Fitusiran prophylaxis in people with hemophilia A or B who switched from prior BPA/CFC prophylaxis: the ATLAS-PPX trial.

ABSTRACT: Fitusiran, a subcutaneous investigational small interfering RNA therapeutic, targets antithrombin to rebalance hemostasis in people with hemophilia A or B (PwHA/B), irrespective of inhibitor status. This phase 3, open-label study evaluated the efficacy and safety of fitusiran prophylaxis in males aged ≥12 years with hemophilia A or B, with or without inhibitors, who received prior bypassing agent (BPA)/clotting factor concentrate (CFC) prophylaxis. Participants continued their prior BPA/CFC prophylaxis for 6 months before switching to once-monthly 80 mg fitusiran prophylaxis for 7 months (onset and efficacy periods). Primary end point was annualized bleeding rate (ABR) in the BPA/CFC prophylaxis and fitusiran efficacy period. Secondary end points included spontaneous ABR (AsBR) and joint ABR (AjBR). Safety and tolerability were assessed. Of 80 enrolled participants, 65 (inhibitor, n = 19; noninhibitor, n = 46) were eligible for ABR analyses. Observed median ABRs were 6.5 (interquartile range [IQR], 2.2-19.6)/4.4 (IQR, 2.2-8.7) with BPA/CFC prophylaxis vs 0.0 (IQR, 0.0-0.0)/0.0 (IQR, 0.0-2.7) in the corresponding fitusiran efficacy period. Estimated mean ABRs were substantially reduced with fitusiran by 79.7% (P = .0021) and 46.4% (P = .0598) vs BPA/CFC prophylaxis, respectively. Forty-one participants (63.1%) experienced 0 treated bleeds with fitusiran vs 11 (16.9%) with BPAs/CFCs. Median AsBR and AjBR were both 2.2 with BPA/CFC prophylaxis and 0.0 in the fitusiran efficacy period. Two participants (3.0%) experienced suspected or confirmed thromboembolic events with fitusiran. Once-monthly fitusiran prophylaxis significantly reduced bleeding events vs BPA/CFC prophylaxis in PwHA/B, with or without inhibitors, and reported adverse events were generally consistent with previously identified risks of fitusiran. This trial was registered at www.ClinicalTrials.gov as #NCT03549871.

Multicenter assessment and longitudinal study of the prevalence of antibodies and related adaptive immune responses to AAV in adult males with hemophilia.

Adeno-associated virus (AAV) based gene therapy has demonstrated effective disease control in hemophilia. However, pre-existing immunity from wild-type AAV exposure impacts gene therapy eligibility. The aim of this multicenter epidemiologic study was to determine the prevalence and persistence of preexisting immunity against AAV2, AAV5, and AAV8, in adult participants with hemophilia A or B. Blood samples were collected at baseline and annually for ≤3 years at trial sites in Austria, France, Germany, Italy, Spain, and the United States. At baseline, AAV8, AAV2, and AAV5 neutralizing antibodies (NAbs) were present in 46.9%, 53.1%, and 53.4% of participants, respectively; these values remained stable at Years 1 and 2. Co-prevalence of NAbs to at least two serotypes and all three serotypes was present at baseline for ~40% and 38.2% of participants, respectively. For each serotype, ~10% of participants who tested negative for NAbs at baseline were seropositive at Year 1. At baseline, 38.3% of participants had detectable cell mediated immunity by ELISpot, although no correlations were observed with the humoral response. In conclusion, participants with hemophilia may have significant preexisting immunity to AAV capsids. Insights from this study may assist in understanding capsid-based immunity trends in participants considering AAV vector-based gene therapy.

A global comparative field study to evaluate the factor VIII activity of efanesoctocog alfa by one-stage clotting and chromogenic substrate assays at clinical haemostasis laboratories.

