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Hotea I, Brinza M, Blag C, Zimta AA, Dirzu N, Burzo C, Rus I, Apostu D, Benea H, Marian M, Mester A, Pasca S, Iluta S, Teodorescu P, Jitaru C, Zdrenghea M, Bojan A, Torok-Vistai T, Niculescu R, Tarniceriu C, Dima D, Truica C, Serban M, Tomuleasa C, Coriu D. Current therapeutic approaches in the management of hemophilia-a consensus view by the Romanian Society of Hematology. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1091. [PMID: 34423003 PMCID: PMC8339806 DOI: 10.21037/atm-21-747] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 05/17/2021] [Indexed: 12/28/2022]
Abstract
Hemophilia A (HA) and hemophilia B (HB) are rare disorders, being caused by the total lack or under-expression of two factors from the coagulation cascade coded by genes of the X chromosome. Thus, in hemophilic patients, the blood does not clot properly. This results in spontaneous bleeding episodes after an injury or surgical intervention. A patient-centered regimen is considered optimal. Age, pharmacokinetics, bleeding phenotype, joint status, adherence, physical activity, personal goals are all factors that should be considered when individualizing therapy. In the past 10 years, many innovations in the diagnostic and treatment options were presented as being either approved or in development, thus helping clinicians to improve the standard-of-care for patients with hemophilia. Recombinant factors still remain the standard of care in hemophilia, however they pose a challenge to treatment adherence because they have short half-life, which where the extended half-life (EHL) factors come with the solution, increasing the half-life to 96 hours. Gene therapies have a promising future with proven beneficial effects in clinical trials. We present and critically analyze in the current manuscript the pros and cons of all the major discoveries in the diagnosis and treatment of HA and HB, as well as identify key areas of hemophilia research where improvements are needed.
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Affiliation(s)
- Ionut Hotea
- Department of Hematology, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania.,Department of Hematology, Ion Chiricuta Clinical Cancer Center, Cluj Napoca, Romania.,Medfuture Research Center for Advanced Medicine, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania
| | - Melen Brinza
- Department of Hematology, Fundeni Clinical Institute, Bucharest, Romania.,Department of Hematology, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
| | - Cristina Blag
- Department of Pediatrics, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania.,Department of Hematology, Emergency Clinical Children's Hospital, Cluj Napoca, Romania
| | - Alina-Andreea Zimta
- Medfuture Research Center for Advanced Medicine, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania
| | - Noemi Dirzu
- Medfuture Research Center for Advanced Medicine, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania
| | - Corina Burzo
- Department of Hematology, Ion Chiricuta Clinical Cancer Center, Cluj Napoca, Romania
| | - Ioana Rus
- Department of Hematology, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania
| | - Dragos Apostu
- Department of Orthopedics, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania.,Department of Orthopedics, Emergency Clinical County Hospital, Cluj Napoca, Romania
| | - Horea Benea
- Department of Orthopedics, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania.,Department of Orthopedics, Emergency Clinical County Hospital, Cluj Napoca, Romania
| | - Mirela Marian
- Department of Hematology, Ion Chiricuta Clinical Cancer Center, Cluj Napoca, Romania
| | - Alexandru Mester
- Department of Oral Health, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania
| | - Sergiu Pasca
- Department of Hematology, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania
| | - Sabina Iluta
- Department of Hematology, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania
| | - Patric Teodorescu
- Department of Hematology, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania
| | - Ciprian Jitaru
- Department of Hematology, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania
| | - Mihnea Zdrenghea
- Department of Hematology, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania.,Department of Hematology, Ion Chiricuta Clinical Cancer Center, Cluj Napoca, Romania
| | - Anca Bojan
