Gene Therapy with Etranacogene Dezaparvovec for Hemophilia B.

BACKGROUND: Moderate-to-severe hemophilia B is treated with lifelong, continuous coagulation factor IX replacement to prevent bleeding. Gene therapy for hemophilia B aims to establish sustained factor IX activity, thereby protecting against bleeding without burdensome factor IX replacement. METHODS: In this open-label, phase 3 study, after a lead-in period (≥6 months) of factor IX prophylaxis, we administered one infusion of adeno-associated virus 5 (AAV5) vector expressing the Padua factor IX variant (etranacogene dezaparvovec; 2×1013 genome copies per kilogram of body weight) to 54 men with hemophilia B (factor IX activity ≤2% of the normal value) regardless of preexisting AAV5 neutralizing antibodies. The primary end point was the annualized bleeding rate, evaluated in a noninferiority analysis comparing the rate during months 7 through 18 after etranacogene dezaparvovec treatment with the rate during the lead-in period. Noninferiority of etranacogene dezaparvovec was defined as an upper limit of the two-sided 95% Wald confidence interval of the annualized bleeding rate ratio that was less than the noninferiority margin of 1.8. Superiority, additional efficacy measures, and safety were also assessed. RESULTS: The annualized bleeding rate decreased from 4.19 (95% confidence interval [CI], 3.22 to 5.45) during the lead-in period to 1.51 (95% CI, 0.81 to 2.82) during months 7 through 18 after treatment, for a rate ratio of 0.36 (95% Wald CI, 0.20 to 0.64; P<0.001), demonstrating noninferiority and superiority of etranacogene dezaparvovec as compared with factor IX prophylaxis. Factor IX activity had increased from baseline by a least-squares mean of 36.2 percentage points (95% CI, 31.4 to 41.0) at 6 months and 34.3 percentage points (95% CI, 29.5 to 39.1) at 18 months after treatment, and usage of factor IX concentrate decreased by a mean of 248,825 IU per year per participant in the post-treatment period (P<0.001 for all three comparisons). Benefits and safety were observed in participants with predose AAV5 neutralizing antibody titers of less than 700. No treatment-related serious adverse events occurred. CONCLUSIONS: Etranacogene dezaparvovec gene therapy was superior to prophylactic factor IX with respect to the annualized bleeding rate, and it had a favorable safety profile. (Funded by uniQure and CSL Behring; HOPE-B ClinicalTrials.gov number, NCT03569891.).

Type 1 VWD classification revisited: novel insights from combined analysis of the LoVIC and WiN studies.

ABSTRACT: There is significant ongoing debate regarding type 1 von Willebrand disease (VWD) defintion. Previous guidelines recommended patients with von Willebrand factor (VWF) levels <30 IU/dL be diagnosed type 1 VWD, whereas patients with significant bleeding and VWF levels from 30 to 50 IU/dL be diagnosed with low VWF. To elucidate the relationship between type 1 VWD and low VWF in the context of age-induced increases in VWF levels, we combined data sets from 2 national cohort studies: 162 patients with low VWF from the Low VWF in Ireland Cohort (LoVIC) and 403 patients with type 1 VWD from the Willebrand in The Netherlands (WiN) studies. In 47% of type 1 VWD participants, VWF levels remained <30 IU/dL despite increasing age. Conversely, VWF levels increased to the low VWF range (30-50 IU/dL) in 30% and normalized (>50 IU/dL) in 23% of type 1 VWD cases. Crucially, absolute VWF antigen (VWF:Ag) levels and increase of VWF:Ag per year overlapped between low VWF and normalized type 1 VWD participants. Moreover, multiple regression analysis demonstrated that VWF:Ag levels in low VWF and normalized type 1 VWD patients would not have been different had they been diagnosed at the same age (ß = 0.00; 95% confidence interval, -0.03 to 0.04). Consistently, no difference was found in the prevalence of VWF sequence variants; factor VIII activity/VWF:Ag or VWF propeptide/VWF:Ag ratios; or desmopressin responses between low VWF and normalized type 1 VWD patients. In conclusion, our findings demonstrate that low VWF does not constitute a discrete clinical or pathological entity. Rather, it is part of an age-dependent type 1 VWD evolving phenotype. Collectively, these data have important implications for future VWD classification criteria.

