Delivering on the promise of gene therapy for haemophilia

What is a cure through gene therapy? An analysis and evaluation of the use of "cure"

The development of gene therapy has always come with the expectation that it will offer a cure for various disorders, of which hemophilia is a paradigm example. However, although the term is used regularly, it is unclear what exactly is meant with "cure". Therefore, the aim of this paper is to analyse how the concept of cure is used in practice and evaluate which of the interpretations is most suitable in discussions surrounding gene therapy. We analysed how cure is used in four different medical fields where the concept raises discussion. We show that cure can be used in three different ways: cure as normalization of the body, cure as obtaining a normal life, or cure as a change in identity. We argue that since cure is a practical term, its interpretation should be context-specific and the various uses can exist simultaneously, as long as their use is suitable to the function the notion of cure plays in each of the settings. We end by highlighting three different settings in the domain of hemophilia gene therapy in which the term cure is used and explore the function(s) it serves in each setting. We conclude that in the clinical application of gene therapy, it could be better to abandon the term cure, whereas more modest and specified definitions of cure are required in the context of health resource allocation decisions and decisions on research funding.

Improving Hemophilia Care in Low- and Middle-Income Countries: Addressing Challenges and Enhancing Quality of Life

Hemophilia, a genetic bleeding disorder caused by a deficiency in clotting factors, impacts millions of people worldwide. The quality of life (QoL) for those affected remains particularly suboptimal in low- and middle-income countries (LMICs). This article delves into the unmet needs in hemophilia care and management in LMICs, spotlighting various challenges and potential strategies for improvement. One of the primary challenges in LMICs is the limited access to comprehensive care which includes a multidisciplinary approach involving hematologists, physiotherapists, psychologists, and social workers. In many LMICs, the healthcare infrastructure is insufficient to provide such integrated services, leading to fragmented care and poorer health outcomes for individuals with hemophilia. Another significant issue is the challenge of prophylactic treatment. Prophylaxis, which involves regular infusions of clotting factor concentrates to prevent bleeding episodes, is the standard of care in high-income countries. However, in LMICs, prophylactic treatment is often not feasible due to the high cost and limited availability of clotting factor concentrates. This results in a reliance on on-demand treatment, which only addresses bleeding episodes as they occur and does not prevent the long-term complications associated with frequent bleeds. Pain management is another critical area with significant gaps. Chronic pain is a common issue for individuals with hemophilia due to repeated joint bleeds leading to joint damage. In many LMICs, access to effective pain management strategies, including both pharmacological and non-pharmacological treatments, is limited. Mental health support is also a crucial yet often overlooked aspect of hemophilia care. The chronic nature of the condition, combined with frequent hospital visits and the physical limitations imposed by the disease, can lead to mental health issues such as anxiety and depression. However, mental health services are frequently under-resourced in LMICs, and there is a lack of awareness about the mental health needs of individuals with hemophilia. Caregiver support playing a crucial role in managing the day-to-day needs of individuals with hemophilia, is another vital component of hemophilia care that is often insufficient in LMICs. Education and awareness about hemophilia are also lacking in many LMICs. There is often a limited understanding of the condition among the general public and even within the medical community, leading to misdiagnoses and delayed treatment. Employment and financial support are critical issues as well. The physical limitations and frequent medical needs associated with hemophilia can make it difficult for individuals to maintain stable employment, leading to financial strain. In many LMICs, social support systems are inadequate to address these challenges. Lastly, the integration of telehealth and digital health technologies presents a promising strategy to overcome some of these challenges providing remote access to specialist care, education, and support, which is particularly valuable in regions where healthcare resources are scarce. By adopting a multifaceted approach that involves collaboration between governments, healthcare systems, international organizations, and patient advocacy groups, it is possible to address these challenges and significantly improve the QoL for individuals with hemophilia in LMICs.

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.

Stable and durable factor IX levels in patients with hemophilia B over 3 years after etranacogene dezaparvovec gene therapy

Etranacogene dezaparvovec (AMT-061) is a recombinant adeno-associated virus serotype 5 (AAV5) vector containing a codon-optimized Padua variant human factor IX (FIX) transgene with a liver-specific promoter. Here, we report 3-year outcomes from a phase 2b, open-label, single-dose, single-arm, multicenter trial conducted among adults with severe or moderately severe hemophilia B (FIX ≤2%). All participants (n = 3) received a single intravenous dose (2 × 1013 gene copies per kg) and will be followed up for 5 years. The primary end point of FIX activity ≥5% at 6 weeks was met. Secondary end points included bleed frequency, FIX concentrate use, joint health, and adverse events (AEs). All participants required routine FIX prophylaxis and had neutralizing antibodies to AAV5 before etranacogene dezaparvovec treatment. After administration, FIX activity rose to a mean of 40.8% in year 1 and was sustained in year 3 at 36.9%. All participants discontinued FIX prophylaxis. Bleeding was completely eliminated in 2 out of 3 participants. One participant required on-demand FIX replacement therapy per protocol because of elective surgical procedures, for 2 reported bleeding episodes, and twice for a single self-administered infusion because of an unreported reason. One participant experienced 2 mild, self-limiting AEs shortly after dosing. During the 3-year study period, there were no clinically significant elevations in liver enzymes, no requirement for steroids, no FIX inhibitor development, and no late-emergent safety events in any participant. Etranacogene dezaparvovec was safe and effective in adults with hemophilia B over 3 years after administration. This trial was registered at www.clinicaltrials.gov as #NCT03489291.