- Department of Hematology, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania.,Department of Hematology, Ion Chiricuta Clinical Cancer Center, Cluj Napoca, Romania
| | - Tunde Torok-Vistai
- Department of Hematology, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania.,Department of Hematology, Ion Chiricuta Clinical Cancer Center, Cluj Napoca, Romania
| | - Radu Niculescu
- Department of Hematology, Fundeni Clinical Institute, Bucharest, Romania
| | - Cristina Tarniceriu
- Department of Anatomy, Grigore T. Popa University of Medicine and Pharmacy, Iasi, Romania.,Department of Hematology, St. Spiridon County Clinical Emergency Hospital, Iasi, Romania
| | - Delia Dima
- Department of Hematology, Ion Chiricuta Clinical Cancer Center, Cluj Napoca, Romania
| | - Cristina Truica
- Department of Hematology, Constantin Opris Emergency Hospital, Baia Mare, Romania
| | - Margit Serban
- Department of Hematology, Victor Babes University of Medicine and Pharmacy, Timisoara, Romania.,European Haemophilia Treatment Center, Timisoara, Romania
| | - Ciprian Tomuleasa
- Department of Hematology, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania.,Department of Hematology, Ion Chiricuta Clinical Cancer Center, Cluj Napoca, Romania.,Medfuture Research Center for Advanced Medicine, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj Napoca, Romania
| | - Daniel Coriu
- Department of Hematology, Fundeni Clinical Institute, Bucharest, Romania.,Department of Hematology, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
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Choi EJ, Hwang TJ, Choi YM, Kim HC, Yoo MC, Song H, Badejo K. Safety and effectiveness of Rixubis in patients with hemophilia B: a real-world, prospective, postmarketing surveillance study in South Korea. Blood Res 2020; 55:246-252. [PMID: 33303707 PMCID: PMC7784123 DOI: 10.5045/br.2020.2020225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 10/30/2020] [Indexed: 11/23/2022] Open
Abstract
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.
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Affiliation(s)
- Eun Jin Choi
- Department of Pediatrics, Daegu Catholic University Medical Center, Daegu, Korea
| | - Tai ju Hwang
- Korea Hemophilia Foundation Clinic, Gwangju, Korea
| | | | | | | | - Haylee Song
- Hematology, Growth and Emerging Markets, Takeda Pharmaceutical International, Singapore
| | - Kayode Badejo
- Global Patient safety Evaluation, Takeda Pharmaceutical Company Ltd, Cambridge, MA, USA
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Liesner R, Andersson NG, Frisk T, Santagostino E, Schulz M, Young L, Giordano P, Tagliaferri A. 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. Haemophilia 2020; 27:e60-e68. [PMID: 33277961 DOI: 10.1111/hae.14215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 10/26/2020] [Accepted: 11/09/2020] [Indexed: 01/19/2023]
Abstract
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.
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Affiliation(s)
- Ri Liesner
- Great Ormond Street Hospital for Children, London, UK
| | - Nadine G Andersson
- Department for Thrombosis and Haemostasis, Skåne University Hospital, Malmo, Sweden
| | - Tony Frisk
- Karolinska University Hospital, Stockholm, Sweden
| | - Elena Santagostino
- Foundation IRCCS Cà Granda, Maggiore Hospital Policlinico, Angelo Bianchi Bonomi Haemophilia and Thrombosis Centre, Milan, Italy
| | | | - Lisa Young
- Pfizer Innovative Health, Walton Oaks, UK
| | - Paola Giordano
- Department of Biomedical Science and Human Oncology, University of Bari "Aldo Moro", Bari, Italy
| | - Annarita Tagliaferri
- Regional Reference Center for Inherited Bleeding Disorders, University Hospital of Parma, Parma, Italy
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Malik PRV, Edginton AN. Integration of Ontogeny Into a Physiologically Based Pharmacokinetic Model for Monoclonal Antibodies in Premature Infants. J Clin Pharmacol 2019; 60:466-476. [DOI: 10.1002/jcph.1540] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 10/10/2019] [Indexed: 12/24/2022]
Affiliation(s)
- Paul R. V. Malik
- School of PharmacyUniversity of Waterloo Kitchener Ontario Canada
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Fukutake K, Taki M, Matsushita T, Sakai M, Takata A, Yamaguchi H, Karumori T. Postmarketing safety and effectiveness of recombinant factor IX (nonacog alfa) in Japanese patients with haemophilia B. Haemophilia 2019; 25:e247-e256. [PMID: 31168882 PMCID: PMC6852692 DOI: 10.1111/hae.13783] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 05/02/2019] [Accepted: 05/13/2019] [Indexed: 11/28/2022]
