Multicenter evaluation of the hemostatic activity of emicizumab in patients with severe hemophilia A.

BACKGROUND: Emicizumab has been approved for the prophylaxis of patients with hemophilia A with or without inhibitors. However, spontaneous and trauma-induced breakthrough bleeds have been reported in patients on emicizumab prophylaxis, and no laboratory assay has been validated to evaluate the hemostatic activity of emicizumab. OBJECTIVES: The thrombin generation assay (TGA) could be a surrogate marker of the hemostatic efficacy of emicizumab. The correlation between TGA and the methods used to measure emicizumab blood concentration was evaluated in this study. METHODS: TGA was modified by the use of a trigger reagent combining a very low concentration of tissue factor and activated factor (F)XI. Emicizumab quantification was performed by 3 methods: the modified 1-step FVIII assay and 2 methods based on liquid chromatography and mass spectrometry (LC-MS). RESULTS: Using tissue factor/activated FXI-triggered TGA and platelet-poor plasma, a relationship was observed between the area under the thrombin generation curve (endogenous thrombin potential [ETP]) and the clinical response of patients to emicizumab. The ultrastructure of fibrin clots was consistent with ETP results and showed that emicizumab had a hemostatic activity equivalent to 20 to 30 IU/dL of FVIII. Finally, pharmacokinetic/pharmacodynamic analyses showed no correlation between ETP and LC-MS nor with modified 1-stage FVIII assay, but a statistically significant correlation between the LC-MS methods and the time-to-peak results of the TGA. CONCLUSION: Using a modified TGA, this study showed that patients who experienced breakthrough bleeds while on emicizumab had a lower thrombin-generating capacity compared with others with good clinical response to emicizumab.

Relationship between plasma tissue Factor Pathway Inhibitor (TFPI) levels, thrombin generation and clinical risk of bleeding in patients with severe haemophilia A or B.

INTRODUCTION: Bleeding severity in severe haemophilic patients, with low thrombin generation (TG) capacity, can vary widely between patients, possibly reflecting differences in tissue factor pathway inhibitor (TFPI) level. AIM: To compare free TFPI (fTFPI) levels in patients with severe haemophilia A (sHA) and severe haemophilia B (sHB) and to investigate in these patients as a whole the relationships between bleeding and TG potential, between TG potential and fTFPI level and between fTFPI level and bleeding tendency. METHODS: Data on bleeding episodes retrospectively recorded during follow-up visits over 5-10 years were collected and used to calculate the annualised joint bleeding rate (AJBR). fTFPI levels and basal TG parameters were determined in platelet-poor plasma (PPP) and platelet-rich plasma (PRP) using calibrated automated tomography (CAT). RESULTS: Mean fTFPI levels did not differ significantly between sHA (n = 34) and sHB (n = 19) patients. Mean values of endogenous thrombin potential (ETP) and thrombin peak (peak) in PPP and PRP were two-fold higher when fTFPI levels < 9.4 versus > 14.3 ng/mL. In patients treated on demand, ETP and peak in PRP were doubled when AJBR was ≤ 4.9 $ \le 4.9$ , AJBR being halved in patients with a low fTFPI level (9.4 ng/mL). In patients on factor prophylaxis, no association was found between TG parameters and either fTFPI level or AJBR. CONCLUSION: In patients treated on demand, bleeding tendency was influenced by fTFPI levels, which in turn affected basal TG potential. In patients on prophylaxis, bleeding tendency is probably determined primarily by the intensity of this treatment.

Stromal cell-derived factor 1 alpha (SDF-1alfa) and cartilage oligomeric matrix protein (COMP): Two potential signature biomarkers of radiological detectable hemophilic arthropathy.