INTRODUCTION: Structural and chemical modifications of factor VIII (FVIII) products may influence their behaviour in FVIII activity assays. Hence, it is important to assess the performance of FVIII products in these assays. Efanesoctocog alfa is a new class of FVIII replacement therapy designed to provide both high sustained factor activity levels and prolonged plasma half-life. AIM: Evaluate the accuracy of measuring efanesoctocog alfa FVIII activity in one-stage clotting assays (OSAs) and chromogenic substrate assays (CSAs). METHODS: Human plasma with no detectable FVIII activity was spiked with efanesoctocog alfa or a full-length recombinant FVIII product comparator, octocog alfa, at nominal concentrations of 0.80 IU/mL, 0.20 IU/mL, or 0.05 IU/mL, based on labelled potency. Clinical haemostasis laboratories (N = 35) tested blinded samples using in-house assays. Data from 51 OSAs (14 activated partial thromboplastin time [aPTT] reagents) and 42 CSAs (eight kits) were analyzed. RESULTS: Efanesoctocog alfa activity was reliably (±25% of nominal activity) measured across all concentrations using OSAs with Actin FSL and multiple other aPTT reagents. Under- and overestimation of FVIII activity occurred with some reagents. No specific trend was observed for any class of aPTT activators. A two- to three-fold overestimation was consistently observed using CSAs and the OSA with Actin FS as the aPTT reagent across evaluated concentrations. CONCLUSION: Under- or overestimation occurred with some specific OSAs and most CSAs, which has been previously observed with other modified FVIII replacement products. Efanesoctocog alfa FVIII activity was measured with acceptable accuracy and reliability using several OSA methods and commercial plasma standards.

Long-term outcomes with emicizumab prophylaxis for hemophilia A with or without FVIII inhibitors from the HAVEN 1-4 studies.

Prophylaxis with emicizumab, a subcutaneously administered bispecific humanized monoclonal antibody, promotes effective hemostasis in persons with hemophilia A (PwHAs). The primary efficacy, safety, and pharmacokinetics of emicizumab were reported previously, but long-term data were limited. Here, data from 401 pediatric and adult PwHAs with/without factor VIII (FVIII) inhibitors who were enrolled in the phase 3 HAVEN 1, HAVEN 2, HAVEN 3, and HAVEN 4 studies (NCT02622321, NCT02795767, NCT02847637, NCT03020160) have been pooled to establish a long-term efficacy, safety, and pharmacokinetics profile. Across a median efficacy period of 120.4 weeks (interquartile range, 89.0-164.4) (data cutoff 15 May 2020), the model-based treated annualized bleed rate (ABR) was 1.4 (95% confidence interval [CI], 1.1-1.7). ABRs declined and then stabilized at <1 in an analysis of 24-week treatment intervals; at weeks 121 to 144 (n = 170), the mean treated ABR was 0.7 (95% CI, 0-5.0). During weeks 121 to 144, 82.4% of participants had 0 treated bleeds, 97.6% had ≤3 treated bleeds, and 94.1% reported no treated target joint bleeds. Bleeding into target joints decreased substantially. Emicizumab was well tolerated, and no participant discontinued because of adverse events beyond the 5 previously described. This data cutoff includes the previously reported 3 thrombotic microangiopathies (one in the PwHA with fatal rectal hemorrhage) and 2 thromboembolic events, all associated with activated prothrombin complex concentrate use, as well as a myocardial infarction and a venous device occlusion. With 970.3 patient-years of exposure, emicizumab prophylaxis maintained low bleed rates in PwHAs of all ages with/without FVIII inhibitors and remains well tolerated, with no new safety concerns identified.

Report of surgeries, their outcome and the thrombin generation assay in patients with Factor XI deficiency: A retrospective single-centre study.

BACKGROUND: In patients with FXI deficiency, the risk of surgery-related bleeding is poorly correlated with plasma FXI activity (FXI:C); the latter can therefore not be used as a reliable predictor of bleeding in surgeries. OBJECTIVES: The aim of this retrospective study was to determine whether thrombin generation assay (TGA) could be used to evaluate the risk of surgery-related bleeding in FXI-deficient patients. TGA parameters were compared to FXI:C values, haemostatic treatments and surgical outcomes. PATIENTS: All patients followed at the haemophilia treatment care centre (Lyon, France) with a FXI:C < 50IU/dL, and for whom a baseline TGA was performed between January 2014 and December 2019, were included. RESULTS: Among the 175 surgeries reported herein in 49 patients, FXI concentrates were used for 11 (6%) surgeries and fresh frozen plasma was used for five (3%) surgeries; these surgeries were performed in patients with two or three impaired TGA parameters. No haemostatic treatment was prescribed for 119 (68%) surgeries. A surgery-related bleeding occurred in 12 patients during 21 (12%) surgeries. Thrombin generation was significantly reduced or delayed in patients who reported surgery related-bleeding. Among the 34 (68%) surgeries performed without haemostatic treatment in patients with three impaired TGA parameters, a surgery-related bleeding was reported in 44% of cases (15 surgeries out of 34). CONCLUSION: The present study confirmed that TGA is an interesting laboratory test in FXI deficiency, for determining the bleeding risk and guiding the haemostatic management of surgeries, while taking into account the surgical bleeding risk and the history of bleeding.

