RESUMEN
Coagulation factor (F) VIII is essential for hemostasis. After activation, it combines with activated FIX (FIXa) on anionic membranes to form the intrinsic tenase enzyme complex, responsible for activating FX in the rate-limiting step of sustained coagulation. Hemophilia A and hemophilia B are due to inherited deficiencies in the activity of FVIII and FIX, respectively. Treatment of hemophilia A over the last decade has benefited from improved understanding of FVIII biology, including its secretion pathway, its interaction with von Willebrand factor in circulation, the biochemical nature of its FIXa cofactor activity, the regulation of FVIIIa by inactivation pathways, and its surprising immunogenicity. This has facilitated biotechnology innovations with first-in-class examples of several new therapeutic modalities recently receiving regulatory approval for hemophilia A, including FVIII mimetic bispecific antibodies and recombinant adeno associated viral (rAAV) vector-based gene therapy. Biological insights into FVIII are also guiding the development and use of gain-of-function FVIII variants aimed at addressing limitations of first-generation rAAV vectors for hemophilia A. Several gain-of-function FVIII variants designed to have improved secretion are currently incorporated in second-generation rAAV vectors and have recently entered clinical trials. Continued mutually reinforcing advancements in the understanding of FVIII biology and treatments for hemophilia A will be necessary to achieve the ultimate goal of hemophilia therapy: normalizing hemostasis and optimizing well-being with minimal treatment burden for all patients worldwide.
RESUMEN
Emicizumab improves the procoagulant activity of select loss-of-function FIX variants with likely dysfunctional assembly of the intrinsic Xase complex that cause hemophilia B. FVIII-mimetics may represent an alternative non-factor therapy for select hemophilia B patients.
RESUMEN
In vivo gene therapy is rapidly emerging as a new therapeutic paradigm for monogenic disorders. For almost three decades, hemophilia A (HA) and hemophilia B (HB) have served as model disorders for the development of gene therapy. This effort is soon to bear fruit with completed pivotal adeno-associated viral (AAV) vector gene addition trials reporting encouraging results and regulatory approval widely anticipated in the near future for the current generation of HA and HB AAV vectors. Here we review the clinical development of AAV gene therapy for HA and HB and examine outstanding questions that have recently emerged from AAV clinical trials for hemophilia and other monogenic disorders.
Asunto(s)
Hemofilia A , Hemofilia B , Humanos , Hemofilia A/genética , Hemofilia A/terapia , Dependovirus/genética , Factor IX/genética , Vectores Genéticos , Hemofilia B/genética , Hemofilia B/terapia , Terapia Genética/métodosRESUMEN
BACKGROUND: The goal of gene therapy for patients with hemophilia A is to safely impart long-term stable factor VIII expression that predictably ameliorates bleeding with the use of the lowest possible vector dose. METHODS: In this phase 1-2 trial, we infused an investigational adeno-associated viral (AAV) vector (SPK-8011) for hepatocyte expression of factor VIII in 18 men with hemophilia A. Four dose cohorts were enrolled; the lowest-dose cohort received a dose of 5 × 1011 vector genomes (vg) per kilogram of body weight, and the highest-dose cohort received 2 × 1012 vg per kilogram. Some participants received glucocorticoids within 52 weeks after vector administration either to prevent or to treat a presumed AAV capsid immune response. Trial objectives included evaluation of the safety and preliminary efficacy of SPK-8011 and of the expression and durability of factor VIII. RESULTS: The median safety observation period was 36.6 months (range, 5.5 to 50.3). A total of 33 treatment-related adverse events occurred in 8 participants; 17 events were vector-related, including 1 serious adverse event, and 16 were glucocorticoid-related. Two participants lost all factor VIII expression because of an anti-AAV capsid cellular immune response that was not sensitive to immune suppression. In the remaining 16 participants, factor VIII expression was maintained; 12 of these participants were followed for more than 2 years, and a one-stage factor VIII assay showed no apparent decrease in factor VIII activity over time (mean [±SD] factor VIII activity, 12.9±6.9% of the normal value at 26 to 52 weeks when the participants were not receiving glucocorticoids vs. 12.0±7.1% of the normal value at >52 weeks after vector administration; 95% confidence interval [CI], -2.4 to 0.6 for the difference between matched pairs). The participants had a 91.5% reduction (95% CI, 88.8 to 94.1) in the annualized bleeding rate (median rate, 8.5 events per year [range, 0 to 43.0] before vector administration vs. 0.3 events per year [range, 0 to 6.5] after vector administration). CONCLUSIONS: Sustained factor VIII expression in 16 of 18 participants who received SPK-8011 permitted discontinuation of prophylaxis and a reduction in bleeding episodes. No major safety concerns were reported. (Funded by Spark Therapeutics and the National Heart, Lung, and Blood Institute; ClinicalTrials.gov numbers, NCT03003533 and NCT03432520.).