Recombinant von Willebrand factor prophylaxis in patients with severe von Willebrand disease: phase 3 study results.

International guidelines conditionally recommend long-term prophylaxis in patients with von Willebrand disease (VWD) and severe and frequent bleeding. As recombinant von Willebrand factor (rVWF; vonicog alfa) may reduce the frequency of treated spontaneous bleeding events (BEs), we investigated the efficacy and safety of rVWF prophylaxis in adults with severe VWD. Patients with BEs requiring VWF therapy in the past year (on-demand VWF therapy [prior on-demand group] or plasma-derived VWF prophylaxis [pdVWF; switch group]) were enrolled in a prospective, open-label, nonrandomized, phase 3 study. The planned duration of rVWF prophylaxis was 12 months; starting rVWF dose was 50 ± 10 VWF: ristocetin cofactor (VWF:RCo) IU/kg twice weekly (prior on-demand group) or based on prior pdVWF weekly dose/dosing frequency (switch group). The primary endpoint was annualized bleeding rate (ABR) of treated spontaneous BEs (sABR) during rVWF prophylaxis. Over the 12-month study period, treated sABR decreased by 91.5% on-study vs historical sABR in 13 patients in the prior on-demand group, and by 45.0% in 10 patients in the switch group (model-based analysis ratio, 0.085; 95% confidence interval [CI], 0.021-0.346 and 0.550; 95% CI, 0.086-3.523, respectively). No treated spontaneous BEs were recorded in 84.6% (11/13) and 70.0% (7/10) of patients, respectively. The safety profile of rVWF was consistent with the previously established profile, with no new adverse drug reactions identified. Findings suggest that rVWF prophylaxis can reduce treated spontaneous BEs in patients previously receiving on-demand VWF therapy and maintains at least the same level of hemostatic control in patients who switch from prophylaxis with pdVWF to rVWF, with a favorable safety profile. This trial was registered at www.clinicaltrials.gov (#NCT02973087) and www.clinicaltrialsregister.eu (#EudraCT 2016-001478-14).

Effect of etranacogene dezaparvovec on quality of life for severe and moderately severe haemophilia B participants: Results from the phase III HOPE-B trial 2 years after gene therapy.

INTRODUCTION: For people with haemophilia B (PwHB), bleeding may occur despite prophylaxis, negatively affecting health-related quality of life (HRQoL). The pivotal phase 3 HOPE-B trial investigating the adeno-associated virus gene transfer product, etranacogene dezaparvovec (EDZ), demonstrated sustained factor IX (FIX) activity and bleed protection in PwHB with baseline FIX levels ≤2%. AIM: Assess how EDZ affects HRQoL in HOPE-B trial participants. METHODS: HRQoL was evaluated using generic and disease-specific patient reported outcomes (PROs) including the EQ-5D-5L and the Hem-A-QoL questionnaires. Mean domain and total scores were compared 6 months pre- and the first 2 years post-EDZ administration using repeated measures linear mixed models. The percentage of participants with minimal clinically important improvements in HRQoL was also evaluated. RESULTS: Two years post-EDZ, there were nominally significant increases in the least squares (LS) mean score for the EQ-5D-5L Index Value (.04; p = .0129), reflecting better HRQoL. Nominally significant decreases in the LS mean scores, reflecting better HRQoL, were also found for the Hem-A-QoL total score (-6.0; p < .0001) and the Treatment (-13.94; p < .0001), Feelings (-9.01; p < .0001), Future (-6.45; p = .0004) and Work/School (-5.21; p = .0098) domains. The percentage of participants with ≥15-point improvement ranged from 45.83% (95% CI: 31.37%, 60.83%) for Treatment to 13.89% (95% CI: 4.67%, 29.50%) for Family Planning. Results were similar for Year 1. CONCLUSION: In conclusion, gene therapy with EDZ improved HRQoL in the first and second years in several Hem-A-QoL domains, including Treatment, Feelings, Work/School and Future domains, whereas improvement in other aspects of HRQoL were not demonstrated.

