Primary prophylaxis in children with severe haemophilia A and B-Implementation over the last 20 years as illustrated in real-world data in the PedNet cohorts.

INTRODUCTION: The prophylactic regimen in children with severe haemophilia is suggested in various publications and guidelines. Few data exist on its implementation in clinical practice. AIM: To investigate the implementation of primary prophylaxis based on real-life data from PedNet during the last 20 years. METHODS: All children from the PedNet cohort (n = 1260) with severe haemophilia A (SHA) or severe haemophilia B (SHB), FVIII/IX < .01 IU/mL, born between 2000 and 2009 (Cohort I; SHA n = 662; SHB n = 88) and 2010-2019 (Cohort II; SHA n = 598; SHB n = 94) were included. RESULTS: In SHA, the median age at start of prophylaxis was 17.3 months (IQR; 12.5-26.1) in Cohort I which decreased to 13.1 months (IQR; 10.4-19.1) in Cohort II (p < .000). "Once-a-week" prophylaxis at start increased from 49% to 68% (SHA) and 38% to 70% (SHB). FVIII doses were reduced from median 43.5 (IQR; 34.6-49.0) to 30.9 IU/kg (IQR; 26.3-46.3), while dosing with FIX did not change. After 2010 approximately 60% of the patients with SHA and SHB started prophylaxis before any joint bleed. The number of CVADs needed in both cohorts was around 30%. Incidences of inhibitors were unchanged: SHA (∼31%) and SHB (∼10%). Sporadic cases were diagnosed significantly later (median 8.3 months; IQR; 3.7-11.9) and they had more joint bleeds before start of prophylaxis. CONCLUSION: Primary prophylaxis nowadays starts at an earlier age: before any joint bleed (60% of patients with SHA and SHB). Approximately 70% started on a once-weekly schedule with significantly reduced doses in SHA but unchanged in SHB.

Capturing Data in Rare Disease Registries to Support Regulatory Decision Making: A Survey Study Among Industry and Other Stakeholders.

INTRODUCTION: In rare diseases, registry-based studies can be used to provide natural history data pre-approval and complement drug efficacy and/or safety knowledge post-approval. OBJECTIVE: The objective of this study was to investigate the opinion of stakeholders about key aspects of rare disease registries that are used to support regulatory decision making and to compare the responses of employees from industry to other stakeholders. METHODS: A web-based survey was used to gauge the importance of (1) common data elements (including safety outcomes), (2) data quality and (3) governance aspects that are generic across different rare diseases. The survey included 47 questions. The data were collected in the period April-October 2019. RESULTS: Seventy-three respondents completed ≥ 80% of the survey. Most of the respondents were from the industry (n = 42, 57%). For safety data, 31 (42%) respondents were in favour of collecting all adverse events. For data quality, the respondents found a level of 30% reasonable for source data verification. For missing data, a level of 20% was considered acceptable. Compared to responders from industry, the other stakeholders found it less relevant to share data with industry and found it less acceptable if the registry is financed by industry. CONCLUSIONS: This study showed that the opinion towards data and governance is well aligned across parties, and issues of data and governance on their own should not pose a barrier to collaboration. This finding is supportive of the European Medicines Agency's efforts to encourage stakeholders to work with existing registries when collecting data to support regulatory decision making.

Inhibitor development in previously untreated patients with severe haemophilia: A comparison of included patients and outcomes between a clinical study and a registry-based study.

AIM: The aim of this study was to investigate whether a disease registry could serve as a suitable alternative to clinical studies to investigate safety of orphan drugs in children. METHODS: We used individual patient data from previously untreated patients (PUPs) with severe haemophilia A from the factor VIII (rAHF-PFM)-clinical study and the PedNet registry. The primary outcome was the patient characteristics at entry and the difference in inhibitor development between the clinical study and the registry-based study at 50 exposure days. RESULTS: Clinical study patients more often had a positive family history of inhibitors (31% vs 10%) and a high-risk F8 genotype (82% vs 63%). In the clinical study 41/55 (75%) and in the registry-based study 162/168 (96%) patients reached 50 exposure days. Inhibitors developed in 16 of the 41 patients in the clinical study (39%) vs 44 of the 162 patients in the registry-based study (27%); seven patients (7%) vs 28 patients (17%) had high-titre inhibitors. The risk of developing an inhibitor during the first 50 exposure days was similar (HR 1.04; 95% CI 0.56-1.94), when adjusted for family history of inhibitors, F8 gene mutation and intensive treatment at first exposure. CONCLUSION: In the registry-based study, patient numbers and completeness of follow-up were higher. The risk of developing an inhibitor to a single product was comparable. Although the sample size of this study was too small to conclude on differences in high- or low-titre inhibitors, this suggests that a registry could serve as a more suitable source for evaluation of high-titre inhibitors in the setting of factor VIII deficiency.