INTRODUCTION: Hemophilia is a rare constitutional bleeding disorder due to a deficiency in Factor VIII or Factor IX. Recurrent hemarthroses, one of the major complications of the disease, lead to hemophilic arthropathy, a disabling condition that requires early diagnosis. Traditionally, clinical examination and plain film radiography have been used to diagnose hemophilic arthropathy. Magnetic resonance imaging (MRI) and ultrasound can be more useful for diagnosing soft-tissue changes. However, but each of these methods has limitations and diagnosis of arthropathy can be delayed. AIM: The aim of this project was to assess plasmatic biomolecules indicative of osteo-cartilaginous damage in patients with hemophilia with or without known arthropathy, in order to improve the diagnosis of this major complication of the disease. METHODS: In this monocentric retrospective study, 40 patients with hemophilia A or B, for whom a plasma sample was available, provided informed consent for further analyses (multiplex immunoassays and ELISA) and collection of relevant clinical information in their medical files. Correlations were sought for between biomarkers of interest and the severity of joint lesions assessed according to Pettersson's radiologic score. RESULTS: Two biomarkers were identified, respectively SDF-1α and COMP. Their plasmatic levels were significantly increased in patients with arthropathy compared to controls and patients without arthropathy. These values correlated significantly with the Pettersson score in patients under regular prophylaxis. CONCLUSION: Two plasma biomarkers have been identified that could help assess the presence and severity of hemophilic arthropathy.

Whole F8 gene sequencing identified pathogenic structural variants in the remaining unsolved patients with severe hemophilia A.

BACKGROUND: No F8 genetic abnormality is detected in approximately 1% to 2% of patients with severe hemophilia A (HA) using conventional genetic approaches. In these patients, deep intronic variation or F8 disrupting genomic rearrangement could be causal. OBJECTIVES: The study aimed to identify the causal variation in families with a history of severe HA for whom genetic investigations failed. METHODS: We performed whole F8 gene sequencing in 8 propositi. Genomic rearrangements were confirmed by Sanger sequencing of breakpoint junctions and/or quantitative polymerase chain reaction. RESULTS: A structural variant disrupting F8 was found in each propositus, so that all the 815 families with a history of severe HA registered in our laboratory received a conclusive genetic diagnosis. These structural variants consisted of 3 balanced inversions, 3 large insertions of gained regions, and 1 retrotransposition of a mobile element. The 3 inversions were 105 Mb, 1.97 Mb, and 0.362 Mb in size. Among the insertions of gained regions, one corresponded to the insertion of a 34 kb gained region from chromosome 6q27 in F8 intron 6, another was the insertion of a 447 kb duplicated region from chromosome 9p22.1 in F8 intron 14, and the last one was the insertion of an Xq28 349 kb gained in F8 intron 5. CONCLUSION: All the genetically unsolved cases of severe HA in this cohort were due to structural variants disrupting F8. This study highlights the effectiveness of whole F8 sequencing to improve the molecular diagnosis of HA when the conventional approach fails.

A single-centre experience of 29 total ankle replacement in haemophiliac patients: Therapeutic management, factor consumption and cost.

INTRODUCTION: In patients with haemophilia, repeated bleeding in large joints leads to chronic haemophilic arthropathy, a rare disease that can be managed surgically with ankle arthrodesis or with total ankle replacement (TAR). TAR has been reported to provide good surgical results in the medium/long-term and allow preservation of joint mobility but the medical therapeutic management of the patients has not been described. AIM: To describe the medical therapeutic management of TAR. METHODS: All patients with haemophilia A/B, with haemophilic ankle arthropathy, and who underwent TAR between April 2006 and October 2019 were retrospectively included. Factor consumption, perioperative and early complications, volume of blood lost, and orthopaedic data were collected. RESULTS: A total of 25 patients underwent 29 TAR (mean age was 44.7 years [range: 26-65]). In the 17 patients with HA without history of anti-FVIII inhibitor, the mean ± SD consumption the day of surgery was 116 ± 16 UI/kg when clotting factors were administered by continuous infusion, 106 ± 13 UI/kg when SHL factors were administered by bolus infusion, and 75 ± 22 UI/kg when EHL factors were administered by bolus infusion. During hospitalisation, the mean factor cost was €38,073 (83.7% of the total cost of surgery). Mean blood loss was significantly lower in patients treated with tranexamic acid (164 mL, range: 40-300) than in those not (300 mL, range: 70-800; p = .01). Six patients had haematoma. The 10-year survival free of any prosthesis removal/arthrodesis was estimated to be 92.2% (95% CI [83; 100]). CONCLUSION: The medical therapeutic management of TAR is complex, carried out by a multidisciplinary team but effective in avoiding the occurrence of complications.