Peri-operative desmopressin combined with pharmacokinetic-guided factor VIII concentrate in non-severe haemophilia A patients.

INTRODUCTION: Non-severe haemophilia A patient can be treated with desmopressin or factor VIII (FVIII) concentrate. Combining both may reduce factor consumption, but its feasibility and safety has never been investigated. AIM: We assessed the feasibility and safety of combination treatment in nonsevere haemophilia A patients. METHODS: Non-severe, desmopressin responsive, haemophilia A patients were included in one of two studies investigating peri-operative combination treatment. In the single-arm DAVID study intravenous desmopressin (0.3 µg/kg) once-a-day was, after sampling, immediately followed by PK-guided FVIII concentrate, for maximally three consecutive days. The Little DAVID study was a randomized trial in patients undergoing a minor medical procedure, whom received either PK-guided combination treatment (intervention arm) or PK-guided FVIII concentrate only (standard arm) up to 2 days. Dose predictions were considered accurate if the absolute difference between predicted and measured FVIII:C was ≤0.2 IU/mL. RESULTS: In total 32 patients (33 procedures) were included. In the DAVID study (n = 21), of the FVIII:C trough levels 73.7% (14/19) were predicted accurately on day 1 (D1), 76.5% (13/17) on D2. On D0, 61.9% (13/21) of peak FVIII:C levels predictions were accurate. In the Little DAVID study (n = 12), on D0 83.3% (5/6) FVIII:C peak levels for both study arms were predicted accurately. Combination treatment reduced preoperative FVIII concentrate use by 47% versus FVIII monotherapy. Desmopressin side effects were mild and transient. Two bleeds occurred, both despite FVIII:C > 1.00 IU/mL. CONCLUSION: Peri-operative combination treatment with desmopressin and PK-guided FVIII concentrate dosing in nonsevere haemophilia A is feasible, safe and reduces FVIII consumption.

A new population pharmacokinetic model for recombinant factor IX-Fc fusion concentrate including young children with haemophilia B.

AIMS: Recombinant factor IX Fc fusion protein (rFIX-Fc) is an extended half-life factor concentrate administered to haemophilia B patients. So far, a population pharmacokinetic (PK) model has only been published for patients aged ≥12 years. The aim was to externally evaluate the predictive performance of the published rFIX-Fc population PK model for patients of all ages and develop a model that describes rFIX-Fc PK using real-world data. METHODS: We collected prospective and retrospective data from patients with haemophilia B treated with rFIX-Fc and included in the OPTI-CLOT TARGET study (NTR7523) or United Kindom (UK)-EHL Outcomes Registry (NCT02938156). Predictive performance was assessed by comparing predicted with observed FIX activity levels. A new population PK model was constructed using nonlinear mixed-effects modelling. RESULTS: Real-world data were obtained from 37 patients (median age: 16 years, range 2-71) of whom 14 were aged <12 years. Observed FIX activity levels were significantly higher than levels predicted using the published model, with a median prediction error of -48.8%. The new model showed a lower median prediction error (3.4%) and better described rFIX-Fc PK, especially for children aged <12 years. In the new model, an increase in age was correlated with a decrease in clearance (P < .01). CONCLUSIONS: The published population PK model significantly underpredicted FIX activity levels. The new model better describes rFIX-Fc PK, especially for children aged <12 years. This study underlines the necessity to strive for representative population PK models, thereby avoiding extrapolation outside the studied population.

Gene therapy for hemophilia: a review on clinical benefit, limitations, and remaining issues.

In the last decade, enormous progress has been made in the development of gene therapy for hemophilia A and B. After the first encouraging results of intravenously administered adeno-associated virus (AAV)-based liver-directed gene therapy in patients with severe hemophilia B were reported in 2011, many gene therapy studies have been initiated. Most of these studies, using AAV vectors with various gene constructs, showed sufficient factor VIII and IX expression in patients to significantly reduce the number of bleeds and the need for prophylaxis in most patients with severe hemophilia. This resulted in great clinical benefit for nearly all patients. In this review, we will summarize the most recent findings of reported and ongoing gene therapy trials. We will highlight the successful outcome of trials with focus on the results of recently reported phase 1 trials and preliminary results of phase 2b/3 trials for hemophilia A and B. These new reports also reveal the impact of side effects and drawbacks associated with gene therapy. We will therefore also discuss the limitations and remaining issues of the current gene therapy approaches. These issues must be resolved before gene therapy will be widely available for the hemophilia patient population.