Asunto(s)
Dependovirus , Factor VIII/genética , Factor VIII/metabolismo , Terapia Genética , Vectores Genéticos , Hemofilia A/sangre , Adolescente , Adulto , Estudios de Seguimiento , Genotipo , Glucocorticoides/efectos adversos , Glucocorticoides/uso terapéutico , Hemofilia A/genética , Hemofilia A/prevención & control , Hepatocitos/metabolismo , Humanos , Terapia de Inmunosupresión , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
Mechanisms thought to regulate activated factor VIII (FVIIIa) cofactor function include A2-domain dissociation and activated protein C (APC) cleavage. Unlike A2-domain dissociation, there is no known phenotype associated with altered APC cleavage of FVIII, and biochemical studies have suggested APC plays a marginal role in FVIIIa regulation. However, the in vivo contribution of FVIIIa inactivation by APC is unexplored. Here we compared wild-type B-domainless FVIII (FVIII-WT) recombinant protein with an APC-resistant FVIII variant (FVIII-R336Q/R562Q; FVIII-QQ). FVIII-QQ demonstrated expected APC resistance without other changes in procoagulant function or A2-domain dissociation. In plasma-based studies, FVIII-WT/FVIIIa-WT demonstrated dose-dependent sensitivity to APC with or without protein S, whereas FVIII-QQ/FVIIIa-QQ did not. Importantly, FVIII-QQ demonstrated approximately fivefold increased procoagulant function relative to FVIII-WT in the tail clip and ferric chloride injury models in hemophilia A (HA) mice. To minimize the contribution of FV inactivation by APC in vivo, a tail clip assay was performed in homozygous HA/FV Leiden (FVL) mice infused with FVIII-QQ or FVIII-WT in the presence or absence of monoclonal antibody 1609, an antibody that blocks murine PC/APC hemostatic function. FVIII-QQ again demonstrated enhanced hemostatic function in HA/FVL mice; however, FVIII-QQ and FVIII-WT performed analogously in the presence of the PC/APC inhibitory antibody, indicating the increased hemostatic effect of FVIII-QQ was APC specific. Our data demonstrate APC contributes to the in vivo regulation of FVIIIa, which has the potential to be exploited to develop novel HA therapeutics.
Asunto(s)
Factor VIII/metabolismo , Hemofilia A/patología , Hemostasis , Proteína C/metabolismo , Proteínas Recombinantes/metabolismo , Animales , Cloruros/toxicidad , Factor VIII/genética , Femenino , Compuestos Férricos/toxicidad , Hemofilia A/inducido químicamente , Hemofilia A/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Proteína C/genética , Proteínas Recombinantes/genéticaRESUMEN
INTRODUCTION: The haemophilia community on Twitter is diverse, consisting of advocacy groups, patients, physicians, researchers and other users. However, the scope of this community is uncharacterized, and limited data is available regarding effective participation in this community. AIM: To assess the types of users active in the haemophilia community on Twitter, as well as major themes present in haemophilia-related tweets. METHODS: Forty-nine thousand five hundred and twelve tweets between September 2019 and September 2021 were classified using regular expressions. A subset of the classified tweets was manually analysed to identify prevalent discussion themes. RESULTS: Among the top 250 users by post count, the largest categories of users were support and advocacy groups, people with bleeding disorders and healthcare providers. The largest thematic categories of tweets were gene therapy, contaminated haemophilia blood products, haemophilia research, clinical management of haemophilia and COVID-19. While misinformation was rare, negative and incorrect perceptions of haemophilia were present among the general public. CONCLUSION: Our results demonstrate patterns of effective Twitter usage for patient care, research and advocacy purposes among the haemophilia community.
Asunto(s)
COVID-19 , Hemofilia A , Medios de Comunicación Sociales , Comunicación , Hemofilia A/terapia , Humanos , SARS-CoV-2RESUMEN
PURPOSE: To provide guidance on the use of anticoagulant and antithrombotic agents in pediatric patients undergoing interventional radiology procedures. MATERIALS AND METHODS: A multidisciplinary writing group conducted a comprehensive literature search to identify studies on the topic of interest. Recommendations were developed for procedural risk and medication dosage and withholding. A modified Delphi technique was used to achieve consensus agreement on the recommendations. RESULTS: A total of 24 studies, including systematic reviews and meta-analyses, randomized controlled trials, and prospective and retrospective cohort studies, were identified as relevant. The expert writing group agreed on procedural risk categorization, laboratory testing thresholds, and medication dosage and withholding recommendations specific to pediatric practice. They additionally described the nuances of anticoagulation in clinical conditions specific to pediatrics. CONCLUSIONS: The Society of Interventional Radiology recommends following the guidance provided in the document when developing multidisciplinary management protocols for anticoagulation and antithrombotic treatment in pediatric patients undergoing interventional radiology procedures.
