Multicentre, randomized, open-label study of on-demand treatment with two prophylaxis regimens of recombinant coagulation factor IX in haemophilia B subjects

Prophylaxis with recombinant factor IX Fc fusion protein reduces the risk of bleeding and delays time to first spontaneous bleed event in previously untreated patients with haemophilia B: A post hoc analysis of the PUPs B-LONG study

OBJECTIVES

Haemophilia B (HB), characterised by deficient factor IX (FIX), leads to spontaneous bleeds. Severe cases require prophylactic FIX replacement. This post hoc analysis assessed the first spontaneous bleeds among previously untreated patients (PUPs) with HB treated with recombinant FIX Fc fusion protein (rFIXFc) (NCT02234310) to identify factors influencing bleeds.

METHODS

Subjects included paediatric PUPs with HB (≤2 IU/dL endogenous FIX). Analyses described treatment patterns (on demand [OD] vs. prophylaxis) and prophylaxis type (started on vs. switched to prophylaxis). Kaplan-Meier analyses assessed the time to first spontaneous bleed, including median time to event and fitting models with predictors for treatment regimen and/or baseline age.

RESULTS

PUPs B-LONG enrolled 33 subjects. Baseline age did not influence the time to first spontaneous bleed for any rFIXFc regimen. Those who started on prophylaxis with rFIXFc (n = 11), compared with those treated OD (n = 22), had an extended time to first spontaneous bleed. Starting prophylaxis afforded a 93% reduced risk of first spontaneous bleed versus starting OD (hazard ratio [95% confidence interval]: 0.071 [0.009-0.592]) (p = .015).

CONCLUSION

rFIXFc prophylaxis, particularly starting early, reduced the risk of bleeding and delayed time to first spontaneous bleed compared with rFIXFc OD. Hence, initial treatment regimens impact bleed patterns in paediatric PUPs.

Cost-Effectiveness of Recombinant Factor IX Fc Prophylaxis and Recombinant Factor IX On-Demand Treatment in Patients with Haemophilia B Without Inhibitors

INTRODUCTION

Recombinant factor IX (rFIX) and recombinant FIX Fc fusion protein (rFIXFc) are standard half-life and extended half-life FIX replacement therapies, respectively, and represent established treatment options indicated for adults and children with haemophilia B. These FIX replacement therapies can be administered as prophylaxis (to prevent bleeding) or 'on-demand' (to stop bleeding). This analysis aimed to estimate the cost-effectiveness of once-weekly prophylaxis with rFIXFc versus on-demand treatment with rFIX in patients with haemophilia B without inhibitors in the Italian healthcare setting.

METHODS

A Markov model was developed to assess a hypothetical cohort of adolescent or adult male patients (≥ 12 years) with haemophilia B (FIX level of ≤ 2 IU/dL) without inhibitors. Model inputs were derived from the pivotal phase 3 clinical studies for rFIXFc and rFIX, published literature and assumptions when published data were unavailable. The model employed a lifelong time horizon with 6-monthly transitions between health states, and it estimated total costs, total quality-adjusted life years (QALYs), number of bleeds, number of surgeries and incremental cost-effectiveness ratio.

RESULTS

rFIXFc prophylaxis was associated with lower total costs per patient (€5,308,625 versus €6,564,510) and greater total QALYs per patient (15.936 versus 11.943) compared with rFIX on-demand; rFIXFc prophylaxis was therefore the dominant treatment strategy. The model also demonstrated that rFIXFc prophylaxis was associated with fewer incremental bleeds (- 682.29) and surgeries (- 0.39) compared with rFIX on-demand.

CONCLUSIONS

rFIXFc prophylaxis provides improved health outcomes and lower costs, and represents a cost-effective treatment option compared with rFIX on-demand for adolescent and adult male patients with haemophilia B. This comparative assessment of cost-effectiveness should help to inform both clinicians and healthcare policy makers when making treatment decisions for patients with haemophilia B.

Unresolved hemostasis issues in haemophilia

Despite rapid technological advancement in factor and nonfactor products in the prevention and treatment of bleeding in haemophilia patients, it is imperative that we acknowledge gaps in our understanding of how hemostasis is achieved. The authors will briefly review three unresolved issues in persons with haemophilia (PwH) focusing on the forgotten function that red blood cells play in hemostasis, the critical role of extravascular (outside circulation) FIX in hemostasis in the context of unmodified and extended half-life FIX products and finally on the role that skeletal muscle myosin plays in prothrombinase assembly and subsequent thrombin generation that could mitigate breakthrough muscle hematomas.

Cost-effectiveness analysis of recombinant factor IX Fc fusion protein compared with recombinant factor IX for the treatment of moderate-severe to severe hemophilia B in China

OBJECTIVE

To evaluate the lifetime cost-effectiveness of recombinant factor IX Fc fusion protein (rFIXFc) and recombinant factor IX (rFIX) for the treatment of hemophilia B (HB) in China.

METHODS

We developed a decision-analytic Markov model including three health states: alive, requiring surgery, and dead. This model estimated the lifetime cost and quality-adjusted life-years (QALYs) of prophylaxis in childhood, followed by on-demand treatment in adulthood for moderate-severe to severe HB patients from China's healthcare system perspective. Efficacy data derived from pivotal clinical trials, clinical guideline recommendations, and expert consultation were applied to two scenarios (full dose and low dose). One-way sensitivity analysis and probabilistic sensitivity analysis (PSA) were performed to assess the robustness of the model.

OUTCOMES

Lifetime cost, QALYs, and the incremental cost-effectiveness ratio were calculated, and the results were compared with willingness-to-pay (WTP) thresholds of one to three times the gross domestic product per capita of China in 2021 ($12,551-$37,653).

RESULTS

RFIXFc was associated with lower cost and more QALYs than rFIX in both scenarios, which suggested that it is a dominant strategy (more effective and cheaper) for moderate-severe to severe HB in China. In the full-dose scenario, rFIXFc saved more money and yielded more QALYs than in the low-dose scenario (low doses are the typical clinical reality in China). PSA demonstrated that rFIXFc had an over 90% probability of being cost-effective with full-dose and low-dose treatment at WTP thresholds of $12,551-$37,653.

CONCLUSIONS

Compared with rFIX, rFIXFc appears to be a cost-effective option for the lifetime management of moderate-severe to severe HB patients in China.

