scholarly journals Bleeding Data across Baseline FIX Expression Levels in People with Hemophilia B: An Analysis Using the 'Factor Expression Study'

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 592-592
Author(s):  
Tom Burke ◽  
Anum Shaikh ◽  
Talaha Ali ◽  
Nanxin Li ◽  
Barbara A Konkle ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Gene Therapy ◽  
Linear Relationship ◽  
The United States ◽  
Hemophilia B ◽  
Clotting Factor ◽  
Bleeding Events ◽  
Trial Investigator ◽  
Factor Expression ◽  
Non Linear

Abstract Introduction Complications such as spontaneous and trauma-related bleeding events typically experienced by people with hemophilia B (PWHB) are associated with long-term joint damage and chronic pain, and burdensome treatment with intravenous factor IX administration. Gene therapy, designed to enable the endogenous production of the missing clotting factor, has potential for curative benefit in PWHB (Dolan et al, 2018). Due to its link to risk for bleeding episodes, factor expression level (FEL) is commonly used as an endpoint in hemophilia gene therapy trials. However, little data currently exist linking FEL to bleeding risk in PWHB, most notably within the mild range. As such, the aim of this analysis was to examine the relationship between annual bleed rate (ABR) data across baseline FEL in PWHB. Methods Data from adult non-inhibitor PWHB, across Europe and the United States (US) who received clotting factor on-demand (OD), were drawn from the 'Cost of HaEmophilia in adults: a Socioeconomic Survey' (CHESS) studies. The CHESS studies are retrospective, burden-of-illness studies in people with hemophilia A or B, capturing the economic and humanistic burden associated with living with hemophilia. Additional data were collected to supplement the existing CHESS studies, particularly in people with exogenous FEL in the mild and moderate range. ABR was defined as the physician-reported number of bleed events experienced by the patient in the 12 months to study capture. A generalized linear model (GLM) was used to analyze variation in ABR data across FEL, adjusting for covariates age, body mass index (BMI), and blood-borne viruses. Following this, a multivariable restricted cubic spline (RCS) GLM regression was performed to create, model, and test for the potential non-linear relationship between FEL and ABR. The RCS regression employed 3 knots, located at baseline FEL values of 1, 5, and 10, and controlled once again for age, BMI, and blood-borne viruses. Results A total of 407 adult non-inhibitor PWHB, receiving an OD therapy regimen and with information on ABR, were profiled. The GLM provided adequate fit for the modeling of bleed data; the average marginal effect at the mean was computed from the GLM regression outputs. After controlling for the effects of all other model covariates, the regression analysis showed a significant association between FEL and ABR; for every 1% increase in FEL, the average ABR decreased by 0.08 units (p<0.001). The results of the RCS regression found a significant non-linear relationship between FEL and ABR, ceteris paribus (p<0.001). Conclusions The results of this analysis found baseline FEL to be significantly associated with ABR in PWHB; as baseline FEL increased, ABR reduced. This highlights the clinical importance of new hemophilia gene therapies potentially increasing FEL to that of the mild or non-hemophilic range in terms of reducing patient burden through the better prevention of bleeding events in PWHB. Disclosures Ali: UniQure: Current Employment. Li: UniQure: Current Employment. Konkle: Pfizer, Sangamo, Sanofi, Sigilon, Spark, Takeda and Uniqure: Research Funding; BioMarin, Pfizer and Sigilon: Consultancy. O'Mahony: BioMarin Pharmaceutical Inc.: Consultancy; Freeline: Consultancy; Uniqure: Speakers Bureau. Pipe: Apcintex: Consultancy; ASC Therapeutics: Consultancy; Bayer: Consultancy; Biomarin: Consultancy, Other: Clinical trial investigator; Catalyst Biosciences: Consultancy; CSL Behring: Consultancy; HEMA Biologics: Consultancy; Freeline: Consultancy, Other: Clinical trial investigator; Novo Nordisk: Consultancy; Pfizer: Consultancy; Roche/Genentech: Consultancy, Other; Sangamo Therapeutics: Consultancy; Sanofi: Consultancy, Other; Takeda: Consultancy; Spark Therapeutics: Consultancy; uniQure: Consultancy, Other; Regeneron/ Intellia: Consultancy; Genventiv: Consultancy; Grifols: Consultancy; Octapharma: Consultancy; Shire: Consultancy.

scholarly journals Etranacogene dezaparvovec for hemophilia B gene therapy

2021 ◽  
Vol 2 ◽  
pp. 263300402110588
Author(s):  
Courtney D. Thornburg
Keyword(s):  
Gene Therapy ◽  
Clinical Trials ◽  
Continuous Production ◽  
Factor Ix ◽  
Hemophilia B ◽  
Clotting Factor ◽  
Plain Language ◽  
Long Term Follow Up