Asunto(s)
Trombosis , Humanos , Niño , Estudios Retrospectivos , Estudios Prospectivos , Trombosis/diagnóstico por imagen , Trombosis/etiología , Trombosis/prevención & control , Anticoagulantes , Consenso , Radiología IntervencionistaRESUMEN
Decades of preclinical and clinical studies developing gene therapy for hemophilia are poised to bear fruit with current promising pivotal studies likely to lead to regulatory approval. However, this recent success should not obscure the multiple challenges that were overcome to reach this destination. Gene therapy for hemophilia A and B benefited from advancements in the general gene therapy field, such as the development of adeno-associated viral vectors, as well as disease-specific breakthroughs, like the identification of B-domain deleted factor VIII and hyperactive factor IX Padua. The gene therapy field has also benefited from hemophilia B clinical studies, which revealed for the first time critical safety concerns related to immune responses to the vector capsid not anticipated in preclinical models. Preclinical studies have also investigated gene transfer approaches for other rare inherited bleeding disorders, including factor VII deficiency, von Willebrand disease, and Glanzmann thrombasthenia. Here we review the successful gene therapy journey for hemophilia and pose some unanswered questions. We then discuss the current state of gene therapy for these other rare inherited bleeding disorders and how the lessons of hemophilia gene therapy may guide clinical development.
Asunto(s)
Terapia Genética/métodos , Trastornos Hemorrágicos/terapia , HumanosRESUMEN
INTRODUCTION: Emicizumab is the first approved non-factor therapy for haemophilia A. It provides superior prophylactic bleeding control compared to other products in both patients with and patients without inhibitors. However, there is no real-world data about the monetary consequences of starting emicizumab. AIM: To examine the estimated costs of starting emicizumab in a cohort of real-world haemophilia A patients with and without inhibitors. METHODS: The cost of haemostatic therapy for 6 months before and after initiating emicizumab for participants in a multicentre observational study was calculated based on the type of product and dosing that was used for prophylaxis and treating breakthrough bleeds, the number of treated bleeds and the participant weight. RESULTS: Ninety-two patients were included, 18 with an active inhibitor. The median age was 8.7 years. The median total cost for all patients decreased from $176,720 to $128,099 (p = .04) after initiating emicizumab, largely because of decrease in the total cost of high-cost outliers. The cost of prophylaxis and the total cost of bleeds also significantly decreased after starting emicizumab, both for patient with and patients without inhibitors. CONCLUSIONS: Starting or switching to prophylaxis with emicizumab results in decreased costs for the treatment of patients with haemophilia A. This real-world data could inform on payer decisions as well as future cost-effective analysis.
Asunto(s)
Anticuerpos Biespecíficos , Hemofilia A , Anticuerpos Monoclonales Humanizados/uso terapéutico , Niño , Hemofilia A/tratamiento farmacológico , Hemorragia/prevención & control , HumanosRESUMEN
Adeno-associated virus (AAV) vectors are a leading platform for gene-based therapies for both monogenic and complex acquired disorders. The success of AAV gene transfer highlights the need to answer outstanding clinical questions of safety, durability, and the nature of the human immune response to AAV vectors. Here, we present longitudinal follow-up data of subjects who participated in the first trial of a systemically delivered AAV vector. Adult males (n = 7) with severe hemophilia B received an AAV2 vector at doses ranging from 8 × 1010 to 2 × 1012 vg/kg to target hepatocyte-specific expression of coagulation factor IX; a subset (n = 4) was followed for 12-15 years post-vector administration. No major safety concerns were observed. There was no evidence of sustained hepatic toxicity or development of hepatocellular carcinoma as assessed by liver transaminase values, serum α-fetoprotein, and liver ultrasound. Subjects demonstrated persistent, increased AAV neutralizing antibodies (NAbs) to the infused AAV serotype 2 (AAV2) as well as all other AAV serotypes tested (AAV5 and AAV8) for the duration of follow-up. These data represent the longest available longitudinal follow-up data of subjects who received intravascular AAV and support the preliminary safety of intravascular AAV administration at the doses tested in adults. Data demonstrate, for the first time, the persistence of high-titer, multi-serotype cross-reactive AAV NAbs for up to 15 years post- AAV vector administration. Our observations are broadly applicable to the development of AAV-mediated gene therapy.