A phase 1b/2 clinical study of marstacimab, targeting human tissue factor pathway inhibitor, in haemophilia

A phase 1b/2, three-month study of marstacimab, a human monoclonal antibody targeting tissue factor pathway inhibitor (TFPI), was conducted in participants with haemophilia A or B, with or without inhibitors. Participants assigned to four cohorts received escalating weekly doses based on inhibitor status (without inhibitors: 300 mg, a single 300-mg loading dose with subsequent 150-mg doses, or 450 mg; with inhibitors: 300 mg). Safety outcomes were treatment-emergent adverse events (TEAEs), injection site reactions, clinical and laboratory parameter changes. Efficacy was assessed by annualised bleeding rates (ABRs). Pharmacokinetics and pharmacodynamics (PD) were also evaluated. Among 26 treated participants [haemophilia A without inhibitor, n = 16 (61.5%); haemophilia A with inhibitor, n = 7 (26.9%); haemophilia B, n = 3 (11.5%)], 24 completed the study. Overall, 80.8% experienced TEAEs. ABR during treatment was significantly reduced versus an external on-demand control group (p < 0.0001) and versus pretreatment ABR (p < 0.0001), with significant reductions observed across all dose cohorts. Marstacimab exposure generally increased in a dose-related manner, with steady-state concentration reached by day 57. Changes in pharmacodynamic biomarkers occurred across all dose cohorts. Marstacimab was safe and well tolerated. Clinically meaningful reductions in ABR and treatment-related changes for all PD biomarkers indicated effective targeting of TFPI. (Clinicaltrials.gov identifier, NCT02974855).

Revised terminal half-life of nonacog alfa as derived from extended sampling data: A real-world study involving 64 haemophilia B patients on nonacog alfa regular prophylaxis

BACKGROUND

Nonacog alfa, a standard half-life recombinant factor IX (FIX), is used as a prophylactic treatment in severe haemophilia B (SHB) patients. Its half-life determined in clinical studies involving a limited sampling (72 h) was shown to be rather short. In our clinical practice, we suspected that its half-life could have been underestimated.

OBJECTIVES

We aimed to evaluate nonacog alfa pharmacokinetics in real world clinical practice based on FIX levels in patients receiving prophylaxis.

METHODS

We retrospectively collected data on patients with SHB receiving prophylaxis from eight centres across France. The terminal half-life (THL), time to reach 5-2 IU/dl and FIX activity at 48, 72 and 96 h were derived by Bayesian estimations using NONMEM analysis.

RESULTS AND CONCLUSIONS

Infusion data (n = 455) were collected from 64 patients with SHB. The median THL measured in 92 pharmacokinetic (PK) studies was 43.4 h. In 26 patients ≤12 years of age, 51 PK studies showed a median time to reach 5 IU/dl of FIX of 70.5 h and a median time to reach 2 IU/dl of 121.5 h. In 38 patients 13-75 years of age, 41 PK studies showed a median time to reach 5 IU/dl of FIX of 92.0 h and a median time to reach 2 IU/dl of 167.5 h. Extending the sampling beyond 72 h makes it possible to observe a plateau, with FIX remaining between 2 and 5 IU/dl for several days and shows that the THL of nonacog alfa might be longer than previously described.

ESSENTIALS

Nonacog alfa terminal half-life (THL) in patients receiving regular prophylaxis was evaluated in clinical practice. The median THL was estimated to be 36.9 h for patients aged .8-12 years. The median THL was estimated to be 49.9 h for patients aged 13-75 years. For patients aged ≤12 and >12 years, the median times to reach 5 IU/dl were 70.5 and 92 h, respectively; to reach 3 IU/dl, 95.5 and 131.5 h, respectively; to reach 2 IU/dl, 121.5 and 167.5 h, respectively. We suggest that the half-life of nonacog alfa might be longer than previously described in both younger and older patients.

IDELVION: A Comprehensive Review of Clinical Trial and Real-World Data

Hemophilia B is a bleeding disorder caused by a deficiency of coagulation factor IX (FIX). Treatment with FIX replacement products can increase FIX activity levels to minimize or prevent bleeding events. However, frequent dosing with standard-acting FIX products can create a high treatment burden. Long-acting products have been developed to maintain bleed protection with extended dosing intervals. Recombinant factor IX–albumin fusion protein (rIX-FP) is a long-acting product indicated for the treatment and prophylaxis of bleeding events and perioperative management in adult and pediatric patients. This review outlines data from all previously treated patients in the Prophylaxis and On-Demand Treatment using Longer Half-Life rIX-FP (PROLONG-9FP) clinical trial program and summarizes real-world data evaluating the use of rIX-FP in routine clinical practice. In the PROLONG-9FP program, rIX-FP demonstrated effective hemostasis in all patients at dose regimens of up to 21 days in patients aged ≥ 18 years and up to 14 days in patients aged < 12 years. rIX-FP has a favorable pharmacokinetic profile and an excellent safety and tolerability profile. Extended dosing intervals with rIX-FP led to high levels of adherence and reduced consumption compared with other FIX therapies. Data from real-world practice are encouraging and reflect the results of the clinical trials.

Effects of replacement therapies with clotting factors in patients with hemophilia: A systematic review and meta-analysis

Background

Different prophylactic and episodic clotting factor treatments are used in the management of hemophilia. A summarize of the evidence is needed inform decision-making.

Objective

To compare the effects of factor replacement therapies in patients with hemophilia.

Methods

We performed a systematic search in PubMed, Central Cochrane Library, and Scopus. We included randomized controlled trials (RCTs) published up to December 2020, which compared different factor replacement therapies in patients with hemophilia. Random-effects meta-analyses were performed whenever possible. The certainty of the evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology. The study protocol was registered in PROSPERO (CRD42021225857).

Results

Nine RCTs were included in this review, of which six compared episodic with prophylactic treatment, all of them performed in patients with hemophilia A. Pooled results showed that, compared to the episodic treatment group, the annualized bleeding rate was lower in the low-dose prophylactic group (ratio of means [RM]: 0.27, 95% CI: 0.17 to 0.43), intermediate-dose prophylactic group (RM: 0.15, 95% CI: 0.07 to 0.36), and high-dose prophylactic group (RM: 0.07, 95% CI: 0.04 to 0.13). With significant difference between these subgroups (p = 0.003, I² = 82.9%). In addition, compared to the episodic treatment group, the annualized joint bleeding rate was lower in the low-dose prophylactic group (RM: 0.17, 95% CI: 0.06 to 0.43), intermediate-dose prophylactic group (RM of 0.14, 95% CI: 0.07 to 0.27), and high-dose prophylactic group (RM of 0.08, 95% CI: 0.04 to 0.16). Without significant subgroup differences. The certainty of the evidence was very low for all outcomes according to GRADE methodology. The other studies compared different types of clotting factor concentrates (CFCs), assessed pharmacokinetic prophylaxis, or compared different frequencies of medication administration.

Conclusions

Our results suggest that prophylactic treatment (at either low, intermediate, or high doses) is superior to episodic treatment for bleeding prevention. In patients with hemophilia A, the bleeding rate seems to have a dose-response effect. However, no study compared different doses of prophylactic treatment, and all results had a very low certainty of the evidence. Thus, future studies are needed to confirm these results and inform decision making.

Clotting factor concentrates for preventing bleeding and bleeding-related complications in previously treated individuals with haemophilia A or B

BACKGROUND

The hallmark of severe hemophilia (A or B) is recurrent bleeding into joints and soft tissues with progressive joint damage, despite on-demand treatment. Prophylaxis has long been used, but not universally adopted, because of medical, psychosocial, and cost controversies.

