Primary prophylaxis in children with haemophilia

Current therapeutic approaches in the management of hemophilia-a consensus view by the Romanian Society of Hematology

Hemophilia A (HA) and hemophilia B (HB) are rare disorders, being caused by the total lack or under-expression of two factors from the coagulation cascade coded by genes of the X chromosome. Thus, in hemophilic patients, the blood does not clot properly. This results in spontaneous bleeding episodes after an injury or surgical intervention. A patient-centered regimen is considered optimal. Age, pharmacokinetics, bleeding phenotype, joint status, adherence, physical activity, personal goals are all factors that should be considered when individualizing therapy. In the past 10 years, many innovations in the diagnostic and treatment options were presented as being either approved or in development, thus helping clinicians to improve the standard-of-care for patients with hemophilia. Recombinant factors still remain the standard of care in hemophilia, however they pose a challenge to treatment adherence because they have short half-life, which where the extended half-life (EHL) factors come with the solution, increasing the half-life to 96 hours. Gene therapies have a promising future with proven beneficial effects in clinical trials. We present and critically analyze in the current manuscript the pros and cons of all the major discoveries in the diagnosis and treatment of HA and HB, as well as identify key areas of hemophilia research where improvements are needed.

Adherence to prophylaxis in adolescents and young adults with severe haemophilia A, a qualitative study with patients

Introduction: Reported levels of adherence to prophylaxis among young people with haemophilia (YPH) vary widely and are predominately based on estimations made by healthcare professionals and parents. Reasons for (non)adherence among YPH in particular have not been evidenced.

Aim: to examine experiences in relation to prophylaxis with YPH themselves, and barriers and facilitators to their adherence.

Methods: 11 Participants were recruited in five haemophilia centres across England and Wales. All patients who met the inclusion criteria (aged 12-25, diagnosed with haemophilia, on prophylaxis) were approached during a routine check-up appointment, and all participants who agreed to take part were interviewed. Interviews were audio recorded, transcribed and analysed using Interpretative Phenomenological Analysis.

Results: Self-reported adherence to prophylaxis was good. Few participants admitted to intentionally skipping injections although they reported sometimes forgetting. However, due to the increasingly personalised and flexible approach to prophylaxis, adherence is not straightforward to define. Barriers to adherence included a busy lifestyle, dislike of the intravenous injection, venous access issues, anxiety or stress and being out of one’s normal routine. Support was an important facilitator to adherence, including support from health professionals at the haemophilia centre as well as friends. Parents appear to be very involved with their child’s haemophilia management, even after they leave home.

Conclusion: What this study adds is that the increasingly flexible and personalised approach to managing prophylaxis in haemophilia may sometimes lead to confusion around treatment frequency and dosing. This may lead to accidental non-adherence, which is distinct from both skipping and forgetting. Advice from haemophilia teams may not always be consistent and is likely to be interpreted differently by different individuals. Some additional training and education of patients and their families to increase their knowledge and skills around prophylaxis may reduce this confusion and therefore is likely to improve adherence further.

Recent advances in (therapeutic protein) drug development

Therapeutic protein drugs are an important class of medicines serving patients most in need of novel therapies. Recently approved recombinant protein therapeutics have been developed to treat a wide variety of clinical indications, including cancers, autoimmunity/inflammation, exposure to infectious agents, and genetic disorders. The latest advances in protein-engineering technologies have allowed drug developers and manufacturers to fine-tune and exploit desirable functional characteristics of proteins of interest while maintaining (and in some cases enhancing) product safety or efficacy or both. In this review, we highlight the emerging trends and approaches in protein drug development by using examples of therapeutic proteins approved by the U.S. Food and Drug Administration over the previous five years (2011–2016, namely January 1, 2011, through August 31, 2016).

Alloantibodies to therapeutic factor VIII in hemophilia A: the role of von Willebrand factor in regulating factor VIII immunogenicity

The rising incidence of neutralizing antibodies (inhibitors) against therapeutic factor VIII prompted the conduct of studies to answer the question as to whether this rise is related to the introduction of recombinant factor VIII products. The present article summarizes current opinions and results of non-clinical and clinical studies on the immunogenic potential of recombinant compared to plasma-derived factor VIII concentrates. Numerous studies provided circumstantial evidence that von Willebrand factor, the natural chaperone protein present in plasma-derived factor VIII products, plays an important role in protecting exogenous factor VIII from uptake by antigen presenting cells and from recognition by immune effectors. However, the definite contribution of von Willebrand factor in reducing the inhibitor risk and in the achievement of immune tolerance is still under debate.

