Hemophilia Therapy Research Articles

Lentiviral Gene Therapy with CD34+ Hematopoietic Cells for Hemophilia A.

Severe hemophilia A is managed with factor VIII replacement or hemostatic products that stop or prevent bleeding. Data on gene therapy with hematopoietic stem-cell (HSC)-based expression of factor VIII for the treatment of severe hemophilia A are lacking. We conducted a single-center study involving five participants 22 to 41 years of age with severe hemophilia A without factor VIII inhibitors. Autologous HSCs were transduced with CD68-LV-ET3 - a lentiviral vector including a new F8 transgene (ET3) with a myeloid-directed CD68 promoter - either without transduction enhancer (group 1) or with transduction enhancer (group 2). Transduced HSCs were transplanted into recipients after myeloablative conditioning. The treatment was assessed for safety (engraftment and regimen-related toxic effects) and efficacy (factor VIII activity and annualized bleeding rate). Participants received CD68-ET3-LV-transduced autologous CD34+ HSCs at doses of 5.0×106 to 6.1×106 per kilogram of body weight. The vector copy numbers in the final drug product were 1.0 and 0.6 copies per cell for the two participants in group 1 and 1.5, 0.6, and 2.2 copies per cell for the three participants in group 2. The duration of severe neutropenia was 7 to 11 days and of severe thrombocytopenia was 1 to 7 days. The median factor VIII activity level, measured with the use of a one-stage assay, after day 28 until the last follow-up visit was 5.2 IU per deciliter (range, 3.0 to 8.7) and 1.7 IU per deciliter (range, 1.0 to 4.0) with a peripheral-blood vector copy number of 0.2 and 0.1 copies per cell, respectively, in the two group 1 participants, and 37.1 IU per deciliter (range, 18.3 to 73.6), 19.3 IU per deciliter (range, 6.6 to 34.5), and 39.9 IU per deciliter (range, 20.6 to 55.1) with a peripheral-blood vector copy number of 4.4, 3.2, and 4.8 copies per cell, respectively, in the three group 2 participants. The annualized bleeding rate was zero for all five participants over a cumulative follow-up of 81 months (median follow-up, 14 months; range, 9 to 27). Gene therapy for hemophilia A with the use of lentiviral vector-transduced autologous HSCs resulted in stable factor VIII expression, with factor VIII activity correlating to vector copy number in the peripheral blood. (Funded by the Ministry of Science and Technology, Government of India, and others; ClinicalTrials.gov number, NCT05265767; Clinical Trials Registry-India number, CTRI/2022/03/041304.).

Evaluating the Cost-Effectiveness of Etranacogene Dezaparvovec Gene Therapy for Hemophilia B Treatment in the USA.

Hemophilia B, a severe genetic disorder, involves substantial treatment costs and frequent interventions. Etranacogene dezaparvovec (EDZ) is a recently approved gene therapy for hemophilia B. This study evaluates the cost-effectiveness of EDZ compared with conventional factor IX (FIX) prophylaxis. A semi-Markov model simulated a cohort of adult males with severe hemophilia B to assess the economic impact of EDZ versus FIX prophylaxis over a lifetime horizon from a health system perspective in the USA. Inputs derived from clinical trials included therapy durability and transition probabilities based on Pettersson Scores. Scenario analyses incorporated frameworks suggested by the Institute for Clinical and Economic Review for single or short-term transformative therapies. Base-case analysis showed that at a cost of US$3.5 million, EDZ led to lifetime cost savings of US$11 million and an additional 0.64 quality-adjusted life years (QALYs) compared with FIX. However, FIX has extremely high annual costs. When annual cost offsets attributed to EDZ were capped at US$150,000, EDZ was found to have a threshold price of US$3.1 million at a willingness-to-pay of US$150,000 per QALY. EDZ proved to be a dominant strategy over FIX prophylaxis in the base-case scenario, providing large cost savings and slightly better outcomes. The substantial costs associated with FIX are a primary driver behind these results. The introduction of cost-offset caps significantly affects the value-based price of EDZ. Using caps on cost offsets in considering price can help to balance affordability and value in the health system.

Non-factor Therapies for Hemophilia: Achievements and Perspectives.