Perspectives and perception of haemophilia gene therapy by French patients.

INTRODUCTION AND AIM: A national survey was initiated by representatives of French patients with haemophilia (AFH) and the French reference centre for haemophilia, in order to appreciate the awareness and knowledge of these patients regarding haemophilia gene therapy (HGT) and understand better their position about this innovative treatment that will soon become available. RESULTS: Of 143 answers received, 137 could be analysed, representing about 3.5% of patients with severe or moderate haemophilia over 16year-old. They were 80.3% with haemophilia A and 19.7 % with haemophilia B, with a severe form of the disease for 80.3 % of them. Curiosity for HGT was formulated by 64.2% of the participants, 33.6 % being interested by this approach as soon as it will be available and 38.7 % preferring to wait until more patients have been treated. Only 3.6 % of the participants would never consider receiving HGT. The level of awareness and knowledge was estimated to be limited by 39.5 % of the patients. More than 60 % of them declared having never or almost never discussed HGT with the team of their haemophilia centre. Before deciding to get HGT, 54.4 % of the participants considered that it will be very important to compare it with their current treatment and 53.7 % would like to be better informed by their care providers. CONCLUSIONS: These results highlight the need for training and education for patients, but also for professionals at haemophilia centres, about HGT and the shared decision-making process. Objective, unbiased and transparent information must be available for patients about this very promising therapy which nonetheless carries more uncertainty and unknowns compared to other haemophilia treatments.

Comparison of one-stage and chromogenic factor VIII assays to tailor the dose of recombinant factor VIII-Fc fusion protein (rFVIIIFc, efmoroctocog alfa) in adult patients with haemophilia A: Single-centre, real-world experience of surgery.

BACKGROUND: Efmoroctocog alfa (rFVIIIFc) is an extended half-life FVIII used notably in surgery for patients with haemophilia A. More information is needed of its usage in real-life. METHODS: Adult patients with HA followed at the Lyon Comprehensive Hemophilia Care Center who underwent a surgery with rFVIIIFc were included in this retrospective analysis. The pharmacokinetics of rFVIIIFc was assessed by plasma factor VIII clotting activity (FVIII:C) using both one-stage (OSA) and chromogenic substrate (CSA) assays. RESULTS: A total of 39 major and 31 minor surgeries were performed in 49 patients treated with rFVIIIFc. The median dose of rFVIIIFc infused before major and minor surgeries respectively was 67.5 ((interquartile range [IQR] 52.6-76.9) and 48.0 (38.5-51.8) IU/kg. For major surgeries, during the first postoperative week, the median residual FVIII:C was 78 (64.5-101.5) IU/dL with OSA and 99 (71-118) IU/dL with CSA (p < .0001). After surgery, rFVIIIFc doses were adjusted according to CSA results. This led to a significant decrease of rFVIIIFc consumption compared to what would have been proposed according to the OSA assay, without unusual bleeding or appearance of inhibitor. Considering the high price of the molecule, this was also associated with a significant cost reduction. CONCLUSION: Dose adjustment of rFVIIIFc according to FVIII: C measured by CSA is effective, safe and well tolerated in patients with haemophilia A undergoing invasive surgery.

Occupational integration of adults with severe haemophilia (INTHEMO): A study based on the FranceCoag registry.