The treatment landscape for hemophilia has been rapidly changing with introduction of novel therapies. Gene therapy for hemophilia is a promising therapeutic option for sustained endogenous factor production to mitigate the need for prophylactic treatment to prevent spontaneous and traumatic bleeding. Etranacogene dezaparvovec is an investigational factor IX (FIX) gene transfer product that utilizes the adeno-associated virus (AAV) 5 vector with a liver-specific promoter and a hyperactive FIX transgene. Here, the development of etranacogene dezaparvovec and available efficacy and safety data from clinical trials are reviewed. Overall, etranacogene dezaparvovec provides sustained FIX expression for more than 2 years and allows for a bleed and infusion-free life in the majority of patients. Safety, efficacy, and quality-of-life data will inform shared decision-making for patients who are considering gene therapy. Long-term follow-up regarding duration of expression and safety are crucial. Plain Language Summary Factor IX Padua gene therapy to boost clotting factor and prevent bleeding for people living with hemophilia B People living with hemophilia have low or missing clotting factor, which can lead to bleeding that is unexpected or caused by a traumatic event (such as a sports injury or surgery). There are two main types of hemophilia: clotting factor (F)VIII deficiency (known as hemophilia A) and FIX deficiency (known as hemophilia B). People living with the severe or moderately severe forms of hemophilia (clotting factor levels below 3% of normal) need regular treatment, typically by infusions into the vein, to stop or prevent bleeding and damage to their joints. Gene therapy is currently being investigated as a new treatment option that introduces a working copy of the clotting factor gene to the liver. Following treatment, clotting factor is produced by the liver. Etranacogene dezaparvovec [Et-ra-na-co-gene dez-a-par-vo-vec] is a form of gene therapy for people living with hemophilia B. This form of gene therapy includes a modified form of FIX (FIX Padua) which produces high levels of FIX activity compared with normal FIX. It is being tested to see whether individuals will have low rates of bleeding and not need to treat themselves with clotting factor. In the clinical trials, participants with FIX levels below 2% (of normal) receive a single gene therapy infusion. The results of the trials have so far shown that patients given etranacogene dezaparvovec have continuous production of FIX, whereby they have reported much less bleeding and factor treatment. Questions relating to the safety of the gene therapy and how long it works will hopefully be answered through long-term follow-up of the patients once the trials are completed.

Employing Factor IX Variants to Avoid Limitations Imposed by Immune Recognition of AAV Vector in Hemophilia B Gene Therapy

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3124-3124 ◽  
Author(s):  
Paul E. Monahan ◽  
Junjiang Sun ◽  
Tong Gui ◽  
David G Wichlan ◽  
Scott W McPhee ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Gene Therapy ◽  
Board Of Directors ◽  
Research Funding ◽  
Specific Activity ◽  
Factor Ix ◽  
Hemophilia B ◽  
Ongoing Clinical Trial ◽  
Advisory Committees

Abstract Abstract 3124 Persistent factor IX expression and phenotypic improvement have been achieved in a human clinical trial for hemophilia B using liver-directed adeno-associated virus (AAV) gene therapy vectors. An ongoing clinical trial uses a vector incorporating self-complementing AAV (scAAV) genome form, factor IX codon optimization (FIXopt) and AAV serotype 8 capsid. As was seen in a previous single-strand AAV serotype 2 trial, dose escalation has been associated with apparent immune-mediated transient inflammation of vector-transduced liver, although in contrast to the previous trial persistent FIX expression has been maintained for the first time. Taken together, these important trials define a consistent threshold load of AAV capsid that has stimulated capsid-specific cytotoxic lymphocyte recognition and potential transaminitis. To advance the successes achieved in these trials while providing a clear margin of safety so that this immunogenic threshold need not be approached, we have pursued steps to limit further the AAV capsid load. Single amino acid substitutions at arginine 338 in the FIX catalytic domain generate FIX variants with increased specific activity. We separately substituted either R338A, R338Q, or R338L (FIX Padua) into a codon optimized human factor IX cDNA and evaluated F.IX expression in tissue culture following plasmid DNA transfection of HEK 293t cells. Each R338 substitution improved FIX specific activity, up to 10 times increased over wild type using the R338LFIXopt cDNA. We next generated scAAV8 vectors incorporating a liver-specific transthyretin (TTR) promoter to express optimized codon F.IX cDNA with or without the R338L substitution. FIX−/− mice receiving portal vein injection of 1 × 1010 vg/animal (4 ×1011 vg/kg) expressed 86.5% of normal FIX activity at 2 months post-transduction from the WTopt vector and 330% normal from the R338LFIXopt. Incorporation of R338Lopt variant resulted in at least 6 to 10 fold increase in FIX specific activity over a follow-up of > 40 weeks. At ten months following FIX gene delivery, mice underwent a tail transection bleeding challenge. FIX vector mice demonstrated therapeutic protection from this major bleeding challenge and furthermore all survived with no late rebleeding (a hallmark of hemophilic phenotype). Greater than 100% normal human FIX activity was maintained for >40 weeks following treatment with the R338LFIX vector (v. 26.3% at euthanasia in WTopt vector group). The prolonged follow-up permitted extended safety evaluation. Factor IX inhibitor antibodies were not detected in any mice throughout the follow-up; FIX-binding IgG1 and IgG2 were negative also. Thrombin/antithrombin III complexes (TAT) examined at 12 weeks and at >30 weeks of age in R338LFIXopt vector mice did not differ from levels in WTFIXopt vector-treated or age-matched C57Bl/6 hemostatically normal mice. Necropsy at 40–44 weeks after vector (1 year of age) showed only age-related changes with no microvascular or macrovascular thrombosis on H&E staining or specific immunostaining for fibrin/fibrinogen deposition; specific staining for fibrosis within myocardium or other sites was negative. We next synthesized a R338LFIXopt expression cassette containing the LP1 promoter/enhancer/intron sequence being used in the ongoing clinical trial and demonstrated equivalent FIX activity from either promoter construct. We then established that the R338LFIXopt vector gives a predictable dose-response across a range of doses as low as 1x 1010 vg/kg I.V. and as high as 4 × 1012 vg/kg I.V. Hemarthrosis is the most common bleeding complication in hemophilia and leads to chronic joint destruction. Bleeding was induced in the joint of FIX−/− mice that had been transduced 4 weeks earlier with the R338LFIX vector. Joints were collected at 2 weeks after induced bleed and the bleeding-induced joint damage was graded using an established histologic score. I.V. R338LFIXopt vector pretreatment resulted in protection against joint degeneration in a dose-dependent fashion in this most relevant clinical scenario. These preclinical studies demonstrate a safety :efficacy profile to advance hemophilia gene therapy using the scAAV8.R338LFIXopt vector. Disclosures: Monahan: Baxter: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Asklepios BioPharmaceutical: Patents & Royalties, Research Funding; CSL Behring: Honoraria; NovoNordisk: Honoraria, Membership on an entity's Board of Directors or advisory committees; PharmaIN: Research Funding; Prolor-Biotech: Research Funding. McPhee:Asklepios Biopharmaceutical: Employment. Samulski:Asklepios Biopharmaceutical: Employment, Patents & Royalties.