Eptacog beta efficacy and safety in the treatment and control of bleeding in paediatric subjects (<12 years) with haemophilia A or B with inhibitors.

INTRODUCTION: Eptacog beta is a new recombinant activated human factor VII bypassing agent approved in the United States for the treatment and control of bleeding in patients with haemophilia A or B with inhibitors 12 years of age or older. AIM: To prospectively assess in a phase 3 clinical trial (PERSEPT 2) eptacog beta efficacy and safety for treatment of bleeding in children <12 years of age with haemophilia A or B with inhibitors. METHODS: Using a randomised crossover design, subjects received initial doses of 75 or 225 µg/kg eptacog beta followed by 75 µg/kg dosing at predefined intervals (as determined by clinical response) to treat bleeding episodes (BEs). Treatment success criteria included a haemostasis evaluation of 'excellent' or 'good' without use of additional eptacog beta, alternative haemostatic agent or blood product, and no increase in pain following the first 'excellent' or 'good' assessment. RESULTS: Treatment success proportions in 25 subjects (1-11 years) who experienced 546 mild or moderate BEs were 65% in the 75 µg/kg initial dose regimen (IDR) and 60% in the 225 µg/kg IDR 12 h following initial eptacog beta infusion. By 24 h, the treatment success proportions were 97% for the 75 µg/kg IDR and 98% for the 225 µg/kg IDR. No thrombotic events, allergic reactions, neutralising antibodies or treatment-related adverse events were reported. CONCLUSION: Both 75 and 225 µg/kg eptacog beta IDRs provided safe and effective treatment and control of bleeding in children <12 years of age.

PHAREO study: Perceived and observed accessibility to therapeutic drugs used for treating patients with inherited bleeding disorders.

WHAT IS KNOWN AND OBJECTIVE: The dispensing of clotting factor concentrates in hospital pharmacies imposes accessibility constraints on patients and their caregivers, thereby increasing the disease burden. Very few studies have addressed these issues so far in terms of individual perceptions and actual difficulties. The PHAREO study aims to report patient's perception of treatment accessibility and evaluate spatial accessibility. METHODS: The PHAREO study is an observational survey based on a questionnaire specifically designed for the study purpose in collaboration with patients' representatives in the second demographic and economic French region. RESULTS AND DISCUSSION: We collected 293 responses (participation rate of 64.1%) which show that 89.8% of respondents were either very or rather satisfied with regard to access to treatment. However, respondents reported difficulties in accessing the hospital pharmacy. The data also showed that 79.2% of respondents tended to over-estimate travel time which was reported above their acceptable threshold for 39.2% of them. The main determinants of dissatisfaction were parental burden (OR 2.5 [1.3; 4.8], p = 0.008) and waiting time at the hospital pharmacy (OR 1.5 [1.1;2.0], p = 0.016, per 10 min increase). WHAT IS NEW AND CONCLUSION: The PHAREO study provides subjective and objective data regarding satisfaction levels of persons with haemophilia and other coagulation deficiencies, with a high representativeness rate for patients on prophylaxis (87.5%). Both respondents and hospital pharmacists pled for an evolution of the current dispensing circuit to improve access to treatment and reduce the burden for patients. Currently, the community pharmacists are apart from the dispensing circuit. The authors propose improvements in the pathway of care for patients and their caregivers by including the community pharmacists alongside the hospital pharmacists in a centralized coordination scheme.

Reccurrent F8 Intronic Deletion Found in Mild Hemophilia A Causes Alu Exonization.

Incorporation of distant intronic sequences in mature mRNA is an underappreciated cause of genetic disease. Several disease-causing pseudoexons have been found to contain repetitive elements such as Alu elements. This study describes an original pathological mechanism by which a small intronic deletion leads to Alu exonization. We identified an intronic deletion, c.2113+461_2113+473del, in the F8 intron 13, in two individuals with mild hemophilia A. In vivo and in vitro transcript analysis found an aberrant transcript, with an insertion of a 122-bp intronic fragment (c.2113_2114ins2113+477_2113+598) at the exon 13-14 junction. This out-of-frame insertion is predicted to lead to truncated protein (p.Gly705Aspfs∗37). DNA sequencing analysis found that the pseudoexon corresponds to antisense AluY element and the deletion removed a part of the poly(T)-tail from the right arm of these AluY. The heterogenous nuclear riboprotein C1/C2 (hnRNP C) is an important antisense Alu-derived cryptic exon silencer and binds to poly(T)-tracts. Disruption of the hnRNP C binding site in AluY T-tract by mutagenesis or hnRNP C knockdown using siRNA in HeLa cells reproduced the effect of c.2113+461_2113+473del. The screening of 114 unrelated families with mild hemophilia A in whom no genetic event was previously identified found a deletion in the poly(T)-tail of AluY in intron 13 in 54% of case subjects (n = 61/114). In conclusion, this study describes a deletion leading to Alu exonization found in 6.1% of families with mild hemophila A in France.