Transition readiness among adolescents and young adults with haemophilia in the Netherlands: Nationwide questionnaire study.

INTRODUCTION: Care for adolescents with haemophilia is transferred from paediatric to adult care around the age of 18 years. Transition programs help to prepare adolescents for this transfer and prevent declining treatment adherence. Evaluating transition readiness may identify areas for improvement. OBJECTIVE: Assess transition readiness among Dutch adolescents and young adults with haemophilia, determine factors associated with transition readiness, and identify areas of improvement in transition programs. METHODS: All Dutch adolescents and young adults aged 12-25 years with haemophilia were invited to participate in a nationwide questionnaire study. Transition readiness was assessed using multiple-choice questions and was defined as being ready or almost ready for transition. Potential factors associated with transition readiness were investigated, including: socio-demographic and disease-related factors, treatment adherence, health-related quality of life, and self-efficacy. RESULTS: Data of 45 adolescents and 84 young adults with haemophilia (47% with severe haemophilia) were analyzed. Transition readiness increased with age, from 39% in 12-14 year-olds to 63% in 15-17 year-olds. Nearly all post-transition young adults (92%, 77/84) reported they were ready for transition. Transition readiness was associated with treatment adherence, as median VERITAS-Pro treatment adherence scores were worse in patients who were not ready (17, IQR 9-29), compared to those ready for transition (11, IQR 9-16). Potential improvements were identified: getting better acquainted with the adult treatment team prior to transition and information on managing healthcare costs. CONCLUSIONS: Nearly all post-transition young adults reported they were ready for transition. Improvements were identified regarding team acquaintance and preparation for managing healthcare costs.

Prophylaxis with recombinant von Willebrand factor in patients with type 3 von Willebrand disease: Results of a post hoc analysis from a phase 3 trial.

OBJECTIVES: To describe efficacy/safety of recombinant von Willebrand factor (rVWF) prophylaxis in patients with type 3 von Willebrand disease (VWD). METHODS: This post hoc analysis of a phase 3 open-label trial provides a more detailed analysis of adults with type 3 VWD, categorized based on prior treatment at screening: "Prior On-Demand (OD)" (OD VWF; ≥3 documented spontaneous bleeding events [BEs] requiring VWF in previous 12 months) or "Switch" (plasma-derived [pd] VWF prophylaxis for ≥12 months). Annualized bleeding rates (ABRs) were evaluated during 12 months of rVWF prophylaxis versus historical data from medical records. RESULTS: In the Prior OD group (n = 10), mean spontaneous ABR (sABR) for treated BEs was reduced by 91.6% (ratio, 0.08; 95% CI, 0.02-0.45) versus mean historical sABR. In the Switch group (n = 8), mean sABR for treated BEs was reduced by 47% (ratio, 0.53; 95% CI, 0.08-3.62). One non-serious adverse event (AE) was considered possibly related to rVWF. No treatment-related, fatal, or life-threatening serious AEs were reported, and no patient developed VWF inhibitors. CONCLUSIONS: rVWF prophylaxis reduced sABR in type 3 VWD patients previously treated with OD VWF therapy, and maintained a similar level of hemostatic control in those switching from pdVWF prophylaxis to rVWF prophylaxis.

Platelet degranulation and bleeding phenotype in a large cohort of Von Willebrand disease patients.

Von Willebrand disease (VWD) is a bleeding disorder caused by quantitative (type 1 or 3) or qualitative (type 2A/2B/2M/2N) defects of circulating von Willebrand factor (VWF). Circulating VWF levels not always fully explain bleeding phenotypes, suggesting a role for alternative factors, like platelets. Here, we investigated platelet factor 4 (PF4) in a large cohort of patients with VWD. PF4 levels were lower in type 2B and current bleeding phenotype was significantly associated with higher PF4 levels, particularly in type 1 VWD. Based on our findings we speculate that platelet degranulation and cargo release may play a role across VWD subtypes.