scholarly journals Lentiviral Hematopoietic Stem and Progenitor Cell Gene Therapy for Wiskott-Aldrich Syndrome (WAS): Up to 8 Years of Follow up in 17 Subjects Treated Since 2010

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3346-3346 ◽  
Author(s):  
Francesca Ferrua ◽  
Maria Pia Cicalese ◽  
Stefania Galimberti ◽  
Stefania Giannelli ◽  
Francesca Dionisio ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Gene Therapy ◽  
Joint Venture ◽  
Conditioning Regimen ◽  
Severe Infection ◽  
Severe Bleeding ◽  
Bleeding Events ◽  
Hematopoietic Stem ◽  
Wiskott Aldrich Syndrome ◽  
Equity Ownership

Background: Wiskott-Aldrich syndrome (WAS) is a rare, X-linked, life-threatening primary immunodeficiency caused by mutations in the gene encoding the WAS protein (WASP). WASP-deficient immune cells have compromised immunological synapse formation, cell migration and cytotoxicity. Thus, WAS is characterized by development of recurrent or severe infections, eczema, and increased risk of autoimmunity and malignancies. In addition, WASP deficiency results in microthrombocytopenia, leading to severe bleeding episodes. When a suitable donor is available, WAS can be treated by hematopoietic stem cell transplant (HSCT), but HSCT can be impeded by complications such as graft versus host disease, rejection and autoimmunity. Importantly, HSCT may carry higher risks in older children (>2-5 yrs) [Shin et al, 2012; Moratto et al, 2011]. An alternative approach is gene therapy (GT). We previously reported interim results of a Phase I/II clinical trial (NCT01515462) in 8 subjects treated with OTL-103, a drug product composed of autologous CD34+ hematopoietic stem and progenitor cells (HSPCs) transduced ex vivo with a lentiviral vector (LV) encoding human WASP cDNA under the control of the endogenous promoter [Ferrua et al, 2019]. We now report updated results on the safety and efficacy of OTL-103 in 17 subjects treated at San Raffaele Hospital as part of the same clinical trial or expanded access programs (EAP) with up to 8 yrs follow up (FU). Methods: NCT01515462: As described in Ferrua et al, 8 male subjects (mean age at GT: 4.8 yrs, range 1.1-12.4) were treated with OTL-103. The source of autologous CD34+ HSPCs was bone marrow (BM; n=5), mobilized peripheral blood (mPB; n=2) or both (n=1). As part of a reduced-intensity conditioning regimen, rituximab was given 22 days prior and busulfan + fludarabine during the week before OTL-103 infusion. At time of reporting, all subjects had ≥3 yrs FU (range: 3-8 yrs). EAP: 9 male subjects (11.2 yrs, 1.4-35.1) received identical treatment to subjects in the clinical trial; autologous CD34+ HSPCs source was mPB in all subjects. At time of reporting, subjects had a median of 1.4 yrs FU (range: 0.1-3.0 yrs) with 6/9 having ≥1 yr FU. Results: At last FU for all subjects (median: 3.0 yrs, range 0.1-8.0), overall survival was 94% (16/17). One EAP subject died 4.5 mo post-GT, due to deterioration of an underlying neurodegenerative condition considered unrelated to OTL-103 by investigator. To date, there have been no reports of insertional oncogenesis or replication-competent LV. While most subjects experienced adverse events (AEs) due to the reduced-intensity conditioning regimen (mainly mild or moderate), there were no reports of AEs related to OTL-103. Efficacy endpoints analyses were performed on surviving patients with ≥1 yr FU. Evidence of engraftment of genetically corrected HSPCs and LV+ colonies in BM was observed within 3 mo and persisted up to 8 yrs - the longest published FU of LV vector durability to date (Figure). WASP expression was restored after GT, shown by increases in the fraction of WASP+ lymphocytes and platelets (PLT) within 3 mo and maintained thereafter (Table). After GT, PLT counts improved, leading to a reduction of frequency and severity of bleeding events. Independence from PLT transfusions and absence of severe bleeding events were observed in all subjects by 9 mo FU (Table). Immune function improved; all evaluable patients discontinued immunoglobulin supplementation after GT (median time to discontinuation: 0.9 years after GT, range: 0.2-5 years). Furthermore, reduction in severe infection rate was observed post-GT, suggestive of immune reconstitution (Table). The decrease