Emicizumab Prophylaxis in Patients Who Have Hemophilia A without Inhibitors.

BACKGROUND: Emicizumab is a bispecific monoclonal antibody that bridges activated factor IX and factor X to replace the function of missing activated factor VIII, thereby restoring hemostasis. In a phase 3, multicenter trial, we investigated its use as prophylaxis in persons who have hemophilia A without factor VIII inhibitors. METHODS: We randomly assigned, in a 2:2:1 ratio, participants 12 years of age or older who had been receiving episodic treatment with factor VIII to receive a subcutaneous maintenance dose of emicizumab of 1.5 mg per kilogram of body weight per week (group A) or 3.0 mg per kilogram every 2 weeks (group B) or no prophylaxis (group C). The primary end point was the difference in rates of treated bleeding (group A vs. group C and group B vs. group C). Participants who had been receiving factor VIII prophylaxis received emicizumab at a maintenance dose of 1.5 mg per kilogram per week (group D); intraindividual comparisons were performed in those who had participated in a noninterventional study. RESULTS: A total of 152 participants were enrolled. The annualized bleeding rate was 1.5 events (95% confidence interval [CI], 0.9 to 2.5) in group A and 1.3 events (95% CI, 0.8 to 2.3) in group B, as compared with 38.2 events (95% CI, 22.9 to 63.8) in group C; thus, the rate was 96% lower in group A and 97% lower in group B (P<0.001 for both comparisons). A total of 56% of the participants in group A and 60% of those in group B had no treated bleeding events, as compared with those in group C, who all had treated bleeding events. In the intraindividual comparison involving 48 participants, emicizumab prophylaxis resulted in an annualized bleeding rate that was 68% lower than the rate with previous factor VIII prophylaxis (P<0.001). The most frequent adverse event was low-grade injection-site reaction. There were no thrombotic or thrombotic microangiopathy events, development of antidrug antibodies, or new development of factor VIII inhibitors. CONCLUSIONS: Emicizumab prophylaxis administered subcutaneously once weekly or every 2 weeks led to a significantly lower bleeding rate than no prophylaxis among persons with hemophilia A without inhibitors; more than half the participants who received prophylaxis had no treated bleeding events. In an intraindividual comparison, emicizumab therapy led to a significantly lower bleeding rate than previous factor VIII prophylaxis. (Funded by F. Hoffmann-La Roche and Chugai Pharmaceutical; HAVEN 3 ClinicalTrials.gov number, NCT02847637 .).

Confirmed long-term safety and efficacy of prophylactic treatment with BAY 94-9027 in severe haemophilia A: final results of the PROTECT VIII extension study.

INTRODUCTION: The phase 2/3 PROTECT VIII main study demonstrated efficacy and safety of BAY 94-9027 (damoctocog alfa pegol; Jivi® ), a B-domain-deleted recombinant factor VIII (FVIII), site-specifically PEGylated to extend its half-life. AIM: To report the final efficacy and safety data for BAY 94-9027 from the PROTECT VIII extension. METHODS: Previously treated males aged 12-65 years with severe haemophilia A (FVIII <1%) who completed the multicentre, open-label PROTECT VIII main study were eligible for the extension. Patients received either on demand or prophylaxis treatments (30-40 IU/kg twice weekly [2 × W], 45-60 IU/kg every 5 days [E5D], or 60 IU/kg every 7 days [E7D]) and could switch to any prophylaxis regimen (variable frequency) as needed. Annualised bleeding rates (ABR), zero bleeds and safety outcomes were included in this final analysis. RESULTS: At extension completion, patients (n = 121) received BAY 94-9027 for a median (range) total time of 3.9 (0.8-7.0) years. Median (Q1; Q3) total ABR was 1.49 (0.36; 4.80) for prophylaxis patients (n = 107), compared with 34.09 (20.3; 36.6) for on-demand patients (n = 14). Median total ABRs for 2 × W (n = 23), E5D (n = 33), E7D (n = 23) and variable frequency (n = 28) groups were 1.57, 1.17, 0.65 and 3.10, respectively. Of prophylaxis patients, 20.6% were bleed-free during the entire extension (median time, 3.2 years) and 50.0% were bleed-free during the last 6 months. No patient developed FVIII inhibitors. No deaths or thrombotic events were reported. CONCLUSIONS: Efficacy and safety of BAY 94-9027 was confirmed, with extension data supporting its use as a long-term treatment option for patients with haemophilia A.

