Extended half-life rFIX in major surgery-How to improve clinical practice: An intraindividual comparison

Recombinant factor IX Fc for the treatment of hemophilia B

Current hemophilia B treatment guidelines recommend routine prophylaxis with factor IX (FIX) replacement products, tailored to maintain plasma activity at levels that will prevent bleeds. However, plasma FIX activity may not be the primary determinant or best indicator of hemostatic efficacy due to its extravascular distribution. FIX replacement therapy has evolved to include extended half-life (EHL) products that provide effective bleed protection when administered at intervals of 7 days or longer. rFIXFc is a recombinant fusion protein with an extended circulation time. rFIXFc has a biodistribution profile consistent with distribution into extravascular space, where it may support hemostasis at sites of vessel injury independent of circulating plasma activity levels. The safety and efficacy of rFIXFc prophylaxis is well established in adults, adolescents and children including previously untreated patients with hemophilia B, with substantial evidence from clinical trials and real-world clinical practice. This review describes the pharmacokinetic characteristics of rFIXFc, summarizes available safety and efficacy data, and evaluates the use of rFIXFc in special populations. Current hemophilia B treatment challenges, including target FIX plasma levels, perioperative use, and management of patients with comorbidities, are discussed together with the potential role of EHL products in the future treatment landscape of hemophilia B.

Recombinant factor IX Fc for major surgery in hemophilia B: factor IX plasma activity levels and effective hemostasis

Background

Major surgical procedures are associated with significant bleeding risk and infectious complications in patients with hemophilia, which may be minimized by factor replacement. Monitoring perioperative factor levels guides dosing to maintain adequate levels for hemostatic control.

Objectives

We report prospectively collected post hoc surgical data in patients with hemophilia B who underwent major surgery with extended half-life recombinant factor IX Fc fusion protein (rFIXFc) in phase 3 studies (B-LONG/Kids B-LONG and B-YOND).

Methods

Achieved FIX plasma levels were described for those who underwent major surgeries with ≥1 peak and/or predose FIX assessment available on the day of surgery (Day 0 [D0]) from the central laboratory. Dosing, injection frequency, adverse events, and hemostatic responses were assessed. Two representative cases were described further including blood loss, transfusions, and concomitant medication assessment.

Results

Of 35 major surgeries, 17 (N = 16 subjects) with sufficient FIX measurements were included in this analysis; 13 of 17 surgeries were orthopedic. On D0, a median loading (preoperative) dose of 101.1 International Units (IU)/kg/injection achieved a median peak FIX of 103.3 IU/dL. Across postoperative Days 1 to 3, 4 to 6, and 7 to 14, the median predose levels were 75.1 IU/dL with 1 injection/d, 71.6 IU/dL with 0 to 1 injection/d, and 43.2 IU/dL with 0 to 1 injection/d, respectively. Hemostasis was rated excellent (14 of 16) or good (2 of 16) across surgeries. Both case studies (knee arthroscopy and ankle fusion) illustrate measured FIX levels with rFIXFc.

Conclusion

The aggregate analysis and representative cases of major surgeries demonstrate that rFIXFc can achieve FIX levels for effective hemostasis during invasive high-risk procedures.

Managing Relevant Clinical Conditions of Hemophilia A/B Patients

The Medical Directors of nine Italian Hemophilia Centers reviewed and discussed the key issues concerning the replacement therapy of hemophilia patients during a one-day consensus conference held in Rome one year ago. Particular attention was paid to the replacement therapy needed for surgery using continuous infusion (CI) versus bolus injection (BI) of standard and extended half-life Factor VIII (FVIII) concentrates in severe hemophilia A patients. Among the side effects, the risk of development of neutralizing antibodies (inhibitors) and thromboembolic complications was addressed. The specific needs of mild hemophilia A patients were described, as well as the usage of bypassing agents to treat patients with high-responding inhibitors. Young hemophilia A patients may take significant advantages from primary prophylaxis three times or twice weekly, even with standard half-life (SHL) rFVIII concentrates. Patients affected by severe hemophilia B probably have a less severe clinical phenotype than severe hemophilia A patients, and in about 30% of cases may undergo weekly prophylaxis with an rFIX SHL concentrate. The prevalence of missense mutations in 55% of severe hemophilia B patients allows the synthesis of a partially changed FIX molecule that can play some hemostatic role at the level of endothelial cells or the subendothelial matrix. The flow back of infused rFIX from the extravascular to the plasma compartment allows a very long half-life of about 30 h in some hemophilia B patients. Once weekly, prophylaxis can assure a superior quality of life in a large severe or moderate hemophilia B population. According to the Italian registry of surgery, hemophilia B patients undergo joint replacement by arthroplasty less frequently than hemophilia A patients. Finally, the relationships between FVIII/IX genotypes and the pharmacokinetics of clotting factor concentrates have been investigated.

Managing surgery in hemophilia with recombinant factor VIII Fc and factor IX Fc: Data on safety and effectiveness from phase 3 pivotal studies

Background

Surgical procedures impose hemostatic risk to people with hemophilia, which may be minimized by optimal factor (F) replacement therapy.

