Factor IX replacement to cover total knee replacement surgery in haemophilia B: a single-centre experience, 2000-2010

Rates of venous thromboembolism and use of thromboprophylaxis after major orthopedic surgery in patients with congenital hemophilia A or B: a systematic review

BACKGROUND

Venous thromboembolism (VTE) is a well-recognized complication after total joint replacement (TJR). Persons with hemophilia A or B are considered at low postoperative VTE risk due to their coagulation factor deficiencies, and administering pharmacologic thromboprophylaxis is often considered contraindicated. However, using factor replacement therapy could increase the postoperative VTE risk.

OBJECTIVES

To analyze best available evidences of VTE rates in persons with hemophilia A or B undergoing lower limb TJR and the use of postoperative pharmacologic thromboprophylaxis.

METHODS

We systematically screened 4 online biomedical databases to identify studies reporting VTE rates in patients with hemophilia after TJR. Case reports and case series with less than 10 patients were excluded.

RESULTS

Twenty-six observational studies were included in this systematic review, reporting 1181 TJRs in patients with hemophilia A or B. Eight studies had VTE rates as the primary outcome. Five studies reported screen-detected VTE, while 21 reported symptomatic VTE events. Overall, 17 VTE events were reported (1.4%; 95% CI, 0.9%-2.3%), including 10 (6.6%) after 151 surgeries with postoperative VTE screening and 7 (0.7%) after 1080 surgeries without postoperative screening. Thromboprophylaxis protocols were specified in 21 studies; postoperative thromboprophylaxis was used in 15 (1.3%) surgeries. This information was not available for 29.0% of the analyzed population.

CONCLUSION

Despite the low thromboprophylaxis use in patients with hemophilia, rates of symptomatic VTE after TJR appeared to be low. We also highlighted the need to better report the thrombotic outcome in persons with hemophilia to face the ongoing changes in the hemophilia landscape.

A single-centre experience of 29 total ankle replacement in haemophiliac patients: Therapeutic management, factor consumption and cost

INTRODUCTION

In patients with haemophilia, repeated bleeding in large joints leads to chronic haemophilic arthropathy, a rare disease that can be managed surgically with ankle arthrodesis or with total ankle replacement (TAR). TAR has been reported to provide good surgical results in the medium/long-term and allow preservation of joint mobility but the medical therapeutic management of the patients has not been described.

AIM

To describe the medical therapeutic management of TAR.

METHODS

All patients with haemophilia A/B, with haemophilic ankle arthropathy, and who underwent TAR between April 2006 and October 2019 were retrospectively included. Factor consumption, perioperative and early complications, volume of blood lost, and orthopaedic data were collected.

RESULTS

A total of 25 patients underwent 29 TAR (mean age was 44.7 years [range: 26-65]). In the 17 patients with HA without history of anti-FVIII inhibitor, the mean ± SD consumption the day of surgery was 116 ± 16 UI/kg when clotting factors were administered by continuous infusion, 106 ± 13 UI/kg when SHL factors were administered by bolus infusion, and 75 ± 22 UI/kg when EHL factors were administered by bolus infusion. During hospitalisation, the mean factor cost was €38,073 (83.7% of the total cost of surgery). Mean blood loss was significantly lower in patients treated with tranexamic acid (164 mL, range: 40-300) than in those not (300 mL, range: 70-800; p = .01). Six patients had haematoma. The 10-year survival free of any prosthesis removal/arthrodesis was estimated to be 92.2% (95% CI [83; 100]).

CONCLUSION

The medical therapeutic management of TAR is complex, carried out by a multidisciplinary team but effective in avoiding the occurrence of complications.

Perioperative continuous infusions of factor VIII versus factor IX for patients with hemophilia A or B undergoing major surgery

Continuous factor VIII (FVIII) or factor IX (FIX) infusions are commonly used for patients with hemophilia A (HA) or B (HB) undergoing surgery to secure perioperative hemostasis. To describe differences between the initial recovery and subsequent FIX and FVIII levels, and describe clinical outcomes among HB and HA patients receiving perioperative continuous infusion (CI) of recombinant FVIII and FIX concentrates. Retrospective chart review was conducted on 8 consecutive patients with HB and 7 consecutive patients with HA who underwent major surgery between 2014 and 2018 and received continuous infusions of standard half-life factor concentrate. Median initial bolus dose per kilogram was higher for HB compared to HA patients [90.8 (IQR 78.0-98.7) vs. 52.1 (IQR 48.6-55.6) IU/kg], while initial CI dose-rates were similar [4.3 (IQR 3.8-4.6) vs. 4.2 (IQR 3.8-4.4) IU/kg/h]. Median post-bolus recovery was higher for FVIII compared to FIX [1.70 (IQR 1.23-1.75) vs. 0.88 (IQR 0.75-1.00) IU/mL]. Median factor levels also were higher for FVIII on post-operative days 1 to 3. HB patients had greater mean intraoperative estimated blood loss [285.7 (range 0-1000) vs. 142.8 (range 0-400) mL] and longer median length of hospital stay [9 (IQR 8-12) vs. 5 (IQR 4-6.5) days]. Our initial evidence suggests greater in vivo yield of rFVIII compared to rFIX in the perioperative setting. We identified poorer clinical outcomes in this small cohort of perioperative HB patients indicating that they may benefit from a higher CI rate for adequate surgical hemostatic coverage.