Non-factor replacement therapies (NFTs) have been developed to address the limitations of conventional replacement therapies, aiming to improve hemostasis and provide enhanced protection against bleeding episodes and long-term joint damage for patients both with and without inhibitors. Factor VIII (FVIII)-mimetic agents, such as emicizumab, have transformed the management of hemophilia A with inhibitors, offering a lower treatment burden and an effective alternative for those without inhibitors as well. Rebalancing agents, including anti-tissular factor pathway inhibitor agents (concizumab and marstacimab) and serpin inhibitors like fitusiran, have shown promising efficacy for patients with hemophilia B with inhibitors and other hemophilia subtypes. Administered subcutaneously, NFTs generate stable thrombin levels and feature a long half-life, which can shift severe hemophilia toward a milder phenotype. These therapies are effective regardless of inhibitor status and hold potential for application in other bleeding disorders. Evaluating the potential thrombotic risk after implementing mitigation measures, along with the development of anti-drug antibodies (ADAs), remain critical areas for further analysis. NFTs pose additional challenges due to their complex mechanism of action and the absence of a standardized laboratory assessment method. Unresolved issues include optimal management strategies for major surgeries and tailored approaches for safe use in older populations. This review highlights the progress and future potential of NFTs in treating persons with hemophilia.

UKHCDO gene therapy taskforce: Guidance for implementation of haemophilia gene therapy into routine clinical practice for adults.

2022 was a landmark year with two adeno-associated viral vectors (AAVs) receiving conditional marketing authorization from EMA for the treatment of persons with severe haemophilia A and severe to moderately severe haemophilia B and a third in 2024. Gene therapy is a transformative, irreversible treatment with long-lasting effects, necessitating development of new clinical pathways to ensure optimal outcomes. To develop a consensus framework and service specification for delivery of AAV gene therapy for haemophilia in adults within the UK using the hub-and-spoke model proposed by the European Association of Haemophilia and Allied Disorders and the European Haemophilia Consortium. The UK Haemophilia Centre Doctors Organisation (UKHCDO) set up a working party to develop expert consensus guidance, working with NHS England to ensure alignment with NHS England commissioning and the national service specification. These guidelines detail the patient pathway, counselling and governance requirements for the hub-and-spoke model. The national service specification requires the hub site to manage governance for AAV-based gene therapy. Proposed regional and national multidisciplinary teams will harmonize clinical practices incorporating expertise from various specialities and professional groups. Key requirements identified include standardized documentation and multidisciplinary collaboration. Nationally agreed patient information and counselling checklists will streamline the informed consent process and facilitate data collection for long-term safety and efficacy monitoring. These guidelines provide a structured framework for the delivery of liver-directed gene therapy. Whilst specific to the United Kingdom they provide a framework for the implementation of gene therapy in other countries for haemophilia and other monogenic disorders.

Efficient generation of liver sinusoidal endothelial-like cells secreting coagulation factor VIII from human induced pluripotent stem cells

Liver sinusoidal endothelial cells (LSECs) and LSEC progenitor cells (LPCs) derived from human pluripotent stem cells (PSCs) are expected as valuable cell sources for the development of cell therapy for hemophilia A, a congenital deficiency of coagulation factor VIII (FVIII), as LSECs are responsible for FVIII production. However, there is room for improvement in the efficiency of LSECs and LPCs differentiation from PSCs. In this study, we sought to optimize the method of mesoderm differentiation induction, the initial step of LSEC differentiation from PSCs, to efficiently induce LSEC-like cells capable of secreting FVIII from human induced pluripotent stem cells (iPSCs). Following optimization of the concentration and stimulation period of CHIR99021 (glycogen synthase kinase 3β inhibitor), bone morphogenetic protein 4, fibroblast growth factor 2, and Activin A in the mesoderm induction step, approximately 65% and 54% of cells differentiated into LPCs and LSEC-like cells, respectively. Furthermore, we observed substantial FVIII protein secretion from LSEC-like cells in vitro. In conclusion, we established an efficient method for obtaining LPCs and functional LSEC-like cells from iPSCs in vitro.