Methods

This analysis evaluates the efficacy and safety of extended half-life factor replacement recombinant FVIII and FIX Fc fusion proteins (rFVIIIFc and rFIXFc) during surgery in phase 3 pivotal (A-LONG/Kids A-LONG and B-LONG/Kids B-LONG) and extension (ASPIRE and B-YOND) studies. Dosing regimens were determined by investigators. Injection frequency, dosing, blood loss, transfusions, and hemostatic response were assessed.

Results

Forty-five major (n = 31 subjects) and 90 minor (n = 70 subjects) procedures were performed in hemophilia A; 35 major (n = 22) and 62 minor (n = 37) procedures were performed in hemophilia B. Unilateral knee arthroplasty was the most common major orthopedic procedure (hemophilia A: n = 15/34; hemophilia B: n = 8/24). On the day of surgery, median total dose in adults/adolescents was 81 IU/kg for rFVIIIFc and 144 IU/kg for rFIXFc; most major procedures required ≤2 injections (including loading dose). Through days 1-14, most major procedures had ≤1 injection/day. Hemostasis was rated excellent (rFVIIIFc: n = 39/42; rFIXFc: n = 29/33) or good (n = 3/42; n = 4/33) in evaluable major surgeries, with blood loss comparable with subjects without hemophilia. Most minor procedures in adults/adolescents required one injection on the day of surgery, including median loading dose of 51 IU/kg (rFVIIIFc) and 80 IU/kg (rFIXFc). No major treatment-related safety concerns were identified. No subjects developed inhibitors or serious vascular thromboembolic events.

Conclusions

rFVIIIFc and rFIXFc were efficacious and well tolerated for the management of perioperative hemostasis across a wide spectrum of major and minor surgeries in hemophilia.

Neurosurgery in a patient with severe hemophilia B: an experience using eftrenonacog alfa as perioperative management

Extended half‐life FIX (EHL‐FIX) concentrates have been developed with the purpose of reducing the frequency of infusions in patients with severe or moderate hemophilia B. We describe the case of a 63‐year‐old patient with severe hemophilia B (sHB) treated with FIX‐Fc fusion protein (rFIXFc) who underwent neurosurgery.

Hemophilia patients may need surgical interventions for complications either related or not to their coagulopathy. Real‐life experience is still limited using eftrenonacog alfa. This case demonstrates that it is an effective and safe treatment option.

Single centre, real-world experience of perioperative rFIXFc use in adult patients with haemophilia B undergoing major and minor surgery

INTRODUCTION

Recombinant factor IX fusion protein concentrate (rFIXFc) is increasingly used for prophylaxis in people with haemophilia B (PWHB), but experience in the perioperative setting is limited.

AIMS

To evaluate real-world perioperative factor usage, bleeding and complications in PWHB (≥18 years) who received rFIXFc for surgical haemostasis and to describe the treatment regimens used.

METHODS

Single centre, retrospective review of all PWHB who underwent a major or minor surgical procedure between June 2017 and July 2020 and received rFIXFc perioperatively for maintenance of surgical haemostasis.

RESULTS

A total of 56 PWHB (45 male and 11 female), including people with mild (n = 32), moderate (n = 4) and severe (n = 20) haemophilia B, underwent 11 major and 131 minor procedures with rFIXFc for surgical haemostasis. Haemostasis was rated as excellent (9/11) or good (2/11) in all major procedures. Median total rFIXFc consumption for orthopaedic surgeries was 972 IU/kg (range 812-1031 IU/kg) and for other major (non-orthopaedic) surgeries was 323 IU/kg (range 167-760 IU/kg). The median number of perioperative rFIXFc infusions was 19 (range 17-26) for orthopaedic surgery and 7 (range 5-17) for other major surgeries. The number of infusions in the postoperative period was determined by procedure and patient factors. Complications included bowel ileus and wound infection. Most minor procedures were managed with single infusion of rFIXFc, with no bleeding complications in 95% of minor procedures. There were no thromboembolic events or inhibitor formation.

CONCLUSION

This unique data provides real-world evidence that rFIXFc is safe and effective in achieving haemostasis in PWHB undergoing surgery.

Recent advances in surgery and its perioperative treatment in people with hemophilia

Introduction: People with hemophilia (PWH) may require some surgical procedures (orthopedic surgery, cardiac surgery, neurosurgery, et cetera) throughout their lives.Areas covered: Articles on surgery and hemophilia published during the year 2020 were analyzed. The principal inclusion factor was a focal point on surgery in hemophilia. Articles that did not concentrate on this subject were not included.Expert opinion: Turoctocog alfa pegol appears to be efficacious for perioperative hemostatic treatment of all kind of surgical operations (minor and major) in PWH A. Long-acting recombinant coagulation factor IX (FIX) albumin fusion protein (rIX-FP) seems to facilitate perioperative management in PWH B. In people suffering from von Willebrand disease (VWD), the utilization of concentrates of von Willebrand factor (VWF) is commonly used for the decrease of exaggerated bleeding during surgical operations. On-demand management with 30-60 IU/kg may keep hemostasis under control during all kind of surgical operations. Factor concentrates with extended half-life (EHL) are a good option to standard half-life (SHL) products in PWH undergoing surgery, permitting diminished number of infusions and inferior consuming, particularly for EHL factor IX (FIX). Supplementary factor VIII (FVIII) and/or bypassing management have demonstrated to be secure and efficacious in association with emicizumab for major surgical procedures.