INTRODUCTION: Health of people with severe haemophilia (PwSH) improves thanks to the advancements in haemophilia care, giving them more opportunities in occupational integration. However, there is little literature on the occupational integration of PwSH. OBJECTIVES: The main objective of our study was to assess the occupational integration of PwSH and to compare it with that of the general population. The secondary objective was to study the association between individual characteristics (sociodemographic, clinical and psycho-behavioural) and occupational integration of PwSH. METHODS: A multicentre, non-interventional, cross-sectional study was conducted in 2018-2020 on PwSH, aged over 18 and under 65 years and included in the FranceCoag registry. Measurements included indicators of occupational integration, sociodemographic, clinical and psycho-behavioural characteristics. The indicators of occupational integration were compared with those of the general population, using indirect standardization. The data of the general population were available from the National Institute of Statistics and Economic Studies (INSEE). Determinants of occupational integration were explored using structural equation modelling. RESULTS: Of 1262 eligible people, 588 were included. PwSH had a lower employment rate than the general population (standardized ratio, .85; 95% CI, .77-.94). There were more PwSH at tertiary education level than expected (standardized ratio, 1.38; 95% CI, 1.17-1.61). HIV infection, poor physical health and mental health concerns were associated with a higher risk of unemployment in PwSH. CONCLUSION: Employment rate of PwSH is lower than that of the general population despite their higher education level. Target interventions focusing on determinants of difficult occupational integration could be helpful for PwSH.

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.

Haemophilia A patients' medication adherence to prophylaxis with efmoroctocog alfa.

INTRODUCTION: Lightening the injection burden is commonly believed to improve prophylaxis adherence. Efmoroctocog alfa (rFVIIIFc) is the first recombinant FVIII-Fc fusion protein available in France. This clotting factor with an extended half-life could thus improve medication adherence. AIM: The study primarily aimed to assess the real-life impact on prophylaxis adherence of haemophilia A patients, when switching from a standard to an extended half-life FVIII. METHODS: This study was an observational, monocentre, non-interventional study aiming at assessing haemophilia A patients' real-life adherence during the first-year post-rFVIIIFc prophylaxis initiation. Medication adherence was assessed using two methods: the medication possession ratio (MPR), which is based on the hospital pharmacy dispensing data, and self-reported VERITAS-Pro® questionnaire. Patients on rFVIIIFc prophylaxis for at least 12 months, following a 12-month standard FVIII prophylaxis, were eligible for inclusion. RESULTS: In 2019, 47 male patients were undergoing rFVIIIFc prophylaxis in our Hemophilia Center, among which 36 meeting the inclusion criteria. Switching from standard to extended half-life FVIII prophylaxis resulted in increased mean dosing, while the mean number of weekly prophylactic injections (2.6 ± 0.5 vs 1.8 ± 0.3) decreased. Following rFVIIIFc initiation, a non-significant increase in median MPR occurred and the self-reported VERITAS-Pro® questionnaire demonstrated improved adherence to rFVIIIFc prophylaxis. Comparing adherent and non-adherent patients revealed age as the only factor likely to impact adherence (p = .07). CONCLUSION: Our patient cohort exhibited high adherence levels before and after FVIII switching, based on MPR and VERITAS-Pro® questionnaire. The latter is likely a useful tool to quantity prophylaxis adherence from a patient's perspective in daily use.

Evolution of clotting factor concentrates prescriptions and impact of recommendations of prophylaxis in children with haemophilia.

Prophylaxis treatment is considered as the reference approach for children with severe haemophilia A or B. However, no consensus about the best prophylaxis protocol has yet been identified in term of dosage and timing of infusions. Guidelines were drawn up in France in the early 2000s by an expert group. The objective of this 16-year study (2001 to 2016) was to describe the clotting factor concentrates (CFCs) use in haemophiac outpatients. This is a retrospective monocentric study. Pharmaceutical and clinical data were captured using medical records. Main outcome measures are CFCs use and clinical data in paediatrics. Eighty haemophiliacs A or B under 12 years old with a factor level less than 2% were included (74% of HA), from pharmaceutical outpatient data. Global use of CFCs followed the evolution of the patients' number and regimen type introduced: increase of prophylaxis and decrease of on demand regimen. The average age at the prophylaxis introduction is significantly different according to the birth year. Prophylaxis introduction was made earlier with an increase of prophylactic regimen joined to an increase of CFCs use. The significant reduction of haemarthrosis in our cohort can be linked to a first infusion age and a prophylaxis introduction much earlier.

