When and how to start prophylaxis in boys with severe hemophilia without inhibitors: communication from the SSC of the ISTH

A post hoc comparative real-world analysis of HEAD-US score for joint health assessment of patients with severe haemophilia A and B in Spain

AIM

Joint damage due to haemarthrosis can be effectively monitored with point-of care ultrasound using the Haemophilia Early Arthropathy Detection with US (HEAD-US) scoring system. A post hoc comparative analysis of the joint status of patients with severe haemophilia A (HA) or B (HB) was performed.

METHODS

The databases of two observational, cross-sectional studies that recruited patients with HA or HB from 12 Spanish centres were analysed to compare the status of the elbows, knees and ankles in patients with severe disease according to treatment modality. The HEAD-US score was calculated in both studies by the same trained operators.

RESULTS

Overall, 95 HA and 41 HB severe patients were included, with a mean age of 35.2 ± 11.8 and 32.7 ± 14.2 years, respectively. The percentage of patients who received prophylaxis, over on-demand (OD) treatment, was much higher in HA (91.6%) than in HB (65.8%) patients. With a similar number of target joints, the HEAD-US score was zero in 6.3% HA and 22.0% HB patients (p < .01), respectively. The HA population showed significantly worse HEAD-US scores. Whilst osteochondral damage occurred more frequently in patients OD or tertiary prophylaxis, our data suggest that articular damage is less prominent in primary/secondary prophylaxis, regardless of the type of haemophilia. These latter treatment modalities were also associated with a lower prevalence of synovial hypertrophy, particularly in HB patients.

CONCLUSION

This post hoc analysis indicates that joint status seems to be significantly influenced by haemophilia type (HA or HB) and treatment modality in these severe Spanish populations with severe disease. Continuing HEAD-US monitoring for the early detection and management of intra-articular abnormalities, as well as more efficiently tailored therapies should be warranted.

Effects of PK-guided prophylaxis on clinical outcomes and FVIII consumption for patients with moderate to severe Haemophilia A

INTRODUCTION

In recent years, there has been increased focus on individualizing treatment for persons with hemophilia including pharmacokinetic-guided (PK) dosing.

AIMS

In this retrospective study clinical outcomes before and after PK-guided prophylaxis were examined.

MATERIALS AND METHODS

Eight Haemophilia Treatment Centres from the United States participated in the study and included 132 patients classified into two cohorts: those undergoing a PK-assessment for product switch (switchers) or to optimize treatment (non-switchers). Subset analyses for the two most common products and patients with dosing per prescription label were included for annual bleeding rates (ABR), mean weekly consumption outcomes, and annualized cost of prophylaxis.

RESULTS

The most common products before and after index date were octocog alfa, rurioctocog alfa pegol, and efmoroctocog alfa. Seventy-four (56%) patients were identified as switchers and 58 (44%) patients were classified as non-switchers. The majority of patients (78.0%) experienced either a decrease in ABR post-index or maintained 0 ABR during pre- and post-index time periods, with similar proportions identified in both switchers (77.0%) and non-switchers (79.3%) populations. Non-switchers were identified as having no significant change in cost of therapy, while switchers experienced increased cost of therapy driven by higher price of extended half-life products. Within subset analyses, patients receiving rurioctocog alfa pegol and efmoroctocog alfa had mean ABR under 1 after index date.

CONCLUSION

PK-guided prophylaxis has the potential to improve clinical outcomes without increase in cost of therapy for patients maintaining product and can aid in maintaining effective protection against bleeds in those switching product.

The hidden joint in children with haemophilia on prophylaxis

Prophylaxis is the gold standard treatment for children with haemophilia (CWH). MRI studies revealed joint damage, even with this treatment; this suggests the presence of subclinical bleeding. In the case of children with haemophilia, it is relevant to detect early signs of joint damage, as this allows the medical team to provide the appropriate treatment and follow-up, in order to avoid arthropathy development and its consequences. The aim of this study is to detect the hidden joint in children with haemophilia on prophylaxis (CWHP) and analyse, by age group, which joint is the most affected. We define the hidden joint in CWH on prophylaxis as the joint that presents joint damage secondary to repetitive bleeding episodes and is detected in the joint evaluation, despite being asymptomatic or with mild symptoms. It is most commonly caused by repetitive subclinical bleeding.

METHODS

This was an observational, analytical, cross-sectional study of 106 CWH on prophylaxis treated in our centre. Patients were divided according to age and type of treatment. Joint damage was defined as a HEAD-US score ≥ 1.

RESULTS

Patients' median age was 12 years. All had severe haemophilia. The median age of onset of prophylaxis was 2.7. Forty-seven (44.3 %) patients received primary prophylaxis (PP) and 59 (55.7 %), secondary prophylaxis. Six hundred and thirty-six joints were analysed. Type of prophylaxis and joint involvement showed statistically significant differences (p < 0.001). However, patients on PP had a greater number of damaged joints at older ages. Twenty-two % (140) of the joints scored ≥1 on HEAD-US. Cartilage was most frequently involved, followed by synovitis, and bone damage. We observed a greater frequency and degree of arthropathy in subjects aged 11 and above. Sixty (12.7 %) joints showed a HEAD-US score ≥ 1, with no history of bleeding. The ankle was the most affected joint, representing the hidden joint according to our definition.

CONCLUSION

Prophylaxis is the best treatment for CWH. However, symptomatic or subclinical joint bleeding may occur. The routine evaluation of joint health is relevant, particularly, of the ankle. In our study, early signs of arthropathy according to age and type of prophylaxis were detected by HEAD-US.

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.

Adherence to prophylaxis and bleeding outcome: A multicenter Nigerian study

In Nigeria, low-dose prophylaxis is the standard of care as it reduces bleeding, development of target joints, arthropathy, and improvement of quality of life. Non-adherence or poor adherence can prevent the achievement of these outcomes. The levels and determinants of (non-)adherence among persons with haaemophilia (PWH) in Sub-Saharan Africa have not been evidenced. We aimed to evaluate self-reported adherence among PWH, provide evidence of determinants/predictors of adherence, and establish the associations between nonadherence and presence of target joints and annualized bleed rate. A cross-sectional survey of 42 participants on low-dose prophylaxis recruited during outpatient appointments in 5 haemophilia treatment centers in Nigeria. We used the validated Haemophilia Regimen Treatment Adherence Scale- Prophylaxis (VERITAS -Pro), 24 questions on six subscales (time, dose, plan, remember, skip, and communicate) questionnaire. The options of VERITAS -Pro were represented in a 5 Likert scale and the possible subscale ranged from 4 points (most adherent) to 20 points (least adherent) and the possible total score ranged from 24 (most adherent) to 120 (least adherent) the cutoff for overall adherence put at > 61 to indicate nonadherence. Information on the presence of target joints, the number of target joints, and annualized bleeding rates were collected from medical files. The mean age of the participants was 9.79 (6.29) years, with 96.6% having hemophilia A and 79.3% having target joints. Overall adherence to the prophylaxis regimen was 81.0%. The mean total VERITAS-Pro for the adherent group and the non-adherent group was 37.35 ±9.08 and 63.0± 6.37, respectively. The mean subscale scores for the adherent group ranged from 0.67 (communication) to 8.68 (planning), while the mean subscale scores range from 1.0 communication to 13.88 (planning) for the nonadherent group. The mean difference of all except the dosing subscale was statistically significant with p<0.05. Only the skipping subscale showed a statistically significant positive correlation with ABR in the non-adherent group p = 0.02. The findings indicate that adherence was very good, and most were in communication with their treatment centers. The skipping subscale was significantly associated with ABR for the nonadherent group. Interventions aimed at improving adherence are the key to better treatment outcomes. A multicenter study was needed to assess the reason for poor adherence.