Practice of Iranian Adolescents with Hemophilia in Prevention of Complications of Hemophilia

BACKGROUND

Prerequisite for management of a chronic disease involves knowledge about its complications and their prevention. Hemophilia in adolescents influences all the aspects of their lives and thier performance.

OBJECTIVES

The present study aimed to determine the performance of Iranian hemophilic adolescents in prevention of disease complications.

PATIENTS AND METHODS

In this descriptive-analytical study, 108 adolescents with hemophilia were selected through convenience sampling. Their performance in preventing the complications of hemophilia was evaluated by sending a semi-structured questionnaire to their addresses throughout Iran. Then, the data was analysed using the Statistical Package for Social Sciences (SPSS) software (v. 13) and descriptive and interferential statistics were used.

RESULTS

Overall, 32.1% of the participants controlled bleeding during the 1(st) hour. Inaccessibility of coagulation products was mainly responsible for inhibiting timely and proper bleeding control. In order to relieve bleeding associated pain, only 39.0% of the adolescents used analgesics. On the other hand, 19.8% of the subjects used nonpharmacological methods to relieve pain. The majority of the adolescents did not participate in sport activities (65.4%) others allocated less than 5 hours a week to physical activities (70.5%). In addition, the participants did not have favorable dietary patterns, exercise habits, and dental care. The results showed a significant relationship between the adolescents' preventive practice with coagulation disorders and utilization of pharmacological pain relief methods. Also, significant relationships were found between severity of the disease; participating in physical activities, number of hours of physical activities; and disease complications.

CONCLUSIONS

Iranian adolescents did not exhibit favorable practices towards complication prevention.

Patient and parent preferences for characteristics of prophylactic treatment in hemophilia

INTRODUCTION

New longer-acting factor products will potentially allow for less frequent infusion in prophylactic treatment of hemophilia. However, the role of administration frequency relative to other treatment attributes in determining preferences for prophylactic hemophilia treatment regimens is not well understood.

AIM

To identify the relative importance of frequency of administration, efficacy, and other treatment characteristics among candidates for prophylactic treatment for hemophilia A and B.

METHOD

An Internet survey was conducted among hemophilia patients and the parents of pediatric hemophilia patients in Australia, Canada, and the US. A monadic conjoint task was included in the survey, which varied frequency of administration (three, two, or one time per week for hemophilia A; twice weekly, weekly, or biweekly for hemophilia B), efficacy (no bleeding or breakthrough bleeding once every 4 months, 6 months, or 12 months), diluent volume (3 mL vs 2.5 mL for hemophilia A; 5 mL vs 3 mL for hemophilia B), vials per infusion (2 vs 1), reconstitution device (assembly required vs not), and manufacturer (established in hemophilia vs not). Respondents were asked their likelihood to switch from their current regimen to the presented treatment. Respondents were told to assume that other aspects of treatment, such as risk of inhibitor development, cost, and method of distribution, would remain the same.

RESULTS

A total of 89 patients and/or parents of children with hemophilia A participated; another 32 were included in the exercise for hemophilia B. Relative importance was 47%, 24%, and 18% for frequency of administration, efficacy, and manufacturer, respectively, in hemophilia A; analogous values were 48%, 26%, and 21% in hemophilia B. The remaining attributes had little impact on preferences.

CONCLUSION

Patients who are candidates for prophylaxis and their caregivers indicate a preference for reduced frequency of administration and high efficacy, but preferences were more sensitive to administration frequency than small changes in annual bleeding rate.

Assessment of the impact of treatment on quality of life of patients with haemophilia A at different ages: insights from two clinical trials on turoctocog alfa

