A consensus statement on clinical trials of bypassing agent prophylaxis in inhibitor patients

Summary. The haemophilia literature increasingly contains reports describing the use of bypassing agent prophylaxis (BAP) in patients with severe haemophilia A and inhibitors. However, it is difficult to interpret and compare the results and draw conclusions about treatment efficacy because of small patient numbers and a lack of standardization among BAP studies. This article presents consensus recommendations for standardizing future BAP clinical trials developed by an international panel of haemophilia opinion leaders.     

Value of prophylaxis vs on‐demand treatment: Application of a value framework in hemophilia

Introduction

Therapeutic advances over the past 30 years have led to longer life expectancy and improved quality of life (QOL) for persons with hemophilia. Access to innovative therapy may be compromised if treatment decisions are driven solely by cost. New strategies are needed to assess true therapeutic values, along with financial cost, as physicians, policymakers, payers and manufacturers work together to improve patient care.

Aim

To provide an evidence‐based assessment of the value of prophylaxis vs on‐demand therapy for hemophilia, based on a widely recognized three‐tiered value framework approach for assessing a range of therapeutic interventions.

Methods

Data from six randomized clinical trials (ESPRIT, Joint Outcomes Study, SPINART, LEOPOLD II, ADVATE and POTTER) and four observational studies comparing primary and secondary prophylaxis vs on‐demand therapy were applied to a hemophilia value framework.

Results

Both primary and secondary prophylaxis showed advantages in Tier 1 “Degree of health/recovery” outcomes, including measures of bleeding, musculoskeletal complications, pain, function/activity and QOL. Tier 2 “Process of Recovery” outcomes, also favoured prophylaxis, including measures of recovery time, return to normal activities, orthopaedic intervention and venous access. In Tier 3 “Sustainability of Health Recovery,” measures of breakthrough bleeds, joint preservation, sustained productivity and QOL showed significant improvement with prophylaxis.

Conclusion

The hemophilia value framework affirmed value of primary and secondary prophylaxis vs on‐demand therapy, with clinical benefit demonstrated in all three tiers. This analysis also demonstrates clinical utility of the value framework process in the determination of optimal and cost‐effective hemophilia care for all stakeholders.     

Recombinant activated factor VII (rFVIIa/NovoSeven) in intractable haemorrhage: use of a clinical scoring system to predict outcome

BACKGROUND AND OBJECTIVES: Recombinant activated factor VII (rFVIIa/NovoSeven) has been advocated in the treatment of life-threatening haemorrhage, but appropriate clinical indications remain uncertain. The aim of this study was to detect factors predictive of outcome and to incorporate them into a prognostically significant scoring system. MATERIALS AND METHODS: Thirty-six patients received rFVIIa for uncontrolled surgical, traumatic or obstetric bleeding in the Northern Region of the UK over a 45-month period. Clinical, laboratory and outcome data were examined. Characteristics of survivor and non-survivor groups were compared. A prognostic scoring system was evaluated retrospectively according to the presence of coagulopathy, renal impairment, hypothermia, greater than 10 units of red cell transfusion, advanced age and obstetric indication, with patients allocated to low, intermediate and high-risk groups. RESULTS: Clinical response occurred in 26 patients (72%) with a reduction in prothrombin time and blood product requirements. Death occurred in 19 (53%). Four patients (11%) suffered thrombotic events. Survivors were younger than non-survivors and less likely to have coagulopathy, renal impairment or hypothermia at the time of administration. Survivors were more likely to have had an initial clinical response in terms of an immediate reduction in haemorrhage. Non-survivors were transfused a greater number of red cell units prior to administration. Survival varied according to prognostic score; low-risk patients had a survival rate of 85%, intermediate-risk patients had a survival rate of 50% and high-risk patients had a survival rate of 18%. CONCLUSIONS: FVIIa has a role in the cessation of haemorrhage, but may not improve survival. Use of a clinical scoring system may help to predict outcome.     