The effect of emicizumab prophylaxis on long-term, self-reported physical health in persons with haemophilia A without factor VIII inhibitors in the HAVEN 3 and HAVEN 4 studies.

INTRODUCTION: Severe haemophilia A (HA) has a major impact on health-related quality of life (HRQoL). AIM: Assess the impact of emicizumab on HRQoL in persons with severe HA (PwHA) without factor VIII (FVIII) inhibitors in the phase 3 HAVEN 3 and 4 studies. METHODS: This pooled analysis examines the HRQoL of PwHA aged ≥ 18 years treated with emicizumab prophylaxis via Haemophilia-Specific Quality of Life Questionnaire for Adults (Haem-A-QoL) and EuroQoL 5-Dimensions 5-levels (EQ-5D-5L). In particular, changes from baseline in Haem-A-QoL 'Physical Health' (PH) domain and 'Total Score' (TS) are evaluated. RESULTS: Among 176 evaluable participants, 96 (55%) had received prior episodic treatment and 80 (45%) prophylaxis; 70% had ≥ 1 target joint and 51% had experienced ≥ 9 bleeds in the previous 24 weeks. Mean Haem-A-QoL PH and TS improved after emicizumab initiation. Mean (standard deviation) -12.0 (21.26)- and -8.6 (12.57)-point improvements were observed in PH and TS from baseline to Week 73; Week 73 scores were 27.9 (24.54) and 22.0 (14.38), respectively. Fifty-four percent of participants reported a clinically meaningful improvement in PH scores (≥ 10 points) by Week 73. Subgroups with poorer HRQoL prior to starting emicizumab (i.e. receiving episodic treatment, ≥ 9 bleeds, target joints) had the greatest improvements in PH scores, and corresponding reductions in missed workdays; change was not detected among those previously taking prophylaxis. No change over time was detected by the EQ-5D-5L questionnaire. CONCLUSIONS: Emicizumab prophylaxis in PwHA without FVIII inhibitors resulted in persistent and meaningful improvements in Haem-A-QoL PH and less work disruption than previous treatment.

The safety of activated eptacog beta in the management of bleeding episodes and perioperative haemostasis in adult and paediatric haemophilia patients with inhibitors.

INTRODUCTION: Haemophilia patients with inhibitors often require a bypassing agent (BPA) for bleeding episode management. Eptacog beta (EB) is a new FDA-approved recombinant activated human factor VII BPA for the treatment and control of bleeding in haemophilia A or B patients with inhibitors (≥12 years of age). We describe here the EB safety profile from the three prospective Phase 3 clinical trials performed to date. AIM: To assess EB safety, immunogenicity and thrombotic potential in children and adults who received EB for treatment of bleeding and perioperative care. METHODS: Using a randomized crossover design, 27 subjects in PERSEPT 1 (12-54 years) and 25 subjects in PERSEPT 2 (1-11 years) treated bleeding episodes with 75 or 225 µg/kg EB initially followed by 75 µg/kg dosing at predefined intervals as determined by clinical response. Twelve PERSEPT 3 subjects (2-56 years) received an initial preoperative infusion of 75 µg/kg (minor procedures) or 200 µg/kg EB (major surgeries) with subsequent 75 µg/kg doses administered intraoperatively and post-operatively as indicated. Descriptive statistics were used for data analyses. RESULTS: Sixty subjects who received 3388 EB doses in three trials were evaluated. EB was well tolerated, with no allergic, hypersensitivity, anaphylactic or thrombotic events reported and no neutralizing anti-EB antibodies detected. A death occurred during PERSEPT 3 and was determined to be unlikely related to EB treatment by the data monitoring committee. CONCLUSION: Results from all three Phase 3 trials establish an excellent safety profile of EB in haemophilia A or B patients with inhibitors for treatment of bleeding and perioperative use.

Emicizumab Prophylaxis in Hemophilia A with Inhibitors.