ITI Treatment is not First-Choice Treatment in Children with Hemophilia A and Low-Responding Inhibitors: Evidence from a PedNet Study.

BACKGROUND: Limited data exist on the clinical impact of low-responding inhibitors and the requirement for immune tolerance induction (ITI) treatment to establish tolerance, reduce bleeding, and improve outcome. The aim of this article is to describe the therapeutic management of children with severe hemophilia A and low-responding inhibitors and its effect on bleeding phenotype. METHODS: The REMAIN (Real-life Management of Inhibitors) study is a satellite study of the PedNet registry. It included unselected children with severe hemophilia A (factor VIII [FVIII] < 0.01 IU/mL) born between January 1, 1990 and December 31, 2009 who developed clinically relevant inhibitors and were followed-up for at least 3 years after the first positive inhibitor test. RESULTS: A total of 260 patients with inhibitors were identified and 68 of them (26%) had low-responding inhibitors (peak < 5 BU/mL). Five patients were lost to follow-up and 63 were included in this study. The median follow-up was 3.7 years (interquartile range: 3.0-7.5). ITI was started in 51/63 (81%) patients. The median time from ITI start to first negative inhibitor titer was similar with low-dose and high-dose ITI regimens (2.5 and 3.1 months, respectively). Ten of the 12 patients who did not receive ITI were treated with regular prophylaxis and reached a negative titer after a median of 6.5 months. Bleeding rate was low in all patients with no difference between treatment regimens. CONCLUSION: In children with low-responding inhibitors negative titers were reached with regular FVIII treatment irrespective of the regimen (i.e., prophylaxis or ITI).

Drug Registries and Approval of Drugs: Promises, Placebo, or a Real Success?

PURPOSE: As part of the approval process, regulatory authorities often require postauthorization studies that involve patient registries; it is unknown, however, whether such registry studies are adequately completed. We investigated whether registry studies for new drugs were performed as agreed at time of approval. METHODS: This study reviewed protocols and follow-up reports for 73 registry studies that were proposed for 43 drugs approved by the Committee for Medicinal Products for Human Use in Europe in the period 2007 to 2010. RESULTS: The data lock point of January 1, 2016, was taken to allow a 5-year follow-up period for each drug after approval. At that time, 2 studies (3%) in registries had been finalized, 19 registries (26%) had not enrolled any patients, and 52 studies (71%) were ongoing. The median enrollment was 31% (interquartile range [IQR], 6-104) of the required number of patients for 41 registry studies that had a predefined sample size, 30% (IQR, 2-101) for nonimposed registries, and 61% (IQR, 18-144) for imposed registries. IMPLICATIONS: Enrollment of patients into postapproval registries is poor, although the results for imposed registries seem better. Currently, registries only have a limited impact on resolving gaps in the knowledge of a drug's benefits and risks at time of marketing authorization.

Risk Factors for the Progression from Low to High Titres in 260 Children with Severe Haemophilia A and Newly Developed Inhibitors.

In children with severe haemophilia A, inhibitors to factor VIII (FVIII) usually develop during the first 50 treatment exposure days and are classified as low or high titre depending on the peak inhibitor titre being greater or less than 5 Bethesda units/mL (BU/mL). Classification of the inhibitor may change with time, as some low-titre inhibitors progress to high titre following re-exposure to FVIII concentrate. The aim of this study was to investigate potential risk factors for such a progression in children with severe haemophilia A and newly diagnosed inhibitors. This study was a follow-up study of the PedNet Registry and included 260 children with severe haemophilia A and inhibitors born between 1990 and 2009 and recruited consecutively from 31 haemophilia centres. Clinical and laboratory data were collected from the date of each child's first positive inhibitor test for at least 3 years. At the time of first positive inhibitor test, 49% (n = 127) had low-titre inhibitors, with 50% of them progressing to high titre and only 25% maintaining low titres. The FVIII gene (F8) mutation type was known in 247 patients (95%), and included 202 (82%) null mutations. The progression to high-titre inhibitors was associated with null F8 mutations (odds ratio [OR]: 2.6; 95% confidence interval [CI]: 1.0­6.5), family history of inhibitors (OR: 7.2; 95% CI: 1.8­28.4) and the use of high-dose immune tolerance induction, defined as ≥100 IU FVIII concentrate/kg/d (OR: 3.9; 95% CI: 1.5­10.0). These results suggest that high-dose immune tolerance induction should be avoided as the initial strategy in patients who develop low-titre FVIII inhibitors.

Registries supporting new drug applications.