Gene therapy for hemophilia

Concept Gene therapy with adeno-associated virus (AAV) vectors treats hemophilia A or B by delivering a functional F8 or F9 gene to hepatocytes. This single infusion enables endogenous production of FVIII or FIX protein, reducing bleeding in patients. Evolution Long-term clinical studies have provided insight into the efficacy, safety, and durability of AAV-mediated gene therapies for hemophilia A and B. Gene therapies have now been approved for hemophilia A (valoctocogene roxaparvovec) and hemophilia B (etranacogene dezaparvovec; fidanacogene elaparvovec) in select regions. Application The approved gene therapies are associated with a strong reduction in bleeding tendency and increased FVIII or FIX activity levels, without the need for additional FVIII or FIX replacement therapies, in the vast majority of patients. Future Steps Improvements in AAV technology, protein expression, and immunogenicity may render AAV-mediated gene therapies more efficient, longer lasting and safer for people with hemophilia A or B.

Efficacy, safety, and quality of life 4 years after valoctocogene roxaparvovec gene transfer for severe hemophilia A in the phase 3 GENEr8-1 trial

BackgroundValoctocogene roxaparvovec, an adeno-associated virus-mediated gene therapy for severe hemophilia A, enables endogenous factor VIII (FVIII) expression and provides bleed protection. ObjectivesDetermine valoctocogene roxaparvovec durability, efficacy, and safety 4 years post-treatment. MethodsIn the phase 3 GENEr8-1 trial, 134 adult males with severe hemophilia A without inhibitors and previously using FVIII prophylaxis received a 6x1013 vg/kg infusion of valoctocogene roxaparvovec. Efficacy endpoints included annualized bleed rate (ABR), annualized FVIII infusion rate, FVIII activity, and the Haemophilia-Specific Quality of Life Questionnaire for Adults (Haemo-QOL-A). Adverse events (AEs) and immunosuppressant use were assessed. Change from baseline was assessed after participants discontinued prophylaxis (scheduled for week 4). ResultsMedian follow-up was 214.3 weeks; 2 participants discontinued since the previous data cutoff. Declines from baseline in mean treated ABR (−82.6%; P<0.0001) and annualized FVIII infusion rate (−95.5%; P<0.0001) were maintained from previous years in the primary analysis population of 112 participants who enrolled from a noninterventional study. During year 4, 81/110 rollover participants experienced 0 treated bleeds. Week 208 mean and median chromogenic FVIII activity were 16.1 IU/dL and 6.7 IU/dL, respectively, in 130 modified intention-to-treat (mITT) participants. Seven participants resumed prophylaxis since the previous data cutoff. Mean change from baseline to week 208 in Haemo-QOL-A Total Score (P<0.0001) remained clinically meaningful for mITT participants. Alanine aminotransferase elevation was the most common AE during year 4 (56/131 participants); none required immunosuppressants. ConclusionsValoctocogene roxaparvovec provides persistent FVIII expression, hemostatic control, and health-related quality of life improvements with no new safety signals.

Reviewing The Latest Treatments for Haemophilia

Abstract: Advancements in haemophilia treatment have been significant in the first 20 years of the 21st century. However, the progress started with the fractionation of plasma in 1946. The first concentrates were developed after discovering FVIII in frozen plasma cryoprecipitate and FIX in the supernatant in the early 1960s, leading to initial attempts at replacement therapy. Unfortunately, due to the lack of screening methods for viral pathogens, people with haemophilia (PWH) received contaminated concentrates, leading to infections with the hepatitis A virus, hepatitis C virus, and human immunodeficiency virus. Thankfully, by 1985, viral screening methods and virucidal techniques were developed, making concentrates safe. The introduction of chromatography steps with monoclonal antibodies in the production process led to increasingly pure products. However, the problem of immunogenicity of administered concentrates persists. The development of alloantibodies against FVIII in a significant percentage of PWH is a serious adverse effect of replacement therapy. The next major advancement came with cloning the F8 and F9 genes, which allowed the production of factor concentrates using recombinant DNA technology. The injected FVIII and FIX molecules have a relatively short circulating half-life in the plasma of people with haemophilia A and B, approximately 12 and 18 hours, respectively. Methods such as conjugating the factor molecule with fragment crystallizable of IgG1, albumin, or adding polyethylene glycol have been applied to prolong the plasma half-life and extend the interval between injections, especially for risk. The next frontier in haemophilia therapy is the development of durable and potentially curative treatments, such as gene addition therapy. Experiments in haemophilia B have shown promising long-lasting responses. However, the results of gene therapy for haemophilia A have not been as remarkable, and the durability of the treatment is yet to be demonstrated. The long-term safety, predictability, durability, and efficacy of gene therapy for haemophilia A and B remain open questions. Currently, only healthy adult PWH has been enrolled in gene therapy clinical trials, and further studies are needed before gene therapy can be widely applied to children and those with pre-existing antibodies against the delivery vector.