Management of children with hemophilia A on emicizumab who need surgery

The introduction of emicizumab into the treatment regime of persons with hemophilia A has dramatically reduced frequency of bleeding in patients with and without inhibitors. However, in children with Hemophilia A (CwHA) who require surgical or other invasive procedures, additional treatment with factor replacement or other hemostatic agents may still be needed to prevent intraoperative or postoperative bleeding. This review will look at the reported outcomes in CwHA on emicizumab who have had surgery and propose recommendations for the best perioperative management of major and minor procedures.

Long-term impact of primary prophylaxis on joint status in patients with severe hemophilia A

Background

Primary prophylaxis with factor VIII concentrates is the therapeutic gold standard for severe hemophilia A. Although this approach will change substantially with the use of nonsubstitutive therapies, the long-term effects of primary prophylaxis remain unclear. We present information on joint health with tailored primary prophylaxis in a consecutive series at a single center.

Methods

We retrospectively analyzed 60 patients who did not develop early inhibitors. The annual bleeding rate and annual joint bleeding rate, prophylaxis characteristics, physical activity, adherence, and development of inhibitors were compared between those with and without joint involvement at the end of follow-up. Joint involvement was defined as a Hemophilia Joint Health Score or Hemophilia Early Arthropathy Detection with an ultrasound score ≥1.

Results

Among 60 patients with median follow-up of 113 ± 6 months after starting prophylaxis, 76.7% had no joint involvement at the end of the follow-up. Those without joint involvement started prophylaxis at a younger median age (1 [IQR 1-1] year vs 3 [IQR 2-4.3] years). They also had lower annual joint bleeding rate (0.0 [IQR 0-0.2] vs 0.2 [IQR 0.1-0.5]), were more often physically active (70% vs 50%), and had lower trough factor VIII levels. Adherence to treatment was not significantly different between groups.

Conclusion

Initiation of primary prophylaxis at a younger age was the main factor associated with long-term preservation of joint status in patients with severe hemophilia A.

Clinical outcomes of low-dose pharmacokinetic-guided extended half-life versus low-dose standard half-life factor VIII concentrate prophylaxis in haemophilia A patients

INTRODUCTION

Despite receiving standard half-life (SHL) factor VIII (FVIII) concentrates prophylaxis, some severe haemophilia A (HA) patients still encounter spontaneous breakthrough bleeding. Individualized pharmacokinetic (PK)-guided dosing of extended half-life (EHL) FVIII concentrates may reduce their bleeding events.

AIM

To compare clinical outcomes before and after switching low-dose prophylaxis using weight-based SHL FVIII to PK-guided EHL FVIII concentrates, taking into consideration of a trough FVIII activity at 1 IU/dl above natural baseline.

METHODS

In this single-centre prospective cohort, Thai severe or moderate HA (FVIII activity ≤3 IU/dl) patients receiving low-dose weight-based SHL FVIII prophylaxis were enrolled. After a 3-day wash-out period, participants underwent low-dose EHL FVIII prophylaxis with PK-based adjustment (myPKFiT^® ) for 6 months. The annualized bleeding rates (ABR), the annualized joint bleeding rates (AJBR), the haemophilia-specific quality-of-life (Haemo-QoL or Haemo-QoL-A) scores, the Hemophilia Joint Health Scores (HJHS) and the annualized FVIII consumption were compared between the two prophylactic periods.

RESULTS

Of 15 eligible subjects (mean age 18.7 ± 6.7 years), ABR, AJBR and HJHS were significantly reduced (mean differences of -11.1 ± 4.9 bleeds/year, -10.4 ± 5.2 joint bleeds/year and -5.1 ± 1.5 marks, respectively; P < .001 for all comparisons) after switching regimen. The quality-of-life scores had also improved (P = .001). Nonetheless, FVIII consumption tended to increase despite no statistical significance (means of 1240.9 ± 531.3 SHL FVIII IU/kg/year versus 1591.7 ± 438.9 EHL FVIII IU/kg/year; P = .05).

CONCLUSIONS

This is the first low-dose, PK-guided, EHL FVIII prophylaxis clinical study in Thailand. Benefits and practicability of this personalized regimen may support the implementation of regular FVIII prophylaxis in developing countries with budget constraints.

CLINICALTRIALS

gov NCT05281185.

Switching from standard to extended half-life FVIII prophylaxis in haemophilia A: Comparison of factor product use, bleed rates and pharmacokinetics

INTRODUCTION

Majority of haemophilia A patients in our comprehensive care centre have switched from standard half-life (SHL) to extended half-life (EHL) FVIII products in a short time.

AIM

We compared the clinical and laboratory outcomes between SHL and EHL FVIII prophylaxis in product switchers.

METHODS

This is a retrospective inception cohort of all adult haemophilia A patients switched to EHL (rFVIIIFc or rFVIII-PEG) prophylaxis in our centre. Dosing, product utilization, annualized bleed rates (ABR), treatment regimen and pharmacokinetics by Web Accessible Population Pharmacokinetic Service (WAPPS)-Hemo were compared between SHL and EHL.

RESULTS

We included 38 patients, whose median age was 38 years (range 17-75). Median FVIII dose was 23 IU/kg for SHL versus 25 IU/kg for EHL. After switching, weekly infusions decreased by 29% from median 2.8 (every 2.5 days) to 2.0 (every 3.5 days) (P = <.001) and factor consumption for prophylaxis by 17% from 60 to 50 IU/kg/week (P = <.001). Weekly infusions decreased in 71% and FVIII utilization in 55% of patients. ABR remained low (1.0 for SHL and .5 for EHL, respectively). In pharmacokinetics, the half-life of FVIII increased from median 13 to 21 h after switching. Times above .01 and .03 IU/ml improved from 85 to 131 h and from 65 to 106 h. Half-lives of the SHL products and von Willebrand factor levels predicted half-lives with the EHL products.

CONCLUSIONS

Our cohort study confirms the successful experience of switching to EHL FVIII products, with decreased infusion frequency, factor consumption and excellent clinical efficacy.