Asunto(s)
Dependovirus/genética , Factor IX/metabolismo , Técnicas de Transferencia de Gen/efectos adversos , Terapia Genética/métodos , Vectores Genéticos/administración & dosificación , Hemofilia B/terapia , Hepatocitos/metabolismo , Infusiones Intraarteriales/métodos , Transducción de Señal/efectos de los fármacos , Adulto , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/inmunología , Cápside/inmunología , Reacciones Cruzadas , Dependovirus/inmunología , Estudios de Seguimiento , Terapia Genética/efectos adversos , Vectores Genéticos/efectos adversos , Humanos , Infusiones Intraarteriales/efectos adversos , Hígado/efectos de los fármacos , Hígado/metabolismo , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Resultado del Tratamiento , Adulto JovenRESUMEN
BACKGROUND: The prevention of bleeding with adequately sustained levels of clotting factor, after a single therapeutic intervention and without the need for further medical intervention, represents an important goal in the treatment of hemophilia. METHODS: We infused a single-stranded adeno-associated viral (AAV) vector consisting of a bioengineered capsid, liver-specific promoter and factor IX Padua (factor IX-R338L) transgene at a dose of 5×1011 vector genomes per kilogram of body weight in 10 men with hemophilia B who had factor IX coagulant activity of 2% or less of the normal value. Laboratory values, bleeding frequency, and consumption of factor IX concentrate were prospectively evaluated after vector infusion and were compared with baseline values. RESULTS: No serious adverse events occurred during or after vector infusion. Vector-derived factor IX coagulant activity was sustained in all the participants, with a mean (±SD) steady-state factor IX coagulant activity of 33.7±18.5% (range, 14 to 81). On cumulative follow-up of 492 weeks among all the participants (range of follow-up in individual participants, 28 to 78 weeks), the annualized bleeding rate was significantly reduced (mean rate, 11.1 events per year [range, 0 to 48] before vector administration vs. 0.4 events per year [range, 0 to 4] after administration; P=0.02), as was factor use (mean dose, 2908 IU per kilogram [range, 0 to 8090] before vector administration vs. 49.3 IU per kilogram [range, 0 to 376] after administration; P=0.004). A total of 8 of 10 participants did not use factor, and 9 of 10 did not have bleeds after vector administration. An asymptomatic increase in liver-enzyme levels developed in 2 participants and resolved with short-term prednisone treatment. One participant, who had substantial, advanced arthropathy at baseline, administered factor for bleeding but overall used 91% less factor than before vector infusion. CONCLUSIONS: We found sustained therapeutic expression of factor IX coagulant activity after gene transfer in 10 participants with hemophilia who received the same vector dose. Transgene-derived factor IX coagulant activity enabled the termination of baseline prophylaxis and the near elimination of bleeding and factor use. (Funded by Spark Therapeutics and Pfizer; ClinicalTrials.gov number, NCT02484092 .).
Asunto(s)
Factor IX/genética , Terapia Genética/métodos , Vectores Genéticos , Hemofilia B/terapia , Transgenes , Adolescente , Adulto , Dependovirus/inmunología , Factor IX/metabolismo , Factor IX/uso terapéutico , Vectores Genéticos/administración & dosificación , Hemofilia B/genética , Hemofilia B/metabolismo , Hemorragia/prevención & control , Humanos , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
New therapies for hemophilia A and hemophilia B will likely continue to change clinical practice. Ranging from extended half-life to nonfactor products and gene therapy, these innovative approaches have the potential to enhance the standard of care by decreasing infusion frequency to increase compliance, promoting prophylaxis, offering alternatives to inhibitor patients, and easing route of administration. Each category has intrinsic challenges that may limit the broader application of these promising therapies. To date, none specifically address the challenge of dispersing treatment to the developing world.
Asunto(s)
Hemofilia A/terapia , Animales , Terapia Genética , Semivida , Hemofilia A/genética , Humanos , Resultado del TratamientoRESUMEN
MYH9-related disease is a rare cause of thrombocytopenia. We report an infant girl who presented with severe thrombocytopenia at birth and was initially diagnosed with and treated for neonatal alloimmune thrombocytopenia. However, persistent thrombocytopenia led to the suspicion of congenital thrombocytopenia and subsequent identification of a novel variant in MYH9 (E1421K). In silico analysis strongly predicts that this is a disruptive substitution. Immunofluorescent analysis of neutrophils demonstrates abnormal aggregates of MYH9 protein. This case also suggests that a very high immature platelet fraction (≥40%) may be useful for rapidly differentiating MYH9-related disease from other causes of neonatal thrombocytopenia.