Abstract
INTRODUCTION In 2010, nonacog alfa became the first recombinant factor IX (rFIX) available in Japan for patients with haemophilia B. AIM To determine real-world safety (adverse events, incidence of inhibitors) and effectiveness of nonacog alfa in Japan. METHODS This multicentre, prospective, observational, postmarketing surveillance study enrolled previously treated and untreated patients (PTPs and PUPs, respectively) who were observed for 1 and 2 years, respectively, after initiating nonacog alfa therapy. Safety and effectiveness were assessed for each treatment type. Annualized bleeding rate (ABR) and incremental recovery of rFIX were also evaluated. RESULTS Overall, 312 of 314 patients enrolled from 173 sites were eligible for the safety analysis set (PTPs, 281; PUPs, 28; other, 3). Mean age was 25.4 (PTPs) and 14.8 (PUPs) years. Haemophilic severity ranged from mild to severe, and 133 (42.6%) patients had haemophilic arthropathy. Of 285 patients (PTPs, 257; PUPs, 28) in the effectiveness set, 112 received on-demand treatment for 1161 bleeding episodes (effectiveness rate, 93.7%) and 185 received routine prophylaxis (effectiveness rate, 95.5%). No spontaneous bleeding was observed in 52.4% of patients during prophylactic treatment. Median ABR was lower during routine prophylaxis (2.0) vs the rest of the observation period (8.3). A weak negative correlation was found between body weight and the reciprocal of rFIX recovery. Eleven adverse drug reactions occurred in 7 PTPs (2.2% [7/312]); recurrence of inhibitor was observed in 1 patient, but no new inhibitor developed in PTPs or PUPs. CONCLUSION Nonacog alfa therapy is safe and effective in the real-world scenario in Japan.
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Affiliation(s)
- Katsuyuki Fukutake
- Department of Laboratory Medicine, Tokyo Medical University, Tokyo, Japan.,Department of Molecular Genetics of Coagulation Disorders, Tokyo Medical University, Tokyo, Japan
| | - Masashi Taki
- Department of Pediatrics, St. Marianna University School of Medicine, Yokohama City Seibu Hospital, Yokohama, Japan
| | - Tadashi Matsushita
- Department of Transfusion Medicine, Nagoya University Hospital, Nagoya, Japan
| | - Michio Sakai
- Department of Pediatrics, University of Occupational and Environmental Health, Kitakyushu, Japan
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Urasinski T, Stasyshyn O, Andreeva T, Rusen L, Perina FG, Oh MS, Chapman M, Pavlova BG, Valenta-Singer B, Abbuehl BE. Recombinant factor IX (BAX326) in previously treated paediatric patients with haemophilia B: a prospective clinical trial. Haemophilia 2014; 21:196-203. [PMID: 25495591 DOI: 10.1111/hae.12548] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/13/2014] [Indexed: 11/26/2022]
Abstract
A newly developed recombinant factor IX (BAX326(1) ) was investigated for prophylactic use in paediatric patients aged <12 years with severe (FIX level <1%) or moderately severe (FIX level 1-2%) haemophilia B. The aim of this prospective clinical trial was to assess the safety, haemostatic efficacy and pharmacokinetic profile of BAX326 in previously treated paediatric patients. BAX326 was administered as prophylaxis twice a week for a period of 6 months, and on demand for treatment of bleeds. Safety was assessed by the occurrence of related AEs, thrombotic events and immunologic assessments. Efficacy was evaluated by annualized bleeding rate (ABR), and by treatment response rating (excellent, good, fair, none). PK was assessed over 72 h. None of the 23 treated paediatric subjects had treatment-related SAEs or AEs. There were no thrombotic events, inhibitory or specific binding antibodies against FIX, rFurin or CHO protein. Twenty-six bleeds (19 non-joint vs. 7 joint bleeds) occurred (mean ABR 2.7 ± 3.14, median 2.0), of which 23 were injury-related. Twenty subjects (87%) did not experience any bleeds of spontaneous aetiology. Haemostatic efficacy of BAX326 was excellent or good for >96% of bleeds (100% of minor, 88.9% of moderate and 100% of major bleeds); the majority (88.5%) resolved after 1-2 infusions. Longer T1/2 and lower IR were observed in younger children (<6 years) compared to those aged 6 to 12 years. BAX326 administered as prophylactic treatment as well as for controlling bleeds is efficacious and safe in paediatric patients aged <12 years with haemophilia B.
