and 9 after gene transfer in all seven participants, and the level in six participants increased to a normal value (>50 IU per deciliter) that was maintained at 1 year after receipt of the dose. In the high-dose cohort, the median annualized bleeding rate among participants who had previously received prophylactic therapy decreased from 16 events before the study to 1 event after gene transfer, and factor VIII use for participant-reported bleeding ceased in all the participants in this cohort by week 22. The primary adverse event was an elevation in the serum alanine aminotransferase level to 1.5 times the upper limit of the normal range or less. Progression of preexisting chronic arthropathy in one participant was the only serious adverse event. No neutralizing antibodies to factor VIII were detected. Conclusions The infusion of AAV5-hFVIII-SQ was associated with the sustained normalization of factor VIII activity level over a period of 1 year in six of seven participants who received a high dose, with stabilization of hemostasis and a profound reduction in factor VIII use in all seven participants. In this small study, no safety events were noted, but no safety conclusions can be drawn. (Funded by BioMarin Pharmaceutical; ClinicalTrials.gov number, NCT02576795; EudraCT number, 2014-003880-38.)

BACKGROUND: Current hemophilia treatment involves frequent intravenous infusions of clotting factors, which is associated with variable hemostatic protection, a high treatment burden, and a risk of the development of inhibitory alloantibodies. Fitusiran, an investigational RNA interference (RNAi) therapy that targets antithrombin (encoded by SERPINC1), is in development to address these and other limitations. METHODS: In this phase 1 dose-escalation study, we enrolled 4 healthy volunteers and 25 participants with moderate or severe hemophilia A or B who did not have inhibitory alloantibodies. Healthy volunteers received a single subcutaneous injection of fitusiran (at a dose of 0.03 mg per kilogram of body weight) or placebo. The participants with hemophilia received three injections of fitusiran administered either once weekly (at a dose of 0.015, 0.045, or 0.075 mg per kilogram) or once monthly (at a dose of 0.225, 0.45, 0.9, or 1.8 mg per kilogram or a fixed dose of 80 mg). The study objectives were to assess the pharmacokinetic and pharmacodynamic characteristics and safety of fitusiran. RESULTS: No thromboembolic events were observed during the study. The most common adverse events were mild injection-site reactions. Plasma levels of fitusiran increased in a dose-dependent manner and showed no accumulation with repeated administration. The monthly regimen induced a dose-dependent mean maximum antithrombin reduction of 70 to 89% from baseline. A reduction in the antithrombin level of more than 75% from baseline resulted in median peak thrombin values at the lower end of the range observed in healthy participants. CONCLUSIONS: Once-monthly subcutaneous administration of fitusiran resulted in dose-dependent lowering of the antithrombin level and increased thrombin generation in participants with hemophilia A or B who did not have inhibitory alloantibodies. (Funded by Alnylam Pharmaceuticals; ClinicalTrials.gov number, NCT02035605 .).

