Patient selection for hemophilia gene therapy: Real-life data from a single center

Gene therapy as an innovative approach to the treatment of hemophilia B-a review

Hemophilia B is a disease that affects the human coagulation system, causing the absence or deficiency of coagulation factor IX, which may manifest itself in uncontrolled bleeding that is life-threatening to patients. Due to its inheritance, the disease more often affects men, and the severity of symptoms directly correlates with the concentration of the missing factor IX; hence, the aim of therapy is to maintain it at a level that allows for sufficient hemostasis. The basic model of treatment offered to patients is based on primary prevention with coagulation factor IX with a prolonged half-life, which, however, does not solve the numerous problems faced by patients. An innovative proposal that, despite initial concerns, is becoming more and more popular every day is the recently approved genetic therapy in Europe, which uses viral vectors to transfer the correct gene that encodes coagulation factor IX. The introduction of a recombinant gene in place of its defective counterpart seems to be a promising solution and the beginning of a new era in which genetic therapies have a chance to develop their full potential and replace existing therapeutic regimens.

Gene Therapy in Hemophilia A: Achievements, Challenges, and Perspectives

Strides in advancements of care of persons with hemophilia include development of long-acting factor replacement therapies, novel substitution and hemostatic rebalancing agents, and most recently approved gene therapy. Several decades of preclinical and clinical trials have led to development of adeno-associated viral (AAV) vector-mediated gene transfer for endogenous production of factor VIII (FVIII) in hemophilia A (HA). Only one gene therapy product for HA (valoctocogene roxaparvovec) has been approved by regulatory authorities. Results of valoctocogene roxaparvovec trial show significant improvement in bleeding rates and use of factor replacement therapy; however, sustainability and duration of response show variability with overall decline in FVIII expression over time. Further challenges include untoward adverse effects involving liver toxicity requiring immunosuppression and development of neutralizing antibodies to AAV vector rendering future doses ineffective. Real-life applicability of gene therapy for HA will require appropriate patient screening, infrastructure setup, long-term monitoring including data collection of patient-reported outcomes and innovative payment schemes. This review article highlights the success and development of HA gene therapy trials, challenges including adverse outcomes and variability of response, and perspectives on approach to gene therapy including shared decision-making and need for future strategies to overcome the several unmet needs.

Lentiviral Gene Therapy with CD34+ Hematopoietic Cells for Hemophilia A

BACKGROUND

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.

METHODS

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-ET3-LV - 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).

RESULTS

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).

CONCLUSIONS

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.).

Haemophilia care in Asia: Learning from clinical practice in some Asian countries

BACKGROUND

The healthcare systems in Asia vary greatly due to the socio-economic and cultural diversities which impact haemophilia management.

METHODS

An advisory board meeting was conducted with experts in haemophilia care from Asia to understand the heterogeneity in clinical practices and care provision in the region.

FINDINGS

The overall prevalence of haemophilia in Asia ranges between 3 and 8.58/100,000 patients. Haemophilia A was more prevalent as compared to haemophilia B with a ratio of around 5:1. There is under-diagnosis in the region due to lack of diagnosis, registries and/or lack of appropriate facilities in suburban areas. Most patients are referred to the haematologists by their families or primary care physicians, while some are identified during bleeding episodes. Genetic testing faces obstacles like resource constraints, services available at limited centres and unwillingness of patients to participate. Prophylaxis is offered for people with haemophilia (PWH) with a severe bleeding phenotype. Recombinant factors are approved in most countries across the region and are the preferred therapy. The challenges highlighted for not receiving a high standard of care include patients' reluctance to use an intravenous treatment, poor patient compliance due to frequency of infusions, budget constraints and lack of funding, insurance, availability and accessibility of factor concentrates. Prevalence of neutralizing antibodies ranged from 5% to 20% in the region. Use of immune tolerance induction and bypassing agents to treat inhibitors depends on their cost and availability.

CONCLUSION

Haemophilia care in Asia has evolved to a great extent. However, some challenges remain for which a strategic approach along with multi-stakeholder involvement are needed.