Emicizumab for All Pediatric Patients with Severe Hemophilia A

Emicizumab is the first approved nonreplacement therapy for bleeding prophylaxis in hemophilia A (HA) patients. In 2018, it was licensed for HA patients with inhibitors, subsequently followed by an "European Medicines Agency (EMA)" approval for patients with severe HA in the absence of inhibitors in 2019. This is immediately raising the question whether emicizumab is suitable as a first-line treatment for all pediatric patients with severe HA. In this review, we want to discuss what we have, what we know, and what we would like to know. Severe HA is characterized by severe spontaneous and traumatic bleedings, particularly into muscles and joints leading to chronic joint damage. Standard of care is the regular, prophylactic replacement of factor VIII to prevent bleedings. Due to approval of emicizumab-the first nonreplacement therapy for bleeding prophylaxis-in HA patients with inhibitors, and severe HA patients without inhibitors, it is of pivotal interest whether emicizumab could be the first-line treatment in all pediatric patients with severe HA. Clinical trials and real-world observational studies could demonstrate a good efficacy and safety for bleeding prevention during emicizumab treatment in HA patients with and without inhibitors. This clearly indicates that emicizumab could improve HA treatment. However, some crucial and critical questions are remaining with regard to the use of emicizumab. Some of this missing information is already under investigation in the context of clinical trials. Until getting finalized data to shed insights into the points that are currently being discussed, there is a variety of expert and expert group recommendations, which are tackling questions concerning the treatment of HA patients. This review will address major information that is already available, but will also focus on important points that remain to be elucidated in the context of HA treatment.

Prophylaxis in children with haemophilia in an evolving treatment landscape

INTRODUCTION

For children with haemophilia, early initiation of prophylaxis is crucial to prevent life-threatening bleeds and maintain joint health throughout life. Options for prophylaxis have recently increased from replacement therapy with standard or extended half-life coagulation factor products to include other haemostasis products, such as the non-replacement therapy emicizumab.

AIM

To review key factors that determine the choice of prophylaxis in young children.

METHODS

Key clinical questions on the implementation of prophylaxis for haemophilia in children were identified and PubMed was searched for evidence supporting guidance on the implementation of prophylaxis.

RESULTS

The results of the literature search and the practical experience of the authors were used to build consensus on when to start prophylaxis, the pros and cons of the products available to guide the choice of product, and practical aspects of starting prophylaxis to guide the choice of regimen.

CONCLUSIONS

In this era of increasing therapeutic choices, available information about the range of treatment options must be considered when initiating prophylaxis in young children. Parents or care givers must be sufficiently informed to allow informed shared decision making. Although plentiful data and clinical experience have been gathered on prophylaxis with clotting factor replacement therapy, its use in young children brings practical challenges, such as the need for intravenous administration. In contrast, our relatively brief experience and limited data with subcutaneously administered non-replacement therapy (i.e., emicizumab) in this patient group imply that starting emicizumab prophylaxis in young children requires careful consideration, despite the more convenient route of administration.

Management of children with hemophilia A: How emicizumab has changed the landscape

The key to having a good quality of life for an adult with hemophilia rests largely on how he or she was managed as children. With effective prophylaxis, young men can begin their adult life with excellent joint function and few, if any, other sequelae from their disease. Unfortunately, this outcome is not always (nor often) attained because of the limitations of the mainstay of treatment, which is factor replacement therapy. In resource-rich countries with an adequate supply of factor concentrates, the treatment burden and formation of inhibitors limit the potential for an ideal outcome, whereas in much of the world, factor concentrates are too expensive to even be an option. The novel agent, emicizumab, which has become available in numerous countries around the world, is reshaping how one approaches the treatment of children with hemophilia A. This Forum Article, based on a State-of-the-Art lecture given at the 2020 International Society on Thrombosis and Haemostasis Virtual Meeting, presents an approach including clinically applicable algorithms for treating children with hemophilia A in the new era with emicizumab.

Haemophilia

Haemophilia A and B are rare congenital, recessive X-linked disorders caused by lack or deficiency of clotting factor VIII (FVIII) or IX (FIX), respectively. The severity of the disease depends on the reduction of levels of FVIII or FIX, which are determined by the type of the causative mutation in the genes encoding the factors (F8 and F9, respectively). The hallmark clinical characteristic, especially in untreated severe forms, is bleeding (spontaneous or after trauma) into major joints such as ankles, knees and elbows, which can result in the development of arthropathy. Intracranial bleeds and bleeds into internal organs may be life-threatening. The median life expectancy was ~30 years until the 1960s, but improved understanding of the disorder and development of efficacious therapy based on prophylactic replacement of the missing factor has caused a paradigm shift, and today individuals with haemophilia can look forward to a virtually normal life expectancy and quality of life. Nevertheless, the potential development of inhibitory antibodies to infused factor is still a major hurdle to overcome in a substantial proportion of patients. Finally, gene therapy for both types of haemophilia has progressed remarkably and could soon become a reality.

Emicizumab prophylaxis in infants with severe haemophilia A without inhibitors: Illustrative real-world cases to support shared decision-making

INTRODUCTION

Emicizumab has been shown to be safe and effective for prevention of bleeds in patients with severe haemophilia A (SHA), both with and without inhibitors. The subcutaneous administration and long half-life make emicizumab an attractive option for prophylaxis in infants with SHA, however data to inform treatment decisions in this younger age group are almost absent.

AIM

The aim of this report is to share real world experience to illustrate how the availability of emicizumab has shifted the prophylaxis paradigm in the management of infants with SHA.

METHOD

We selected four cases from our own cohort of infants with SHA to outline the rationale for emicizumab prophylaxis in a range of scenarios familiar to paediatric haemophilia treaters.

RESULTS

In Case 1 emicizumab was commenced at 7 days following initial treatment of neonatal ICH with a FVIII infusion. In Case 2 emicizumab was commenced at 5 weeks due to parental anxiety regarding the potential for ICH during infancy. Case 3 commenced emicizumab at 15 months in lieu of standard primary prophylaxis. Case 4 switched to emicizumab prophylaxis at 14 months after a period of primary prophylaxis with FVIII concentrates to alleviate parental anxiety regarding future inhibitor development. No patient had any bleeding events after commencement of emicizumab (median follow up 12 months), and no drug-related adverse effects were observed.

CONCLUSION

Despite the paucity of data in infants with SHA the potential role of emicizumab prophylaxis should be discussed with families when clinically relevant, with decisions tailored to individual need.

Clinical phenotype of severe and moderate haemophilia: Who should receive prophylaxis and what is the target trough level?

INTRODUCTION

One of the most often stated tenets of haemophilia care is that prophylaxis converts a person from a severe to a moderate phenotype. In this review, we argue that this is not an accurate assumption and that people on prophylaxis predominantly have factor VIII/IX levels in the mild range.

MODERATE HAEMOPHILIA AND PROPHYLAXIS

People with moderate haemophilia, who are treating with on-demand regimens, experience joint bleeds and often develop significant arthropathy. This is especially true for people with a baseline level of 1-3 IU/dl, as first reported 55 years ago, and confirmed in more recent studies. Evidence is emerging suggesting that people with severe haemophilia who are using prophylaxis have better musculoskeletal outcomes than people with moderate haemophilia treated episodically.

TROUGH LEVELS

The debate around the optimum trough level whilst on prophylaxis is ongoing. It is not appropriate to extrapolate information about baseline levels to recommendations about target trough levels on prophylaxis because these are different situations. Studies are emerging that support higher target trough levels than previously used, but in spite of this, the aim of achieving zero bleeds remains elusive with both factor replacement and non-replacement therapies.