OBJECTIVES

To determine the effectiveness of clotting factor concentrate prophylaxis in managing previously-treated individuals with hemophilia A or B.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. In addition, we searched MEDLINE and Embase and online trial registries. Most recent search of Group's Coagulopathies Trials Register: 24 February 2021.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs evaluating people with hemophilia A or hemophilia B, who were previously treated with clotting factor concentrates to manage their hemophilia.

DATA COLLECTION AND ANALYSIS

Two authors independently reviewed trials for eligibility, assessed risk of bias and extracted data. The authors used the GRADE criteria to assess the certainty of the evidence.

MAIN RESULTS

Ten trials (including 608 participants) were eligible for inclusion. Eight of the trials (477 participants) had arms comparing two or more prophylactic regimens to one another and four of the trials (n = 258) compared prophylaxis to on-demand treatment (two trials had multiple arms and were included in both comparisons). Comparison of two or more prophylactic regimens For trials comparing one prophylaxis regimen to another, given the heterogeneity of the data, none of the data were pooled for this comparison. Considering the individual trials, three trials reported the primary outcome of joint bleeding, and none showed a dfference between dosing regimens (low-certainty evidence). For the secondary outcome of total bleeding events, prophylaxis with a twice-weekly regimen of FIX likely results in reduced total bleeds compared to a once-a-week regimen of the same dose, mean difference (MD) 11.2 (5.81 to 16.59) (one trial, 10 participants, low-certainty evidence). Transient low-titer anti-FVIII inhibitors were reported in one of the trials. Blood-transmitted infections were not identified. Other adverse events reported include hypersensitivity, oedema, and weight gain. These were, however, rare and unrelated to study drugs (very low-certainty evidence). Comparison of prophylactic and on-demand regimens Four of the trials (258 participants) had arms that compared prophylaxis to on-demand treatment. Prophylaxis may result in a large decrease in the number of joint bleeds compared to on-demand treatment, MD -30.34 (95% CI -46.95 to -13.73) (two trials, 164 participants, low-certainty evidence). One of these trials (84 participants) also reported the long-term effects of prophylaxis versus on-demand therapy showing improved joint function, quality of life, and pain; but no differences between groups in joint structure when assessed by magnetic resonance imaging (MRI). In one trial (84 participants) validated measures for joint health and pain assessment showed that prophylaxis likely improves joint health compared to an on-demand regimen with an estimated change difference of 0.94 points (95% CI 0.23 to 1.65) and improves total pain scores, MD -17.20 (95% CI -27.48 to -6.92 (moderate-certainty evidence). Two trials (131 participants) reported that prophylaxis likely results in a slight increase in adverse events, risk ratio 1.71 (1.24 to 2.37) (moderate-certainty evidence). No inhibitor development and blood-transmitted infections were identified. Overall, the certainty of the body of evidence was judged to be low because of different types of bias that could have altered the effect.   AUTHORS' CONCLUSIONS: There is evidence from RCTs that prophylaxis, as compared to on-demand treatment, may reduce bleeding frequency in previously-treated people with hemophilia. Prophylaxis may also improve joint function, pain and quality of life, even though this does not translate into a detectable improvement of articular damage when assessed by MRI.  When comparing two different prophylaxis regimens, no significant differences in terms of protection from bleeding were found. Dose optimization could, however, result in improved efficacy. Given the heterogeneity of the data, pooled estimates were not obtained for most comparisons.  Well-designed RCTs and prospective observational controlled studies with standardised definitions and measurements are needed to establish the optimal and most cost-effective treatment regimens.

Safety, Immunogenicity, and Hemostatic Efficacy of Nonacog Gamma in Patients With Severe or Moderately Severe Hemophilia B: A Continuation Study

This phase 3, prospective, open-label, multicenter, continuation study (NCT01286779) investigated the use of a recombinant factor IX (FIX), nonacog gamma (BAX 326, RIXUBIS^®) in patients with severe or moderately severe hemophilia B. The study population included 85 patients transitioning from a phase 1/3 pivotal study (NCT01174446), a pediatric study (NCT01488994), and 30 newly recruited patients, naïve to nonacog gamma. Patients received nonacog gamma as prophylaxis treatment (standard, modified or PK-tailored) or on-demand, as determined by the investigator. Treatment was assessed for safety, immunogenicity, hemostatic efficacy and consumption. In this study, after ≥100 exposure days, nonacog gamma resulted in no treatment-related serious adverse events, and no patients developed inhibitory antibodies to FIX. Nonacog gamma was efficacious at controlling bleeding episodes, with an 89.1% overall hemostatic efficacy rating of excellent or good, and 56% of bleeds resolved with one infusion. The annualized bleeding rate was considerably lower during prophylactic treatment (median ABR of 1.3 in 108 patients) than during on-demand treatment (median ABR of 16.5 in 13 patients). These results show that in previously treated patients and nonacog gamma-naïve patients, long-term use of nonacog gamma had acceptable safety and tolerability, and was efficacious as a prophylactic treatment for the management of bleeding episodes.

NCT01286779, EudraCT: 2010-022726-33

First open-label, single-arm, prospective study of real-world use of FIX replacement therapy in a predominantly pediatric hemophilia B population in China

BACKGROUND

Nonacog alfa (recombinant factor IX [FIX]) is approved in China for the control and prevention of bleeding events in patients with hemophilia B. This was the first study to assess prophylaxis and on-demand therapy with recombinant FIX replacement in a real-world setting in China. This study aimed to evaluate the safety and efficacy of nonacog alfa in Chinese patients with hemophilia B.

METHODS

In this open-label, multicenter study (clinicaltrials.gov identifier NCT02336178), patients received on-demand or prophylactic treatment with intravenous nonacog alfa for approximately 6 months or 50 exposure days, whichever occurred first. The primary safety outcome was medically important events (i.e., development of FIX inhibitors, allergic reactions, and thrombotic events). Key secondary efficacy outcomes included the annualized bleeding rate for on-demand treatment and prophylaxis, response to on-demand treatment, the number of infusions per bleeding event, and the number of breakthrough bleeding events within 48 hours of prophylaxis.

RESULTS

Seventy male patients (mean [standard deviation] age 7.8 [7.2] years) were enrolled (on-demand, n = 37; prophylaxis, n = 57 [24 patients were included in both groups]). Thirty-eight (54%) patients had up to 50 FIX exposure days before the study. The only medically important event was a transient low-titer FIX inhibitor (incidence 1.4%, 95% confidence interval, 0-7.7). The mean annualized bleeding rate was 26.3 for on-demand treatment and 6.5 for prophylaxis. A mean (standard deviation) of 1.5 (1.7) nonacog alfa infusions were given per bleeding episode; 78.8% of episodes resolved with 1 infusion. Response was "excellent" or "good" for 88% of the on-demand infusions. Twenty-three bleeding events (n = 11 patients) occurred within 48 hours of 2032 prophylaxis doses (1.13%).