in bleeding events and severe infection rates occurred despite the integration of subjects into normal daily activities. Eczema progressively resolved or was reduced compared to baseline. Conclusions: This combined analysis of 17 subjects treated in a clinical trial or EAP with up to 8 yrs FU demonstrates that GT continues to be an effective treatment for WAS. All surviving subjects achieved high levels of multilineage engraftment, sustained restoration of WASP expression in lymphocytes and PLTs, improved PLT counts, and fewer bleeding events. A significant reduction in severe infection rate suggests reconstitution of immune function. Importantly, clinical benefit was also attained in older subjects (>5 yrs), a group considered at higher risk when treated with allogeneic HSCT. Disclosures Jones: Orchard Therapeutics: Employment, Equity Ownership. Dott:Orchard Therapeutics: Employment, Equity Ownership. Naldini:Genenta Science: Consultancy, Equity Ownership; Magenta Therapeutics: Equity Ownership; San Raffaele Telethon Institute for Gene Therapy (SR-TIGET), a joint venture between Fondazione Telethon and Ospedale San Raffaele (OSR): Other: Wiskott-Aldrich Syndrome (WAS) gene therapy was licensed to GlaxoSmithKline (GSK) in 2014. It was then licensed to Orchard Therapeutics (OTL) in April 2018. OTL is the current sponsor of the clinical trial.. Aiuti:San Raffaele Telethon Institute for Gene Therapy (SR-TIGET), a joint venture between Fondazione Telethon and Ospedale San Raffaele (OSR): Other: Wiskott-Aldrich Syndrome (WAS) gene therapy was licensed to GlaxoSmithKline (GSK) in 2014. It was than licensed to Orchard Therapeutics (OTL) in April 2018. OTL is the current sponsor of the clinical trial.; San Raffaele Telethon Institute for Gene Therapy (SR-TIGET), a joint venture between Fondazione Telethon and Ospedale San Raffaele (OSR): Other: Study PI.

The Cost-effectiveness of Gene Therapy for Severe Hemophilia B: Microsimulation Study from the United States Perspective

Blood ◽  
2021 ◽  
Author(s):  
Nancy S. Bolous ◽  
Yichen Chen ◽  
Huiqi Wang ◽  
Andrew M. Davidoff ◽  
Meenakshi Devidas ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Cost Effectiveness ◽  
Cost Effective ◽  
The United States ◽  
Hemophilia B ◽  
Sensitivity Analyses ◽  
Severe Hemophilia ◽  
On Demand ◽  
The Us ◽  
Qaly Threshold

Adeno-associated virus (AAV)-mediated gene therapy is a novel treatment promising to reduce morbidity associated with hemophilia. While multiple clinical trials continue to evaluate efficacy and safety, limited cost-effectiveness data have been published. This study compared the potential cost-effectiveness of AAV-mediated factor IX(FIX)-Padua gene therapy for severe hemophilia B patients in the United States (US) to on-demand FIX replacement and primary FIX prophylaxis, using either standard or extended half-life FIX products. A microsimulation Markov model was constructed and transition probabilities between health states and utilities were informed by published data. Costs were aggregated using a micro-costing approach. An 18-years-old till death time-horizon from the perspective of a third-party payer in the US was conducted. Gene therapy was more cost-effective than both alternatives considering a $150,000/QALY threshold. The price for gene therapy was assumed $2,000,000 in the base-case scenario, yet one of the one-way sensitivity analyses was conducted using observed manufacturing, administration and five-year follow-up cost of $87,198 for AAV-mediated gene therapy vector as derived from the manufacturing facility and clinical practice at St. Jude Children's Research Hospital. One-way sensitivity analyses showed 10/102 scenarios in which gene therapy was not cost-effective compared to alternative treatments. Notably, gene therapy remained cost-effective in a hypothetical scenario in which we estimated that the discounted factor concentrate price was 20% of the wholesale acquisition cost in the US. Probabilistic sensitivity analysis estimated gene therapy cost-effective at 92% of simulations considering $150,000/QALY threshold. In conclusion, based on detailed simulation inputs and assumptions, gene therapy was more cost-effective than on-demand treatment and prophylaxis for patients with severe hemophilia B.