How I manage pregnancy in carriers of hemophilia and patients with von Willebrand disease.

Women with inherited bleeding disorders, including carriers of hemophilia A and B, or with von Willebrand disease, have an increased risk of bleeding during pregnancy and delivery. The unborn child may also be affected by the bleeding disorder for which specific measures have to be considered. This requires a multidisciplinary approach, with a team that includes a hematologist, a pediatric hematologist, a clinical geneticist, an obstetrician-perinatologist, and an anesthesiologist. An optimal approach includes prepregnancy genetic counseling, prenatal diagnostic procedures, and a treatment plan for delivery for both the mother and child. Recent retrospective studies show that even if strict guidelines are followed, these women are still at risk of postpartum bleeding. This occurs even if coagulation factor levels are normalized, either due to the pregnancy-induced rise of factor levels or by infusion of coagulation factor concentrates at the time of delivery. In this article, we describe our current diagnostic and clinical management of pregnancy and delivery in women with inherited bleeding disorders. We also briefly discuss possible interventions to improve the outcome of current strategies by increasing target factor levels during and after delivery.

Quantification of the relationship between desmopressin concentration and Von Willebrand factor in Von Willebrand disease type 1: A pharmacodynamic study.

INTRODUCTION: Desmopressin can be used to prevent bleeding in von Willebrand disease (VWD), but the relationship between desmopressin and von Willebrand factor activity (VWF:Act) has yet to be quantified. AIM: To quantify the relationship between desmopressin dose, its plasma concentration and the VWF:Act response in type 1 VWD patients. METHODS: Forty-seven VWD patients (median age 25 years, IQR: 19-37; median body weight 71 kg, IQR: 59-86) received an IV desmopressin dose of .3 mcg/kg. In total, 177 blood samples were available for analysis. We developed an integrated population pharmacokinetic-pharmacodynamic (PK-PD) model using nonlinear mixed effect modelling. Subsequently, we performed Monte Carlo simulations to investigate the efficacy of the current dosing regimen. RESULTS: A one-compartment PK model best described the time profile of the desmopressin concentrations. In the PD turnover model, the relationship between desmopressin plasma concentration and release of VWF:Act from the vascular endothelium was best described with an Emax model. Typically, VWF:Act increased 452% with an EC50 of .174 ng/ml. Simulations demonstrated that after .3 mcg/kg desmopressin intravenously, >90% patients with a VWF:Act baseline of ≥.20 IU/mL attain a VWF:Act >.5 IU/ml up to ≥4 h after administration. A capped dose of 30 mcg was sufficient in patients weighing over 100 kg. CONCLUSION: The relationship between desmopressin and VWF:Act was quantified in a PK-PD model. The simulations provide evidence that recently published international guidelines advising an intravenous desmopressin dose of .3 mcg/kg with a capped dose of 30 mcg > 100 kg gives a sufficient desmopressin response.

Patient-reported outcomes in autosomal inherited bleeding disorders: A systematic literature review.

AIM: Currently, it is unknown which patient-reported outcomes are important for patients with autosomal inherited bleeding disorders. Therefore, the purpose of this study is to systematically review the available literature assessing patient-reported outcomes and their measurement methods in autosomal inherited bleeding disorders. METHODS: The Embase, Medline ALL, Web of Science Core Collection, Cochrane Central Register of Controlled Trails and Google Scholar databases were searched from inception until 14 August 2020. Studies on patient-reported outcomes in patients with von Willebrand disease, inherited platelet function disorders and coagulation factor deficiencies were included. RESULTS: Twenty-one articles met the inclusion criteria. Three studies were assessed as having poor quality, and therefore a high risk of bias. Nineteen studies had fair quality rating. Different measurements methods were used, ranging from predefined to self-developed questionnaires. The majority of included studies focused on von Willebrand disease. Patients with von Willebrand disease reported lower health-related quality of life compared to the general population. Overall, this trend was especially visible in the following domains: vitality, physical and social functioning and pain. Women with inherited bleeding disorders scored lower on health-related quality of life compared to men, especially women with heavy menstrual bleeding. Patients with joint bleeds or heavy menstrual bleeding reported an increased level of pain. CONCLUSION: Patients with autosomal inherited bleeding disorders report lower health related quality of life, especially those with joint bleeds or heavy menstrual bleeding. Numerous measurement methods are used in patients with autosomal inherited bleeding disorders, highlighting the need for studies using established, standardized measurement methods.

