Real-World Utilisation and Bleed Rates in Patients with Haemophilia B Who Switched to Recombinant Factor IX Fusion Protein (rIX-FP): A Retrospective International Analysis

Six-Year, Real-World Use of Prophylaxis with Recombinant Factor IX-Albumin Fusion Protein (rIX-FP) in Persons with Hemophilia B: A Single-Center Retrospective-Prospective Study

Background: Extended half-life (EHL) factor IX (FIX) concentrates allow for prophylaxis with prolonged dosing intervals and high bleeding protection in persons with hemophilia B. Long-term real-world studies are lacking. Methods: In a retrospective-prospective study, the six-year use of prophylaxis with the EHL recombinant FIX-albumin fusion protein (rIX-FP) was analyzed, comparing outcomes with previous standard half-life (SHL) FIX in patients already on prophylaxis. Results: Prophylaxis with rIX-FP was prescribed in 15 patients (10 severe, 5 moderate; follow-up: 57 ± 17 months). Based on a pharmacokinetic assessment and clinical needs, the first regimen was 47 ± 7 IU/Kg every 9 ± 2 days. All but one patient remained on rIX-FP prophylaxis, adjusting infusion frequency and/or dose; the last prescribed frequency was ≥10 days in 10/13 patients, being reduced in seven and increased in four vs. the first regimen. The weekly FIX dose was unchanged; FIX trough levels were >5% in all patients. The annual infusion number and FIX IU/Kg significantly decreased (~60%) in eight patients previously on SHL FIX prophylaxis, with similar concentrate costs. Very low bleeding rates (most traumatic bleeds and the last quartile of the infusion interval), improved orthopedic and pain scores, unchanged HEAD-US scores and problem joints, and high treatment adherence (>90%) and satisfaction were registered. Conclusions: Personalized, carefully adjusted rIX-FP regimens contribute to the diffusion and optimization of prophylaxis in persons with severe and moderate hemophilia B, with long-term favorable bleeding, joint, and patient-reported outcomes.

Benefits of rIX-FP prophylaxis in patients with Haemophilia B: real-world evidence from a Spanish reference centre

Standard FIX prophylaxis for PWHB require frequent injections, which has led to the development of extended half-life products like rIX-FP (albutrepenonacog alfa) that has shown good efficacy in clinical studies. This ambispective study aims to report a real-world experience with rIX-FP in a Spanish centre with PWHB who switched from SHL-FIX or began prophylaxis with rIX-FP. Five PWHB were included in this study, Four PTP switched to rIX-FP with prophylaxis every 7 days whilst one PUP started with an every-14-days regimen. 3 PTPs extended their dosing intervals to every 14 days or every 21 days. In all PTPs, median annualized spontaneous and joint bleeding rates were maintained at 0.00 and median (range) of ABR was 0.92 (0.00-2.77) after switch to rIX-FP. Mean trough level with previous product was 3.68% (SD = 2.06), while it was 7.08% (SD = 3) with all rIX-FP dosing intervals. After switching to rIX-FP, all PTP reduced their annual infusion rate between 50 and 84% and their annual FIX consumption by 61% (59-67%). This is the first reported real-world experience with albutrepenonacog alfa in a small cohort in Spain and demonstrates good bleeding control together with a reduction of the infusion rate, factor consumption and higher through factor level than previous treatment.

Real-World Effectiveness of rFIXFc Prophylaxis in Patients with Haemophilia B Switched from Standard Half-Life Therapy in Three European Countries

INTRODUCTION

The current study describes real-world clinical outcomes and factor usage among patients with haemophilia B switching from standard half-life factor IX (SHL FIX) treatment to recombinant factor IX Fc fusion protein (rFIXFc) prophylaxis in European treatment centres.

METHODS

This non-interventional, retrospective, multicentre chart review evaluated medical records from adult and paediatric patients with haemophilia B in Denmark, Germany and the UK. Patients had documented SHL FIX treatment, on-demand or prophylaxis, for ≥ 6 months before starting rFIXFc prophylaxis, and subsequent data for ≥ 6 months afterwards (up to 24 months). Primary endpoints included annualised bleeding rates (ABRs), prophylactic factor consumption and injection frequency.