The underevaluated impacts of the therapeutic revolution of hemophilia on women and girls

The advent of new treatment options over the last decades has markedly improved the lives of male persons with hemophilia (PwH). However, this therapeutic revolution has not benefited women and girls with hemophilia (WGH) and symptomatic carriers of the disease to the same extent as their male counterparts. This inequity is primarily due to the exclusion of WGH from clinical trials and a failure to fully recognize their specific treatment needs. Additionally, the indirect impact of innovative therapies, when used for male PwH, on the lives of mothers, other relatives, and partners of these individuals has been largely overlooked until now. In addition to improving access of WGH and carriers to new hemostatic treatments and comprehensive hemophilia care, it is imperative to strive for alleviating the mental burden imposed on them by this chronic disease. The recently proposed concept of a "hemophilia-free mind," primarily focused on male PwH, should therefore also be applied to WGH, symptomatic carriers, and the predominantly female support network of PwH.

The current challenges faced by people with hemophilia B

Hemophilia B (HB) is a rare, hereditary disease caused by a defect in the gene encoding factor IX (FIX) and leads to varying degrees of coagulation deficiency. The prevailing treatment for people with HB (PWHB) is FIX replacement product. The advent of recombinant coagulation products ushered in a new era of safety, efficacy, and improved availability compared with plasma-derived products. For people with severe HB, lifelong prophylaxis with a FIX replacement product is standard of care. Development of extended half-life FIX replacement products has allowed for advancements in the care of these PWHB. Nonetheless, lifelong need for periodic dosing and complex surveillance protocols pose substantive challenges in terms of access, adherence, and healthcare resource utilization. Further, some PWHB on prophylactic regimens continue to experience breakthrough bleeds and joint damage, and subpopulations of PWHB, including women, those with mild-to-moderate HB, and those with inhibitors to FIX, experience additional unique difficulties. This review summarizes the current challenges faced by PWHB, including the unique subpopulations; identifying the need for improved awareness, personalized care strategies, and new therapeutic options for severe HB, which may provide future solutions for some of the remaining unmet needs of PWHB.

Perspectives and perception of haemophilia gene therapy by French patients

INTRODUCTION AND AIM

A national survey was initiated by representatives of French patients with haemophilia (AFH) and the French reference centre for haemophilia, in order to appreciate the awareness and knowledge of these patients regarding haemophilia gene therapy (HGT) and understand better their position about this innovative treatment that will soon become available.

RESULTS

Of 143 answers received, 137 could be analysed, representing about 3.5% of patients with severe or moderate haemophilia over 16year-old. They were 80.3% with haemophilia A and 19.7 % with haemophilia B, with a severe form of the disease for 80.3 % of them. Curiosity for HGT was formulated by 64.2% of the participants, 33.6 % being interested by this approach as soon as it will be available and 38.7 % preferring to wait until more patients have been treated. Only 3.6 % of the participants would never consider receiving HGT. The level of awareness and knowledge was estimated to be limited by 39.5 % of the patients. More than 60 % of them declared having never or almost never discussed HGT with the team of their haemophilia centre. Before deciding to get HGT, 54.4 % of the participants considered that it will be very important to compare it with their current treatment and 53.7 % would like to be better informed by their care providers.

CONCLUSIONS

These results highlight the need for training and education for patients, but also for professionals at haemophilia centres, about HGT and the shared decision-making process. Objective, unbiased and transparent information must be available for patients about this very promising therapy which nonetheless carries more uncertainty and unknowns compared to other haemophilia treatments.

Cost-Effectiveness of a Hypothetical Gene Therapy for Alzheimer's Disease: A Markov Simulation Analysis