CONCLUSION

In the real-world setting, nonacog alfa is safe and effective for on-demand treatment and for prophylaxis for patients with hemophilia B in China.

Real-world outcomes with recombinant factor IX Fc fusion protein (rFIXFc) prophylaxis: Longitudinal follow-up in a national adult cohort

INTRODUCTION

In 2017, all people with severe haemophilia B (PWSHB) in Ireland switched from standard half-life (SHL) recombinant FIX (rFIX) to rFIX Fc fusion protein (rFIXFc) prophylaxis.

AIMS

To evaluate prophylaxis regimens, bleeding rates and factor usage for two years of rFIXFc prophylaxis in a real-world setting.

METHODS

Data collected retrospectively from electronic diaries and medical records of PWSHB for a two-year period on rFIXFc prophylaxis were compared with paired baseline data on SHL rFIX treatment.

RESULTS

28 PWSHB (≥18 years) were enrolled, and at switchover 79% were receiving prophylaxis and 21% episodic treatment with SHL rFIX. At 24 months following switchover, all remained on rFIXFc prophylaxis with reduced infusion frequency; median dose per infusion once weekly (55 IU/kg, 20/28), every 10 days (63 IU/kg, 2/28) or every 14 days (98 IU/kg, 6/28). Median annualised bleed rate improved significantly on rFIXFc prophylaxis (2.0 versus 3.3 on SHL FIX) (p = 0.01). Median FIX trough level with once-weekly infusions was 0.09 IU/ml (0.06-0.14 IU/ml). Management of bleeding episodes was similar with rFIXFc and SHL rFIX; one infusion was sufficient to treat 74% and 77% of bleeds, respectively, with similar total median treatment per bleeding episode. Factor consumption reduced by 28% with rFIXFc prophylaxis (57 IU/kg/week, range 40-86 IU/kg/week) compared with SHL rFIX (79 IU/kg/week, range 44-210 IU/kg/week) (p = 0.002).

CONCLUSION

This study provides important insights into real-world experience of switching to rFIXFc prophylaxis in an adult population, demonstrating high rates of prophylaxis, with reduced infusion frequency, bleeding and FIX consumption.

The Cost-effectiveness of Gene Therapy for Severe Hemophilia B: Microsimulation Study from the United States Perspective

Adeno-associated virus (AAV)-mediated gene therapy is a novel treatment promising to reduce morbidity associated with hemophilia. While multiple clinical trials continue to evaluate efficacy and safety, limited cost-effectiveness data have been published. This study compared the potential cost-effectiveness of AAV-mediated factor IX(FIX)-Padua gene therapy for severe hemophilia B patients in the United States (US) to on-demand FIX replacement and primary FIX prophylaxis, using either standard or extended half-life FIX products. A microsimulation Markov model was constructed and transition probabilities between health states and utilities were informed by published data. Costs were aggregated using a micro-costing approach. An 18-years-old till death time-horizon from the perspective of a third-party payer in the US was conducted. Gene therapy was more cost-effective than both alternatives considering a $150,000/QALY threshold. The price for gene therapy was assumed $2,000,000 in the base-case scenario, yet one of the one-way sensitivity analyses was conducted using observed manufacturing, administration and five-year follow-up cost of $87,198 for AAV-mediated gene therapy vector as derived from the manufacturing facility and clinical practice at St. Jude Children's Research Hospital. One-way sensitivity analyses showed 10/102 scenarios in which gene therapy was not cost-effective compared to alternative treatments. Notably, gene therapy remained cost-effective in a hypothetical scenario in which we estimated that the discounted factor concentrate price was 20% of the wholesale acquisition cost in the US. Probabilistic sensitivity analysis estimated gene therapy cost-effective at 92% of simulations considering $150,000/QALY threshold. In conclusion, based on detailed simulation inputs and assumptions, gene therapy was more cost-effective than on-demand treatment and prophylaxis for patients with severe hemophilia B.

Once-weekly prophylaxis regimen of nonacog alfa in patients with hemophilia B: an analysis of timing of bleeding event onset

In a pivotal, multicenter, open-label study, 25 patients aged 12-54 years with moderately severe/severe hemophilia B received on-demand nonacog alfa (6 months; dose at investigator's discretion) followed by once-weekly prophylaxis with nonacog alfa 100 IU/kg (12 months). During prophylaxis, patients had a median spontaneous annualized bleeding rate (sABR) of 1.0 and significant reductions in ABR (P < 0.0001). This post hoc analysis examined the time of onset of spontaneous bleeding events (sBEs) and spontaneous target joint bleeding events (sTJBEs). The postdosing day (D) of onset of sBEs observed during prophylaxis and steady-state FIX activity data (FIX:C) between 144 and 196 h postdose were collected at weeks 26 and 78. Twelve patients (48%) had no sBEs; the remaining 13 (52%) had the following onset of sBEs: less than 1 D (0%), 1 to less than 2D (5%), 2 to less than 3 D (22%), 3 to less than 4 D (9%), 4 to less than 5D (22%), 5 to less than 6D (23%), 6 to less than 7D (11%), and at least 7D (8%). Reductions in sBEs and sTJBEs during on-demand versus prophylaxis treatment were experienced by all 13 patients. Target joint sABR during prophylaxis was 0 for 5/13 patients. ABR reduction ranged from 66.1% (27.2→9.2) to 97.8% (46.2→1.0); sTJBE reductions ranged from 6.2% (2.1→2.0) to 100% (from 40.1, 19.1, 3.9, 9.0, 6.1--0). During prophylaxis, 47% (8/17) of trough FIX activity samples were more than 2%. In sBE patients, ABR and number of TJBEs were reduced with once-weekly nonacog alfa. When sBEs occurred, they followed no apparent pattern for day of occurrence. Clinicaltrials.gov identifier: NCT01335061.

Adult lifetime cost of hemophilia B management in the US: payer and societal perspectives from a decision analytic model

AIMS

Hemophilia B (HB) is a rare congenital disorder characterized by bleeding-related complications which are managed by prophylactic or post-bleeding event ("on-demand") replacement of clotting factor IX (FIX). The standard of care for severe HB is life-long prophylaxis with standard half-life (SHL) or extended half-life (EHL) products given every 2-3 or 7-14 days, respectively. FIX treatment costs in the US have been investigated, but the lifetime costs of HB treatment have not been well characterized, particularly related to the impact of joint health deterioration and associated health resource utilization. We developed a decision-analytic model to explore outcomes, costs and underlying cost drivers associated with FIX treatment options over the lifetime of an adult with severe or moderately severe HB.

MATERIALS AND METHODS

With participation from clinicians, health technology assessment specialists and patient advocates, a Markov model was constructed to estimate bleeding events and costs associated with health states including "bleed into joint", "bleed not into joint", "no bleed" and "death". Sub-models of joint health were based on 0, 1, or ≥2 areas of chronic joint damage. US third-party payer and societal perspectives were considered with a lifetime horizon; sensitivity analyses tested the robustness of primary findings.