Haemophilia and its treatment interfere with patients' life, so health-related quality of life (HRQoL) should be assessed when evaluating treatments. This study investigated the HRQoL of patients with haemophilia A treated prophylactically with a new recombinant factor VIII. Two phase 3 trials investigated turoctocog alfa in patients with severe haemophilia A: one in children, one in adults and adolescents. HRQoL was a secondary endpoint assessed by the HAEMO-QOL age-specific, self-administered questionnaires. Parent-completed versions were also included for parents of children and adolescents. All HAEMO-QOL questionnaires allow the calculation of domain-specific and total scores ranging from 0 to 100, lower scores indicating better HRQoL. Mean change in all scores was described for 25 children aged 4-7 years, 21 children aged 8-12 years, 18 adolescents aged 13-18 years and 129 adults, overall, and according to the treatment regimen received prior to the study (on-demand; prophylaxis; mixed). Mean changes in HAEMO-QOL total score were 1.4 for children aged 4-7 years, -2.6 for children aged 8-12 years, -5.8 for adolescents and -1.6 for adults. In parent-completed versions, mean changes in total score were -6.0 for children aged 4-7 years, -4.7 for children aged 8-12 years, and -10.0 for adolescents. Patients receiving on-demand treatment before the trial showed greater improvement in HRQoL scores than patients already on prophylaxis. HRQoL of patients remained fairly stable over the course of the trials. However, improvements were observed for adolescents. Switching to prophylaxis was identified as a potential driver of improvement of HRQoL in patients with haemophilia A.

A novel B-domain O-glycoPEGylated FVIII (N8-GP) demonstrates full efficacy and prolonged effect in hemophilic mice models

Frequent infusions of intravenous factor VIII (FVIII) are required to prevent bleeding associated with hemophilia A. To reduce the treatment burden, recombinant FVIII with a longer half-life was developed without changing the protein structure. FVIII-polyethylene glycol (PEG) conjugates were prepared using an enzymatic process coupling PEG (ranging from 10 to 80 kDa) selectively to a unique O-linked glycan in the FVIII B-domain. Binding to von Willebrand factor (VWF) was maintained for all conjugates. Upon cleavage by thrombin, the B-domain and the associated PEG were released, generating activated FVIII (FVIIIa) with the same primary structure and specific activity as native FVIIIa. In both FVIII- and VWF-deficient mice, the half-life was found to increase with the size of PEG. In vivo potency and efficacy of FVIII conjugated with a 40-kDa PEG (N8-GP) and unmodified FVIII were not different. N8-GP had a longer duration of effect in FVIII-deficient mouse models, approximately a twofold prolonged half-life in mice, rabbits, and cynomolgus monkeys; however, the prolongation was less pronounced in rats. Binding capacity of N8-GP on human monocyte-derived dendritic cells was reduced compared with unmodified FVIII, resulting in several-fold reduced cellular uptake. In conclusion, N8-GP has the potential to offer efficacious prevention and treatment of bleeds in hemophilia A at reduced dosing frequency.

Safety and prolonged activity of recombinant factor VIII Fc fusion protein in hemophilia A patients

Current factor VIII (FVIII) products display a half-life (t(1/2)) of ∼ 8-12 hours, requiring frequent intravenous injections for prophylaxis and treatment of patients with hemophilia A. rFVIIIFc is a recombinant fusion protein composed of a single molecule of FVIII covalently linked to the Fc domain of human IgG(1) to extend circulating rFVIII t(1/2). This first-in-human study in previously treated subjects with severe hemophilia A investigated safety and pharmacokinetics of rFVIIIFc. Sixteen subjects received a single dose of rFVIII at 25 or 65 IU/kg followed by an equal dose of rFVIIIFc. Most adverse events were unrelated to study drug. None of the study subjects developed anti-rFVIIIFc antibodies or inhibitors. Across dose levels, compared with rFVIII, rFVIIIFc showed 1.54- to 1.70-fold longer elimination t(1/2), 1.49- to 1.56-fold lower clearance, and 1.48- to 1.56-fold higher total systemic exposure. rFVIII and rFVIIIFc had comparable dose-dependent peak plasma concentrations and recoveries. Time to 1% FVIII activity above baseline was ∼ 1.53- to 1.68-fold longer than rFVIII across dose levels. Each subject showed prolonged exposure to rFVIIIFc relative to rFVIII. Thus, rFVIIIFc may offer a viable therapeutic approach to achieve prolonged hemostatic protection and less frequent dosing in patients with hemophilia A. This trial was registered at www.clinicaltrials.gov as NCT01027377.

Ectopic platelet-delivered factor (F) VIII for the treatment of Hemophilia A: Plasma and platelet FVIII, is it all the same?