BACKGROUND: Emicizumab (ACE910) bridges activated factor IX and factor X to restore the function of activated factor VIII, which is deficient in persons with hemophilia A. This phase 3, multicenter trial assessed once-weekly subcutaneous emicizumab prophylaxis in persons with hemophilia A with factor VIII inhibitors. METHODS: We enrolled participants who were 12 years of age or older. Those who had previously received episodic treatment with bypassing agents were randomly assigned in a 2:1 ratio to emicizumab prophylaxis (group A) or no prophylaxis (group B). The primary end point was the difference in bleeding rates between group A and group B. Participants who had previously received prophylactic treatment with bypassing agents received emicizumab prophylaxis in group C. RESULTS: A total of 109 male participants with hemophilia A with inhibitors were enrolled. The annualized bleeding rate was 2.9 events (95% confidence interval [CI], 1.7 to 5.0) among participants who were randomly assigned to emicizumab prophylaxis (group A, 35 participants) versus 23.3 events (95% CI, 12.3 to 43.9) among those assigned to no prophylaxis (group B, 18 participants), representing a significant difference of 87% in favor of emicizumab prophylaxis (P<0.001). A total of 22 participants in group A (63%) had zero bleeding events, as compared with 1 participant (6%) in group B. Among 24 participants in group C who had participated in a noninterventional study, emicizumab prophylaxis resulted in a bleeding rate that was significantly lower by 79% than the rate with previous bypassing-agent prophylaxis (P<0.001). Overall, 198 adverse events were reported in 103 participants receiving emicizumab prophylaxis; the most frequent events were injection-site reactions (in 15% of participants). Thrombotic microangiopathy and thrombosis were reported in 2 participants each (in the primary analysis) who had received multiple infusions of activated prothrombin complex concentrate for breakthrough bleeding. No antidrug antibodies were detected. CONCLUSIONS: Emicizumab prophylaxis was associated with a significantly lower rate of bleeding events than no prophylaxis among participants with hemophilia A with inhibitors. (Funded by F. Hoffmann-La Roche and Chugai Pharmaceutical; HAVEN 1 ClinicalTrials.gov number, NCT02622321 .).

Identification of new F8 deep intronic variations in patients with haemophilia A.

INTRODUCTION: With current molecular diagnosis, about 1 to 5% of haemophilia A (HA) patients remain genetically unresolved. In these cases, deep intronic variation or structural variation disrupting the F8 gene could be causal. AIM: To identify the causal variation in four genetically unresolved mild-to-severe HA patients using an F8 mRNA analysis approach. METHODS: Ectopic F8 mRNA analysis was performed in four unrelated HA patients. An in vitro minigene assay was performed in order to confirm the deleterious splicing impact of each variation identified. RESULTS: In all probands, mRNA analysis revealed an aberrant splicing pattern, and sequencing of the corresponding intronic region found a deep intronic substitution. Two of these were new variations: c.2113+601G>A and c.1443+602A>G, while the c.143+1567A>G, found in two patients, has previously been reported. The c.1443+602A>G and the c.143+1567A>G variants both led to the creation of a de novo acceptor or donor splice site, respectively. Moreover, the c.143+1567A>G was found in 3/6 patients with genetically unresolved moderate HA registered in our laboratory. Haplotype analysis performed in all patients carrying the c.143+1567A>G variation suggests that this variation could be a recurrent variation. The c.2113+601G>A led to the exonization of a 122-bp antisense AluY element by increasing the strength of a pre-existing cryptic 5' splice site. For each point variation, in vitro splicing analysis confirmed its deleterious impact on splicing of the F8 transcript. CONCLUSION: We identified three deep intronic variations, leading to an aberrant mRNA splicing process as HA causing variation.

A novel protocol for accurate and reliable postoperative bolus administration of recombinant factor VIIa using an automated mini-pump system.

INTRODUCTION: Recombinant FVIIa (rFVIIa) is widely used to manage bleeding risk during and after surgery in patients with haemophilia complicated by inhibitors. In the postoperative period, rFVIIa must be delivered frequently and regularly to maintain haemostasis, considering its short half-life. Preparation and manual administration of bolus doses of rFVIIa at regular intervals may place a strain on available nursing resources. A programmable mini-pump may offer an approach to facilitate regular administration of bolus doses of rFVIIa at specified intervals. AIM: To investigate if a mini-pump is a practical and effective way to deliver rFVIIa in the postoperative period. METHODS: It was first necessary to establish that rFVIIa remains stable and sterile in the mini-pump reservoir for an extended period. Four days after loading the mini-pump under sterile conditions no evidence of bacterial or fungal growth was observed and in vitro procoagulant activity of rFVIIa remained stable. The mini-pump was used to deliver rFVIIa as bolus doses to two patients with inhibitors who had undergone surgery. Nurses were asked to report their satisfaction with the use of the mini-pump using a specific questionnaire. RESULTS: Haemostasis was evaluated as excellent in both cases; nurses were satisfied with use of the mini-pump. CONCLUSION: This pilot study shows that intermittent delivery of rFVIIa at fixed intervals using an automated mini-pump offers accurate and reliable administration in the postoperative setting. This approach may reduce burden on nursing staff, potentially minimize the risk of human error and avoid delay in administration of rFVIIa.