Parallel use of by-passing agents in haemophilia with inhibitors: a critical review

In the absence of new outbreaks of transfusion-related infections, the occurrence of neutralizing antibodies currently remains the most prominent complication in haemophilia. Coagulation factor products that may circumvent the inadequate activation of factor X in classical haemophilia, often referred to as bypassing agents, have demonstrated a high degree of efficacy. A smaller number of patients have been described in whom either bypassing agent, or both, demonstrate diminished efficacy. In those cases, the use of both bypassing agents in parallel was attempted, either using simultaneous (combined) or alternating (sequential) infusion of the two drugs, reportedly with successful haemostasis. We speculated whether such treatment might cause thromboembolism. A thorough literature search disclosed 17 reports regarding the parallel use of bypassing agents in the same bleeding episode in 49 patients; reporting nine patients with acquired haemophilia and forty patients with congenital haemophilia with inhibitors. Notable incidences of thromboembolic manifestations were observed: in nine patients with acquired haemophilia, five and in 40 patients with congenital haemophilia five suffered from significant thrombotic complications, and overall four cases were fatal. Although efficacy of parallel treatment was reported excellent in most cases, thromboembolism is rare in haemophilia and parallel treatment with activated prothrombin complex concentrate and activated recombinant human factor VII appears to increase the risk of thrombosis in these patients.     

Prediction of the haemostatic effects of bypassing therapy using comprehensive coagulation assays in emicizumab prophylaxis-treated haemophilia A patients with inhibitors

In emicizumab prophylaxis, the concomitant therapy using bypassing agents (BPAs) is required for breakthrough bleeding and invasive procedures with attention to thrombotic complications. To predict coagulant effects of BPAs in emicizumab-treated patients with haemophilia A (PwHA) with inhibitor (PwHAwI), blood samples from emicizumab-treated PwHAwI (n = 8) and PwHA without inhibitor (n = 2) in phase 1/2 and HAVEN 1 study, spiked with activated prothrombin complex concentrates (aPCC) or recombinant factor VIIa (rFVIIa) ex vivo, and blood samples from emicizumab-treated PwHAwI-receiving BPAs were analysed by Ca²⁺-triggered rotational thromboelastometry (ROTEM) and ellagic acid/tissue factor-triggered clot waveform analysis (CWA). Spiked aPCC, corresponded to 10–100 U/kg, markedly shortened ROTEM parameters beyond the normal range, while spiked rFVIIa, corresponded to 90–270 μg/kg, shortened them within near-normal range. Each of the spiked BPA-improved adjusted maximum coagulation velocity of CWA to within or near the normal range. In blood samples at post-infusion of aPCC (44–73 U/kg) or rFVIIa (79–93 μg/kg), the parameters of both assays improved to approximately the normal range. Taken together, ex vivo results of spiking tests in ROTEM and CWA, except aPCC spiking test in ROTEM, were relatively consistent with in vivo ones, and could usefully predict the coagulant effects of concomitant bypassing therapy for emicizumab-treated PwHAwI.     

Cost‐effectiveness of recombinant activated factor VII vs. plasma‐derived activated prothrombin complex concentrate in the treatment of mild‐to‐moderate bleeding episodes in patients with severe haemophilia A and inhibitors in Spain

Several analyses have shown that recombinant activated factor VII (rFVIIa) is a cost‐effective intervention compared with plasma‐derived activated prothrombin complex concentrate (pd‐aPCC) for the on‐demand treatment of mild‐to‐moderate bleeds in haemophilia patients with inhibitors. The aim of the study was to assess the cost‐effectiveness of rFVIIa vs. pd‐aPCC in the treatment of bleeding episodes in severe haemophilia A patients with inhibitors in Spain. A decision analytic model was designed to evaluate the costs and clinical outcomes of using rFVIIa or pd‐aPCC to treat mild‐to‐moderate joint bleeds in children (≤14 years old) and adults with inhibitors. Data were obtained from a published meta‐analysis and a panel of haemophilia experts. The analysis was conducted from the perspective of the Spanish National Healthcare System. One‐way sensitivity analyses were performed to assess the impact of model assumptions on study results. In the Treur meta‐analysis, rFVIIa resulted in cumulative joint bleed resolution of 88% and 95% after 24 and 36 h, respectively, compared with 62% and 76%, respectively, with pd‐aPCC (Treur et al. Haemophilia 2009; 15 : 420–36). Here, the mean cost per bleed was estimated at €8473 and €15 579 in children and adults treated with rFVIIa, vs. €8627 and €15 677 in children and adults treated with pd‐aPCC. rFVIIa treatment was found to be the dominating option (cheaper and more effective). The one‐way sensitivity analysis also confirmed that rFVIIa was less costly than pd‐aPCC. The model suggests that rFVIIa is a cost‐effective option compared with pd‐aPCC for the treatment of mild‐to‐moderate bleeding episodes in a Spanish setting.     