PURPOSE: Knowledge of the benefits and risks of new drugs is incomplete at the time of marketing approval. Registries offer the possibility for additional, post-approval, data collection. For all new drugs, which were approved in the European Union between 2007 and 2010, we reviewed the frequency, the type, and the reason for requiring a registry. METHODS: The European Public Assessment Reports, published on the website of the European Medicine Agency, were reviewed for drugs approved by the Committee for Medicinal Products for Human Use. We searched for key characteristics of these drugs, including therapeutic area (ATC1 level), level of innovation (the score is an algorithm based on availability of treatment and therapeutic effect), and procedural characteristics. In addition, we identified if these registries were defined by disease (disease registry) or exposure to a single drug (drug registry). RESULTS: Out of 116 new drugs approved in the predefined period, for 43 (37%), 1 to 6 registry studies were identified, with a total of 73 registries. Of these 46 were disease registries and 27 (single) drug registries. For 9 drugs, the registry was a specific obligation imposed by the regulators. The level of innovation and the orphan status of the drugs were determinants positively predicting post-approval registries (OR 10.3 [95% CI 1.0-103.9] and OR 2.8 [95% CI 1.0-7.5], respectively). CONCLUSIONS: The majority of registries required by regulators are existing disease registries. Registries are an important and frequently used tool for post-approval data collection for orphan and innovative drugs.

Different impact of factor VIII products on inhibitor development?

Inhibitors are the most serious side effect of haemophilia treatment; they occur in 25-30 % of all patients with severe haemophilia A. Over the last 2 decades, conflicting data on the impact of clotting products have been published. Due to small studies of selected cases, appreciation of the impact of any particular product has been difficult. Moreover, the emphasis on inhibitor testing has led to increased detection of low-titre inhibitors (to >10 %), while the percentage of high-titre inhibitors is still around 20 %. Other non-genetic risk factors, such as dosing and intensive treatment, are able to increase individual inhibitor risk. Early prophylaxis might reduce inhibitor risk. Well-defined large PUP studies including products should be considered. This can only be achieved in collaboration with all stakeholders. In conclusion, while the impact of FVIII products on inhibitor development is large, presently the actual impact of any specific product is unclear.

Increased inhibitor incidence in severe haemophilia A since 1990 attributable to more low titre inhibitors.

Many studies have reported an increased incidence of inhibitors in previously untreated patients (PUPs) with severe haemophilia A after the introduction of recombinant products. It was the objective of this study to investigate whether the inhibitor incidence has increased between 1990 and 2009 in an unselected cohort of PUPs with severe haemophilia A (FVIII< 1 %). Patients were consecutively recruited from 31 haemophilia treatment centres in 16 countries and followed until 50 exposure days or until inhibitor development. Inhibitor development was studied in five-year birth cohorts comparing cumulative incidences. Furthermore the risk for inhibitor development per five-year birth cohort was studied using multivariable Cox regression, adjusting for potential genetic and treatment-related confounders. A total of 926 PUPs were included with a total cumulative inhibitor incidence of 27.5 %. The inhibitor incidence increased from 19.5 % in 1990-1994 (lowest) to 30.9 % in 2000-2004 (highest; p-value 0.011). Low titre inhibitor incidence increased from 3.1 % in 1990-1994 to 10.5 % in 2005-2009 (p-value 0.009). High titre inhibitor incidences remained stable over time. After 2000, risk of all inhibitor development was increased with adjusted hazard ratios 1.96 (95 % CI 1.06-2.83) in 2000-2004 and 2.34 (1.42-4.92) in 2005-2009. Screening for inhibitors was intensified over this 20-year study period from a median of 1.9 to 2.9 tests/year before 2000 to 2.7 to 4.3 tests/year after 2000. In conclusion, the cumulative inhibitor incidence has significantly increased between 1990 and 2009. The high titre inhibitor incidence has remained stable.

Assessment of clotting factor concentrates--pivotal studies and long-term requirements.

Assessment of quality in terms of safety and efficacy of clotting factor concentrates (CFCs) is very important for all new therapeutic products. In rare diseases this is often complicated due to small number of trial participants. In hemophilia, an extra complication is the large impact previous treatments have on both the risk on inhibitors and the overall response to bleedings. For new CFCs, safety needs to be evaluated against inhibitor risk whereas efficacy is primarily judged against the most common clinical manifestations of the disease, namely, bleeding into joints and muscles. In this article the challenges are described for hemophilia that recruits patients globally. Recommendations of ISTH are discussed; these propose to substitute the single-arm prelicensure study with a two-stage approach, which considers epidemic and endemic incidence rate, and might increase the feasibility of studying multiple new products in populations with rare disease without compromising the assessment of product safety and efficacy. We also suggest that the annual bleeding rate (ABR) is an unreliable predictor of efficacy. The response to treatment highly depends on the current disease status of every patient participating in a clinical trial. The phenotype of patients with hemophilia is highly influenced by previous treatment history. Patients with severe hemophilia of the same age can demonstrate a different response to treatment.