RESULTS

Total adult lifetime costs per patient with severe and moderately severe HB were $21,086,607 for SHL FIX prophylaxis, $22,987,483 for EHL FIX prophylaxis, and $20,971,826 for on-demand FIX treatment. For FIX prophylaxis, the cost of FIX treatment accounts for >90% of the total HB treatment costs.

CONCLUSIONS

This decision analytic model demonstrated significant economic burden associated with the current HB treatment paradigm.

Safety and effectiveness of Rixubis in patients with hemophilia B: a real-world, prospective, postmarketing surveillance study in South Korea

Background

Rixubis (recombinant factor IX, nonacog gamma) is indicated for the control and prevention of bleeding episodes, perioperative management, and routine prophylaxis in hemophilia B patients. This real-world, postmarketing surveillance study aimed to evaluate the safety and effectiveness of Rixubis in adult and pediatric hemophilia B patients in South Korea.

Methods

This prospective, observational, multicenter study (clinicaltrials.gov identifier NCT029 22231) was conducted in hemophilia B patients between April 2015 and April 2019, who were observed for up to 6 months after the initiation of Rixubis treatment. Safety was evaluated based on the number and severity of adverse events (AEs) and serious AEs (SAEs). Hemostatic effectiveness was assessed by physicians and patients by using a four-point scale and rated as excellent, good, fair, or no response based on treatment type.

Results

In all, 58 patients were enrolled from four centers by seven physicians during the study period. The safety and effectiveness analysis sets included 57 and 54 patients, respectively. Overall, 11 AEs were reported in eight patients (14.0%), of which three were SAEs and occurred in three patients (5.3%). All 11 AEs were reported as unexpected and mild in severity, with no anaphylactic reaction, and 10 AEs (90.9%) resolved. The majority of AEs (10) were unrelated to Rixubis. Of the 142 hemostatic effectiveness assessments, 123 (86.6%) were reported as good or excellent.

Conclusion

Rixubis demonstrated an acceptable safety and effectiveness profile in the treatment of bleeding, perioperative management, and prophylaxis in hemophilia B patients in a real-world setting in South Korea.

Safety and efficacy of nonacog alfa for the treatment of haemophilia B in children younger than 6 years of age in a routine clinical care setting: the EUREKIX registry study

INTRODUCTION

European regulatory authorities request postmarketing safety and efficacy data for factor IX (FIX) products.

AIM

Collect additional clinical data from routine nonacog alfa use in children aged <6 years with haemophilia B.

METHODS

The EUREKIX registry included retrospective and prospective data collection phases. Safety was assessed via adverse drug reactions (ADRs)/adverse events (AEs) and events of special interest (ESIs) as the primary objective; efficacy was evaluated via annualised bleeding rates (ABRs).

RESULTS

The retrospective phase comprised 37 subjects. Of these, 25 had severe haemophilia B. One subject experienced 2 ADRs; another experienced 4 ESIs of hypersensitivity. Median ABR in subjects receiving a predominantly on-demand regimen (prophylaxis <50% of time; n = 11) was 2.0; median ABR was 3.8 in those receiving predominantly prophylactic treatment (prophylaxis ≥50% of time; n = 24). Joint bleeding was infrequent (median ABR, 0.4; n = 35). The prospective phase included 26 subjects, with 17 continuing from the retrospective phase. A total of 20 subjects had severe haemophilia B. Three subjects experienced 7 treatment-related AEs; 3 experienced 4 ESIs. Median ABR was 4.5 and 1.1 in subjects who received predominantly on-demand (n = 5) or prophylactic treatment (n = 19), respectively; the overall median ABR for joint bleeding events was 0.0.

CONCLUSIONS

Overall, nonacog alfa treatment effectively controlled bleeding events, with no new safety signals identified. These data support the safety and efficacy of nonacog alfa in routine clinical settings in children aged <6 years.

Primary prophylaxis was associated with lower arthropathy in Colombian men with haemophilia B: A longitudinal analysis (2015-2019)

INTRODUCTION

The risk of chronic haemophilic arthropathy (CHA) is related to severity. Evidence suggests that primary prophylaxis (PPr) could reduce CHA incidence and its impact on quality of life.

AIM

To evaluate the association between PPr and CHA in Colombian males with haemophilia B (HB) during 2015 to 2019.

METHODS

A panel-time analysis was performed with data provided by the National Health System to update a nationwide open cohort of people with congenital coagulopathies. The association was evaluated in a logistic random-effect regression model (LRERM), adjusted by age at diagnosis, prophylaxis dose and frequency, severity, haemarthrosis and high-titre inhibitors.

RESULTS

During 2015-2019, a total of 362 men with HB and treated with either, primary, secondary or tertiary prophylaxis were identified. At baseline, CHA prevalence in the cohort was 36.84% (n = 133), median age was 19.0 years (IQR: 10.0-27.0), and median age at diagnosis was 1.0 year (IQR: 0.0-4.0). PPr was prescribed in 37.85% (n = 137), and median dose (IU/Kg/dose) was almost the same for primary vs. secondary/tertiary prophylaxis. Patients in PPr had a lower frequency of severe HB, CHA, haemarthrosis, infectious complications and high-titre inhibitors than those in secondary or tertiary prophylaxis (STPr). In the LRERM, PPr was associated with a significant reduction of 89.70% in the odds of CHA (aOR = 0.103, IC 95%: 0.040, 0.270; P < .001), compared with STPr.

CONCLUSIONS

PPr decreased the odds of CHA by 89.70% in males with HB in Colombia. Our findings are consistent with previous studies and support the strategy to prescribe PPr to our patients.

Budget impact analysis of extended half-life recombinant factor IX (rFIXFc) in the treatment of haemophilia B

Introduction

Prophylaxis with factor IX (FIX) concentrates, produced by recombinant DNA technology (rFIX) or human plasma-derived concentrates, is the treatment of choice for haemophilia B (HB); rFIX covalently fused to the Fc domain of human immunoglobulin G1 (rFIXFc) allows for prophylaxis/treatment with one infusion every 7-14 days. The purpose of this study is to quantify the financial impact of prophylaxis with rFIXFc vs. other approved rFIX and reimbursed for treatment of HB in Italy.

Methods

The number of patients was estimated according to Italian epidemiological data and use of rFIX. Dose and frequency of administration used for weekly prophylaxis were those recommended in the Summary of Product Characteristics (SPC), while clinical trials and literature data were used to calculate bleeding rates and management. Drug costs were calculated using regional ex-factory net prices. In the model, a reference scenario (Reference) vs. an alternative scenario (Alternative) were created to account for introduction of rFIXFc, estimating an increasing trend of the market share of rFIXFc in a 3-year timeframe. The analysis was developed in the perspective of the National Health Service and included healthcare costs related to rFIX for prophylaxis and resolution of bleeding events.

Results

The model estimated an overall cumulative expenditure (years 1-3) of €209,453,646 for the Reference and €207,465,568 for Alternative scenarios, with calculated cumulative savings of €1,988,068.