Gene Therapy for Hemophilia A and B: Patient Selection and Follow-up, Requirements for a Cure

1999 ◽  
Vol 82 (08) ◽  
pp. 572-575 ◽  
Author(s):  
Jeanne Lusher
Keyword(s):  
Gene Therapy ◽  
Factor Viii ◽  
Hepatitis A ◽  
Hemophilia A ◽  
The United States ◽  
Factor Ix ◽  
Clotting Factor ◽  
R Factor ◽  
New Variant ◽  
Clotting Factor Concentrates

IntroductionThe treatment of hemophilia A and B has improved considerably in recent years. The availability of hepatitis A and B vaccines, safer clotting factor concentrates (particularly recombinant factor VIII and recombinant factor IX concentrates), and synthetic agents, such as desmopressin,1 has resulted in earlier, more aggressive treatment and prophylactic regimens aimed at preventing chronic, debilitating joint disease.2-8There have been no new cases of human immunodeficiency virus (HIV) disease attributable to clotting factor in North America since 1987, and documented instances of hepatitis transmission by clotting factor concentrates have been rare in the 1990s. Concerns remain that certain nonenveloped viruses, such as human parvovirus B19 and hepatitis A virus, can still be transmitted by some plasma-derived clotting factor concentrates,9and questions linger as to whether the agents causing Creutzfeld-Jacob disease (CJD) and new variant CJD might also be transmitted. Overall, however, the products available to treat hemophilia today are safer than ever before.An increasing number of persons with hemophilia are receiving exclusively recombinant (r) products, and manufacturers are now producing new, second-generation r-factor VIII products that are stabilized with sugars, rather than albumin, or are smaller, truncated molecules.10 Scientists are now designing specific changes into the factor VIII genes in an attempt to derive unique and improved forms of r-factor VIII.11 The next logical areas of focus are to bring to fruition the promise of an “unlimited supply” of r-factor VIII and r-factor IX products, to meet the needs of persons with hemophilia, not only in developed countries, but throughout the world, and to be able to cure hemophilia through gene therapy.As gene therapy trials begin in humans with hemophilia, the scientists involved, the United States Food and Drug Administration (FDA), and perhaps most importantly, members of the hemophilia community must decide which categories of affected individuals should be entered in these trials, particularly the earliest, Phase I trials. Who is most likely to benefit if gene therapy proves to be both effective and safe? Who should be the first patients to be enrolled in each new trial? Who is at greatest risk if something unexpected happens? What would be considered a good outcome? Clearly, some of these questions are more difficult to answer than others.

Adeno-Associated Virus-Mediated Gene Transfer of Factor IX for Treatment of Hemophilia B by Gene Therapy

1999 ◽  
Vol 82 (08) ◽  
pp. 540-546 ◽  
Author(s):  
Roland Herzog ◽  
Katherine High
Keyword(s):  
Gene Therapy ◽  
Gene Transfer ◽  
Coagulation Factor ◽  
Factor Ix ◽  
Biologically Active ◽  
Hemophilia B ◽  
Clotting Factor ◽  
Severe Hemophilia ◽  
Dog Model ◽  
Life Threatening