Social participation is reduced in type 3 Von Willebrand disease patients and in patients with a severe bleeding phenotype.

INTRODUCTION: The negative impact of haemophilia on social participation is well established in previous studies, however, the impact of Von Willebrand disease (VWD) on social participation has not been studied. AIM: To compare the social participation of a large cohort of VWD patients in the Netherlands with the general Dutch population. In addition, to identify factors associated with social participation in VWD. METHODS: Patients participating in the "Willebrand in the Netherlands" study completed an extensive questionnaire on educational level, absenteeism from school or work, and occupational disabilities. RESULTS: Seven-hundred and eighty-eight VWD patients were included (mean age 38.9 years, 59.5% females), of whom 136 children < 16 years. Adult patients with type 3 VWD more often had a low educational level (52.9%) compared to type 1 (40.2%), type 2 VWD (36.8%) and the general population (36.4%) (p = .005). Moreover, in patients aged ≥16 years the days lost from school and/or work in the year prior to study inclusion differed significantly between the VWD types (p = .011). Using negative binomial regression analysis, the occurrence of bleeding episodes requiring treatment in the year preceding study inclusion was significantly associated with the number of days lost from school and/or work among patients aged ≥16 years. Multivariable logistic regression analysis showed that a higher total bleeding score, older age and presence of at least one comorbidity were significantly associated with occupational disability in patients aged ≥16 years. CONCLUSION: Our study shows that social participation was lower in type 3 VWD and VWD patients with a more severe bleeding phenotype.

Outcomes of long-term von Willebrand factor prophylaxis use in von Willebrand disease: A systematic literature review.

BACKGROUND: Von Willebrand Disease (VWD) is a common inherited bleeding disorder. Patients with VWD suffering from severe bleeding may benefit from the use of secondary long-term prophylaxis. AIM: Systematically summarize the evidence on the clinical outcomes of secondary long-term prophylaxis in patients with VWD and severe recurrent bleedings. METHODS: We searched Medline and EMBASE through October 2019 for relevant randomized clinical trials (RCTs) and comparative observational studies (OS) assessing the effects of secondary long-term prophylaxis in patients with VWD. We used Cochrane Risk of Bias (RoB) tool and the RoB for Non-Randomized Studies of interventions (ROBINS-I) tool to assess the quality of the included studies. We conducted random-effects meta-analyses and assessed the certainty of the evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. RESULTS: We included 12 studies. Evidence from one placebo controlled RCT suggested that VWD prophylaxis as compared to no prophylaxis reduced the rate of bleeding episodes (Rate ratio [RR], .24; 95% confidence interval [CI], .17-.35; low certainty evidence), and of epistaxis (RR, .38; 95%CI, .21-.67; moderate certainty evidence), and may increase serious adverse events RR 2.73 (95%CI .12-59.57; low certainty). Evidence from four before-and-after studies in which researchers reported comparative data suggested that VWD prophylaxis reduced the rate of bleeding (RR .34; 95%CI, .25-.46; very low certainty evidence). CONCLUSION: VWD prophylaxis treatment seems to reduce the risk of spontaneous bleeding, epistaxis, and hospitalizations. More RCTs should be conducted to increase the certainty in these benefits.

Adherence to prophylaxis and its association with activation of self-management and treatment satisfaction.