Total knee replacement for patients with severe hemophilic arthropathy in Taiwan: A nationwide population-based retrospective study

BACKGROUND

Total knee replacement (TKR) surgery is a treatment option for advanced hemophilic arthropathy. Due to its rarity and complexity, previous reports could only demonstrate the results of single-site studies including few cases. This population-based study aimed to investigate the major epidemiological characteristics, mean consumption of coagulation factors, length of hospital stays, complications, and failure rate of primary TKR for severe hemophilia patients in Taiwan.

METHODS

A cohort of 996 hemophilia patients registered between 1995 and 2011 was included, and 103 primary TKRs were performed on 75 patients. Unilateral TKR was performed on 47 patients and bilateral TKRs on the remaining 28 patients, including 12 simultaneous and 16 staged surgeries. The mean age at surgery was 32.3 years (range, 17.3-55.7), and the mean follow-up duration was 77.9 months (range, 2.3-176.8).

RESULTS

Failure was noted in 8 patients (8.5%) at mean 32.8 months (range, 2.3-95) after surgery. Four patients revealed aseptic loosening, whereas infection in 4. The 10-year prosthesis survivorship was 88.6%. For patients receiving unilateral TKR, the mean length of hospital stay was 15 days (range, 7-32). The mean cost of factor supplement was United States Dollar (USD) 43 543 with a mean 4-unit packed red blood cells transfusion (range, 0-38). The total admission cost was USD 48 326 (range, USD 4165-262 619).

CONCLUSION

The prevalence of TKA for hemophilia patients was 7.5% in Taiwan. The mean hospital stay was 14 days, and the 10-year prosthesis survivorship was 88.6%. The mean daily factor usage was decreased from 235.7 units preoperatively to 202.1 units postoperatively. In comparison with the staged-bilateral TKRs, the simultaneous procedures significantly reduced the mean total cost from USD 101 923 to USD 61 587 (p = 0.023). Therefore, in terms of cost-effectiveness, bilateral simultaneous TKR is more preferable than staged procedures.

Trends of outcomes and healthcare utilization following orthopaedic procedures in adults with haemophilia: A 3-decade retrospective review

INTRODUCTION

Haemophilic arthropathy is a serious complication of haemophilia often requiring surgical intervention. It is unclear whether advances in comprehensive care are associated with a reduction in orthopaedic interventions and peri-procedural resource utilization.

AIM

To determine temporal patterns of orthopaedic interventions in persons with haemophilia (PWH), and evaluate changes in healthcare utilization and outcomes.

METHODS

In this Canadian multicentre retrospective cohort study, adult PWH from Northern Alberta and British Columbia who underwent orthopaedic procedures (1990-2018) were included. Temporal changes in the type of procedures, length of stay (LOS), factor utilization and outcomes were examined.

RESULTS

Sixty-five patients (78% haemophilia A) underwent 102 surgeries at a median age of 46.3. Of the 46 severe PWH, 28 (61%) were on prophylaxis at time of surgery. The proportion of total knee arthroplasties (TKA) declined over time (56% 1990-1999, 51% 2000-2009, 27% 2010-2018), with a concomitant rise in ankle arthrodesis (0% 1990-1999, 18% 2000-2009, 27% 2010-2018). Over time, PWH underwent orthopaedic procedures at an older age (P = .02). There was a significant reduction in perioperative factor VIII utilization (P = .003) and median LOS (P < .0001). Major bleeds, prosthetic joint infections and thrombosis were not observed in the last decade.

CONCLUSION

In the last three decades, there was a decline in the proportion of TKA, likely reflecting the impact of widespread use of tertiary prophylaxis. However, ankle arthrodesis rates increased, suggesting that higher trough levels may be required to prevent ankle arthropathy. We observed a significant reduction in LOS and factor utilization, reflecting improvements in perioperative management.

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.