Asunto(s)
Proteínas Motoras Moleculares , Mutación Missense , Cadenas Pesadas de Miosina , Agregación Patológica de Proteínas , Trombocitopenia Neonatal Aloinmune , Sustitución de Aminoácidos , Plaquetas/metabolismo , Plaquetas/patología , Femenino , Enfermedades Genéticas Congénitas/sangre , Enfermedades Genéticas Congénitas/genética , Enfermedades Genéticas Congénitas/patología , Enfermedades Genéticas Congénitas/terapia , Humanos , Recién Nacido , Proteínas Motoras Moleculares/genética , Proteínas Motoras Moleculares/metabolismo , Cadenas Pesadas de Miosina/genética , Cadenas Pesadas de Miosina/metabolismo , Neutrófilos/metabolismo , Neutrófilos/patología , Agregación Patológica de Proteínas/genética , Agregación Patológica de Proteínas/metabolismo , Agregación Patológica de Proteínas/patología , Agregación Patológica de Proteínas/terapia , Trombocitopenia Neonatal Aloinmune/sangre , Trombocitopenia Neonatal Aloinmune/genética , Trombocitopenia Neonatal Aloinmune/patología , Trombocitopenia Neonatal Aloinmune/terapiaAsunto(s)
Hemofilia B , Dependovirus/genética , Factor IX/genética , Terapia Genética , Hemofilia B/genética , Hemofilia B/terapia , HumanosAsunto(s)
Factor Xa , Rivaroxabán , Anticoagulantes , Niño , Inhibidores del Factor Xa/efectos adversos , Humanos , Hemorragias Intracraneales/inducido químicamente , Hemorragias Intracraneales/tratamiento farmacológico , Piridonas , Proteínas Recombinantes/uso terapéutico , Rivaroxabán/uso terapéuticoAsunto(s)
Heparina , Hirudinas , Catéteres , Humanos , Fragmentos de Péptidos , Proteínas Recombinantes , Terapia TrombolíticaRESUMEN
Following successful efforts in adeno-associated virus (AAV) gene addition for hemophilia B gene therapy, the development of valoctocogene roxaparvovec (Roctavian; Biomarin) over the past decade represents a potential new hemophilia A (HA) treatment paradigm. Roctavian is the first licensed HA gene therapy and was conditionally approved in Europe in August of 2022 and approved in the U.S. in June of 2023. Beyond Roctavian, there are ongoing pivotal trials of additional AAV vectors for HA and others that are progressing through pre-clinical development or early-phase clinical trial as well as non-AAV approaches also in clinical development. This review focuses on the clinical development of Roctavian for which the collective clinical trials represent the largest body of work thus far available for any licensed AAV product. From this pioneering clinical development, several outstanding questions have emerged for which the answers will undoubtedly be important to the clinical adaptation of Roctavian and future efforts in HA gene therapy. Most notably, unexplained year-over-year declines in factor VIII (FVIII) expression after Roctavian treatment contrast with observed stable FVIII expression in AAV HA gene therapy clinical trials with more modest initial FVIII expression. This observation has been qualitatively replicated in animal models. The development and approval of Roctavian is a landmark in HA therapeutics, though next-generation approaches are needed before HA gene therapy fulfills its promise of stable FVIII expression that normalizes hemostasis.
RESUMEN
The hemophilias are the most common severe inherited bleeding disorders and are caused by deficiency of clotting factor (F) VIII (hemophilia A) or FIX (hemophilia B). The resultant bleeding predisposition significantly increases morbidity and mortality. The ability to improve the bleeding phenotype with modest increases in clotting factor levels has enabled the development and regulatory approval of adeno-associated viral (AAV) vector gene therapies for people with hemophilia A and B. The canine hemophilia model has proven to be one of the best predictors of therapeutic response in humans. Here, we report long-term follow-up of 12 companion dogs with severe hemophilia that were treated in a real-world setting with AAV gene therapy. Despite more baseline bleeding than in research dogs, companion dogs demonstrated a 94% decrease in bleeding rates and 61% improvement in quality of life over a median of 4.1 years (range 2.6-8.9). No new anti-transgene immune responses were detected; one dog with a pre-existing anti-FVIII inhibitor achieved immune tolerance with gene therapy. Two dogs expressing 1%-5% FVIII post gene therapy experienced fatal bleeding events. These data suggest AAV liver-directed gene therapy is efficacious in a real-world setting but should target expression >5% and closely monitor those with levels in the 1%-5% range.