IntroductionPatients with severe hemophilia have circulating blood coagulation factor VIII (hemophilia A) or factor IX (hemophilia B) levels below 1% of normal due to a genetic defect in the respective X-linked gene. The resulting bleeding disorder is characterized by spontaneous joint bleeds or, in a more life-threatening situation, into critical closed spaces, such as the intracranial or retroperitoneal space. Current treatment for hemophilia is based on intravenous infusions of clotting factor concentrates. These can be episode-based in response to bleeds (which does not prevent ongoing tissue damage nor the risk of a life-threatening bleed) or prophylactic (an expensive and not always practical alternative). The goal of a gene-based therapy is to introduce a functional clotting factor gene into a patient in order to provide a continuous supply of factor levels above 1%.1,2 Clinical endpoints for the efficacy of potential gene therapy trials for hemophilia are, therefore, well-defined and unequivocal.The relatively small size of the factor IX coding sequence (1.4 kb) and the fact that a number of cell types other than hepatocytes (which normally synthesize factor IX) are capable of producing biologically-active factor IX have contributed to the development of hemophilia B into an important model for the treatment of genetic diseases by gene therapy. The factor IX gene can be incorporated into a variety of vector systems. Various target tissues can be chosen for gene transfer as long as the secreted factor IX reaches the circulation and tight regulation of transgene expression is not required.3 Possibly most important in research on gene therapy for coagulation factor deficiencies, and genetic disorders in general, is the availability of a large animal model with severe disease. In this case, it is the well-characterized hemophilia B dogs maintained at the University of North Carolina at Chapel Hill. The animals contain a point-mutation in the portion of the factor IX gene encoding the catalytic domain. This mutation results in an absence of circulating factor IX antigen and, consequently, severe hemophilia B that closely mimics the human disease.4 Gene therapy strategies for hemophilia B have typically established a method of gene transfer, resulting in expression of factor IX in mice, and subsequently, attempted scale-up to the dog model. These investigations have established experiments in the hemophilic dog model as a critical step for the assessment of the efficacy of gene therapy protocols showing initial promise in mice. For example, reimplantation of primary myoblasts that had been transduced ex vivo with a retrovirus was successful in mice, but not in the canine model.5 Adenoviral gene transfer, characterized by varying success in mice, depending on the strain and dose used, has persistently resulted in high, but transient expression following intravenous infusion into dogs.6,7 Cellular immune responses and hepatotoxicity have limited the expression of factor IX from adenoviral vectors to just a few weeks. Repeat administration of the vector was complicated by the induction of neutralizing antibodies to viral particles in injected animals following the first administration. Retroviral gene transfer to hepatocytes was successful in long-term expression of factor IX in hemophilia B dogs but required a partial hepatectomy prior to infusion of the vector through the portal vein. The resulting expression levels were no higher than 0.1% of normal human factor IX levels.8

scholarly journals BAX 335 hemophilia B gene therapy clinical trial results - potential impact of CpG sequences on gene expression

Blood ◽  
2020 ◽  
Author(s):  
Barbara A Konkle ◽  
Christopher Walsh ◽  
Miguel A Escobar ◽  
Neil C Josephson ◽  
Guy Young ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Immune Responses ◽  
Phase 1 ◽  
Factor Ix ◽  
Hemophilia B ◽  
Clotting Factor ◽  
Open Label ◽  
Serious Adverse Events ◽  
Dose Escalation Study ◽  
Cpg Oligodeoxynucleotides

Gene therapy has the potential to maintain therapeutic blood clotting factor IX (FIX) levels in patients with hemophilia B by delivering a functional human F9 gene into liver cells. This phase 1/2, open-label dose-escalation study investigated BAX 335 (AskBio009, AAV8.sc-TTR-FIXR338Lopt), an adeno-associated virus (AAV) serotype 8-based FIX Padua gene therapy, in patients with hemophilia B. This report focuses on 12-month interim analyses of safety, pharmacokinetics, effects on FIX activity, and immune responses for dosed participants. Eight adult males (\aged 20-69 years; range FIX activity, 0.5%-2.0%) received 1 of 3 BAX 335 IV doses: 2.0 × 1011; 1.0 × 1012; or 3.0 × 1012 vector genomes/kg. Three (37.5%) participants had 4 serious adverse events (SAEs), all considered unrelated to BAX 335. No SAE led to death. No clinical thrombosis, inhibitors, or other FIX Padua-directed immunity were reported. FIX expression was measurable in 7 of 8 participants; peak FIX activity displayed dose dependence (32.0%-58.5% in cohort 3). One participant achieved sustained therapeutic FIX activity of ~20%, without bleeding or replacement therapy, for 4 years; in others, FIX activity was not sustained beyond 5-11 weeks. In contrast to some previous studies, corticosteroid treatment did not stabilize FIX activity loss. We hypothesize that the loss of transgene expression could have been caused by stimulation of innate immune responses including CpG oligodeoxynucleotides introduced into the BAX 335 coding sequence by codon optimization. Registered at www.clinicaltrials.gov as NCT01687608.

Suppression of Inhibitor Formation in Protein and Gene Therapy for Hemophilia Using Ex Vivo Expanded Treg

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 13-13
Author(s):  
Debalina Sarkar ◽  
David M Markusic ◽  
Cox Terhorst ◽  
Todd Brusko ◽  
Roland W Herzog
Keyword(s):  
Gene Therapy ◽  
Replacement Therapy ◽  
Immune Tolerance ◽  
Hemophilia A ◽  
Ex Vivo ◽  
Coagulation Factors ◽  
Hemophilia B ◽  
Clotting Factor ◽  
Treg Population