Phase 3 Clinical Trial: Perioperative Use of Nonacog Gamma, a Recombinant Factor IX, in Previously Treated Patients With Moderate/Severe Hemophilia B

Hemostatic management is essential for ensuring the safety of patients with hemophilia during surgery. This phase 3, prospective, uncontrolled trial, evaluated hemostatic efficacy, consumption, and safety of a recombinant factor IX concentrate, nonacog gamma (BAX 326, Rixubis^® [Baxalta US Inc., a Takeda company, Lexington, MA, USA]), in intraoperative and postoperative settings in previously treated patients (PTPs) with severe or moderately severe hemophilia B undergoing elective surgery (N = 38 surgeries; 21 major, 17 minor). Predefined preoperative hemostatic factor IX levels (80-100% of normal for major and 30-60% for minor surgeries) were maintained for each patient. Intraoperative efficacy was rated as “excellent” or “good” for all surgeries. Postoperative hemostatic efficacy on day of discharge was rated as “excellent,” “good,” and “fair,” respectively, for 29 (76.3%), 7 (18.4%), and 2 (5.3%) surgical procedures. All adverse events were considered unrelated to study drug; most frequently reported was mild procedural pain (9 patients). No thrombotic events, severe allergic reactions, or inhibitor formation were observed. Nonacog gamma was well tolerated and effective for intraoperative and postoperative hemostatic management of PTPs with hemophilia B.

NCT01507896, EudraCT: 2011-000413-39

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.

New developments in the management of moderate-to-severe hemophilia B

Hemophilia B is an X-linked genetic deficiency of coagulation factor IX (FIX) activity associated with recurrent deep tissue and joint bleeding that may lead to long-term disability. FIX replacement therapy using plasma-derived protein or recombinant protein has significantly reduced bleeding and disability from hemophilia B, particularly when used in a prophylactic fashion. Although modern factor replacement has excellent efficacy and safety, barriers to the broader use of prophylaxis remain, including the need for intravenous (IV) access, frequent dosing, variability in individual pharmacokinetics, and cost. To overcome the requirement for frequent factor dosing, novel forms of recombinant FIX have been developed that possess extended terminal half-lives. Two of these products (FIXFc and rIX-FP) represent fusion proteins with the immunoglobulin G1 (IgG1) Fc domain and albumin, respectively, resulting in proteins that are recycled in vivo by the neonatal Fc receptor. The third product has undergone site-specific PEGylation on the activation peptide of FIX, similarly resulting in a long-lived FIX form. Clinical trials in previously treated hemophilia B patients have demonstrated excellent efficacy and confirmed less-frequent dosing requirements for the extended half-life forms. However, gaps in knowledge remain with regard to the risk of inhibitor formation and allergic reactions in previously untreated patient populations, safety in elderly patients with hemophilia, effects on in vivo FIX distribution, and cost-effectiveness. Additional strategies designed to rebalance hemostasis in hemophilia patients include monoclonal-antibody-mediated inhibition of tissue factor pathway inhibitor activity and siRNA-mediated reduction in antithrombin expression by the liver. Both of these approaches are long acting and potentially involve subcutaneous administration of the drug. In this review, we will discuss the biology of FIX, the evolution of FIX replacement therapy, the emerging FIX products possessing extended half-lives, and novel “rebalancing” approaches to hemophilia therapy.

The features of clearance in recombinant factor IX (BeneFIX(®) )

INTRODUCTION

Dosage adjustment is very important to perform continuous infusion (CI) of recombinant factor IX (rFIX) concentrates more effectively and economically, and clearance (CL) is strongly related to the infusion rate. However, previous reports have shown that the CL of rFIX concentrates varies widely (4.2-11.4 mL kg(-1) h(-1) ).

AIM

The goal of this study was to gain a better understanding of the CL of the rFIX concentrate (BeneFIX(®) ) to precisely set the infusion rate of rFIX concentrates.

METHODS

We estimated CLs by five different calculation approaches: from area under the blood concentration-time curve (AUC), from in vivo recovery (IVR) and half-life, from actual FIX activity value during CI, and from the simulation by one-compartment model in seven patients with haemophilia B.

RESULTS

The mean CL calculated from AUC was 3.8 ± 0.4 mL kg(-1) h(-1) (range = 3.3-4.3 mL kg(-1) h(-1) ).

CONCLUSION

The mean CL calculated from IVR and distribution half-life was 4.4 ± 0.4 mL kg(-1) h(-1) (range = 4.0-5.1 mL kg(-1) h(-1) ). The mean CL calculated from IVR and terminal half-life was 2.1 ± 0.5 mL kg(-1) h(-1) (range = 1.7-2.8 mL kg(-1) h(-1) ). The mean CL during CI was 4.9 ± 0.6 mL kg(-1) h(-1) (range = 4.2-5.6 mL kg(-1) h(-1) ). In addition, when we simulated the theoretical CL using a one-compartment model, the adjusted mean CL during CI was 4.8 ± 0.5 mL kg(-1) h(-1) (range = 4.0-5.4 mL kg(-1) h(-1) ). The CL obtained from distribution half-life was comparable to the CL during CI, while the CL calculated from terminal half-life did not reflect actual CL. Further, the rFIX concentrate was characterized by a one-compartment model under certain conditions.