Drug-induced liver injury related to gene therapy: A new challenge to be managed.

Gene therapy is being successfully developed for the treatment of several genetic disorders. Various methods of gene transfer have been developed to enable the production of the deficient enzyme or protein. One of the most important is adeno-associated virus vectors, which have been shown to be viable for use in invivo gene therapy. Several gene therapies have already been approved. They are also promising for acquired diseases. Important examples include gene therapy for haemophilia A and B, X-linked myotubular myopathy, spinal muscular atrophy and several liver diseases such as Criggler-Najjar disease, alpha-1 antitrypsin deficiency and Fabry disease. However, the introduction of a foreign compound into hepatocytes leads to hepatic reactions with heterogeneous phenotypic expression and a wide spectrum of severity, ranging from mild transaminase elevation to acute liver failure. Several mechanisms appear to be involved in liver injury, including an immune response, but also direct toxicity depending on the method of gene transfer. As a result, the incidence, expression and severity of liver injury vary from indication to indication and from patient to patient. Patients treated for haemophilia A are more prone to transaminase elevation than those treated for haemophilia B. Corticosteroids are successfully used to correct liver reactions but also to prevent degradation of the transferred gene and loss of therapeutic activity. The aim of this review is to describe the risk of liver injury according to the indication for gene therapy and the short- and long-term management currently proposed to prevent or correct liver reactions in clinical practice.

Liver-related aspects of valoctocogene roxaparvovec gene therapy for hemophilia A: expert guidance for clinical practice

AbstractAdeno-associated virus–based gene therapy (valoctocogene roxaparvovec) is an attractive treatment for hemophilia A. Careful clinical management is required to minimize the risk of hepatotoxicity, including assessment of baseline liver condition to determine treatment eligibility and monitoring liver function after gene therapy. This article describes recommendations (developed by a group of hemophilia experts) on hepatic function monitoring before and after gene therapy. To prevent harmful liver-related effects, gene therapy is contraindicated in patients with uncontrolled liver infections, autoimmune hepatitis, liver stiffness ≥8 kPa, or cirrhosis. Before using gene therapy in patients with liver steatosis or other liver disorders, the risk of liver damage should be considered using a highly individualized approach. Treatment is not recommended in patients with abnormal liver enzymes, including alanine aminotransferase (ALT) at any level above the upper limit of normal (ULN). Therefore, pretreatment assessment of liver health should include laboratory tests, abdominal ultrasound, and liver stiffness measurements by transient elastography (TE). In the first year after therapy, ALT levels should be monitored 1 to 2 times per week to detect elevations ≥1.5× ULN, which may require immunosuppressant therapy. Patients with ALT elevation should receive prednisone 60 mg/d for 2 weeks, followed by stepwise tapering when ALT returns to baseline. ALT monitoring should continue long term (every 3-6 months), along with abdominal ultrasound (every 6 months) and TE (yearly) evaluations. When patients with good liver health are selected for treatment and closely monitored thereafter, ALT elevations can be promptly treated and are expected to resolve without long-term hepatic sequelae.

Evaluating clinically translatable conditioning for platelet gene therapy in murine hemophilia A with inhibitors