Abstract Abstract 13 Hemophilia A and B result from deficiency in clotting factor VIII (FVIII) or IX (FIX), respectively. In a subset of patients, treatment by factor replacement therapy is limited by formation of inhibitory antibodies to the clotting factors, representing a serious complication that increases risks of morbidity and mortality. Immune responses to the therapeutic coagulation factors are also a concern in newly emerging gene therapies. Regulatory T cells (Treg) offer to be a novel alternative pathway toward immune tolerance. Treg has been identified as a major component of immune tolerance to coagulation factors in pre-clinical studies. Therefore, we hypothesize that ex vivo expanded autologous Treg can suppress inhibitor formation. Our study seeks to test this approach in hemophilic mice. Initially, we optimized in vitro expansion of murine BALB/c-derived Treg. Using flow sorting, GFP+ cells were purified (>98% purity) from spleens of BALB/c knock-in mice containing a GFP reporter linked to FoxP3 expression with an IRES sequence. Sorted cells were stimulated in culture using anti-CD28/anti-CD3 beads in the presence of high-level IL-2 (1000 U/ml). IL-2 was replenished every second day in culture. After ∼1 week, cells were freshly stimulated. At the end of 2 weeks, viability, purity, and FoxP3/GFP expression was confirmed. Greater than 30-fold expansion was repeatedly accomplished. Assumming a dose of 1×106 Treg/mouse, expansion is sufficiently robust to treat >30 mice starting with Treg from 2–3 donor mice. Ex vivo expanded Tregs were adoptively transferred to male hemophilia A mice (BALB/c F8e16 −/−), which were then treated with F.VIII (1 IU human B domain-deleted F.VIII, IV, once per week) for two months. Bethesda assays demonstrated that Treg transplant had effectively suppressed inhibitor formation. Inhibitor titers in control mice were 15–20 BU at 1 month and 30–40 BU at two months. In contrast, Treg treated mice (n=5 per group) formed at most low-titer inhibitors (2–3 BU for both time points). By 2 months, peripheral Treg frequencies had returned to near baseline. To further demonstrate presence of a Treg population capable of suppressing antibody formation against F.VIII, a secondary transfer of sorted CD4+CD25+ splenocytes was performed. Recipient hemophilia A mice were immunized against F.VIII in adjuvant. Compared to mice receiving control Treg, there was significant (P<0.05) suppression of inhibitor formation against F.VIII. In other experiments, Treg therapy was also able to significantly reduce inhibitor titers in hemophilia A mice with pre-existing F.VIII inhibitors. We chose hemophilia A mice (n=6) that developed on average 25 BU from F.VIII replacement therapy. Half of these received Treg transplant, and all mice received 8 more weeks of F.VIII treatment. Inhibitor titers in the control group increased to ∼100 BU. Treg therapy substantially reduced this response (to 15–20 BU, P<0.001). In order to evaluate Treg therapy for hemophilia B, BALB/c F9 −/− × FoxP3-GFP mice were generated. Treg were isolated from these mice as described above, expanded in vitro, and transferred to (BALB/c F9 −/−) hemophilia B mice. Two days later, to test their effectiveness in a gene therapy setting, these mice were treated by intramuscular injection of AAV1 vector expressing human F.IX. By 6 weeks after gene transfer, control mice had formed high-titer antibody against hF.IX (>20 mg IgG/ml plasma, ∼ 10 BU). In contrast, anti-hF.IX formation was undetectable in mice that had received Treg prior to vector administration (n=4/group). While perhaps not as potent as antigen-specific Treg, our data demonstrate the ability of highly purified and ex vivo expanded bulk Treg to control inhibitor formation and thus support their utility for tolerance induction in hemophilia. Their effectiveness may involve emergence of a more specific Treg population after repeated in vivo exposure to antigen. In gene therapy, Treg transplant may be a more desirable alternative to use of immune suppressive drugs. Providing additional immune regulation around the time of vector administration, i.e. when activation signals are provided to the immune system, could be sufficient to prevent immune rejection long-term while inducing antigen-experienced Treg for durable tolerance. Disclosures: Herzog: Genzyme Corp.: Royalties, AAV-FIX technology, Royalties, AAV-FIX technology Patents & Royalties.

Efficacy, PK and Safety Results of Clinical Study Of Recombinant Fusion Protein Linking Coagulation Factor IX With Albumin (rIX-FP) In Previously Treated Patients With Hemophilia B

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1109-1109 ◽  
Author(s):  
Aaron Lubetsky ◽  
Toshko Lissitchkov ◽  
Elena Santagostino ◽  
Gantcho Jotov ◽  
Tami Barazani-Brutman ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Phase I ◽  
Half Life ◽  
Factor Ix ◽  
Hemophilia B ◽  
Bleeding Events ◽  
Spontaneous Bleeding ◽  
Previously Treated Patients ◽  
Bleeding Episodes ◽  
The Mean