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 new paradigm for personalized prophylaxis for patients with severe haemophilia A.

AIM: For patients with severe haemophilia A, guidelines recommend prophylactic treatment with FVIII, with dose calculations targeting a predetermined FVIII trough level. However, this pharmacokinetic (PK) approach is suboptimal, with some patients experiencing breakthrough bleeds. We aimed to improve FVIII dosing by incorporating the thrombin generation assay, a global haemostasis assay whose main pharmacodynamic (PD) parameter, endogenous thrombin potential (ETP), predicts spontaneous bleeding risk. METHODS: We performed post hoc combined PK-PD modelling using data from 66 adults who received human-cl rhFVIII (Nuwiq® , Octapharma AG) in a phase IIIb study. Time-to-event analyses simulated the probability of spontaneous bleeding for different FVIII exposures and baseline ETPs. RESULTS: Ninety-one spontaneous bleeds occurred in 20/66 patients. The relationship between FVIII:C and ETP was non-linear, and the sigmoid Emax model adequately described the data. Individual PK-PD Bayesian estimation significantly improved predictive performance. Simulations showed that the mean spontaneous annual bleeding rate decreased with increasing baseline ETP or dosing: with ETP values of 200, 400 and 600 (nmol/L)·min annual bleeding rates were 2.36, 1.25 and 0.66, respectively, on 40 IU/kg human-cl rhFVIII every 3 days; and annual bleeding rates were 2.09, 1.10, and 0.60, respectively, on 60 IU/kg every 3 days. CONCLUSION: Prophylactic FVIII dosing is more clinically meaningful when incorporating ETP alongside FVIII level. For the first time, FVIII dosing can be personalized with the aim of eliminating spontaneous breakthrough bleeds.

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.

A Prolonged Treatment Response in Acquired Von Willebrand Syndrome.

Acquired von Willebrand syndrome (AVWS) is a rare bleeding disorder. We report herein a case of AVWS due to a monoclonal gammopathy of undetermined significance, in which a transient but prolonged response to a treatment by intravenous immunoglobulin (IVIG) was observed. The diagnosis was fortuitously made in a preoperative setting for neurosurgery, after biological exploration of an isolated prolonged activated partial thromboplastin time. AVWS was confirmed by an accelerated clearance of an infused plasma-derived von Willebrand factor (VWF) concentrate. High doses of IVIG were used to perform the neurosurgery. Fifty-four days after IVIG, the patient was still responding to treatment with normal levels of factor VIII and VWF.

Tissue factor pathway inhibitor is the main determinant of thrombin generation in haemophilic patients.

The thrombin generation (TG) assay evaluates haemostatic balance, which is influenced by the levels of many coagulation factors and inhibitors. Our objective was to identify the determinant factors of TG in haemophilia A (HA) and haemophilia B (HB) patients and to compare them to those in healthy controls. Coagulation factor and inhibitor levels, and TG, were measured in platelet-poor plasma from 40 patients with HA, 32 patients with HB and 40 healthy subjects. Data were analysed using multiple regression models. In HA patients, factor VIII was a positive determinant of endogenous thrombin potential (ETP) and peak, whereas tissue factor pathway inhibitor (TFPI) and factor V were negative determinants of ETP and peak. In HB patients, FIX was a positive determinant of ETP and peak, FVII being a positive determinant of peak. Antithrombin and protein S (PS) were negative determinants of ETP while FX was a negative determinant of peak. Above all, in HB patients, TFPI was a negative determinant of ETP and peak. In healthy subjects, FVIII was a positive determinant of ETP and peak, whereas FX and protein S were negative determinants of these parameters. TFPI was not a negative determinant of either peak or ETP. In haemophilic patients, the determinant factors of TG are all implicated in FXa generation and inhibition, the crucial determinant factor being TFPI whatever the type of haemophilia, A or B. These findings contribute to the rationale that recently place TFPI as a target for innovative therapies of haemophilia.