Assessment of individual dose utilization vs. physician prescribing recommendations for recombinant activated factor VII (rFVIIa) in paediatric and adult patients with congenital haemophilia and alloantibody inhibitors (CHwI): the Dosing Observational Study in Hemophilia (DOSE)

Recent data from the Dosing Observational Study in Hemophilia diary study has described home treatment with recombinant activated factor VII (rFVIIa) in congenital haemophilia with inhibitors (CHwI). The current analysis compares prescribed and patient/caregiver‐reported rFVIIa administration in paediatric and adult CHwI patients in this study. Patients with ≥4 bleeding episodes within a 3‐month period prescribed rFVIIa as first‐line therapy for bleeding episodes were eligible. Patients/caregivers completed a diary for ≥90 days or until the patient experienced four bleeds. Initial, total and mean rFVIIa doses reported for each bleeding episode were calculated and compared with the physician‐prescribed doses. Of 52 enrolled patients (25 children; 27 adults), 39 (75%) completed the study. Children and adults had similar mean durations of bleeding episodes. Both patient groups were administered higher initial rFVIIa doses for joint bleeds than prescribed: median (range) 215.2 (74.1–400.0) mcg kg^?1 vs. 200.0 (61.0–270.0) mcg kg^?1 for children, and 231.3 (59.3–379.7) mcg kg^?1 vs. 123.0 (81.0–289.0) mcg kg^?1 for adults. The median infused dose for joint bleeds was higher in adults than children (175.2 vs. 148.0 mcg kg^?1), but children received significantly more doses per joint bleed than adults (median 6.5 vs. 3.0). The median total dose per joint bleed was higher in children than adults (1248.7 vs. 441.6). For children and adults, both initial and additional doses administered for bleeds were higher than prescribed. Children received higher total doses per bleed due to an increased number of infusions per bleed.     

Results of the WIRK prospective,non‐interventional observational study of recombinant activated factor VII (rFVIIa) in patients with congenital haemophilia with inhibitors and other bleeding disorders

Recombinant activated factor VII (rFVIIa) has been available for the treatment of acute bleeding and for prevention of bleeding during surgery and invasive procedures in patients with congenital haemophilia with inhibitors (CHwI) and acquired haemophilia since 1996. The study objective was to assess the efficacy and safety of rFVIIa in patients with CHwI, acquired haemophilia, congenital FVII deficiency and Glanzmann's thrombasthenia, in a real‐life clinical setting. There were no specific inclusion or exclusion criteria; participation was offered to all German haemophilia centres known to use rFVIIa to treat patients with the above indications. Data on rFVIIa use and efficacy for the treatment of acute bleeding episodes and invasive procedures were recorded. Adverse drug reactions and recurrent bleeding episodes were also monitored. In total, 64 patients (50.0% women) received rFVIIa treatment. Patients experienced 281 evaluable bleeding episodes and underwent 44 invasive procedures. In 252 of 281 (89.7%) bleeding episodes, a stop (66.5%) or a significant reduction (23.1%) in bleeding was observed. No bleeding complications were reported for 42 of 44 (95.5%) invasive procedures covered with rFVIIa. A clear positive association was observed between early initiation of rFVIIa treatment for acute bleeding and efficacy. The total cumulative dose and number of injections were 468.3 ± 545.8 μg kg^?1 and 3.6 ± 4.6 respectively. No drug‐related adverse events were reported. rFVIIa use in Germany provided effective haemostatic cover without associated adverse events in the management of acute bleeds and invasive procedures across a range of bleeding disorders.     