Conclusions

The increasing use of rFIXFc as a substitute for other rFIX concentrates in the treatment of HB can represent a financially viable choice for the Italian National Health Service while ensuring effective control of bleeding.

Phase 1, single-dose escalating study of marzeptacog alfa (activated), a recombinant factor VIIa variant, in patients with severe hemophilia

Essentials Marzeptacog alfa (activated) [MarzAA] is a novel variant of activated human factor VII. A phase 1 dose escalation trial of MarzAA was conducted in subjects with severe hemophilia. MarzAA was safe and tolerated at intravenous doses up to 30 μg kg-1 Data observed support further trials for hemophilia patients with inhibitors to factors VIII/IX.

SUMMARY

Background Marzeptacog alfa (activated) (MarzAA), a new recombinant activated human factor VII (rFVIIa) variant with four amino acid substitutions, was developed to provide increased procoagulant activity and a longer duration of action in people with hemophilia. Objectives To investigate the safety, tolerability, immunogenicity, pharmacokinetics (PK) and pharmacodynamics (PD) of single ascending intravenous bolus doses of MarzAA in non-bleeding patients with congenital hemophilia A or B with or without inhibitors. Methods This international, phase 1, open-label study (NCT01439971) enrolled males aged 18-64 years with severe hemophilia A or B, with or without FVIII or FIX inhibitors. Subjects were assigned to single-dose MarzAA cohorts (0.5, 4.5, 9, 18 or 30 μg kg-1 ). Blood sampling was performed predose and postdose, and subjects were monitored for 60 days postdose. Safety endpoints included adverse events, vital sign changes, electrocardiograms, laboratory abnormalities, and immunogenicity; secondary endpoints included evaluation of PK and PD. Results Overall, in 25 patients, MarzAA was well tolerated at all dose levels tested, and was not associated with dose-limiting toxicity. No treatment-emergent severe or serious adverse events occurred. MarzAA showed linear dose-response PK across the 4.5-30 μg kg-1 dose range, with a terminal half-life of ⁓ 3.5 h. Dose-dependent shortening of the activated partial thromboplastin time and prothrombin time, and evidence of an increase in peak thrombin as determined with a thrombin generation assay, were observed at all doses. Conclusions MarzAA was tolerated at doses up to 30 μg kg-1 . The safety profile and pharmacological effects observed support further clinical trials for the treatment of hemophilic patients with inhibitors.

The benefits of prophylaxis in patients with hemophilia B

INTRODUCTION

The health benefits of prophylactic dosing regimens for clotting factor therapy in patients with hemophilia include reduced joint damage and improved quality of life; as such, prophylaxis is recommended in treatment guidelines. However, many patients with hemophilia B are treated on demand, and prophylaxis has been utilized less frequently than in hemophilia A. Areas covered: This review discusses the opportunities and evidence for prophylaxis in hemophilia B, in the context of treatment guidelines and with regard to factor IX (FIX) replacement therapies, including long-acting recombinant FIX (rFIX). Expert commentary: Long-acting rFIX concentrates may increase uptake of and adherence to prophylaxis regimens through attainment of higher trough levels with longer dosing intervals. In this new era of hemophilia B treatment, physicians may be able to achieve better clinical outcomes for their patients and reconsider treatment goals. Maintaining higher FIX trough levels will undoubtedly have long-term benefits for patients, such as preserving joint function. The long-acting rFIX concentrates support robust prophylaxis regimens and offer physician's flexibility in treating patients to best suit their needs, whether to enable an active lifestyle, to achieve higher trough levels for better bleed protection, or simply to decrease the burden of treatment by reducing injection frequency.

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.

A new modeling approach allowing prediction and comparison of the long-term outcomes of treatments for hemophilia B

Aim: To develop a modeling approach to compare clinical outcomes of nonacog beta pegol to a standard-acting factor IX (FIX) product. Methods: Regression analysis linked FIX activity to bleed rates. Pharmacokinetic parameters were used to estimate FIX activity over time. The probability of bleeds was estimated for both treatment arms. A Markov model estimated the presence of target joints and annualized bleed rates (ABRs). Results: Higher FIX activity showed reduced ABRs (p < 0.001). Target joints resulted in higher bleed rates (p < 0.001). When FIX activity levels and bleed risks were applied to the Markov model, ABRs for nonacog beta pegol and its comparator were 2.40 and 6.36, respectively. Conclusion: This model provides a starting point for assessing the added value of new FIX products.

Thrombogenicity evaluation in 221 patients with haemophilia B treated with nonacog alfa

Risk for thrombotic events with factor IX replacement therapy in patients with haemophilia B remains a concern for patients, those who treat them, and regulatory agencies, based on experience with early use of prothrombin complex concentrates. The current post hoc analysis assessed the incidence of thrombotic events and changes in prothrombin fragment 1 + 2, thrombin–antithrombin complex, and d-dimer in 221 patients with haemophilia B who received nonacog alfa in clinical studies. Thrombotic event and coagulation marker data were collected from 8 interventional studies utilizing on-demand, prophylactic, and preventive regimens in patients with haemophilia B. Mean age was 25 years (min–max, 0–69), with 51 (23%) patients aged less than 12 years and 15 (7%) aged less than 2 years. None tested positive for inhibitors. Mean time on study was 60.9 ± 32 weeks and mean number of exposure days was 69.3 (min–max, 1–496). Sixty-nine (31%) patients regularly received infusions that were approximately 100 IU/kg as part of a routine prophylaxis regimen, and 29 (13%) patients underwent surgical procedures. No clinical thrombotic events were reported, and no patient experienced clinically significant changes in coagulation markers between baseline and end-of-study testing. These collective data support the low thrombotic risk associated with nonacog alfa in paediatric, adult, and surgical patients with haemophilia B receiving different treatment regimens, including doses of approximately 100 IU/kg. Although careful thrombotic clinical evaluation is important, regular coagulation marker monitoring does not appear to be warranted in patients with haemophilia B.

Trenonacog alfa for prophylaxis, on-demand and perioperative management of hemophilia B

INTRODUCTION

Current treatment for hemophilia B involves replacing the missing coagulation factor IX (FIX) with either plasma-derived or recombinant (r) FIX. Trenonacog alfa is the third normal half-life rFIX that has been granted FDA approval. Area covered: In this review, the authors examine trenonacog alfa for the treatment of hemophilia B including prophylaxis, on-demand and perioperative hemostasis. They compare the PK profile to nonacog alfa and evaluate the drug's efficacy and safety from published studies. Expert opinion: Trenonacog alfa appears to be an effective and safe treatment option for patients with hemophilia B with a PK profile similar to that of nonacog alfa. Despite the advent of extended half-life rFIX and other novel therapeutic approaches, normal half-life rFIX products, including trenonacog alfa, are likely to continue to have a place in hemophilia B treatment for at least the immediate future while the new landscape takes shape, particularly in countries that cannot afford the newer treatments.