RESULTS

Data from 30 patients (24/30 [80.0%] with severe disease) showed overall mean (standard deviation, SD) ABRs of 4.7 (6.3) on SHL FIX treatment and 1.7 (2.3) after switching to rFIXFc prophylaxis. The reduction in mean (SD) ABRs was greater when switching from SHL FIX on-demand treatment (n = 6), with a decrease from 10.5 (9.9) to 2.6 (4.5), than when switching from SHL FIX prophylaxis (n = 24), with a decrease from 3.3 (4.3) to 1.5 (1.4). Among prior SHL FIX prophylaxis patients, switching to rFIXFc prophylaxis increased the proportion of those with zero bleeds from 21.7% to 45.8% during the 6 months before and after switching, respectively. In the total population, five of six target joints (83.3%) present when patients started rFIXFc prophylaxis subsequently resolved. In patients switching from SHL FIX prophylaxis to rFIXFc prophylaxis, mean (SD) weekly injection frequency was reduced by 1.0 (0.7) and mean (SD) factor consumption was reduced by 27.7 (49.6) IU/kg/week.

CONCLUSION

This study demonstrates the effectiveness of rFIXFc prophylaxis in real-world clinical practice. Improvements in both clinical effectiveness and factor usage associated with rFIXFc prophylaxis may potentially reduce patient burden and improve quality of life.

Switching and increasing prophylaxis regimen with a genetically recombinant fusion of coagulation factor IX and albumin in haemophilia B: a case report

PURPOSE OF REVIEW

We present a case of a boy diagnosed in 2007 with severe haemophilia B [factor IX (FIX) concentration < 1%] at age of 9 months. He was initially treated with recombinant FIX concentrates, but changes in regimens were frequent due to spontaneous hemarthros. In 2013, he entered a phase III trial (NCT01662531) and received rIX-FP, IDELVION at 50 IU/kg once a week. Although the boy was safely maintained with this regimen (2015-2017), the number of hemarthros increased after he started to play football. Thus, rIX-FP regimen was modified (40 IU/kg twice/week) to optimize therapy. This modification was efficient on maintaining patient's thought levels (33%), helped during his fully incorporation at school and social life, and significantly improved synovial hypertrophy. In the last year, the boy has not suffered any bleeding episode and his joint situation improved significantly, which allowed reducing doses to weekly recommended doses.

RECENT FINDINGS

FIX replacement therapies with intravenous plasma-derived FIX (pdFIX) or standard half-life recombinant FIX (rFIX) concentrates are hampered by the relatively short terminal elimination half-life (t1/2) of these substances (around 17-34 h), resulting in the need for frequent infusions (e.g. once every 3 or 4 days) to maintain protective FIX levels. In the past years, the first genetically recombinant fusion of rFIX with another protein - a recombinant human albumin - was developed (albutrepenonacog-alfa or rIX-FP; IDELVION) as a strategy to extend the t1/2 of rFIX-FP (around 95 h).

SUMMARY

We provide information about the difficult management of a patient with a major bleeding haemorrhagic phenotype, which caused serious limitations in the patient's daily life, impacting his quality of life at his young age, and how the switch to IDELVION allowed the situation to improve considerably.

Extended half-life factor IX prophylaxis up to every 21 days in hemophilia B: a longitudinal analysis of the efficacy and safety in selected adult patients

Background

Extended half-life factor IX (FIX) products have revolutionized prophylactic treatment for patients with hemophilia B as patients maintain protective FIX levels with minimal occurrence of spontaneous bleeding. rIX-FP is an extended half-life FIX product that allows prolonged dosing intervals.

Objectives

To assess individualized and prolonged prophylactic dosing interval up to 21 days in adult patients (≥18 years) with hemophilia B in the rIX-FP clinical trial program.

Methods

Patients who were included in the PROLONG-9FP phase III study or who received rIX-FP during surgery could continue into an extension study for long-term assessment. Patients began 7-day prophylaxis with rIX-FP, and after 6 months, they could extend dosing intervals to every 14 days. In the extension study, adult patients could switch to a 21-day regimen if well-controlled on a 14-day regimen.

Results

Eleven patients transitioned from a 7-day prophylaxis regimen to a 14-day regimen and finally to a 21-day regimen, 5 of whom were treated on demand at enrollment. Patients who switched to the 21-day regimen had a median annualized spontaneous bleeding rate of 0.0 across all regimens. The median observed FIX activity remained >5 IU/dL until day 21 after a single 100-IU/kg dose of rIX-FP. After 6 months on the 21-day regimen, 2 patients switched back to a 14-day regimen. No inhibitors, anaphylactic reactions, or thromboembolic events occurred.