Turoctocog alfa pegol (N8-GP) is a novel glycoPEGylated extended half-life recombinant factor VIII (FVIII) product developed for prophylaxis and treatment of bleeds in patients with haemophilia A, to enable higher activity levels with less frequent injections compared with standard FVIII products. This phase III (NCT01480180), multinational, open-label, non-randomised trial evaluated the safety and clinical efficacy of N8-GP when administered for treatment of bleeds and for prophylaxis, in previously treated patients aged ≥12 years with severe haemophilia A. Patients were allocated to receive N8-GP for prophylaxis or on-demand treatment for up to 1.8 years. Patients on prophylaxis were administered one dose of 50 IU/kg of N8-GP every fourth day. Bleeds were treated with doses of 20-75 IU/kg. Total exposure to N8-GP in the trial was 14,114 exposure days (159 patient-years). For the prophylaxis arm (n=175), the median annualised bleeding rate (ABR) was 1.33 (interquartile range, 0.00-4.61), the mean ABR was 3.70 (95 % confidence interval 2.94-4.66) and 70 (40 %) patients had no bleeds during the trial. Across treatment arms, 83.6 % of bleeds resolved with one injection and 95.5 % with up to two injections. N8-GP had a favourable safety profile and was well tolerated. The frequency and types of adverse events reported were as expected in this population. One patient developed inhibitory antibodies against FVIII (≥0.6 Bethesda units [BU]) after 93 N8-GP exposure days. No clinically significant safety concerns were identified and N8-GP was effective for prophylaxis and treatment of bleeds in previously treated patients. Turoctocog alfa pegol (N8-GP) is a novel glycoPEGylated extended half-life recombinant factor VIII (FVIII) product developed for prophylaxis and treatment of bleeds in patients with haemophilia A, to enable higher activity levels with less frequent injections compared with standard FVIII products. This phase III (NCT01480180), multinational, open-label, non-randomised trial evaluated the safety and clinical efficacy of N8-GP when administered for treatment of bleeds and for prophylaxis, in previously treated patients aged ≥12 years with severe haemophilia A. Patients were allocated to receive N8-GP for prophylaxis or on-demand treatment for up to 1.8 years. Patients on prophylaxis were administered one dose of 50 IU/kg of N8-GP every fourth day. Bleeds were treated with doses of 20-75 IU/kg. Total exposure to N8-GP in the trial was 14,114 exposure days (159 patient-years). For the prophylaxis arm (n=175), the median annualised bleeding rate (ABR) was 1.33 (interquartile range, 0.00-4.61), the mean ABR was 3.70 (95 % confidence interval 2.94-4.66) and 70 (40 %) patients had no bleeds during the trial. Across treatment arms, 83.6 % of bleeds resolved with one injection and 95.5 % with up to two injections. N8-GP had a favourable safety profile and was well tolerated. The frequency and types of adverse events reported were as expected in this population. One patient developed inhibitory antibodies against FVIII (≥0.6 Bethesda units [BU]) after 93 N8-GP exposure days. No clinically significant safety concerns were identified and N8-GP was effective for prophylaxis and treatment of bleeds in previously treated patients.

SummaryThe prophylactic administration of factor IX (FIX) is considered the most effective treatment for haemophilia B. The inter-individual variability and complexity of the pharmacokinetics (PK) of FIX, and the rarity of the disease have hampered identification of an optimal treatment regimens. The recent introduction of extended half-life recombinant FIX molecules (EHL-rFIX), has prompted a thorough reassessment of the clinical efficacy, PK and pharmacodynamics of plasma-derived and recombinant FIX. First, using longer sampling times and multi-compartmental PK models has led to more precise (and favourable) PK for FIX than was appreciated in the past. Second, investigating the distribution of FIX in the body beyond the vascular space (which is implied by its complex kinetics) has opened a new research field on the role for extravascular FIX. Third, measuring plasma levels of EHL-rFIX has shown that different aPTT reagents have different accuracy in measuring different FIX molecules. How will this new knowledge reflect on clinical practice? Clinical decision making in haemophilia B requires some caution and expertise. First, comparisons between different FIX molecules must be assessed taking into consideration the comparability of the populations studied and the PK models used. Second, individual PK estimates must rely on multi-compartmental models, and would benefit from adopting a population PK approach. Optimal sampling times need to be adapted to the prolonged half-life of the new EHL FIX products. Finally, costs considerations may apply, which is beyond the scope of this manuscript but might be deeply connected with the PK considerations discussed in this communication.Supplementary Material to this article is available online at www.thrombosis-online.com.