BackgroundPlatelet gene therapy is effective in hemophilia A (HA) mice even with inhibitors. Fludarabine (Flu), along with busulfan (Bu) or melphalan (Mel), preconditioning has been shown to be highly effective for hematopoietic stem cell transplantation in the clinic. ObjectivesTo evaluate the efficacy of Bu–Flu and Mel–Flu preconditioning in platelet gene therapy of HA with inhibitors. MethodsBu–Flu and Mel–Flu were used to condition HA mice preimmunized with recombinant human factor (F)VIII. An optimal 660 centigray total body irradiation was used as a control regimen in parallel. Platelet–FVIII expression was introduced by transplantation of 2bF8 lentivirus (LV)-transduced hematopoietic stem cells. Animals were analyzed by fluorescence-activated cell sorting, quantitative polymerase chain reaction, FVIII assays, and tail bleeding tests. ResultsBu–Flu, but not Mel–Flu, enabled successful 2bF8 gene therapy. All recipients achieved >55% chimerism post hematopoietic stem cell transplantation in both Bu–Flu and 660 centigray groups, with comparable copy numbers of 2bF8 cassette and the platelet–FVIII levels. The bleeding phenotype was rescued in 2bF8LV-transduced recipients. FVIII inhibitor titers declined with time, with comparable disappearance time of inhibitors between the 2 groups. When animals were rechallenged with recombinant human FVIII after the titers dropped to undetectable levels, no inhibitors were detected in 2bF8LV-transduced recipients. In contrast, all untransduced transplanted control mice produced inhibitors. These data demonstrate that immune tolerance was established in 2bF8LV-transduced primed HA mice under Bu–Flu conditioning. ConclusionBu–Flu preconditioning allows for successfully introducing platelet–FVIII expression to restore hemostasis and induce immune tolerance in primed HA mice, suggesting that this approach is a promising clinically translatable strategy for gene therapy of HA with inhibitors.

The impact of capping health system cost savings on the projected cost-effectiveness of etranacogene dezaparvovec compared with factor IX prophylaxis for the treatment of hemophilia B.

This viewpoint discusses cost-effectiveness estimates for EtranaDez, a gene therapy for hemophilia B, using the Institute for Clinical and Economic Review's (ICER) framework for single and short-term therapies (SSTs). EtranaDez offers long-term benefits from a single administration, in contrast to the high costs and frequent dosing required by current factor IX prophylaxis. However, the projected gains in health from EtranaDez are small relative to the cost implications of the therapy, and consequently, how the cost offsets associated with EtranaDez are counted has a substantial impact on assessing its cost-effectiveness. Strategies for assessing cost offsets used in the ICER SST framework include a 50/50 cost-sharing model between the health care system and the manufacturer and a cap of $150,000 annually on health care cost offsets. Results from the standard full cost-offset analysis as reported by ICER depicted EtranaDez as a dominant therapy with substantial cost savings compared with factor IX prophylaxis. However, while considering the ICER SST framework, particularly the $150,000 annual cap scenario, the cost-effectiveness was significantly reduced. The incremental cost-effectiveness ratio varied notably between these scenarios, challenging the conventional perception of value of gene therapy in health care. These cost-sharing scenarios highlight the potential of the ICER SST framework to help curtail inefficient health care spending. In cases in which the cost of existing treatment is exceedingly high, the application of such frameworks would improve efficiency in resource allocation, fostering a balance between incentives for innovation and economic sustainability in managed care systems.

Hemophilia Healing with AAV: Navigating the Frontier of Gene Therapy.

Gene therapy for hemophilia has advanced tremendously after thirty years of continual study and development. Advancements in medical science have facilitated attaining normal levels of Factor VIII (FVIII) or Factor IX (FIX) in individuals with haemophilia, thereby offering the potential for their complete recovery. Despite the notable advancements in various countries, there is significant scope for further enhancement in haemophilia gene therapy. Adeno-associated virus (AAV) currently serves as the primary vehicle for gene therapy in clinical trials targeting haemophilia. Subsequent investigations will prioritize enhancing viral capsid structures, transgene compositions, and promoters to achieve heightened transduction efficacy, diminished immunogenicity, and more predictable therapeutic results. The present study indicates that whereas animal models have transduction efficiency that is over 100% high, human hepatocytes are unable to express clotting factors and transduction efficiency to comparable levels. According to the current study, achieving high transduction efficiency and high levels of clotting factor expression in human hepatocytes is still insufficient. It is also crucial to reduce the risk of cellular stress caused by protein overload. Despite encountering various hurdles, the field of haemophilia gene therapy holds promise for the future. As technology continues to advance and mature, it is anticipated that a personalized therapeutic approach will be developed to cure haemophilia effectively.