Splicing analysis of 26 F8 nucleotide variations using a minigene assay.

BACKGROUND: Classically, the study of splicing impact of variation located near the splice site is performed by both in silico and mRNA analysis. However, RNA sample was rarely available. OBJECTIVE: To characterize a panel of putative haemophilia A splicing variations. MATERIALS AND METHODS: Twenty-six F8 variations identified from a cohort of 2075 haemophilia A families were studied using both bioinformatic tools and in vitro minigene assays in HeLa and Huh7 cells. RESULTS: An aberrant splicing was demonstrated for 21/26 tested sequence variations. A good correlation between in silico and in vitro analysis was obtained for variations affecting donor splice site (12/14) and for the synonymous variations located inside an exon (6/6). Conversely, no concordant results were observed for the six variations affecting acceptor splice sites. The variations resulted more frequently in exon skipping (n = 13) than in activation of nearby cryptic splice sites (n = 5), in use of a de novo splice site (n = 2) or in insertion of large intronic sequences (n = 1). This study allowed to reclassify 5 synonymous substitutions c.1167A>G (p.Gln389Gln), c.1569G>T (p.Leu523Leu), c.1752G>A (p.Gln584Gln), c.5586G>A (p.Leu1862Leu) and c.6066C>T (p.Gly2022Gly) as splicing variations. The pathological significance of five variations remained unclear (c.222G>A [p.Thr74Thr], c.237C>T [p.Asn79Asn], c.240C>T [p.Ile80Ile], c.2113+5_2113+8del and c.2113+5G>A). DISCUSSION: The minigene assay herein gave additional evidences for the clinical significance of 21/26 F8 putative splice site mutations. Such investigation should be performed for each F8 putative splice site variation for which no mRNA sample is available, notably to greatly improve the genetic counselling given to female carriers.

Potential limits of AAV-based gene therapy with the use of new transgenes expressing factor IX fusion proteins.

INTRODUCTION: The variety of treatment for haemophilia B (HB) has recently improved with the emergence of both AAV-based gene therapy and bioengineered human factor IX (hFIX) molecules with prolonged half-life due to fusion to either albumin (Alb) or immunoglobulin Fc fragment (Fc). AIM: Adeno-associated viral vectors (AAV) mediating expression of hFIX-Alb and hFIX-Fc fusion proteins was investigated for gene therapy of HB to explore if their extended half-life translates to higher plasma levels of FIX. METHODS: Single-stranded cross-packaged AAV2/8 vectors expressing hFIX-Alb, hFIX-Fc and hFIX were evaluated in vitro, and in mice. RESULTS: Both hFIX-Alb and hFIX-Fc fusion proteins were synthesized and expressed as single chains of expected size following AAV-mediated gene transfer in vitro and in vivo. The procoagulant properties of these hFIX-fusion proteins were comparable to wild-type hFIX. However, their expression levels were threefold lower than wild-type hFIX in vivo most likely due to inefficient secretion. CONCLUSION: This, the first, evaluation of hFIX-fusion proteins in the context of AAV gene transfer suggests that the hFIX-fusion proteins are secreted inefficiently from the liver, thus preventing their optimal use in gene therapy approaches.

BAY 94-9027 prophylaxis is efficacious and well tolerated for up to >5 years with extended dosing intervals: PROTECT VIII extension interim results.