CONCLUSIONS

We recommend that people with moderate haemophilia, especially those with a baseline of 1-3 IU/dl, should be offered prophylaxis based on the same criteria as people with severe haemophilia. Trough levels should be maintained above 3 IU/dl or higher if a level of 3 IU/dl does not control breakthrough bleeding and prophylaxis should be tailored to the bleeding phenotype. This advice is in line with recently published guidelines from the World Federation of Haemophilia and the UK Haemophilia Centre Doctors' Organisation.

Ultrasound evaluation of joint damage and disease activity in adult patients with severe haemophilia A using the HEAD-US system

INTRODUCTION

The Haemophilia Early Arthropathy Detection with Ultrasound (HEAD-US) system and scoring scale has proven to be an accurate and time-efficient imaging method for identifying joint damage in patients with haemophilia.

AIM

Observational, multicentre, cross-sectional study conducted in 8 centres in Spain that assessed the joint status of adult patients with severe haemophilia A (SHA) using HEAD-US.

METHODS

Joint status of the elbow, knee and ankle was evaluated in adults with SHA receiving on-demand (OD) treatment, or primary (PP), secondary (SP), tertiary (TP) or intermittent (IP) prophylaxis.

RESULTS

Of the 95 patients enrolled, 87 received prophylaxis (6.3% PP, 38.9% SP, 43.2% TP and 3.2% IP). Mean age was 35.2 years, and 59% of patients had not undergone image testing in the last year. The HEAD-US score was 0 in all joints in 6.3% of patients. The ankle was the most affected joint, regardless of treatment regimen. Patients receiving OD treatment, TP or IP had the overall worst scores, mainly in the ankles and elbows; a similar but milder profile was observed in patients on SP; and patients on PP had the best score in all joints.

CONCLUSION

Joint function may be effectively preserved in patients with SHA on PP, but OD treatment or later initiation of prophylaxis does not seem to prevent progression of arthropathy. Disease worsening was observed in patients OD, TP or IP, most often affecting ankles and elbows. Closer ultrasound imaging monitoring may improve management of these patients.

Use of ultrasound for assessment of musculoskeletal disease in persons with haemophilia: Results of an International Prophylaxis Study Group global survey

AIM

The objective of this survey was to understand the global trends of imaging assessments in persons with haemophilia, focusing on point-of-care ultrasound (POCUS). Insights into the barriers impeding its widespread proliferation as a frontline imaging modality were obtained.

METHODS

The survey opened in September of 2017 and closed in May of 2018. Haemophilia Treatment Centres (HTCs) treating both paediatric/adult patients were the population of interest. A REDCap survey of 25 questions was disseminated to 232 clinical staff in 26 countries.

RESULTS

The majority of respondents (88.3%, 91/103) reported that POCUS is most useful to confirm or rule out a presumed acute joint bleed. European HTCs reported the highest routine use of POCUS at 59.5% (22/37) followed by HTCs in the "Other" countries of the world at 46.7% (7/15) and North American HTCs at 43.9% (25/57). At the time of the survey, physiotherapists were identified as the clinical staff who perform POCUS 52.8% (28/53) of the time, in contrast with nurses/nurse practitioners who represent only 5.7% (3/53) of users. The greatest perceived barriers to the implementation of POCUS are the lack of trained healthcare professionals who can perform POCUS at 69.2% (74/107) and the overall time commitment required at 68.2% (73/107).

CONCLUSION

Despite POCUS being used in 49.5% (54/109) of sampled HTCs, it is still utilized almost 30% less globally than full diagnostic ultrasound. A list of barriers has been identified to inform HTCs which challenges they will likely need to overcome should they choose to incorporate this imaging modality into their practice.

Measurements of eftrenonacog alfa by 19 different combinations reagents/instrument: A single-centre study

INTRODUCTION

Recombinant factor IX Fc fusion protein (rFIXFc) is an extended half-life concentrate for the treatment of haemophilia B (HB). rFIXFc activity monitoring is crucial in several clinical situations. However, differences were observed between one-stage clotting (OSC) and chromogenic assays, but not for all factor IX (FIX) concentrations.

AIMS

To compare rFIXFc measurements obtained using different instruments and common OSC and chromogenic asssays.

METHODS

FIX:C measurements were performed in rFIXFc-spiked plasma aliquots (targeted FIX levels of 1.5, 1, 0.5, 0.2, 0.05, 0.02 and 0.01 IU/mL) and plasma samples collected from two patients with HB at various time points after rFIXFc infusion, using three instruments (STA-R MAX, ACLTOP700 and CS2100i) and common clotting and chromogenic FIX:C assays.

RESULTS

The same reagent could give different FIX:C measurements when adapted to different instruments. Moreover, the same reagent/instrument combination could give different results depending of the FIX concentration. For OSC assays, only STA-Cephascreen on STA-R MAX and CS2100i, SynthAFax on ACLTOP 700 and Actin on CS2100i provided acceptable recoveries for all rFIXFc concentrations. The chromogenic assays ROX-FIX and Biophen FIX:C underestimated rFIXFc for concentrations lower than 0.05 and 0.2 IU/mL, respectively.

CONCLUSIONS

Our study demonstrates that the same reagent adapted to different instruments could lead to different rFIXFc values. As rFIXFc under/overestimation could be associated with inappropriate treatment or biased calculation of pharmacokinetic parameters, the reagent/instrument combination used by haemostasis laboratories should be considered and regularly evaluated by external quality assessment programmes.

Recombinant factor VIII Fc fusion protein for the treatment of severe haemophilia A: Final results from the ASPIRE extension study

Introduction

The efficacy and safety of recombinant factor VIII Fc fusion protein (rFVIIIFc) as an extended half‐life treatment for severe haemophilia A were demonstrated in the Phase 3 A‐LONG and Kids A‐LONG studies. Eligible subjects who completed A‐LONG and Kids A‐LONG could enrol in ASPIRE (NCT01454739), an open‐label extension study.

Aim

To report the long‐term safety and efficacy of rFVIIIFc in subjects with severe haemophilia A who enrolled in ASPIRE.

Methods

Previously treated subjects received one or more of the following regimens: individualized prophylaxis (IP), weekly prophylaxis, modified prophylaxis or episodic treatment. Subjects could switch treatment regimen at any time. The primary endpoint was inhibitor development.

Results

A total of 150 subjects from A‐LONG and 61 subjects from Kids A‐LONG enrolled in ASPIRE. Most subjects received the IP regimen (A‐LONG: n = 110; Kids A‐LONG: n = 59). Median (range) treatment duration in ASPIRE for subjects from A‐LONG and Kids A‐LONG was 3.9 (0.1‐5.3) years and 3.2 (0.3‐3.9) years, respectively. No inhibitors were observed (0 per 1000 subject‐years; 95% confidence interval, 0‐5.2) and the overall rFVIIIFc safety profile was consistent with prior studies. For subjects on the IP regimen, annualized bleed rates (ABR) remained low (median overall ABR for adults and adolescents was <1.0) and extended‐dosing intervals were maintained (median of 3.5 days) for the majority of subjects in ASPIRE.

Conclusion

ASPIRE results, which include up to 5 years of follow‐up data, confirm earlier reports on the consistent and well‐characterized safety and efficacy of rFVIIIFc treatment for severe haemophilia A.