Long-term clinical outcomes of prophylaxis with an rFVIIIFc or rFIXFc in adults aged ≥50 years with hemophilia A or B

Advances in therapies for hemophilia have led to an increased life expectancy for people with hemophilia. Limited data exist on the aging population of people with hemophilia who face additional challenges of age-related comorbidities. Efmoroctocog alfa (a recombinant factor VIII Fc fusion protein [herein referred to as rFVIIIFc]) and eftrenonacog alfa (a recombinant factor IX Fc fusion protein [rFIXFc]) are extended half-life factor replacements for hemophilia A and B, respectively, with demonstrated long-term safety and efficacy. The objective of this post hoc analysis was to describe long-term outcomes in participants 50+ years of age treated with rFVIIIFc or rFIXFc in pivotal Phase 3 trials and their extension studies: A-LONG (NCT01181128; n=21) and ASPIRE (NCT01454739; n=20 [95%]); B-LONG (NCT01027364; n=26) and B-YOND (NCT01425723; n=16 [62%]). Approximately half of participants (48%) with hemophilia A and 62% of participants with hemophilia B had a comorbidity at baseline. More than half of the participants were taking 1+ concomitant medication at baseline, with arthropathy and joint pain reported as the most common indications. Prophylaxis with rFVIIIFc or rFIXFc in individuals 50+ years of age with hemophilia A or B, respectively, resulted in low annualized bleed rates and improvements in joint health. Positive impacts on health-related quality of life were observed in individuals on either rFVIIIFc or rFIXFc prophylaxis. The results for the older subgroups were consistent with the overall study populations, demonstrating that prophylaxis with rFVIIIFc or rFIXFc provides long-term clinical benefits irrespective of age and presence of target joints in patients with severe hemophilia.

Human umbilical cord mesenchymal stem cell-based gene therapy for hemophilia B using scAAV-DJ/8-LP1-hFIXco transduction

BackgroundHemophilia B is an X-linked bleeding disorder caused by a mutation in the gene responsible for encoding coagulation factor IX (FIX). Gene therapy offers promising potential for curing this disease. However, the current method of relatively high dosage of virus injection carries inherent risks. The purpose of this study was to introduce a novel scAAV-DJ/8-LP1-hFIXco vector transduced human umbilical cord blood derived mesenchymal stem cells (HUCMSCs) as an alternative cell-based gene therapy to conventional gene therapy for Hemophilia B.MethodsThe LP1-hFIXco gene structure was designed by us through searching the literature from NCBI and the scAAV-DJ/8-LP1-hFIXco vector was constructed by a commercial company. The HUCMSCs were cultivated in routine approach and transduced with scAAV-DJ/8-LP1-hFIXco vector. The human FIX activation system was employed for detection of hFIXco activity. The RNA and protein expression levels of the hFIXco were evaluated using PCR and western blot techniques. In animal studies, both NSG and F9-KO mice were used for the experiment, in which clotting time was utilized as a parameter for bleeding assessment. The immunohistochemical analysis was used to assess the distribution of HUCMSCs in mouse tissue sections. The safety for tumorigenicity of this cell-based gene therapy was evaluated by pathological observation after hematoxylin-eosin staining.ResultsThe transduction of HUCMSCs with the scAAV-DJ/8-LP1-hFIXco vector results in consistent and sustainable secretion of human FIXco during 5 months period both in vitro and in mouse model. The secretion level (hFIXco activity: 97.1 ± 2.3% at day 7 to 48.8 ± 4.5% at 5 months) was comparable to that observed following intravenous injection with a high dose of the viral vector (hFIXco activity: 95.2 ± 2.2% to 40.8 ± 4.3%). After a 5-month observation period, no clonal expansions of the transduced cells in tissues were observed in any of the mice studied.ConclusionsWe have discovered a novel and safer HUCMSCs mediated approach potentially effective for gene therapy in hemophilia B.

Recent Advances in Gene Therapy for Hemophilia: Projecting the Perspectives.