INTRODUCTION: Prophylactic replacement therapy (prophylaxis) in patients with haemophilia (PWH) requires lifelong, frequent (self)infusions. Prophylaxis effectiveness depends on adherence, and the drivers of treatment adherence among PWH are unclear. AIM: To quantify prophylaxis adherence and associations between adherence and patients' treatment attitudes and satisfaction in a large cohort of children and adults with haemophilia. METHODS: In a nationwide, cross-sectional, questionnaire-based study, PWH with complete information currently using prophylaxis were selected. Validated Hemophilia Regimen Treatment Adherence Scale-Prophylaxis (VERITAS-Pro; normalised score range: 0-100, optimum 0) measured treatment adherence; the Patient Activation Measure (PAM-13; total score range 0-100, optimum 100) measured activation of self-management; Hemophilia Patient Satisfaction Scale (Hemo-Sat; range 0-100, optimum 0) measured treatment satisfaction. Groups were compared according to age (children: <12 years; adolescents: 12-18 years; adults >18 years) and adherence levels using non-parametric tests, and correlations were assessed using Spearman's rho. RESULTS: Among 321 participants (median age 33 years, interquartile range [IQR]:15-54 years), adherence was high (median VERITAS-Pro total score 17, 89% adherent) but worsened with age, with median scores of 5, 14 and 20 in children, adolescents, adults, respectively (p < .001). Attitudes towards treatment (median 66 vs. 68) participants and treatment satisfaction (12 vs. 10) were similar between adherent and non-adherent patients. The VERITAS-Pro total score was moderately correlated with PAM-13 (r = .41) but not with Hemo-Sat (r = -.11). DISCUSSION: Prophylaxis adherence was high (89%) but decreased significantly with age and was not correlated with treatment attitude or treatment satisfaction.

Similar sports participation as the general population in Dutch persons with haemophilia; results from a nationwide study.

INTRODUCTION: Although sports participation is advocated in people with haemophilia (PWH), detailed data concerning sports participation in Dutch PWH is lacking. AIM: to assess sports participation in Dutch PWH (6-65 years) compared to the Dutch general population (GP). METHODS: Data from a nationwide, cross-sectional study in PWH were analysed. Sports participation (type, duration, frequency) was assessed by the Modifiable Activities Questionnaire (MAQ), limitations in activities using the (Paediatric) Haemophilia Activities List ((Ped)HAL). Sports in the two highest categories according to the National Hemophilia Foundation classification were considered high-risk sports. Groups were compared using Chi-square testing. RESULTS: A total of 524 Adult PWH (median age: 45 (IQR: 30-55); 37% severe) and 126 paediatric PWH (median age: 11 (IQR: 8-14); 52% severe) were included. Sports participation was higher in adults (70%) than the GP (58%) and similar to the GP in children (PWH: 68%, GP: 72%). High-risk sports participation decreased with age in PWH: from 65% (6-12 years) to 17% (50-65 years), which was also observed in the GP. Sports participation in children was independent of severity (non-severe: 67% vs. severe: 65%; P = 0.97), but not in adults (non-severe: 75%, severe: 62%; P < 0.01). Non-severe PWH played more high-risk sports than severe PWH: children at 65% vs. 48% (P = 0.05), adults at 25% vs. 15% (P = 0.07). DISCUSSION: These results suggest that sports participation in PWH was comparable to the GP. Sports participation was dependent of haemophilia severity in adults. Children were more involved in high-risk sports than adults. More studies on sports-related injury-risk are needed for adequate counselling.

Validation of a perioperative population factor VIII pharmacokinetic model with a large cohort of pediatric hemophilia a patients.

AIMS: Population pharmacokinetic (PK) models are increasingly applied to perform individualized dosing of factor VIII (FVIII) concentrates in haemophilia A patients. To guarantee accurate performance of a population PK model in dose individualization, validation studies are of importance. However, external validation of population PK models requires independent data sets and is, therefore, seldomly performed. Therefore, this study aimed to validate a previously published population PK model for FVIII concentrates administrated perioperatively. METHODS: A previously published population PK model for FVIII concentrate during surgery was validated using independent data from 87 children with severe haemophilia A with a median (range) age of 2.6 years (0.03-15.2) and body weight of 14 kg (4-57). First, the predictive performance of the previous model was evaluated with MAP Bayesian analysis using NONMEM v7.4. Subsequently, the model parameters were (re)estimated using a combined dataset consisting of the previous modelling data and the data available for the external validation. RESULTS: The previous model underpredicted the measured FVIII levels with a median of 0.17 IU mL-1 . Combining the new, independent and original data, a dataset comprising 206 patients with a mean age of 7.8 years (0.03-77.6) and body weight of 30 kg (4-111) was obtained. Population PK modelling provided estimates for CL, V1, V2, and Q: 171 mL h-1  68 kg-1 , 2930 mL 68 kg-1 , 1810 mL 68 kg-1 , and 172 mL h-1  68 kg-1 , respectively. This model adequately described all collected FVIII levels, with a slight median overprediction of 0.02 IU mL-1 . CONCLUSIONS: This study emphasizes the importance of external validation of population PK models using real-life data.