Abstract Background The standard of care for patients with severe hemophilia B is replacement treatment with Factor IX (FIX) 2-3 times a week. A fusion protein genetically linking recombinant human coagulation FIX with recombinant human albumin (rIX-FP) was developed with the aim to extend the half-life of FIX. In the completed Phase I pharmacokinetic study, the mean half-life of rIX-FP was found to be over 5 times longer than the subjects’ previous FIX. Thus, rIX-FP has potential to prevent bleedings for longer periods, allowing reduction in the frequency of injections compared to standard FIX and to reduce the number of injections required to treat a single bleed. Aims This was a Phase I/II open-label, multicenter study of rIX-FP in previously treated patients 12-65 years of age with severe hemophilia B (FIX ≤ 2%). The study evaluated the safety and efficacy of rIX-FP, including prevention of bleeding episodes during weekly prophylaxis of rIX-FP. Methods After completion of a 14-day rIX-FP pharmacokinetic assessment, 13 subjects in the prophylaxis arm received weekly prophylaxis of rIX-FP for approximately 11 months, and 4 subjects in the on-demand arm received rIX-FP upon occurrence of bleeding events. The treatment doses were initially selected based upon the pharmacokinetic profile of rIX-FP and subject’s bleeding phenotype, and doses could be adjusted at the Investigator’s discretion. Results Seventeen subjects were enrolled from hemophilia treatment centers in Israel and Bulgaria; the mean age was 26 years (range 13 to 46 years). Following a single injection of 25 IU/kg rIX-FP (n=13), the mean FIX activity level was 3.75% and 2.67% above baseline at Day 7 and Day 14, respectively, and the mean half-life of rIX-FP was 95 hours (comparable to the previously reported Phase I data). Over the 11 month treatment period, rIX-FP demonstrated a good safety profile with a total of over 700 EDs. The treatment was well tolerated and no FIX inhibitor formation was observed. There was no AE considered to be related to treatment with rIX-FP. No subject was withdrawn from the study due to safety concerns or lack of hemostatic efficacy. All 13 prophylaxis subjects were successfully maintained on a weekly routine regimen of rIX-FP for the entire duration of the study, with annualized spontaneous bleeding rates of 1.255 and 1.134 (mean and median respectively). Furthermore, three prophylaxis subjects who received only on-demand treatment prior to study entry had greater than 80% reduction in the annualized bleeding rate compared to their annualized bleeding rate prior to study entry. All bleeding events were treated successfully with ≤ 2 injections of rIX-FP, with approximately 90% of bleeds treated with a single injection of rIX-FP. The mean weekly consumption of rIX-FP was reduced markedly compared to the subjects’ weekly consumption of the previous FIX product. Conclusion This Phase I/II study demonstrated the clinical efficacy of rIX-FP for once weekly routine prophylaxis to prevent spontaneous bleeding episodes and for the treatment of bleeding episodes. In addition, rIX-FP showed an excellent safety and an improved PK profile over currently marketed factor IX products. Disclosures: Lubetsky: CSL Behring: Investigator for CSL clinical trial of rIX-FP Other. Lissitchkov:CSL Behring: Investigator for CSL Behring clinical trial of rIX-FP Other. Santagostino:CSL Behring: Honoraria, Investigator for CSL Behring clinical trial of rIX-FP Other, Research Funding, Speakers Bureau. Jotov:CSL Behring: sub-investigator for CSL Begring trial of rIX-FP Other. Barazani-Brutman:CSL Behring: study coordinator for CSL Behring rIX-FP trials Other. Voigt:CSL Behring: Employment. Moises:CSL Behring: Employment. Jacobs:CSL Behring: Employment. Martinowitz:CSL Behring: Honoraria, Investigator for CSL rIX-FP trials Other, Speakers Bureau.

scholarly journals A Hemophilia Disorder Review: Gene Therapy for Hemophilia B Treatment using rAAV vectors

Bionatura ◽  
2019 ◽  
Vol 02 (Bionatura Conference Serie) ◽  
Author(s):  
Abad Gallardo Claudia Sofía ◽  
Merchán Muñoz Brian David
Keyword(s):  
Gene Therapy ◽  
Blood Clotting ◽  
Hemophilia A ◽  
Factor Ix ◽  
Hemophilia B ◽  
Clotting Factor ◽  
Adeno Associated Virus ◽  
Long Term Effect ◽  
Blood Clotting Factor

Hemophilia is an X-linked recessive disorder characterized by the deficiency in one protein essential for blood coagulation. There are two main types of variants of this disease; hemophilia A (HA) which is related with blood clotting factor VIII (FVIII) deficiency and hemophilia B (HB) which is related with factor IX (FIX) deficiency. Nowadays, there are several options to treat this disorder, however, the most efficient is gene therapy since it has a long-term effect, and contrasts with traditional methods. This review is focused on hemophilia B treatment because FIX is a smaller protein than FVIII (<1kb), and thereby is easier to study. Within gene therapy, methods which use recombinant adeno-associated virus (rAAV) vectors are the best alternative to treat HB since they are safe and reliable. Moreover, rAAV vectors have the advantage of having a low inflammatory potential, a non-pathogenic status, plus the potential for long-term expression of the transferred gene. However, some patients showed an immune response to the capsids of the vectors before treatment. Hence, possible solutions were needed; one of them being the use of anti-antibodies. Finally, clinical trials results showed that under the use of the optimized codon hFIXco and serotype 8 the levels of expression were persistent, demonstrating the potential of gene therapy for hemophilia B treatment.

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