One of the well-known X-linked genetic disorders is hemophilia, which could be hemophilia A as a result of a mutation in the F8 (factor VIII) gene or hemophilia B as a result of a mutation in the F9 (factor IX) gene, leading to insufficient levels of the proteins essential for blood coagulation cascade. In patients with severe hemophilia, factor VIII or factor IX activities in the blood plasma are considerably low, estimated to be less than 1%. This is responsible for spontaneous or post-traumatic bleeding episodes, or both, leading to disease complications and death. Current treatment of hemophilia relies on the prevention of bleeding, which consists of expensive lifelong replacement infusion therapy of blood plasma clotting factors, their recombinant versions, or therapy with recombinant monoclonal antibodies. Recently emerged gene therapy approaches may be a potential game changer that could reshape the therapeutic outcomes of hemophilia A or B using a one-off vector in vivo delivery and aim to achieve long-term endogenous expression of factor VIII or IX. This review examines both traditional approaches to the treatment of hemophilia and modern methods, primarily focusing on gene therapy, to update knowledge in this area. Recent technological advances and gene therapeutics in the pipeline are critically reviewed and summarized. We consider gene therapy to be the most promising method as it may overcome the problems associated with more traditional treatments, such as the need for constant and expensive infusions and the presence of an immune response to the antibody drugs used to treat hemophilia.

Exploring the Low Uptake of Gene Therapy in Hemophilia.

Exploring the Low Uptake of Gene Therapy in Hemophilia.

The longitudinal kinetics of AAV5 vector integration profiles and evaluation of clonal expansion in mice

Adeno-associated virus (AAV)-based vectors are used clinically for gene transfer and persist as extrachromosomal episomes. A small fraction of vector genomes integrate into the host genome, but the theoretical risk of tumorigenesis depends on vector regulatory features. A mouse model was used to investigate integration profiles of an AAV serotype 5 (AAV5) vector produced using Sf and HEK293 cells that mimics key features of valoctocogene roxaparvovec (AAV5-hFVIII-SQ), a gene therapy for severe hemophilia A. The majority (95%) of vector genome reads were derived from episomes, and mean (± standard deviation) integration frequency was 2.70±1.26 and 1.79±0.86 integrations per 1000 cells for Sf- and HEK293-produced vector. Longitudinal integration analysis suggested integrations occur primarily within 1 week, at low frequency, and their abundance was stable over time. Integration profiles were polyclonal and randomly distributed. No major differences in integration profiles were observed for either vector production platform, and no integrations were associated with clonal expansion. Integrations were enriched near transcription start sites of genes highly expressed in the liver (P = 1x10−4) and less enriched for genes of lower expression. We found no evidence of tumorigenesis or fibrosis caused by the vector integrations.

AAV vectors for long-term gene therapy of hemophilia B: Are we there yet?

AAV vectors for long-term gene therapy of hemophilia B: Are we there yet?

Patient Perspective on Disease Burden and Gene Therapy for Hemophilia A and B: The "Haemvolution for Patients" Italian Survey.

Hemophilia is a rare X-linked congenital bleeding disorder due to a deficiency of factor VIII (hemophilia A [HA]) or factor IX (hemophilia B [HB]). Replacement and nonreplacement treatments are available but have limitations. Gene therapy (GT) provides an effective, long-term, single-dose treatment option, now approaching clinical practice. This study aimed to understand patient perspectives on GT for HA and HB in Italy using a qualitative questionnaire distributed through Italian patient associations, addressing patient views on daily life, treatments, unmet needs, quality of life (QoL), and GT for hemophilia. In total, 141 participants had HA, and 14 had HB (severe 78.6%). Daily life was most affected by pain and/or joint function limitations (57.5% of participants), high infusion frequency (42.5%), management of breakthrough bleeding episodes (40.3%), and anxiety/fear of severe or sudden bleeding (38.8%). Despite current treatments, about half of the participants experienced three or more annual bleeding episodes. Most participants knew of GT (87.2%) and expected improvements in QoL (60.5%), reduced frequency of current treatments (53.5%), and a permanent cure (49.1%); 46.4% were unaware of its once-off dosage and 46.4% were not concerned about the costs they anticipated to be associated with GT. Although several fears were reported, 25.0% of participants were willing to undergo GT with the support of a multidisciplinary team. This survey provided valuable insight into patient perspectives on hemophilia and GT in Italy. Overall, relevant proportions of patients still experience limitations affecting their daily life. Most were positive about GT and anticipated improvements in their clinical outcomes and QoL.