Summary Although it has been suggested that switching of factor VIII (FVIII) products may increase inhibitor formation this is disputed. Half of UK patients changed rFVIII brands because of national contracting in 2010, presenting an opportunity to compare inhibitor incidence of switchers with non-switchers. Centres were requested to test all the patients for inhibitors prior to the switching date and 6-monthly thereafter. Positive and negative inhibitor test data were also collected to analyse for testing bias. A total of 1198 patients with severe haemophilia A and treated with Advate, Kogenate/Helixate or Refacto AF preswitch were included in the analysis, of whom 516 switched to Refacto-AF and 682 did not switch products. Five new inhibitors were reported amongst previously treated patients (>50 exposure days) with a median titre at the time of detection of 1.25 BU mL−1 (IQR 0.7–23.05). One inhibitor occurred in a non-switcher using Kogenate, an incidence of 1.5 per 1000 treatment-years (95% CI 0.2–10.5). Four inhibitors arose in patients who had switched from Kogenate (two) or Advate (two) to ReFacto-AF, an incidence of 7.8 per 1000 treatment-years (95% CI 2.9–20.8). These incidence rates did not differ significantly from one another (incidence rate ratio 5.3 (95% CI 0.5–260.3) or from the historical rate of 6.05 inhibitors/1000 treatment-years (95% CI 5.18–7.06). Only one inhibitor (non-switcher) persisted. Non-switchers were significantly older (P = 0.03), and used significantly less FVIII per year (P = 0.005) prior to switching. Following switching, factor usage increased similarly (P = 0.53) in both groups. Switching from FLRFVIII to Refacto-AF (BDDRFVIII) was not associated with an increased inhibitor development.

Background Vatreptacog alfa, a recombinant factor VIIa (rFVIIa) analog with three amino acid substitutions and 99% identity to native FVIIa, was developed to improve the treatment of hemophilic patients with inhibitors. Objectives To confirm the safety and assess the efficacy of vatreptacog alfa in treating bleeding episodes in hemophilic patients with inhibitors. Patients and methods In this international, multicenter, randomized, double-blind, active-controlled, crossover, confirmatory phase III trial (adept™2) in patients with hemophilia A or B and inhibitors, bleeds were randomized 3 : 2 to treatment with vatreptacog alfa (one to three doses at 80 μg kg−1) or rFVIIa (one to three doses at 90 μg kg−1). Treatment failures after three doses of trial product (TP) were managed according to the local standard of care. Results In the 72 patients enrolled, 567 bleeds were treated with TP. Both vatreptacog alfa and rFVIIa gave 93% effective bleeding control at 12 h. Vatreptacog alfa was superior to rFVIIa in secondary efficacy outcomes, including the number of doses used to treat a bleed and sustained bleeding control 24–48 h after the first dose. Eight patients (11%) developed antibodies against vatreptacog alfa, including four with cross-reactivity against rFVIIa and one with an in vitro neutralizing effect to vatreptacog alfa. Conclusions This large randomized controlled trial confirmed the well-established efficacy and safety profile of rFVIIa, and showed that vatreptacog alfa had similar or better efficacy than rFVIIa. However, because of the development of anti-drug antibodies, a positive benefit–risk profile is unlikely to be achieved with vatreptacog alfa.