A multicenter, open-label phase 3 study of emicizumab prophylaxis in children with hemophilia A with inhibitors

Emicizumab, a bispecific humanized monoclonal antibody, bridges activated factor IX (FIX) and FX to restore the function of missing activated FVIII in hemophilia A. Emicizumab prophylaxis in children with hemophilia A and FVIII inhibitors was investigated in a phase 3 trial (HAVEN 2). Participants, previously receiving episodic/prophylactic bypassing agents (BPAs), were treated with subcutaneous emicizumab: 1.5 mg/kg weekly (group A), 3 mg/kg every 2 weeks (group B), or 6 mg/kg every 4 weeks (group C). Pharmacokinetics, safety, and efficacy (including an intraindividual comparison of participants from a noninterventional study) were evaluated. Eighty-five participants aged <12 years were enrolled. In group A (n = 65), the annualized rate of treated bleeding events (ABRs) was 0.3 (95% confidence interval [CI], 0.17-0.50), and 77% had no treated bleeding events. Intraindividual comparison of 15 participants who previously took BPA prophylaxis showed that emicizumab prophylaxis reduced the ABR by 99% (95% CI, 97.4-99.4). In groups B (n = 10) and C (n = 10), ABRs were 0.2 (95% CI, 0.03-1.72) and 2.2 (95% CI, 0.69-6.81), respectively. The most frequent adverse events were nasopharyngitis and injection-site reactions; no thrombotic events occurred. Two of 88 participants developed antidrug antibodies (ADAs) with neutralizing potential, that is, associated with decreased emicizumab plasma concentrations: 1 experienced loss of efficacy, and, in the other, ADAs disappeared over time without intervention or breakthrough bleeding. All other participants achieved effective emicizumab plasma concentrations, regardless of the treatment regimen. Emicizumab prophylaxis has been shown to be a highly effective novel medication for children with hemophilia A and inhibitors. This trial was registered at www.clinicaltrials.gov as #NCT02795767.

Continued benefit demonstrated with BAY 81-8973 prophylaxis in previously treated children with severe haemophilia A: Interim analysis from the LEOPOLD Kids extension study

INTRODUCTION

BAY 81-8973 (Kovaltry®), a recombinant factor VIII (rFVIII) product, was efficacious and well tolerated in paediatric previously treated patients (PTPs) with severe haemophilia A for ≥50 exposure days (EDs) in the LEOPOLD Kids study. Because long-term prophylaxis (≥100 EDs) can provide substantial patient benefits, FVIII products should demonstrate long-term safety and efficacy.

AIM

To demonstrate long-term (≥100 EDs) efficacy and safety of BAY 81-8973 in paediatric PTPs.

METHODS

PTPs aged ≤12 years with severe haemophilia A without inhibitors could continue in the ongoing open-label extension study after completing ≥50 EDs in the LEOPOLD Kids main study. Patients received BAY 81-8973 for prophylaxis (25-50 IU/kg ≥2×/week), bleed treatment, and surgery. Bleeds were documented in electronic patient diaries. Inhibitor development was monitored every 6 months.

RESULTS

At the August 2017 interim data cutoff, 46 patients (median [range] age at enrolment, 6.0 [1.0-11.0] years) had spent a median (range) of 602.5 (148-1069) EDs and 4.6 (1.0-5.9) years in the main plus extension studies. Median (quartile [Q]1; Q3) annualised bleeding rate for bleeds within 48 h after a prophylaxis infusion and total bleeds was 1.0 (0.2; 1.9) and 2.0 (0.4; 3.6), respectively. Most (>94%) bleeds were mild or moderate; 71.8% were treated with ≤1 infusion. BAY 81-8973 was also well tolerated with only one treatment-related adverse event (transient, low-titre inhibitor which did not require treatment adjustment).

CONCLUSION

BAY 81-8973 was efficacious for prophylaxis and treatment of bleeds during >4.5 years in paediatric PTPs with severe haemophilia A.

Hemophilia prophylaxis adherence and bleeding using a tailored, frequency-escalated approach: The Canadian Hemophilia Primary Prophylaxis Study

BACKGROUND

Standard of care for persons with severe hemophilia A includes regular replacement of factor VIII (FVIII). Prophylaxis regimens using standard half-life (SHL) FVIII concentrates, while effective, are costly and require frequent intravenous infusions.

AIM

This study evaluated the adherence of 56 boys with severe hemophilia A to tailored, frequency-escalated prophylaxis with an SHL recombinant FVIII concentrate.

METHODS

We reviewed the factor infusion and bleeding logs of study subjects. Adherence to the prescribed regimen was calculated on a weekly basis, and bleeding rates were determined from self/proxy-reported bleeding logs. The primary outcome was adherence to the prescribed prophylaxis regimen.

RESULTS

The median (range of values [ROV]) weekly adherence to prophylaxis was 85.7% (37.4%-99.8%). The median (ROV) adherent weeks on steps 1 (weekly), 2 (twice weekly), and 3 (alternate-day) were 92.9% (50%-100%), 80.3 (32%-96%), and 72.6% (14%-98%); relative to step 1, subjects were less likely to be adherent on steps 2 and 3 (P < 0.00). On step 1, our cohort had higher adherence than previously reported rates. The median (ROV) adherence to the breakthrough bleeding protocol was 47.1% (0%-100%). At any given time, bleeding risk was reduced by 15% for each 10% increase in adherence during the preceding 12 weeks (hazard ratio, 0.85; 95% confidence interval, 0.81-0.90).

CONCLUSION

This cohort had high rates of adherence to the prescribed prophylaxis regimen. Initiating prophylaxis with once-weekly infusions facilitated adherence to the prophylaxis regimen in this cohort of boys with severe hemophilia A started on primary prophylaxis at a very young age.

Comparative pharmacokinetics of two extended half-life FVIII concentrates (Eloctate and Adynovate) in adolescents with hemophilia A: Is there a difference?

Essentials The PK parameters of Eloctate vs Adynovate were compared using one-stage and chromogenic assays in 25 boys (12-18 years). The FVIII levels were taken at 3, 24, 48, and 72 hours following a dose of either FVIII; levels analyzed by WAPPS PK program. The PK profiles (half-life, clearance, and time to 5%, 3%, and 1%) were not statistically different for the two EHL FVIIIs. The significant interpatient variability in PK is mainly related to VWF levels (and blood group).

BACKGROUND

A head-to-head comparison of the pharmokinetcs (PK) of extended half-life (EHL) factor VIII (FVIII) concentrates in the same subjects has not been reported. Recently, boys (ages 12-18 years) with hemophilia A in Canada were required to switch from Eloctate to Adynovate.

OBJECTIVES

Compare the PK profiles of Eloctate vs Adynovate in the same boys.

METHODS

Boys switching from Eloctate to Adynovate prophylaxis had FVIII levels sampled at 3, 24, 48, and 72 hours following a regular prophylactic infusion of Eloctate and then 1-3 months later, of Adynovate. Testing was done by one-stage assay (OSA) and chromogenic assay (CA). The PK parameters were determined with the Web Accessible Population Pharmacokinetic Service (WAPPS)-Hemo PK tool.