Dosing of factor VIII concentrate by ideal body weight is more accurate in overweight and obese haemophilia A patients.

AIMS: Under- and, especially, overdosing of replacement therapy in haemophilia A patients may be prevented by application of other morphometric variables than body weight (BW) to dose factor VIII (FVIII) concentrates. Therefore, we aimed to investigate which morphometric variables best describe interindividual variability (IIV) of FVIII concentrate pharmacokinetic (PK) parameters. METHODS: PK profiling was performed by measuring 3 FVIII levels after a standardized dose of 50 IU kg-1 FVIII concentrate. A population PK model was constructed, in which IIV for clearance (CL) and central volume of distribution (V1) was quantified. Relationships between CL, V1 and 5 morphometric variables (BW, ideal BW [IBW], lean BW, adjusted BW, and body mass index [BMI]) were evaluated in normal weight (BMI < 25 kg m-2 ), overweight (BMI 25-30 kg m-2 ) and obese haemophilia A patients (BMI > 30 kg m-2 ). RESULTS: In total, 57 haemophilia A patients (FVIII≤0.05 IU mL-1 ) were included with median BW of 83 kg (range: 53-133) and median age of 48 years (range: 18-77). IBW best explained observed variability between patients, as IIV for CL and V1 was reduced from 45.1 to 37.6 and 26.% to 14.1%, respectively. CL, V1 and half-life were similar for all BMI categories. The national recommended dosing schedule did not result in adequate trough levels, both in case of dosing based on BW and IBW. However, dosing based on IBW prevented unnecessary high FVIII peaks. CONCLUSION: IBW is the most suitable morphometric variable to explain interindividual FVIII PK variability and is more appropriate to dose overweight and obese patients.

Treatment of acquired hemophilia A, a balancing act: results from a 27-year Dutch cohort study.

Acquired hemophilia A (AHA) is a severe auto-immune bleeding disorder. Treatment of AHA is burdensome and optimal management is still unresolved. Therefore a retrospective nationwide multi-center cohort study (1992-2018) was performed to evaluate clinical presentation and treatment efficacy and safety of AHA in the Netherlands. Multivariate logistic and Cox regression analysis was used to study independent associations between patient characteristics and clinical outcomes. A total of 143 patients (median age 73 years; 52.4% male) were included with a median follow-up of 16.8 months (IQR 3.6-41.5 months). First-line immunosuppressive treatment was mostly steroid monotherapy (67.6%), steroids/cyclophosphamide (11.9%) and steroids/rituximab (11.9%), with success rates of 35.2%, 80.0% and 66.7% respectively, P < .05. Eventually 75% of patients achieved complete remission (CR). A high anti-FVIII antibody titer, severe bleeding and steroid monotherapy were associated with lower CR rates. Infections, the most important adverse event, occurred significantly more often with steroid combination therapy compared to steroids alone (38.7% vs 10.6%; P = .001). Overall mortality was 38.2%, mostly due to infections (19.2%) compared to 7.7% fatal bleeds. Advanced age, underlying malignancy and ICU admission were predictors for mortality. This study showed that AHA is characterized by significant disease-related and treatment-related morbidity and mortality. A high anti-FVIII titer, severe bleeding and steroid monotherapy were associated with a lower CR rate. The efficacy of steroid combination therapies however, was overshadowed by higher infection rates and infections represented the most important cause of death. The challenging and delicate balance between treatment effectivity and safety requires ongoing monitoring of AHA and further identification of prognostic markers.