Introduction and Objectives: Neutralizing antibodies (inhibitors) directed against the FVIII protein may increase the bleeding frequency and compromise the management of bleeding episodes in nonsevere haemophilia A patients. The median annual bleeding frequency in patients without inhibitors is described to be 0 (IQR 0-3) for mild haemophilia and 1 (IQR 0-13) for moderate haemophilia. The aim of this study was to evaluate the burden of bleeding and to describe the treatment strategies that are used for bleeding episodes in a large group of unselected inhibitor patients with nonsevere haemophilia A. Materials and Methods: We included all inhibitor patients from the INSIGHT study, an international multicentre cohort study including all 2709 nonsevere HA patients (FVIII:C 2-4 IU/dL) that received at least 1 exposure to FVIII concentrate between 1980-2011. Data of the 1st inhibitor period were analyzed. Results: We included 107 nonsevere HA inhibitor patients (median baseline FVIII:C 9 IU/dL (IQR 6-16); median age of 38 years (IQR 15-61)). A high titre inhibitor (> 5 BU/mL) was present in 57 (53%) patients. In 30 (28%) patients the FVIII:C level was decreased ≤1 IU/dL. Eighty-nine patients (83%) received treatment for bleeding episodes. Most patients had spontaneous bleeds (n = 49, 46%); a higher proportion of high titre patients had spontaneous bleeds compared to low titre patients (83% vs. 53%, relative risk (RR) 2.7, 95% confidence interval (CI) 1.3-5.8). The median number of bleeding episodes per inhibitor year was 2 (IQR 1-5); this did not differ between patients with FVIII:C ≤ 1 IU/dL and those with measurable FVIII levels (p = 0.5), patients with low titre and high titre inhibitors (p = 0.5) and patients receiving eradication treatment or not (p = 0.7). In order to treat bleedings, FVIII concentrate was used in 59 patients (55%), FVIII bypassing agents in 50 (47%) and desmopressin in 18 patients (17%). Desmopressin was used more often in patients with remaining circulating FVIII:C levels compared to patients with a FVIII:C ≤ 1 IU/dL and in patients without eradication treatment compared to patients with eradication treatment (25% vs. 3%; RR 7.4, CI 1.0-53.5 and 25% vs. 0%; RR 14.0, CI 0.9 - 224.6, respectively). Conclusion: Inhibitor development in nonsevere HA patients aggravates the burden of bleeding with the majority (83%) of the patients needing treatment for bleeding episodes, at a median of 2 bleeding episodes per year.

Multiple factors are likely to contribute to the pathogenesis of thrombosis in Essential thrombocythaemia (ET) including platelet number, activation of platelets and leukocytes; the formation of platelet leucocyte aggregates, and circulating prothrombotic and endothelial factors. The normal functional activity of platelets depends on the presence of platelet glycoprotein complexes, which play an important role in platelet adhesion and aggregation. A number of polymorphisms in platelet glycoproteins have been correlated with thrombotic events in hematologically normal patients. Particular polymorphisms of interest include three within the glycoprotein Ibα gene: −5T/C (affecting a Kozak sequence), 1018C/T (T145M, encoding Human Platelet Antigen − 2), a variable number of tandem repeats (VNTR) in a region encoding the macroglycopeptide and one polymorphism C807T, within the glycoprotein Ia gene. To date whether there is a relationship between these platelet glycoprotein polymorphisms and the clinical features of ET has not been determined. In this study samples obtained from 797 ET patients recruited to the 3 large prospective PT–1 trials were genotyped for the polymorphisms of interest and the results were correlated with clinical events including haemorrhagic and arterial or venous thrombotic events in the year prior to diagnosis and following trial entry (median 30 months). The VNTR data were analysed using the sum of the number of repeats of both alleles and treated as a continuous variable using logistic regression for retrospective and a Cox survival model for prospective analyses; other polymorphisms were analysed using the Chi-squared test for the retrospective clinical events, and log-rank survival analysis for the prospective clinical events. Neither the C807T, −5T/C Kozak nor the T145M polymorphism was associated with clinical events in the ET patient cohort. Interestingly the number of VNTR repeats was inversely associated with (p=0.02) rate of arterial events after trial entry in this patient cohort, but not for events in the year prior to diagnosis or post trial entry venous thrombotic or haemorrhagic events. This analysis suggested that a decreasing sum of VNTR were associated with an increased risk of arterial thrombosis, the degree of increase in risk was 75% per repeat (95% confidence interval 1.0–2.9). After multivariate analysis of this data with correction for age, sex, JAK2V617F and MPLW515L/K status the effect of the number of VNTR repeats remained significant (p=0.048). These results suggest that the C807T, T145M and −5T/C Kozak polymorphisms do not correlate with clinical events in ET. However a reduction in the number of VNTR within the glycoprotein Ibα gene was progressively associated with arterial events post trial entry (p=0.024) and remained significant on multivariate analysis (p=0.048).