RESULTS

Twenty-five boys (mean age 15.3 years; range: 12.1-18.4; 9 O blood group) underwent switching. Mean (range) terminal half-lives with the OSA were 16.1 hours (10.4 to 23.4; Eloctate) and 16.7 hours (11.0 to 23.6; Adynovate) (NS). With the CA, these were 18.0 hours (12.0 to 25.5; Eloctate) and 16.0 hours (10.3 to 22.9; Adynovate) (P = 0.001). There were no significant differences between the two EHL-FVIIIs in clearance, area under the concentration vs time curve (AUC), Vss, or time for FVIII levels to drop to 5%, 3%, and 1%. At the 72-h time point, mean observed FVIII levels following a mean dose of 39.3 IU/kg of Eloctate were 4.4% (OSA) and 4.4% (CA). For Adynovate, these were 5.1% (OSA) and 5.3% (CA) following similar doses. There was considerable interpatient variation in PK, mainly explained by differences in blood group/von Willebrand factor (VWF) levels.

CONCLUSIONS

Eloctate and Adynovate have almost identical PK parameters. When switching from one to another no prophylaxis regimen change is needed.

Impact of prophylaxis on health-related quality of life of boys with hemophilia: An analysis of pooled data from 9 countries

BACKGROUND

Prophylaxis reduces the frequency of bleeds in boys with severe hemophilia and is the standard care for their management in resource-abundant countries. The effect of prophylaxis on Health-Related Quality of Life (HRQoL) has not been established, because the sample sizes of most studies are too small to explore the relationship of multiple factors that influence HRQoL.

METHODS

The aim of this study was to assess the impact of hemophilia severity and treatment regimen on HRQoL and to establish the minimum important difference (MID) using the international level of score distributions. HRQoL data were pooled from 7 studies across 9 countries. HRQoL was measured using the Canadian Hemophilia Outcomes-Kids' Life Assessment Tool (CHO-KLAT). A mixed-effect linear regression analysis was employed to assess the impact of prophylaxis on the CHO-KLAT score.

RESULTS

Data from 401 boys with hemophilia were analyzed (57.6% severe hemophilia and 57.6% receiving prophylaxis). The model revealed that receiving prophylaxis was significantly associated with higher HRQoL (regression coefficient 8.5, 95% confidence interval [CI] 3.9-13.1). Boys with severe hemophilia had a significantly lower HRQoL as compared to boys with moderate and mild hemophilia whose CHO-KLAT scores were 7.0 and 6.6 points higher, respectively. There was a significant interaction between treatment and disease severity (P = 0.023), indicating prophylaxis has the most significant impact in boys with severe hemophilia. Based on these pooled data, the MID of the CHO-KLAT was established at 6.5.

CONCLUSIONS

This study confirms the positive effect of prophylaxis on HRQoL in boys with hemophilia in a real-world setting and provides initial benchmarks for interpreting HRQoL scores based on use of the CHO-KLAT instrument.

Using pharmacokinetics for tailoring prophylaxis in people with hemophilia switching between clotting factor products: A scoping review

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

Anti-tissue factor pathway inhibitor (TFPI) therapy: a novel approach to the treatment of haemophilia

Novel approaches to the treatment of haemophilia are needed due to the limitations of the current standard of care, factor replacement therapy. Aspirations include lessening the treatment burden and effectively preventing joint damage. Treating haemophilia by restoring thrombin generation may be an effective approach. A promising target for restoring thrombin generation is tissue factor pathway inhibitor (TFPI), a multivalent Kunitz-type serine protease inhibitor that regulates tissue factor-induced coagulation via factor Xa-dependent feedback inhibition of the tissue factor-factor VIIa complex. Inhibition of TFPI reverts the coagulation process to a more primitive state evolutionarily, whilst regulation by other natural inhibitors is preserved. An aptamer and three monoclonal antibodies directed against TFPI have been investigated in clinical trials. As well as improving thrombin generation in the range associated with mild haemophilia, anti-TFPI therapies have the advantage of subcutaneous administration. However, the therapeutic window needs to be defined along with the potential for complications due to the novel mechanism of action. This review provides an overview of TFPI, its role in normal coagulation, the rationale for TFPI inhibition, and a summary of anti-TFPI therapies, previously or currently in development.

Navigating Speed Bumps on the Innovation Highway in Hemophilia Therapeutics

The unprecedented emergence of novel therapeutics for both hemophilia A and B during the last half decade has been accompanied by the promise of even more extraordinary progress in ameliorative and curative strategies for both disorders. Paradoxically, the speed of innovation has created new dilemmas for persons with hemophilia and their physicians with respect to optimizing individual choices from the expanding menu of standard and novel therapies and approaches to symptom or risk reduction, and ultimately, to normalizing the hemophilia phenotype. Among the most disruptive new approaches, challenges remain in the form of the adverse reactions that have been observed with nonfactor therapies, as well as in the uncertain long-term safety profile of potentially curative gene therapy. Together, these challenges have generated uncertainty as to how to adopt novel therapies and treatment strategies across a diverse patient population, creating speed bumps on the hemophilia innovation highway. It is from this perspective that this article discusses the current state of gene therapy and bleeding prophylaxis for hemophilia A and B, as well as prevention and treatment of the factor VIII inhibitor phenotype in hemophilia A. It further posits that these speed bumps may provide important clues to the mechanistic understanding of both symptom manifestation and resilience within the hemophilia phenotype, as well as opportunities to reconsider and reconfigure the current paradigms for symptom prediction and individualized therapeutic decision making.

Pharmacokinetic-based prediction of real-life dosing of extended half-life clotting factor concentrates on hemophilia

The improvement of clotting factor concentrates (CFCs) has undergone an impressive boost during the last six years. Since 2010, several new recombinant factor (rF)VIII/IX concentrates entered phase I/II/III clinical trials. The improvements are related to the culture of human embryonic kidney (HEK) cells, post-translational glycosylation, PEGylation, and co-expression of the fragment crystallizable (Fc) region of immunoglobulin (Ig)G1 or albumin genes in the manufacturing procedures. The extended half-life (EHL) CFCs allow an increase of the interval between bolus administrations during prophylaxis, a very important advantage for patients with difficulties in venous access. Although the inhibitor risk has not been fully established, phase III studies have provided standard prophylaxis protocols, which, compared with on-demand treatment, have achieved very low annualized bleeding rates (ABRs). The key pharmacokinetics (PK) parameter to tailor patient therapy is clearance, which is more reliable than the half-life of CFCs; the clearance considers the decay rate of the drug concentration-time profile, while the half-life considers only the half concentration of the drug at a given time. To tailor the prophylaxis of hemophilia patients in real-life, we propose two formulae (expressed in terms of the clearance, trough and dose interval between prophylaxis), respectively based on the one- and two-compartmental models (CMs), for the prediction of the optimal single dose of EHL CFCs. Once the data from the time decay of the CFCs are fitted by the one- or two-CMs after an individual PK analysis, such formulae provide to the treater the optimal trade-off among trough and time-intervals between boluses. In this way, a sufficiently long time-interval between bolus administration could be guaranteed for a wider class of patients, with a preassigned level of the trough. Finally, a PK approach using repeated dosing is discussed, and some examples with new EHL CFCs are shown.