Conclusion

Patients who are well controlled on a once-weekly regimen might extend their treatment interval to 14 days, and in adult patients, further extension to up to 21 days (100 IU/kg) may be considered.

Clinical experience of switching patients with severe hemophilia to rVIII-SingleChain or rIX-FP

OBJECTIVE

Prophylaxis treatment is the current standard of care for patients with severe hemophilia. Factor concentrates with improved pharmacokinetics have offered more options for individualizing treatment. The treatment focus may be on increased protection, aiming for higher trough factor levels or longer dosing intervals to reduce the burden of hemophilia. Both aspects can have long-term effects on joint health. Products, such as rVIII‑SingleChain and rIX-FP have been developed to reduce the treatment burden for patients with hemophilia and optimize prophylactic efficacy. The objective of this report is to provide a summary of the clinical experience of different Hemophilia Treatment Centers in managing the switch to rVIII-SingleChain or rIX-FP in patients with hemophilia.

METHODS

This report summarizes a selection of patient cases presented at the 3rd Alliance for Coagulation Academy Meeting in October 2020. The cases from the participating centers provide examples of the clinical experience in managing patients' switch to rVIII-SingleChain and rIX‑FP, including which types of patients are suitable for switching, and practical steps in managing a switch.

RESULTS

It is important to take into consideration the physical and social fulfillment of the patient when deciding to switch to rVIII-SingleChain or rIX-FP. The physician plays an important role in the motivation of patients as they understand not only the patient's needs but the potential benefits of the new treatment.

CONCLUSION

The selected patient cases reported here demonstrate that patients may wish to switch factor products for a variety of reasons; therefore, it is critical to understand why patients switch and what they expect from switching.

Real-World Use of Albutrepenonacog Alfa, A Recombinant Coagulation Factor IX Albumin Fusion Protein, for Personalized Prophylaxis in Japanese Individuals With Hemophilia B: A Case Series

Currently, the mainstay of disease management for hemophilia B, a hemorrhagic disease caused by a congenital deficiency or molecular abnormalities of blood coagulation factor IX (FIX), is prophylaxis using FIX concentrate. On-demand injections of FIX concentrate may also be required, even during prophylaxis, when a patient with hemophilia B is bleeding. Albutrepenonacog alfa (rFIX-FP) is a human albumin fusion gene recombinant FIX, which is administered once every seven, 14, or 21 days, depending on patient preferences and symptoms. Studies have demonstrated its efficacy and safety in a range of patients; however, to date, reports of real-world experiences of the use of rFIX-FP in Japan are limited. We present a case series of three Japanese individuals with moderately severe (FIX activity 1 to <2%) or severe (FIX activity <1%) hemophilia B who benefited from prophylaxis using rFIX-FP in our clinical practice setting. We highlighted the good effectiveness of rFIX-FP in a patient with moderately severe hemophilia B who required prophylaxis due to joint bleeding, which was causing deterioration of his left ankle joint, as well as in a patient with severe hemophilia B and atherothrombotic cerebral infarction, whose trough level had to be ≥5% for concomitant use of an antiplatelet drug, and in a patient with severe hemophilia B who was working in nursing care, which involved heavy labor and night shifts, and who had previously been treated with on-demand FIX concentrate. In all three cases, rFIX-FP improved disease symptoms, and the patients were able to maintain steady states of therapy due to the treatment characteristics of rFIX-FP, which stabilizes FIX at high trough levels.

Association of factor expression levels with annual bleeding rate in people with haemophilia B

INTRODUCTION

Gene therapy clinical trials measure steady-state clotting factor expression levels (FELs) to evaluate the modulation of the bleeding phenotype, aiming to offer consistent protection against breakthrough bleeding events. The link between FELs and bleeding risk in people with haemophilia B (PwHB) is not well understood.

AIM

We evaluated the association between FEL and ABR in PwHB.

METHODS

This cross-sectional study extended the CHESS burden of illness studies in Europe and the United States. Recruitment of additional adult males with haemophilia B supplemented the existing CHESS sample size of PwHB and FELs. PwHB receiving prophylaxis were excluded, as fluctuating FELs may have confounded the analysis. Demographic and clinical characteristics were reported descriptively. Any recorded baseline FEL was reported by the haemophilia-treating physicians according to the medical records. Generalised linear models with log link explored the association between changes in FEL and ABR.