Efficacy and safety of a recombinant factor IX (Bax326) in previously treated patients with severe or moderately severe haemophilia B undergoing surgical or other invasive procedures: a prospective, open-label, uncontrolled, multicentre, phase III study

Haemostatic management of haemophilia B patients undergoing surgery is critical to patient safety. The aim of this ongoing prospective trial was to investigate the haemostatic efficacy and safety of a recombinant factor IX (rFIX) (Bax326) in previously treated subjects (12-65 years, without history of FIX inhibitors) with severe or moderately severe haemophilia B, undergoing surgical, dental or other invasive procedures. Haemostatic efficacy was assessed according to a predefined scale. Blood loss was compared to the average and maximum blood loss predicted preoperatively. Haemostatic FIX levels were achieved peri- and postoperatively in 100% of subjects (n = 14). Haemostasis was 'excellent' intraoperatively in all patients and postoperatively in those without a drain, and 'excellent' or 'good' at the time of drain removal and day of discharge in those with a drain employed. Following the initial dose, the mean FIX activity level rose from 6.55% to 107.58% for major surgeries and from 3.60% to 81.4% for minor surgeries. Actual vs. predicted blood loss matched predicted intraoperative blood loss but was equal to or higher than (but less than 150%) the maximum predicted postoperative blood loss reflecting the severity of procedure and FIX requirements. There were no related adverse events, severe allergic reactions or thrombotic events. There was no evidence that BAX326 increased the risk of inhibitor or binding antibody development to FIX. BAX326 was safe and effective for peri-operative management of 14 subjects with severe and moderately severe haemophilia B.

Population pharmacokinetic modeling for dose setting of nonacog beta pegol (N9-GP), a glycoPEGylated recombinant factor IX

BACKGROUND

nonacog beta pegol (N9-GP) is a glycoPEGylated recombinant factor IX (rFIX) molecule with a prolonged half-life.

OBJECTIVES

To provide information on potential dose regimens for N9-GP for phase 3 pivotal and surgery trials.

METHODS

A population pharmacokinetic model was developed from single-dose data derived from the first human-dose trial with N9-GP in hemophilia B patients, and was used to extrapolate to steady-state conditions for different N9-GP dose regimens for prophylaxis. The model was also used to compare prophylaxis using N9-GP with standard prophylactic regimens using rFIX or plasma-derived (pd) FIX (40 IU kg(-1) every third day). Plasma activity following dosing with N9-GP, rFIX and pdFIX for surgery and on-demand treatment of bleeds was also simulated.

RESULTS

A linear two-compartmental model best described the pharmacokinetic profiles of N9-GP, rFIX and pdFIX. A prophylactic regimen of 10 U kg(-1) N9-GP once weekly predicted mean peak and trough levels of 18 and 4.2 U dL(-1) , while 40 U kg(-1) once weekly predicted values of 72 and 17 U dL(-1) , respectively. Standard prophylactic regimens with rFIX and pdFIX predicted mean peak and trough levels of 34 and 3.9 IU dL(-1) for rFIX, and mean values of 43 and 2.1 IU dL(-1) for pdFIX. Additional simulations predicted significantly reduced dosing frequency and factor concentrate consumption for N9-GP vs. rFIX and pdFIX for surgery and the treatment of bleeds.

CONCLUSIONS

N9-GP may allow prophylaxis, surgical dosing regimens and on-demand treatment of bleeding episodes with less frequent injections and lower factor concentrate consumption; this possibility is being investigated in prospective clinical trials.

Haemophilia B: current pharmacotherapy and future directions

INTRODUCTION

Hemophilia B is a rare hereditary hemorrhagic disorder characterized by deficiency of the clotting factor IX (FIX). Hemophilia B patients experience mild to severe bleeding complications according to the degree of FIX defect. Nowadays, the most challenging complication of individuals with hemophilia B is the development of alloantibodies, which render the standard replacement therapy with FIX concentrates ineffective, exposing them to a significantly increased morbidity and mortality.

AREAS COVERED

This review summarizes the most important events leading to the development of the current FIX products available for the treatment of hemophilia B patients. In addition, it focuses on the more recent advances in the production of new FIX molecules aimed at improving the clinical management of such patients.

EXPERT OPINION

Although the availability of plasma-derived FIX concentrates has greatly improved the clinical management of hemophilia B patients, the introduction of FIX products using recombinant DNA technology has represented the most significant therapeutic progress in hemophilia B therapy, ensuring an advanced level of safety. The development of rFIX products with extended half lives will further improve the therapeutic armamentarium for hemophilia B patients.