Economic Burden of Illness among Persons with Hemophilia B from HUGS Vb: Examining the Association of Severity and Treatment Regimens with Costs and Annual Bleed Rates

OBJECTIVES

To determine US societal burden of illness, including direct and indirect costs and annual bleed rate (ABR), for persons with hemophilia B (HB), a rare and debilitating genetic disorder, and to examine associations of hemophilia severity and treatment regimens with costs and ABR.

METHODS

From 2009 to 2014, the Hemophilia Utilization Group Studies Part Vb collected prospective data from 10 US hemophilia treatment centers. Participants with HB completed initial surveys on sociodemographic characteristics, clinical characteristics, and treatment patterns. During the 2-year follow-up, participants reported bleeding episodes, work absenteeism, and caregiver time quarterly. These data were used to calculate ABR and indirect costs. Direct costs were calculated using 1-year clinical chart records and 2-year dispensing records.

RESULTS

Of the 148 participants, 112 with complete medical records and one or more follow-up survey were included. Total mean annual per-person costs were $85,852 (median $20,160) for mild/moderate HB, $198,733 (median $147,891) for severe HB, and $140,240 (median $63,617) for all participants without inhibitors (P < 0.0001). Mean ABR for participants with severe HB on prophylaxis (5.5 ± 7.9 bleeds/y) was almost half that of those treated episodically. Clotting factor and indirect costs accounted for 85% and 9% of total costs, respectively. Compared with episodic treatment, prophylaxis use was associated with 2.5-fold higher clotting factor costs (P < 0.01), low but significantly more missed parental workdays (P < 0.0001) and clinician (P < 0.001) or nursing visits (P < 0.0001), less part-time employment and unemployment, and lower hospitalizations costs (P = 0.17) and ABR (P < 0.0001).

CONCLUSIONS

HB is associated with high economic burden, primarily because of clotting factor costs. Nevertheless, prophylaxis treatment leads to clinical benefits and may reduce other nonfactor costs.

Continuous prophylaxis with recombinant factor IX Fc fusion protein and conventional recombinant factor IX products: comparisons of efficacy and weekly factor consumption

BACKGROUND

Continuous prophylaxis for patients with hemophilia B requires frequent injections that are burdensome and that may lead to suboptimal adherence and outcomes. Hence, therapies requiring less-frequent injections are needed. In the absence of head-to-head comparisons, this study compared the first extended-half-life-recombinant factor IX (rFIX) product-recombinant factor IX Fc fusion protein (rFIXFc)-with conventional rFIX products based on annualized bleed rates (ABRs) and factor consumption reported in studies of continuous prophylaxis.

METHODS

This study compared ABRs and weekly factor consumption rates in clinical studies of continuous prophylaxis treatment with rFIXFc and conventional rFIX products (identified by systematic literature review) in previously-treated adolescents and adults with moderate-to-severe hemophilia B. Meta-analysis was used to pool ABRs reported for conventional rFIX products for comparison. Comparisons of weekly factor consumption were based on the mean, reported or estimated from the mean dose per injection.

RESULTS

Five conventional rFIX studies (injections 1 to >3 times/week) met the criteria for comparison with once-weekly rFIXFc reported by the B-LONG study. The pooled mean ABR for conventional rFIX was slightly higher than but comparable to rFIXFc (difference=0.71; p = 0.210). Weekly factor consumption was significantly lower with rFIXFc than in conventional rFIX studies (difference in means = 42.8-74.5 IU/kg/week [93-161%], p < 0.001).

CONCLUSION

Comparisons of clinical study results suggest weekly injections with rFIXFc result in similar bleeding rates and significantly lower weekly factor consumption compared with more-frequently-injected conventional rFIX products. The real-world effectiveness of rFIXFc may be higher based on results from a model of the impact of simulated differences in adherence.

Tailoring treatment of haemophilia B: accounting for the distribution and clearance of standard and extended half-life FIX concentrates

The prophylactic administration of factor IX (FIX) is considered the most effective treatment for haemophilia B. The inter-individual variability and complexity of the pharmacokinetics (PK) of FIX, and the rarity of the disease have hampered identification of an optimal treatment regimens. The recent introduction of extended half-life recombinant FIX molecules (EHL-rFIX), has prompted a thorough reassessment of the clinical efficacy, PK and pharmacodynamics of plasma-derived and recombinant FIX. First, using longer sampling times and multi-compartmental PK models has led to more precise (and favourable) PK for FIX than was appreciated in the past. Second, investigating the distribution of FIX in the body beyond the vascular space (which is implied by its complex kinetics) has opened a new research field on the role for extravascular FIX. Third, measuring plasma levels of EHL-rFIX has shown that different aPTT reagents have different accuracy in measuring different FIX molecules. How will this new knowledge reflect on clinical practice? Clinical decision making in haemophilia B requires some caution and expertise. First, comparisons between different FIX molecules must be assessed taking into consideration the comparability of the populations studied and the PK models used. Second, individual PK estimates must rely on multi-compartmental models, and would benefit from adopting a population PK approach. Optimal sampling times need to be adapted to the prolonged half-life of the new EHL FIX products. Finally, costs considerations may apply, which is beyond the scope of this manuscript but might be deeply connected with the PK considerations discussed in this communication.

A national French noninterventional study to assess the long-term safety and efficacy of reformulated nonacog alfa

BACKGROUND

Nonacog alfa, the recombinant Factor IX (F IX) used for the treatment of hemophilia B, was approved in Europe in 1998. A reformulated version was approved for European use in 2007.

STUDY DESIGN AND METHODS

This postmarketing study, as recommended by the risk management plan, was conducted to confirm the safety of reformulated nonacog alfa in a usual care setting in France. This open-label, noninterventional, prospective, longitudinal postmarketing study comprised 19 French hemophilia centers. Patients with hemophilia B receiving reformulated nonacog alfa for prophylaxis or on-demand treatment were followed up on usual care schedule.

RESULTS

A total of 58 subjects were enrolled, of whom 29 (50%) were less than 18 years of age. Hemophilia was severe (baseline F IX activity < 1%) in 47 (81%) patients. All subjects except one were already treated with reformulated nonacog alfa before enrollment. One subject was receiving reformulated nonacog alfa as immune tolerance induction at time of enrollment. At enrollment, treatment regimen was mainly prophylactic in subjects less than 18 years and on-demand in subjects 18 years or older. Median duration of follow-up in the survey was 3.3 (2.3-3.8) years. The median annualized bleeding rate was 3.9 (1.5-5.2) for prophylaxis regimen and 12.2 (3.9-22.1) for on-demand regimen. One subject, a previously untreated patient, developed F IX inhibitors during follow-up. No allergic reaction, no blood cell agglutination, no lack of efficacy or recovery, and no thrombotic events were reported.

CONCLUSION

Reformulated nonacog alfa was shown to be safe in a usual care setting.