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Affiliation(s)
- T Urasinski
- Department of Paediatrics, Paediatric Haematology and Oncology, Pomeranian Medical University in Szczecin, Szczecin, Poland
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Recombinant long-acting glycoPEGylated factor IX in hemophilia B: a multinational randomized phase 3 trial. Blood 2014; 124:3880-6. [PMID: 25261199 DOI: 10.1182/blood-2014-05-573055] [Citation(s) in RCA: 131] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This multinational, randomized, single-blind trial investigated the safety and efficacy of nonacog beta pegol, a recombinant glycoPEGylated factor IX (FIX) with extended half-life, in 74 previously treated patients with hemophilia B (FIX activity ≤2 IU/dL). Patients received prophylaxis for 52 weeks, randomized to either 10 IU/kg or 40 IU/kg once weekly or to on-demand treatment of 28 weeks. No patients developed inhibitors, and no safety concerns were identified. Three hundred forty-five bleeding episodes were treated, with an estimated success rate of 92.2%. The median annualized bleeding rates (ABRs) were 1.04 in the 40 IU/kg prophylaxis group, 2.93 in the 10 IU/kg prophylaxis group, and 15.58 in the on-demand treatment group. In the 40 IU/kg group, 10 (66.7%) of 15 patients experienced no bleeding episodes into target joints compared with 1 (7.7%) of 13 patients in the 10 IU/kg group. Health-related quality of life (HR-QoL) assessed with the EuroQoL-5 Dimensions visual analog scale score improved from a median of 75 to 90 in the 40 IU/kg prophylaxis group. Nonacog beta pegol was well tolerated and efficacious for the treatment of bleeding episodes and was associated with low ABRs in patients receiving prophylaxis. Once-weekly prophylaxis with 40 IU/kg resolved target joint bleeds in 66.7% of the affected patients and improved HR-QoL. This trial was registered at www.clinicaltrials.gov as #NCT01333111.
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Franchini M, Frattini F, Crestani S, Sissa C, Bonfanti C. Treatment of hemophilia B: focus on recombinant factor IX. Biologics 2013; 7:33-8. [PMID: 23430394 PMCID: PMC3575125 DOI: 10.2147/btt.s31582] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Hemophilia B is a recessive X-linked bleeding disorder characterized by deficiency of the coagulation factor IX (FIX). In hemophilia B patients the severity of the bleeding phenotype is related to the degree of the FIX defect. Hemophilia B treatment has improved greatly in the last 20 years with the introduction first of plasma-derived and then of recombinant FIX concentrates. Replacement therapy may be administered through on-demand or prophylaxis regimens, but the latter treatment modality has been shown to be superior in prevention of hemophilic arthropathy and in improvement of patients' quality of life. The purpose of this narrative review is to summarize the current knowledge on treatment strategies for hemophilia B, focusing on recombinant FIX products either clinically used or in development. There is only one rFIX product that is licensed to treat hemophilia B patients; from the analysis of the literature data presented in this review, the authors conclude that this rFIX product has demonstrated an excellent safety profile and excellent clinical efficacy for halting and preventing bleeds in hemophilia B patients. While prophylaxis has emerged as the best therapeutic strategy for such patients because of its ability to prevent hemophilic arthropathy and to improve patients' quality of life, the pharmacokinetically tailored dosing of rFIX is another key point when planning hemophilia B treatment, as it allows optimization of the factor concentrate usage. Further clinical studies are needed to better assess the safety and efficacy (ie, the incidence of adverse reactions and inhibitor development) of newer rFIX products.