Background: Alzheimer's disease is a prevalent neurodegenerative condition causing significant health and economic burden. With limited therapeutic options, clinical trials have been investigating Alzheimer's disease treatment using more novel approaches, including gene therapy. However, there is limited evidence on the cost-effectiveness of such treatments. Objectives: This research aims to explore the cost-effectiveness of a hypothetical gene therapy for patients with Alzheimer's disease at varying degrees of severity. Methods: A Markov model with a 20-year time horizon was constructed for simulated cohorts with mild cognitive impairment due to Alzheimer's disease, assigned to receive either standard of care or a one-time gene therapy administration. Varying costs of care due to disease severity and treatment efficacy were utilized to determine the effect of those variables at different willingness-to-pay thresholds. Results: Under the initial assumption that the hypothetical gene therapy grants a 30% risk reduction in disease progression and entry into institutional care, the maximum cost-effective price for gene therapy is $141,126 per treatment using the threshold of $150,000 per quality-adjusted life year (QALY). By increasing the treatment effectiveness to 50%, cost-effective price nearly doubled at each willingness-to-pay threshold (e.g., $260,902 at the $150,000/QALY threshold). Conclusion: Despite being cost-effective at a very high price, the hypothetical gene therapy for AD would still need to be priced considerably lower than other approved gene therapies on the market. Thus, a comprehensive pharmacoeconomic assessment remains critical in pricing innovative therapy and determining coverage for patients in need.

Delivery of gene therapy in haemophilia treatment centres in the United States: Practical aspects of preparedness and implementation

INTRODUCTION

Haemophilia treatment centres (HTCs) and healthcare providers (HCPs) will need to adapt to a new treatment paradigm with the emergence of adeno-associated virus (AAV)-based gene therapy for the treatment of haemophilia in adults.

AIM

This review examines the upcoming patient and institutional journeys, along with practical aspects of preparedness for clinical delivery of gene therapy by HTCs.

METHODS

Based on our clinical experience and examination of published literature, we explored the parallel journeys for patients and treatment centres to navigate before, during, and after administration of gene therapy.

RESULTS

The patient journey includes: information gathering; decision making; comprehensive patient assessment; preparation for the infusion itself; short- and long-term monitoring; lifestyle modifications; and the possible need for immunosuppressive treatment. Informed decision-making may require patient education with extensive discussions and an understanding that not all people with haemophilia will choose or be eligible for gene therapy, although eligibility criteria continue to evolve. The institutional journey includes: consideration of biosafety procedures; planning for product procurement, handling, storage, and administration; development of detailed protocols and guidance documents; contingency planning for immunosuppressive and haemostatic management; consideration of clinical capabilities and staff training needs; coordination of efforts by the full multidisciplinary team; and collaboration between referring, dosing, and follow-up treatment centres. Documented protocols and guidance documents are pivotal for this complex therapy to ensure safe handling, optimal delivery, and post-infusion management and follow-up.

CONCLUSION

Successful implementation of this new treatment modality will require communication and collaboration among multiple stakeholders.

How to translate and implement the current science of gene therapy into haemophilia care?

Gene-based therapy opens an entirely new paradigm in managing people with haemophilia (PWH), offering them the possibility of a functional cure by enabling continuous expression of factor VIII (FVIII) or factor IX (FIX) after transfer of a functional gene designed to replace the PWH's own defective gene. In recent years, significant advances in gene therapy have been made, resulting in clotting factor activity attaining near-normal levels, as reflected by 'zero bleeding rates' in previously severely inflicted patients following a single administration of adeno-associated viral (AAV) vectors. While this new approach represents a major advancement, there are still several issues that must be resolved before applying this technology in clinical practice. First, awareness, communication, and education about the therapeutic potential and modalities of gene therapy must be further strengthened. To this end, objective, unbiased, transparent, and regularly updated information must be shared, in an appropriate way and understandable language with the support of patients' organizations. Second, healthcare providers should adopt a patient-centred approach, as the 'one size fits all' approach is inappropriate when considering gene therapy. Instead, a holistic patient view taking into account their physical and mental dimensions, along with unexpressed expectations and preferences, is mandatory. Third, the consent procedure must be improved, ensuring that patients' interests are maximally protected. Finally, gene therapy is likely to be first delivered in a few centres, with the highest expertise and experience in this domain. Thus, patients should be managed based on a hub-and-spoke model, taking into account that the key to gene therapy's success lies in an optimal communication and collaboration both within and between haemophilia centres sharing their experiences in the frame of international registries. This review describes recent progress and explains outstanding hurdles that must be tackled to ease the implementation of this paradigm-changing new therapy.

Gene Therapy and Hemophilia: Where Do We Go from Here?