Tailored frequency-escalated primary prophylaxis for severe haemophilia A: results of the 16-year Canadian Hemophilia Prophylaxis Study longitudinal cohort

BACKGROUND

Severe haemophilia A has high morbidity, and treatment, while effective, is very expensive. We report the 16-year follow-up of the Canadian Hemophilia Prophylaxis Study, which examined the effectiveness of tailored frequency-escalated primary prophylaxis with a focus on health outcomes within the domains of body structures and functions, and activities and participation (according to the WHO International Classification of Functioning, Disability and Health [WHO-ICF] framework) and a view to reducing consumption of costly clotting factor, which accounts for more than 90% of the cost of care of severe haemophilia.

METHODS

In this longitudinal study, boys with severe haemophilia A from 12 Canadian centres were enrolled at age 1·0-2·5 years. They were treated with standard half-life recombinant factor VIII (SHL-rFVIII), beginning as once-weekly prophylaxis with 50 IU/kg and escalating in frequency (with accompanying dose adjustments) in response to breakthrough bleeding as determined by the protocol. The primary endpoint for this analysis was joint health, as measured by the modified Colorado Child Physical Examination Scores (CCPES) at study end. All analyses were done by intention to treat. The trial is complete, and is registered with ClinicalTrials.gov, number NCT01085344.

FINDINGS

Between June 26, 1997, and Jan 30, 2007, 56 boys were enrolled. They were followed for a median of 10·2 years (to a maximum of 16·1 years). Median rFVIII usage was about 3600 IU/kg per year. The median end-of-study CCPES physical examination score was 1 (IQR 1-3; range 0-12) for the left ankle and 1 (1-2; 0-12) for the right ankle, with all other joints having a median score of 0. No treatment-related safety events occurred over the duration of the study, including central venous catheter infections. The median annualised index joint bleeding rate was 0·95 per year (IQR 0·44-1·35; range 0·00-13·43), but 17 (30%) patients had protocol-defined unacceptable breakthrough bleeding at some point during the study.

INTERPRETATION

Tailored frequency-escalated prophylaxis leads to very little arthropathy and very good health outcomes within the WHO-ICF domains, and only uses a moderate amount of expensive clotting factor as compared with standard prophylaxis protocols. Some sequelae of bleeding were observed in our cohort, and future studies should consider a more stringent protocol of escalation.

FUNDING

This study was initially funded by grants from the Medical Research Council of Canada/Pharmaceutical Manufacturers Association of Canada Partnership Fund and the Bayer/Canadian Blood Services/Hema-Quebec Partnership Fund. Subsequent renewals were funded by Bayer.

Australian multicentre study of current real-world prophylaxis practice in severe and moderate haemophilia A and B

INTRODUCTION

With the emergence of novel treatment products for haemophilia and an increasing focus on the benefits of pharmacokinetic driven individualized prophylaxis, robust national data with regard to current patterns of factor consumption and adherence are required.

AIM

To characterize current Australian practice with regard to use of prophylactic clotting factor infusions in patients with moderate or severe haemophilia A (HA) and haemophilia B (HB).

METHODS

This was a retrospective, non-interventional study utilizing Australian Bleeding Disorder Registry (ABDR) data collected over a 12 month period. Registered and consented patients with moderate or severe HA or HB without inhibitors were included.

RESULTS

A total of 718 HA (551 severe, 167 moderate) and 166 HB (87 severe, 79 moderate) patients were included. Regular prophylaxis was prescribed in 453 patients (82%) with severe HA, 42 patients (25%) with moderate HA, 66 patients (75%) with severe HB and 11 patients (14%) with moderate HB. Near universal prophylaxis was achieved in the paediatric subgroup. The mean weekly dose of factor VIII in severe HA was 84 international units/kg/wk (IU/kg/wk) vs 71 IU/kg/wk of factor IX in severe HB. Most patients on prophylaxis were treated ≥3 times/wk (HA) or 2 times/wk (HB). Non-adherence peaked in the 20-29 year age group. Older individuals on regular prophylaxis used more factor than was expected for their prescribed regimen.

CONCLUSION

Prophylaxis rates in severe haemophilia are comparable with other developed nations. The benefit of a national registry is demonstrable. Furthermore research into the underlying reasons for non-compliance in young adults with haemophilia is required.

Effect of late prophylaxis in hemophilia on joint status: a randomized trial

Essentials High-quality data are lacking on use of prophylaxis in adults with hemophilia and arthropathy. SPINART was a 3-year randomized clinical trial of late/tertiary prophylaxis vs on-demand therapy. Prophylaxis improved function, quality of life, activity and pain but not joint structure by MRI. Prophylaxis improves function but must start before joint bleeding onset to prevent arthropathy.

SUMMARY

Background Limited data exist on the impact of prophylaxis on adults with severe hemophilia A and pre-existing joint disease. Objectives To describe 3-year bleeding, joint health and structure, health-related quality-of-life (HRQoL) and other outcomes from the open-label, randomized, multinational SPINART study. Patients/Methods Males aged 12-50 years with severe hemophilia A, ≥ 150 factor VIII exposure days, no inhibitors and no prophylaxis for > 12 consecutive months in the past 5 years were randomized to sucrose-formulated recombinant FVIII prophylaxis or on-demand therapy (OD). Data collected included total and joint bleeding events (BEs), joint structure (magnetic resonance imaging [MRI]), joint health (Colorado Adult Joint Assessment Scale [CAJAS]), HRQoL, pain, healthcare resource utilization (HRU), activity, and treatment satisfaction. Results Following 3 years of prophylaxis, adults maintained excellent adherence, with a 94% reduction in BEs despite severe pre-existing arthropathy; 35.7% and 76.2% of prophylaxis participants were bleed-free or had fewer than two BEs per year, respectively. As compared with OD, prophylaxis was associated with improved CAJAS scores (least squares [LS] mean, - 0.31 [n = 42] versus + 0.63 [n = 42]) and HAEMO-QoL-A scores (LS mean, + 3.98 [n = 41] versus - 6.00 [n = 42]), less chronic pain (50% decrease), and approximately two-fold less HRU; activity, Euro QoL-5D-3L (EQ-5D-3L) scores and satisfaction scores also favored prophylaxis. However, MRI score changes were not different for prophylaxis versus OD (LS mean, + 0.79 [n = 41] versus + 0.96 [n = 38]). Conclusions Over a period of 3 years, prophylaxis versus OD in adults with severe hemophilia A and arthropathy led to decreased bleeding, pain, and HRU, better joint health, activity, satisfaction, and HRQoL, but no reduction in structural arthropathy progression, suggesting that pre-existing joint arthropathy may be irreversible.

Modeling of Body Weight Metrics for Effective and Cost-Efficient Conventional Factor VIII Dosing in Hemophilia A Prophylaxis

The total body weight-based dosing strategy currently used in the prophylactic treatment of hemophilia A may not be appropriate for all populations. The assumptions that guide weight-based dosing are not valid in overweight and obese populations, resulting in overdosing and ineffective resource utilization. We explored different weight metrics including lean body weight, ideal body weight, and adjusted body weight to determine an alternative dosing strategy that is both safe and resource-efficient in normal and overweight/obese adult patients. Using a validated population pharmacokinetic model, we simulated a variety of dosing regimens using different doses, weight metrics, and frequencies; we also investigated the implications of assuming various levels of endogenous factor production. Ideal body weight performed the best across all of the regimens explored, maintaining safety while moderating resource consumption for overweight and obese patients.