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Affiliation(s)
- Massimo Franchini
- Department of Transfusion Medicine and Hematology, Carlo Poma Hospital, Mantua, Italy
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Prolonged half-life and preserved enzymatic properties of factor IX selectively PEGylated on native N-glycans in the activation peptide. Blood 2011; 118:2333-41. [PMID: 21700771 DOI: 10.1182/blood-2011-02-336172] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Current management of hemophilia B entails multiple weekly infusions of factor IX (FIX) to prevent bleeding episodes. In an attempt to make a longer acting recombinant FIX (rFIX), we have explored a new releasable protraction concept using the native N-glycans in the activation peptide as sites for attachment of polyethylene glycol (PEG). Release of the activation peptide by physiologic activators converted glycoPEGylated rFIX (N9-GP) to native rFIXa and proceeded with normal kinetics for FXIa, while the K(m) for activation by FVIIa-tissue factor (TF) was increased by 2-fold. Consistent with minimal perturbation of rFIX by the attached PEG, N9-GP retained 73%-100% specific activity in plasma and whole-blood-based assays and showed efficacy comparable with rFIX in stopping acute bleeds in hemophilia B mice. In animal models N9-GP exhibited up to 2-fold increased in vivo recovery and a markedly prolonged half-life in mini-pig (76 hours) and hemophilia B dog (113 hours) compared with rFIX (16 hours). The extended circulation time of N9-GP was reflected in prolonged correction of coagulation parameters in hemophilia B dog and duration of effect in hemophilia B mice. Collectively, these results suggest that N9-GP has the potential to offer efficacious prophylactic and acute treatment of hemophilia B patients at a reduced dosing frequency.
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Replacement therapy with recombinant factor IX. A multicentre evaluation of current dosing practices in Italy. BLOOD TRANSFUSION = TRASFUSIONE DEL SANGUE 2010; 9:60-9. [PMID: 21084016 DOI: 10.2450/2010.0011-10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Accepted: 04/15/2010] [Indexed: 11/21/2022]
Abstract
BACKGROUND The in vivo recovery of recombinant factor IX (rFIX) is reported to be lower than that of plasma-derived products, with potential clinical implications for dosing. In clinical practice, a conversion (augmentation) factor is suggested to calculate the necessary doses of rFIX. The aim of this study was to assess the range of values for the conversion factor in usual clinical practice in Italy. MATERIALS AND METHODS The study was questionnaire-based and proposed to all Italian Haemophilia centres treating patients with haemophilia B. Age, weight, dosage used in the last effective infusion, treatment regimen (prophylaxis versus on-demand), human immunodeficiency virus (HIV) and hepatitis C virus (HCV) status, and years of previous therapy with rFIX were recorded for patients with severe haemophilia B treated with rFIX. Mean, standard deviation, median and range were calculated for demographic and treatment data for the overall population and for subgroups. The conversion factor for the theoretical dosage of 40 IU/Kg was calculated. RESULTS Among 207 patients with severe haemophilia B being followed in 24 centres, 138 (66.7%) were being treated with rFIX. The sample of 207 patients represents 83.1% of the population of Italian patients with severe haemophilia B. The age range of the studied patients was 0-72 years (mean, 24 years) and the weight range was 3-108 kg (mean, 60 kg). Nineteen patients (14.4%) were positive for HIV and 51 (42.9%) were positive for HCV. The mean dosage of rFIX was 44 IU/Kg, with no significant difference between those receiving the product as prophylaxis or on-demand. A reduction in dosage was observed with increasing age (0.23 IU/kg/year). The mean value for the conversion factor was 1.10 ± 0.36 (median 1.00, range 0.51-2.08), when estimated for the whole population. No effect of HIV and HCV status was found on the dose prescribed. No evident correlation was found with the underlying genetic mutation. DISCUSSION We found that dosing of rFIX in clinical practice is very close to that of plasma-derived FIX concentrates. As a consequence, dosing in the non-surgical setting should be started using the same criteria as those for plasma-derived FIX and treatment effectiveness verified on a clinical basis rather than relying on in vivo recovery assessments.
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