RESULTS

The study included 407 PwHB and no inhibitors receiving on-demand treatment. Mean age was 36.7 years; 56% from the EU, 44% from the United States. Mean baseline FEL was 9.95 IU/dl (SD, 10.47); mean ABR was 2.4 bleeds/year (SD, 2.64). After adjusting for covariates, the model showed that for every 1% increase in FEL the average ABR decreased by .08 (p < .001). Predicted number of bleeding events according to FEL showed a significant non-linear relationship between FEL and ABR (p < .05).

CONCLUSION

This analysis showed a significant relationship between FEL and ABR, where increases in FEL were associated with decreases in ABR among men with HB in Europe and the US.

Albumin-Fusion Recombinant FIX in the Management of People with Hemophilia B: An Evidence-Based Review

Albutrepenonacog-alfa (Idelvion®, CSL Behring) is a recombinant fusion protein in which the recombinant FIX (rFIX) links a recombinant human albumin, extending the half-life of rFIX even beyond 100 hours. In 2016, this drug was approved worldwide for the treatment of pediatric and adult persons with hemophilia B (PWH-B). Its efficacy and safety were described in the PROLONG-9FP program and subsequently confirmed in the real-world practice, even if to date there are not many manuscripts that extensively and completely deal with the use of albutrepenonacog-alfa in daily practice, also evaluating its impact on the quality of life of patients treated with this drug; this review therefore aims to analyze all the publications currently available regarding the real-world use of this extended half-life concentrate, also noting which topics need further study and research.

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.

Expert opinion paper on the treatment of hemophilia B with albutrepenonacog alfa

Introduction: Current guidelines recommend prophylactic treatment of hemophilia B with the missing coagulation factor IX, either with standard half-life or extended half-life products. Extended half-life products have half-lives three to six times longer than the former, allowing a reduction in the number of weekly injections and therefore, potentially impacting on treatment adherence and quality of life. Albutrepenonacog alfa is an extended half-life fusion protein of coagulation factor IX with recombinant human albumin, indicated for both on-demand and prophylactic treatment for bleeding in patients with hemophilia B of all ages.Areas covered: The authors review the clinical and pharmacokinetic characteristics of albutrepenonacog alfa, as well as the available information regarding trough levels and real-world evidence. Given the availability of other factor IX products in the market, indirect comparisons of clinical and pharmacokinetic characteristics are presented.Expert opinion: The authors exhibit their expert opinion on which patient profiles are candidates for prophylactic treatment with albutrepenonacog alfa, and on the management of patients in terms of dosing, regimens of administration and protocols for switching the treatment.

Progress in the Development of Anti-tissue Factor Pathway Inhibitors for Haemophilia Management

The unprecedented progress in addressing unmet needs in haemophilia care to date includes developing several novel therapies that rebalance haemostasis by restoring thrombin generation in patients with haemophilia A or B with and without inhibitors. These novel therapies are FVIII mimetics, antithrombin interference RNA therapy and several monoclonal antibodies directed against the tissue factor pathway inhibitor (anti-TFPI). In this review, we provide an update on the progress made in developing anti-TFPI therapie. Phase 1 data from the three anti-TFPI studies showed acceptable safety profiles, and currently, available phase 2 data are encouraging. While these data support these molecules' further development progression, there is uncertainty on several aspects of their evolution. Two of the three anti-TFPIs have shown drug-related thrombosis, with one study consequently terminated. None of the thrombotic events is predictable with current monitoring tools, and none correlate with known coagulation parameters. All three anti-TFPIs undergo target mediated drug disposition, which impacts the formulation of dosing regimen fo these therapies. They would require more frequent dosing than some of the extended half-life clotting factor products and antithrombin RNAi therapy. There is no assay to measure the TFPI as the physiological levels are very low, which makes monitoring the impact of the anti-TFPI a challenge. The anti-TFPIs have several advantages, including their bioavailability when administered subcutaneously, their stable pharmacokinetics and their ability to prevent bleeds in haemophilia A or B patients with and without inhibitors. Whether these advantages can be realized will depend on the outcome of the currently ongoing studies.