Intermediate-dose versus high-dose prophylaxis for severe hemophilia: comparing outcome and costs since the 1970s.

Prophylactic treatment in severe hemophilia is very effective but is limited by cost issues. The implementation of 2 different prophylactic regimens in The Netherlands and Sweden since the 1970s may be considered a natural experiment. We compared the costs and outcomes of Dutch intermediate- and Swedish high-dose prophylactic regimens for patients with severe hemophilia (factor VIII/IX < 1 IU/dL) born between 1970 and 1994, using prospective standardized outcome assessment and retrospective collection of cost data. Seventy-eight Dutch and 50 Swedish patients, median age 24 years (range, 14-37 years), were included. Intermediate-dose prophylaxis used less factor concentrate (median: Netherlands, 2100 IU/kg per year [interquartile range (IQR), 1400-2900 IU/kg per year] vs Sweden, 4000 IU/kg per year [IQR, 3000-4900 IU/kg per year]); (P < .01). Clinical outcome was slightly inferior for the intermediate-dose regimen (P < .01) for 5-year bleeding (median, 1.3 [IQR, 0.8-2.7] vs 0 [IQR, 0.0-2.0] joint bleeds/y) and joint health (Haemophilia Joint Health Score >10 of 144 points in 46% vs 11% of participants), although social participation and quality of life were similar. Annual total costs were 66% higher for high-dose prophylaxis (mean, 180 [95% confidence interval, 163 - 196] × US$1000 for Dutch vs 298 [95% confidence interval, 271-325]) × US$1000 for Swedish patients; (P < .01). At group level, the incremental benefits of high-dose prophylaxis appear limited. At the patient level, prophylaxis should be tailored individually, and many patients may do well receiving lower doses of concentrate without compromising safety.

Intensity of factor VIII treatment and inhibitor development in children with severe hemophilia A: the RODIN study.

The objective of this study was to examine the association of the intensity of treatment, ranging from high-dose intensive factor VIII (FVIII) treatment to prophylactic treatment, with the inhibitor incidence among previously untreated patients with severe hemophilia A. This cohort study aimed to include consecutive patients with a FVIII activity < 0.01 IU/mL, born between 2000 and 2010, and observed during their first 75 FVIII exposure days. Intensive FVIII treatment of hemorrhages or surgery at the start of treatment was associated with an increased inhibitor risk (adjusted hazard ratio [aHR], 2.0; 95% confidence interval [CI], 1.3-3.0). High-dose FVIII treatment was associated with a higher inhibitor risk than low-dose FVIII treatment (aHR, 2.3; 95% CI, 1.0-4.8). Prophylaxis was only associated with a decreased overall inhibitor incidence after 20 exposure days of FVIII. The association with prophylaxis was more pronounced in patients with low-risk F8 genotypes than in patients with high-risk F8 genotypes (aHR, 0.61, 95% CI, 0.19-2.0 and aHR, 0.85, 95% CI, 0.51-1.4, respectively). In conclusion, our findings suggest that in previously untreated patients with severe hemophilia A, high-dosed intensive FVIII treatment increases inhibitor risk and prophylactic FVIII treatment decreases inhibitor risk, especially in patients with low-risk F8 mutations.

Correlation between phenotype and genotype in a large unselected cohort of children with severe hemophilia A.

Phenotypic variability is well recognized in severe hemophilia A. A few studies, mainly in adults treated lifelong on demand, suggest that bleeding phenotype correlates with factor VIII gene (F8) mutation type. Because treatment regimens influence outcomes to a large extent, examining bleeding phenotype during the first years of life may be the most suitable way to define this variability. We set out to analyze the very early phenotypic expression of severe hemophilia A in 621 consecutively enrolled, well-characterized previously untreated patients and to correlate this with patients' F8 mutation. Detailed information was collected on bleeds and treatment of the first 75 exposure days or until inhibitor development. F8 mutation type was known for 531 patients; 402 had null mutations and 129 had non-null mutations. Considering only patients who had not started prophylaxis or developed an inhibitor before select bleeding events, we found that patients with null mutations experienced their first bleed and first joint bleed at younger median ages than patients with non-null mutations (9.7 vs 10.9 months and 13.8 vs 16.1 months, respectively). We conclude that F8 mutation type accounts for only a small component of the significant phenotypic variability found among patients with severe hemophilia A.