Status and trend analysis of prophylactic usage of recombinant factor VIII in Chinese pediatric patients with hemophilia A: ReCare - a retrospective, phase IV, non-interventional study

BACKGROUND

No study has reported the status and chronological trend of prophylactic recombinant factor VIII (rFVIII) use in Chinese pediatric patients with hemophilia A (HA).

OBJECTIVE

We aimed to analyze the status and trend of rFVIII-containing prophylaxis in Chinese pediatric patients with HA.

METHODS

ReCARE (Retrospective study in Chinese pediatric hemophilia A patients with rFVIII contained REgular prophylaxis) was a retrospective study conducted in 12 hemophilia treatment centers across China. The trend of prophylaxis was evaluated by determining the mean duration of prophylaxis, mean injection frequency (per week), mean dose of each injection (IU/kg), mean total dose injected/week (IU) and proportion of rFVIII consumption relative to factor VIII (FVIII) consumption over the study period.

RESULTS

We analyzed 183 male pediatric patients with HA (mean age, 7.1 ± 4.23 years), who received intermittent prophylaxis between 1 November 2007 and 31 May 2013. The mean duration of prophylaxis with rFVIII increased from 16.72 weeks in 2008 to 32.77 in 2012. Per injection dose of rFVIII increased significantly from 2008 to 2013 (25.89 to 28.31 IU/kg, p < .001). An increase was also reported in the mean total FVIII consumed (699.97 ± 173.25 IU in 2008 and 891.30 ± 730.341 in 2013) and mean proportion of rFVIII used (33.33 ± 57.73% in 2008 to 85.50 ± 29.077% in 2013).

CONCLUSION

Our data revealed an overall improvement in treatment dosage and duration with an increase in the number of patients receiving prophylaxis. The total proportion of rFVIII also increased gradually indicating the development of economy and safety awareness.

TRIAL REGISTRATION

The trial is registered at ClinicalTrials.gov (CT.gov identifier: NCT02263066).

Rare bleeding disorders-old diseases in the era of novel options for therapy

Rare diseases are defined as life-threatening or chronically debilitating diseases with a prevalence of less than one per 2000 according to the European Union or one per 1250 according to the USA. Congenital rare bleeding disorders RBD are reported in most populations, with incidence varying from 1 in 5000 (Hemophilia A), 1:30,000 (Hemophilia B) to much rarer (1:500,000 for FVII deficiency, 1-3 million for Prothrombin or FXIII deficiency). Acquired Hemophilia A is also a rare bleeding disorder with estimated frequency of 1 in million. Most RBDs are inherited as autosomal recessive (AR); however, heterozygous carriers with varying degrees of corresponding factor deficiency may render an unpredictable propensity for bleeding. In patients with bleeding symptoms, laboratory assessment and especially molecular techniques currently enable accurate diagnosis and may provide tools for prenatal and family counseling. Currently hemostasis control is mainly based upon replacement of the missing coagulation factors (unless presence of inhibitors renders it impossible), however future gene therapy and disruptive, non-replacement alternatives may be promising for patients with RBD.

Data Analysis Protocol for the Development and Evaluation of Population Pharmacokinetic Models for Incorporation Into the Web-Accessible Population Pharmacokinetic Service - Hemophilia (WAPPS-Hemo)

BACKGROUND

Hemophilia is an inherited bleeding disorder caused by a deficiency in a specific clotting factor. This results in spontaneous bleeding episodes and eventual arthropathy. The mainstay of hemophilia treatment is prophylactic replacement of the missing factor, but an optimal regimen remains to be determined. Rather, individualized prophylaxis has been suggested to improve both patient safety and resource utilization. However, uptake of this approach has been hampered by the demanding sampling schedules and complex calculations required to obtain individual estimates of pharmacokinetic (PK) parameters. The use of population pharmacokinetics (PopPK) can alleviate this burden by reducing the number of plasma samples required for accurate estimation, but few tools incorporating this approach are readily available to clinicians.

OBJECTIVE

The Web-accessible Population Pharmacokinetic Service - Hemophilia (WAPPS-Hemo) project aims to bridge this gap by providing a Web-accessible service for the reliable estimation of individual PK parameters from only a few patient samples. This service is predicated on the development of validated brand-specific PopPK models.

METHODS

We describe the data analysis plan for the development and evaluation of each PopPK model to be incorporated into the WAPPS-Hemo platform. The data sources and structure of the dataset are discussed first, followed by the procedures for handling both data below limit of quantification (BLQ) and absence of such BLQ data. Next, we outline the strategies for building the appropriate structural and covariate models, including the possible need for a process algorithm when PK behavior varies between subjects or significant covariates are not provided. Prior to use in a prospective manner, the models will undergo extensive evaluation using a variety of techniques such as diagnostic plots, bootstrap analysis and cross-validation. Finally, we describe the incorporation of a validated PopPK model into the Bayesian post hoc model to produce individualized estimates of PK parameters.

RESULTS

Dense PK data has been collected for more than 20 brands of factor concentrate from both industry-sponsored and investigator-driven studies. The model development process is underway for the majority of molecules, with refinement and validation to be completed in 2017. Further, the WAPPS-Hemo co-investigator network has contributed more than 300 PK assessments for use in model development and evaluation. This constitutes the largest repository of this type of PK data globally.

CONCLUSIONS

The WAPPS-Hemo service aims to eliminate barriers to the uptake of individualized PK-tailored hemophilia treatment. By incorporating this tool into routine practice, clinicians can implement a personalized dosing strategy without performing rigorous sampling or complex calculations. This service is centred on validated models developed according to the robust approach to PopPK modeling described herein.

CLINICALTRIAL

ClinicalTrials.gov NCT02061072; https://clinicaltrials.gov/ct2/show/NCT02061072 (Archived by WebCite at http://www.webcitation.org/6mRIXJh55).

The use of pharmacokinetics in dose individualization of factor VIII in the treatment of hemophilia A

INTRODUCTION

Hemophilia A is a bleeding disorder resulting from a lack of clotting factor VIII (FVIII), and treatment typically consists of prophylactic replacement of the deficient factor. However, high between subject variability precludes the development of a 'one size fits all' dosing strategy and necessitates an individualized approach. We sought to summarize the data on the pharmacokinetics of FVIII available as a basis for the development of population pharmacokinetic models to be used in dose tailoring. Areas covered: We reviewed the pharmacokinetics of FVIII as used for the treatment of hemophilia A, with a focus on the variability observed between patients and the application of pharmacokinetic methods to dose individualization. We also explored the covariates affecting pharmacokinetic parameters, the differences between plasma-derived and recombinant FVIII and the development of extended half-life products. Expert opinion: The pharmacokinetics of factor VIII in patients with hemophilia shows a high interpatient variability, and is affected by age, weight, level of von Willebrand factor, and blood group. A population approach to estimating individual pharmacokinetics is likely to provide the most successful strategy to tailor factor concentrate dosing to the individual needs and to ensure optimal patient outcomes, while also improving the cost-effectiveness of prophylactic replacement therapy.