Pharmacokinetics of activated recombinant coagulation factor VII (NovoSeven®) in children vs. adults with haemophilia A

To establish the pharmacokinetic profile of activated recombinant coagulation factor VII (rFVIIa; NovoSeven in children with haemophilia A, and to compare it with the pharmacokinetic profile in adults with haemophilia A. Twelve children (2-12 years) received one single dose of rFVIIa 90 and 180 micrograms kg(-1) in randomized order separated by a washout period of 48 h to 1 month. Six adults (18-55 years) received a single dose of rFVIIa 90 micrograms kg(-1). The pharmacokinetic analyses were based on a non-compartmental method. In children, the plasma level of FVII increased proportionally with the dose. The total body clearance normalized for body weight was significantly faster in children than in adults (FVII:C, 58 vs. 39 mL kg(-1) h(-1) and FVIIa, 78 vs. 53 mL kg(-1) h(-1), P < 0.05). A trend towards a larger volume of distribution at steady-state in children than in adults was observed (P > 0.05). Dose proportionality was established for plasma concentrations of FVII in children with haemophilia A at the dose levels investigated (90 and 180 micrograms kg(-1) rFVIIa). Following administration of rFVIIa 90 micrograms kg(-1), significantly faster clearance was observed in children compared with adults, suggesting that higher doses of rFVIIa may be needed to achieve the same plasma levels as in adults.     

Recombinant activated factor VII safety and efficacy in the treatment of cranial haemorrhage in patients with congenital haemophilia with inhibitors: an analysis of the Hemophilia and Thrombosis Research Society Registry (2004–2008)

Summary. Cranial haemorrhage (CH) is a potentially serious complication in patients with severe congenital haemophilia with inhibitors (CHwI). Treatment includes bypassing agents, such as recombinant activated factor VII (rFVIIa). To examine the US experience in treating CH with rFVIIa, a retrospective review of the Hemophilia and Thrombosis Research Society 2004–2008 database was conducted. Among 29 patients with CHwI, 56 of the reported haemorrhages met the study criteria. Of these, 75% were traumatic and 80% were extracranial (ECH). The majority (8/11, 73%) of intracranial haemorrhages (ICHs) developed spontaneously. Conversely, most ECHs (39/45, 87%) followed trauma. ICHs were treated with a median/mean of 23/58 rFVIIa infusions over a median/mean of 7/9 days while ECHs were treated with a median/mean of 1/3 infusions (P = 0.011) over a median/mean of 1/1 day. The median/mean initial rFVIIa doses for all CHs were 106/137 μg kg⁻¹, and were similar for ICHs and ECHs. All ECHs were effectively controlled with rFVIIa; 44/45 bleeds were controlled within 24 h, one bleed was successfully treated perioperatively, and 27 ECHs required only a single dose. Nine out of 11 ICHs were effectively treated with rFVIIa; six ICHs were controlled within 24 h, one within 72 h and in two cases haemostasis was achieved during the perioperative period. No serious treatment‐associated adverse events were reported. One patient died as a result of ICH despite the reported control of bleeding. In conclusion, standard dosing of rFVIIa was found to be safe and effective in treating CH with an efficacy rate of 100% for ECH and 82% for ICH.     

Consensus protocol for the use of recombinant activated factor VII [eptacog alfa (activated); NovoSeven®] in elective orthopaedic surgery in haemophilic patients with inhibitors

Summary.  Patients with haemophilia complicated by inhibitors have a significant burden of joint disease, which is associated with a negative impact on their quality of life. Successful elective orthopaedic surgery can result in decreased bleed frequency into a new joint, less time spent in hospital, increased mobility and improved well being. This paper describes a new protocol for use of recombinant activated factor VII (rFVIIa) in elective orthopaedic surgery, based on a review of published data as well as the personal experience of a group of expert physicians. The protocol offers guidance on the planning of the surgery and preoperative testing as well as the bolus schedule for rFVIIa and advice on the concomitant use of antifibrinolytic agents and fibrin sealants. A total of 10 operations involving 13 procedures in eight patients in five comprehensive care centres have been undertaken until now using the protocol, which employs an initial bolus dose of rFVIIa in the range of 120–180 μg kg⁻¹ to cover surgery. The clinical experience reported here encompasses all cases of elective orthopaedic surgery using rFVIIa as initial treatment carried out in the UK and Republic of Ireland over the last 2 years. In all cases, there was good control of haemostasis during surgery and the final outcome was rated as 'excellent' or 'extremely satisfactory' by the reporting clinicians. Although the initial cost of product to cover surgery such as arthroplasty is high, it needs to be borne in mind that this may be offset in subsequent years by savings resulting from avoidance of bleeding episodes in the affected joint.     