Hemophilia A is the most common inherited bleeding diathesis and is due to a deficiency of functional coagulation factor (F) VIII. Most patients have a severe deficiency and require a program of prophylactic plus acute infusions of recombinant FVIII to prevent significant joint and other target organ damage. One of the greatest challenges remaining in the care of these patients is that one fifth to third of the patients develop inhibitors to the infused proteins. While a significant portion of such inhibitors can be either overcome or the inhibitors eliminated, some patients with persistent and significant titers of inhibitors need to rely on second tier therapies that are not as effective at preventing significant bleeding morbidity or mortality. A number of groups have been developing therapeutic strategies for FVIII gene therapy for this disorder. Virtually all of these therapies have in common a rise in the plasma level of FVIII, and interpretation of their efficacy is straightforward related to levels achieved. However, several groups have also shown that FVIII can be ectopically expressed in developing megakaryocytes, where although plasma FVIII levels remain undetectable, this FVIII can be released and be effective at sites of platelet activation. Moreover, it is clear that this platelet (p) FVIII is protected to a degree from inhibitors, making pFVIII a particularly attractive strategy for gene therapy for hemophilia A. Yet at the same time, we have shown that pFVIII has a different availability and distribution in a growing thrombus than plasma FVIII. The clinical implications and challenges of these findings as murine and canine hemophilia A preclinical studies go forward with pFVIII are discussed.

Haemophilia and joint disease: pathophysiology, evaluation, and management

In patients with haemophilia, regular replacement therapy with clotting factor concentrates (prophylaxis) is effective in preventing recurrent bleeding episodes into joints and muscles. However, despite this success, intra-articular and intramuscular bleeding is still a major clinical manifestation of the disease. Bleeding most commonly occurs in the knees, elbows, and ankles, and is often evident from early childhood. The pathogenesis of haemophilic arthropathy is multifactorial, with changes occurring in the synovium, bone, cartilage, and blood vessels. Recurrent joint bleeding causes synovial proliferation and inflammation (haemophilic synovitis) that contribute to end-stage degeneration (haemophilic arthropathy); with pain and limitation of motion severely affecting patients' quality of life. If joint bleeding is not treated adequately, it tends to recur, resulting in a vicious cycle that must be broken to prevent the development of chronic synovitis and degenerative arthritis. Effective prevention and management of haemophilic arthropathy includes the use of early, aggressive prophylaxis with factor replacement therapies, as well as elective procedures, including restorative physical therapy, analgesia, aspiration, synovectomy, and orthopaedic surgery. Optimal treatment of patients with haemophilia requires a multidisciplinary team comprising a haematologist, physiotherapist, orthopaedic practitioner, rehabilitation physician, occupational therapist, psychologist, social workers, and nurses. Journal of Comorbidity 2011;1:51-59.

Gene therapy for haemophilia: prospects and challenges to prevent or reverse inhibitor formation

Monogenic hereditary diseases, such as haemophilia A and B, are ideal targets for gene therapeutic approaches. While these diseases can be treated with protein therapeutics, such as factor VIII (FVIII) or IX (FIX), the notion that permanent transfer of the genes encoding these factors can cure haemophilia is very attractive. An underlying problem with a gene therapy approach, however, is the patient's immune response to the therapeutic protein (as well as to the transmission vector), leading to the formation of inhibitory antibodies. Even more daunting is reversing an existing immune response in patients with pre-existing inhibitors. In this review, we will describe the laboratory and clinical progress, and the challenges met thus far, in achieving the goal of gene therapy efficacy, with a focus on the goal of tolerance induction.

Secondary prophylaxis in adolescent and adult haemophiliacs

Progressive arthropathy of large joints of the limbs (knees, ankles, elbows), resulting from recurrent joint bleeds and subsequent long-term degenerative phenomena, is one of the main causes of morbidity and of deterioration of quality of life in adult severe hemophiliacs. While primary prophylaxis (i.e. the regular continuous long-term infusion of factor concentrates started before the age of two years and/or after no more than one joint bleed) is nowadays considered the gold standard for preserving joint function in patients with severe haemophilia, the benefits of secondary prophylaxis (i.e., all the long-term regular treatments not fulfilling the criteria of primary prophylaxis) are still controversial. In this review we present the literature data on secondary prophylaxis, focusing on adolescent and adults haemophiliacs along with clinical experience in Italy. On the whole, the more recently published studies suggest the effectiveness of early and delayed secondary prophylaxis. However, a number of questions are still unanswered, including the optimal dose, dosing interval and duration of secondary prophylaxis. Only large, prospective, long-term, possibly randomized studies will help to definitively assess the clinical impact of this strategy in adolescent and adult hemophiliacs.