Gene therapy for hemophilia using adeno-associated virus (AAV) derived vectors can reduce or eliminate patients' disease-related complications and improve their quality of life. Broad implementation globally will lead to societal gains and foster health equity. Several vector products each for factor IX (FIX) or factor VIII (FVIII) deficiency are in advanced clinical development. Safety data are reassuring. Efficacy data for up to 8 and 5 years, respectively, vary considerably among vector types and among individuals, but indicate significant reduction in bleeds and factor use. Products will soon be approved for marketing. This review highlights the relevant considerations for implementation of hemophilia gene therapy, specifically across a broad range of socioeconomic backgrounds globally, based on recent publications and our own experience. We address the current efficacy and safety data and relevant aspects of vector immunology. We then discuss pertinent implementation steps including pre-implementation and readiness assessments, considerations on cost, cost-effectiveness and payment models, approaches to education and informed consent, and the operational needs as well as the need for monitoring of health outcomes and implementation outcomes. To prevent a lag or complete lack of establishing access to this life-changing therapy option for all patients with hemophilia worldwide, adaptable pathways supported by collaborative and international efforts of all stakeholders are needed.

Improving patient informed consent for haemophilia gene therapy: the case for change

Adeno-associated virus-based gene therapy points to a coming transformation in the treatment of people living with haemophilia, promising sustained bleed control and potential improvement in quality of life. Nevertheless, the consequences of introducing new genetic material are not trivial. The perceived benefits should not minimise the challenges facing patients in understanding the long-term risks and providing a valid and meaningful informed consent, whether in a research or clinical setting. Informed consent is a fundamentally important doctrine in both medical ethics and health law, upholding an individual's right to define their personal goals and make their own autonomous choices. Patients should be enabled to recognise their clinical situation, understand the implications of treatment and integrate every facet of their life into their decision. This review describes informed consent processes for haemophilia gene therapy clinical trials, factors affecting patients' decision making and the availability of patient-centred decision support interventions, to ensure that patients' interests are being protected. Regulatory guidance has been published for physicians and manufacturers in haemophilia on informed consent, including for gene therapy, while best-practice recommendations for patient-physician discussions are available. In all settings, however, communicating and presenting highly technical and complex therapeutic information is challenging, especially where multiple barriers to scientific knowledge and health literacy exist. We propose several evidence-informed strategies to enhance the consent procedure, such as utilising validated literacy and knowledge assessment tools as well as participatory learning environments over an extended period, to ensure that patients are fully cognisant of the consent they give or deny. Further research is needed to define new, creative approaches for patient education and the upholding of ethical values in the informed consent process for gene therapy. The lessons learnt and approaches developed within haemophilia could set the gold standard for good practice in ensuring ethical preparedness amidst advances in genetic therapies.

Plain language summary

Improving the informed consent process for people living with haemophilia considering gene therapy. Gene therapy is the process of replacing faulty genes with healthy ones. In haemophilia, gene therapy involves introducing a working copy of the gene for the clotting factor that patients are missing. Following treatment, patients should begin producing their own clotting factor normally. However, people living with haemophilia (PwH) need to be fully informed regarding the potential benefits and risks of gene therapy and what this means for them, whether as part of a research study or routine medical care.Patients must be respected and supported to make decisions about their own health and wellbeing, recognising their legal and moral right to set personal goals and make treatment choices. For this to happen in practice, patients should be aware of their individual health needs, understand the effects of treatment and consider lifestyle preferences in relation to their decisions. This article attempts to describe how informed consent is obtained in haemophilia gene therapy clinical trials, what affects a patient's ability to make decisions and the availability of information and support to respect and protect the interests of PwH.Regulators responsible for approving medical products have published guidance on informed consent for physicians and pharmaceutical manufacturers in haemophilia, including for gene therapy. Recommendations have been made about the best ways for PwH to discuss gene therapy with their physicians. Yet, poor communication of complex topics, such as gene therapy, can be problematic, especially if patients lack the skills and confidence to understand and discuss the science, or for physicians with limited time in clinic.We propose strategies to improve the consent process, so patients can feel more able to make informed decisions about new treatments. Further research is needed to find new, creative approaches for educating patients and ensuring that the informed consent process for gene therapy in haemophilia is ethical.

Etranacogene dezaparvovec for hemophilia B gene therapy

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.