Single 270 μg kg−1-dose rFVIIa vs. standard 90 μg kg−1-dose rFVIIa and APCC for home treatment of joint bleeds in haemophilia patients with inhibitors: a randomized comparison

Summary. Evidence suggests greater doses of recombinant activated factor VII (rFVIIa; NovoSeven^®, Novo Nordisk A/S, Bagsværd, Denmark) than currently administered may result in enhanced haemostasis and convenience for patients with haemophilia A and B with inhibitors. This study evaluated efficacy and safety of rFVIIa and an activated prothrombin complex concentrate (APCC; Factor Eight Inhibitor Bypassing Activity [FEIBA]^®, Baxter AG, Vienna, Austria) for controlling joint bleeds in a home‐treatment setting. Patients received each of three treatments in one of six possible sequences: 270 μg kg^?1 rFVIIa at hour 0 + placebo at hours 3 and 6, 90 μg kg^?1 rFVIIa at hours 0, 3 and 6, and 75 U kg^?1 APCC at hour 0. Efficacy was assessed by the requirement for additional haemostatics within 9 h and by a novel global response algorithm. The percentage of rFVIIa 270 μg kg^?1 group patients requiring additional haemostatics within 9 h (8.3%) was significantly lower than that for the APCC group (36.4%, P = 0.032). The percentage of rFVIIa 90 × 3 μg kg^?1 group patients requiring such rescue medication (9.1%) was also lower compared to the APCC group. This result approached, but did not reach statistical significance (P = 0.069). Both rFVIIa treatment groups showed similar use of rescue medication (8.3% and 9.1% of episodes for rFVIIa 270 μg kg^?1 and rFVIIa 90 × 3 μg kg^?1 groups respectively). No significant differences in treatment response were observed with the global response algorithm (P = 0.173). No safety issues were identified. A single dose of rFVIIa 270 μg kg^?1 is as safe and effective as rFVIIa 90 × 3 μg kg^?1 dosing, and may be considered a potentially more effective alternative to APCCs for the management of joint bleeding in this population.     

Real‐world experience with use of Antihemophilic Factor (Recombinant), PEGylated for prophylaxis in severe haemophilia A

Introduction

Prophylaxis with extended half‐life factor VIII (FVIII) is approved for haemophilia A, but data regarding routine clinical use are limited.

Aim

To assess real‐world experience of ADYNOVATE^® (Antihemophilic Factor (Recombinant), PEGylated prophylaxis in children and adults with haemophilia A.

Methods

A retrospective chart review was conducted in three US haemophilia treatment centres. Records of all patients who began Adynovate prophylaxis in routine clinical practice were identified. Demographic, clinical and patient‐reported information beginning 6 months before initiation of Adynovate until the record review was analysed.

Results

Fifteen patients (aged 9 months to 28 years), with median 9 months’ use of Adynovate (range 1‐15 months), were identified. All had switched from another prophylactic regimen, 13 (87%) from standard half‐life recombinant FVIII. Nine (60%) patients had ≥1 bleed within 6 months preswitch. The most frequent reason for switching was to reduce infusion frequency (14 patients). After switching, infusion frequency reduced for 13 patients, and overall weekly factor consumption decreased by 19%. Eight (53%) patients had no bleeds postswitch, three (20%) had spontaneous joint bleeds (vs four pre‐switch), and three (20%) had only mild traumatic bleeds. Patient/parental satisfaction with Adynovate was documented as positive in 13 of 15 (87%) cases; 2 patients were not satisfied and discontinued Adynovate. No adverse events were considered related to Adynovate.

Conclusion

In patients who switched from a standard half‐life FVIII to Adynovate prophylaxis in routine clinical practice, bleeding control was generally improved or maintained, with a lower infusion frequency and factor consumption in most patients.