INTRODUCTION: BAY 94-9027 is an extended-half-life, site-specifically PEGylated, B-domain-deleted recombinant factor VIII (FVIII). The PROTECT VIII main study demonstrated efficacy of bleed control using extended-interval prophylaxis with BAY 94-9027 for 36 weeks. AIM: To report long-term efficacy and safety of prophylaxis with BAY 94-9027 in a descriptive analysis of the ongoing PROTECT VIII extension with a total treatment time of up to >5 years. METHODS: Previously treated males aged 12-65 years with severe haemophilia A who completed the PROTECT VIII main study were eligible for the open-label extension. Patients received on-demand treatment or prophylaxis (30-40 IU/kg twice weekly, 45-60 IU/kg every 5 days, or 60 IU/kg every 7 days) and could switch regimens as needed. RESULTS: Patients (N = 121; on demand, n = 14; prophylaxis, n = 107) accumulated a median (range) of 3.9 years (297-1965 days) and 223 (23-563) total exposure days by 31 January 2018. During the extension, median (quartile [Q]1; Q3) annualized bleeding rates (ABRs) for total bleeds were 1.6 (0.3; 4.6) for patients receiving prophylaxis and 34.1 (20.3; 36.6) for patients receiving on-demand treatment. ABRs for twice-weekly (n = 23), every-5-days (n = 33), every-7-days (n = 23) and variable frequency (n = 28) treatments were 1.7, 1.2, 0.7 and 3.1, respectively. Of prophylaxis patients, 20.6% were bleed-free throughout the extension (median time, 3.2 years), and 44.5% were bleed-free during the last 6 months. No patients developed FVIII inhibitors. CONCLUSIONS: BAY 94-9027 prophylaxis was efficacious and well tolerated with dosing intervals up to every 7 days for a median (range) of 3.9 years (0.8-5.4 years).

Management of bleeding and invasive procedures in haemophilia A patients with inhibitor treated with emicizumab (Hemlibra® ): Proposals from the French network on inherited bleeding disorders (MHEMO), the French Reference Centre on Haemophilia, in collaboration with the French Working Group on Perioperative Haemostasis (GIHP).

INTRODUCTION: Emicizumab (Hemlibra® ) recently became available and requires an adaptation for managing bleeding, suspected bleeding and emergency or scheduled invasive procedures in haemophilia A patients with inhibitor. This implicates a multidisciplinary approach and redaction of recommendations for care that must be regularly adapted to the available data. AIM: The following text aims to provide a guide for the management of people with haemophilia A with inhibitor treated with emicizumab in case of bleeding or invasives procedures. METHODS: The French network on inherited bleeding disorders (MHEMO), the French Reference Centre on Haemophilia (CRH), in collaboration with the French Working Group on Perioperative Haemostasis (GIHP) have been working together to make proposals for the management of these situations. RESULTS: Haemostatic treatment and other medications should be given stepwise, according to the severity and location of the bleeding or the risk of bleeding of the procedure as well as the haemostatic response obtained at each step in order to ensure an optimal benefit/risk ratio. CONCLUSION: The lack of data means that it is only possible to issue proposals rather than recommendations.

Once-weekly prophylaxis with glycoPEGylated recombinant factor VIII (N8-GP) in severe haemophilia A: Safety and efficacy results from pathfinder 2 (randomized phase III trial).

INTRODUCTION: Turoctocog alfa pegol (N8-GP) is a site-specific, 40 kDa glycoPEGylated recombinant factor VIII (FVIII) product with an extended half-life. The comprehensive main phase of the pivotal pathfinder 2 trial showed N8-GP dosed every 4 days (Q4D) provided favourable safety and efficacy for preventing bleeds in 175 patients with haemophilia A. AIM AND METHODS: We investigated the safety and efficacy of N8-GP prophylaxis when administered weekly (Q7D) for 24 weeks to patients with low bleeding rates in the pathfinder 2 extension trial. Patients (≥12 years) with ≤2 bleeds during the preceding 6 months of the pathfinder 2 main phase were eligible for randomization to receive N8-GP 50 IU/kg Q4D or 75 IU/kg Q7D. Safety and efficacy endpoints were incidence of FVIII inhibitors and annualized bleeding rate (ABR), respectively. RESULTS: Fifty-five of 143 (38.5%) patients on prophylaxis who continued into the extension phase were randomized to receive 50 IU/kg Q4D (n = 17) or 75 IU/kg Q7D (n = 38). Nine patients in the Q7D cohort reverted to 50 IU/kg Q4D. No inhibitors were detected. In both cohorts, >50% of patients experienced no bleeds. Median ABR for overall, joint, spontaneous, traumatic and muscle was 0.00 for both cohorts. Overall estimated success rate for treating bleeding episodes was 87.5%; 94.7% of bleeds were controlled with ≤2 injections. CONCLUSIONS: Weekly N8-GP was well tolerated and efficacious and may benefit selected "low bleeder" patients with haemophilia A.