Confirmation of longer FIX activity half-life with prolonged sample collection after single doses of nonacog alfa in patients with haemophilia B

A multicentre, single-dose study enrolled 12 previously treated patients with moderately severe to severe (factor IX [FIX] levels ≤2 IU/dl) haemophilia B to assess FIX pharmacokinetics after nonacog alfa administration and to evaluate the impact of length of sampling time on half-life (t_½). After refraining from FIX replacement for four days, patients received 50 IU/kg as an intravenous (IV) infusion over 10 minutes. Blood samples were collected predose and 0.25, 0.5, 1, 3, 6, 9, 24, 50, 72, and 96 h post dose. Tolerability and safety were assessed by monitoring adverse events and were subsequently summary tabulated. FIX activity was measured by a one-stage clotting assay with a lower limit of quantification of 0.010 IU/ml, and inhibitors to FIX were measured using the Bethesda assay. Pharmacokinetic parameters were calculated by noncompartmental analysis and were descriptively summarised. Half-life estimates were calculated first using all available data, then excluding 96-h observations (truncated at 72 h) and, finally, excluding both 72- and 96-h observations (truncated at 50 h). No patient was positive for FIX inhibitors. No treatment-emergent adverse events were reported. Prolonging the duration of the sample collection to 96 h resulted in a terminal t_½ estimate of 39.6 ±7.4 h in the eight patients aged 18 years and older, which was longer than the estimates obtained using shorter periods of observation: 29.6 ± 5.5 h (truncated at 72 h) and 27.2 ± 7.0 h (truncated at 50 h). To accurately assess an adult patient's t_½, sampling should be continued for at least 96 h.

[Rapid Report Hemophilia - Evidence in treatment of hemophilia from the IQWiG's perspective]

The German Institute for Quality and Efficiency in Health Care (IQWiG) conducted a rapid report to assess the therapy of hemophilia patients. Based on a systematic literature search the IQWiG identified 16 studies which show that there is now sufficient information regarding questions that previously lacked data. A benefit assessment of prophylactic and on-demand-treatment concerning different treatment outcomes shows the superiority of the prophylactic therapy regarding major bleedings for all age groups. For the group of youths and adults the analysis shows additional benefits concerning health status and pain within the preceding four weeks. The alignment of guidelines with the identified evidence shows minor correspondence between the guidelines' references and included studies. However, the guidelines' statements primarily correspond with the results of the conducted benefit assessment.

CONCLUSION

The IQWiG's rapid report shows prophylactic therapy to be superior to on-demand therapy. These findings represent a clear indication for attending physicians and payers for prophylaxis in patients with severe hemophilia A.

Once-weekly prophylactic dosing of recombinant factor IX improves adherence in hemophilia B

Regular prophylactic treatment in severe hemophilia should be considered an optimal treatment. There is no general agreement on the optimal prophylaxis regimen, and adherence to prophylaxis is a main challenge due to medical, psychosocial, and cost controversies. Improved approaches in prophylaxis regimen of hemophilia B are needed to make patients’ lives easier. There is some evidence to support the efficacy of once-weekly prophylaxis. Longer sampling schedules are required for the determination of pharmacokinetic (PK) properties of factor IX (FIX). The half-life of FIX seems to be longer than previously described and is expected to be 34 hours. The clinical significance of maintaining a 1% trough level is widely debated in hemophilia B. The overall relationship between factor concentrate levels and incidence of joint bleeding was found to be very weak. Data also indicate that the distribution of FIX into an extravascular FIX compartment may contribute to hemostasis independently of circulating plasma FIX levels. Clinical assessment of the frequency and severity of bleeds remain an important measure of the efficacy of treatment. Role of PK-guided therapy remains to be established. Two prospective randomized studies had evaluated the efficacy and safety of 100 IU/kg once-weekly prophylaxis with nonacog alfa, and this prophylaxis regimen was found to be associated with lower annual bleeding rate compared with on-demand treatment in adolescents and adults with moderately severe-to-severe hemophilia B. Secondary prophylaxis therapy with 100 IU/kg nonacog alfa once weekly reduced annual bleeding rate by 89.4% relative to on-demand treatment. Residual FIX may be supportive of effectiveness. Once-weekly prophylaxis was well tolerated in the two studies, with a safety profile similar to that reported during the on-demand treatment period. To individually tailor treatment to clinical response and to minimize costs of factor concentrate, it would be of interest to investigate the efficacy of lower doses of the drug administered once a week.

Nonacog beta pegol (N9-GP) in haemophilia B: A multinational phase III safety and efficacy extension trial (paradigm™4)

INTRODUCTION

Paradigm™4 was an international extension trial investigating the safety and efficacy of nonacog beta pegol, a recombinant glycoPEGylated factor IX (FIX) with extended half-life, in haemophilia B patients (FIX activity ≤2%; aged 13-70years) who had previously participated in phase III pivotal (paradigm™2) or surgery (paradigm™3) trials.

METHODS

Patients chose to continue treatment with nonacog beta pegol in either one of two once-weekly prophylaxis arms (10IU/kg or 40IU/kg), or an on-demand arm (40IU/kg for mild/moderate bleeds; 80IU/kg for severe bleeds). The primary objective was to evaluate immunogenicity; key secondary objectives included assessing safety and haemostatic efficacy in the treatment and prevention of bleeds.

RESULTS

Seventy-one patients received prophylaxis or on-demand treatment. No patient developed an inhibitor and no safety concerns were identified. The success rate for the treatment of reported bleeds was 94.6%; most (87.9%) resolved with one injection. The median annualised bleeding rate for patients on prophylaxis was 1.36 (interquartile range [IQR] 0.00-2.23) and 1.00 (IQR 0.00-2.03) for the 10 and 40IU/kg treatment arms, respectively. The mean FIX activity trough achieved for 10 and 40IU once weekly was 9.8% and 21.3%, respectively. Fourteen patients on prophylaxis underwent 23 minor surgical procedures; haemostatic perioperative outcomes for all of those evaluated were 'excellent' or 'good'.

CONCLUSIONS

Nonacog beta pegol showed a favourable tolerability profile (with no safety issues identified) with good prophylactic protection and control of bleeding in previously treated adult and adolescent haemophilia B patients.

Gene therapy in an era of emerging treatment options for hemophilia B

Factor IX deficiency (hemophilia B) is less common than factor VIII deficiency (hemophilia A), and innovations in therapy for hemophilia B have generally lagged behind those for hemophilia A. Recently, the first sustained correction of the hemophilia bleeding phenotype by clotting factor gene therapy has been described using recombinant adeno-associated virus (AAV) to deliver factor IX. Despite this success, many individuals with hemophilia B, including children, men with active hepatitis, and individuals who have pre-existing natural immunity to AAV, are not eligible for the current iteration of hemophilia B gene therapy. In addition, recent advances in recombinant factor IX protein engineering have led some hemophilia treaters to reconsider the urgency of genetic cure. Current clinical and preclinical approaches to advancing AAV-based and alternative approaches to factor IX gene therapy are considered in the context of current demographics and treatment of the hemophilia B population.