Hemophilia gene therapy: first, do no harm

The introduction of adeno-associated virus-mediated, liver-directed gene therapy into the hemophilia treatment landscape brings not only great promise but also considerable uncertainty to a community that has a history punctuated by the devastating effects of HIV and hepatitis C virus. These infections were introduced into people with hemophilia through the innovation of factor concentrates in the 1970s and 1980s. Concentrates, heralded as a major advance in treatment at the time, brought devastation and death to the community already challenged by the complications of bleeding into joints, vital organs, and the brain. Over the past 5 decades, considerable advances in hemophilia treatment have improved the survival, quality of life, and participation of people with hemophilia, although challenges remain and health equity with their unaffected peers has not yet been achieved. The decision to take a gene therapy product is one in which an informed, holistic, and shared decision-making approach must be employed. Bias on the part of health care professionals and people with hemophilia must be addressed and minimized. Here, we review data leading to the regulatory authorization of valoctocogene roxaparvovec, an adeno-associated virus 5 gene therapy, in Europe to treat hemophilia A and etranacogene dezaparvovec-drlb in the United States and Europe to treat hemophilia B. We also provide an overview of the decision-making process and recommend steps that should be taken by the hemophilia community to ensure the safety of and optimal outcomes for people with hemophilia who choose to receive a gene therapy product.

Design of a Real-World Observational Study in Previously Untreated and Minimally Treated Hemophilia A Patients: Protect-NOW

Background  The efficacy, safety, and immunogenicity of each of Octapharma's factor VIII (FVIII) products, Nuwiq, octanate, and wilate, have been investigated in previously untreated patients (PUPs) with severe hemophilia A in prospective clinical trials. The aim of the Protect-NOW study is to evaluate the effectiveness, safety, and utilization patterns of Nuwiq, octanate, and wilate in PUPs and minimally treated patients (MTPs; <5 exposure days [EDs] to FVIII concentrates or other blood products containing FVIII) with severe hemophilia A in a real-world setting. Real-world data provide valuable information that complement data obtained from interventional clinical trials. Methods  Protect-NOW (ClinicalTrials.gov identifier: NCT03695978; ISRCTN identifier: 11492145) is a real-world study in PUPs and MTPs treated with either the human cell line-derived recombinant FVIII Nuwiq (simoctocog alfa) or a plasma-derived FVIII concentrate containing von Willebrand factor (octanate or wilate). It is a prospective and (partly) retrospective, observational, international, noncontrolled, noninterventional study. A total of 140 PUPs and MTPs with severe hemophilia A will be enrolled across around 50 specialized centers worldwide and followed for either 100 EDs or a maximum period of 3 years from ED1. The primary objectives are to assess effectiveness in the prevention and treatment of bleeding episodes and overall safety, including inhibitor development. The secondary objectives are to assess utilization patterns (including dosage and frequency of administration) and the effectiveness in surgical prophylaxis. Conclusions  The Protect-NOW study will provide information on the treatment of PUPs and MTPs in routine clinical practice, which will help guide clinical decision making for treating these patients in the future.

Expectation and loss when gene therapy for haemophilia is not an option: An exigency sub-study

BACKGROUND

Qualitative studies have explored why people with haemophilia (PwH) might consider or forgo gene therapy, the impact it has had on those who have received it, and what support might be needed throughout the process. No studies have yet examined what withdrawal prior to transfection might mean for PwH and their families.

AIMS

To understand the experiences of PwH and their families of withdrawal from gene therapy and to understand what support mechanisms might be required.

METHODS

Qualitative interviews were conducted with people with severe haemophilia who consented to take part in a gene therapy study in the UK but either withdrew or were withdrawn before transfection.

RESULTS

Nine PwH and a family member were invited to this sub-study. Eight participants were recruited: six PwH (five haemophilia A and one haemophilia B) and two family members. Four participants were excluded from a study after consenting but before transfection, having failed to meet all the inclusion criteria; two withdrew after consenting but before transfection due to concerns including duration of factor expression and the time commitment involved in follow-up. The mean age of participants was 40.5 years (range 25-63 years). Two major themes emerged during the interviews: Expectation and loss.

CONCLUSIONS

PwH have many expectations about the difference gene therapy can make to their lives. Studies show that these expectations may not be fully realised. For those who have either withdrawn or been withdrawn from gene therapy, any expectations they had may now be unachievable. The nature of these expectations and the loss expressed by the participants indicate that support needs to be provided to help them and their families manage it.

Scaling genetic resources: New paradigms for diagnosis and treatment of rare genetic disease

Development of genetic tests for rare genetic diseases has traditionally focused on individual diseases. Similarly, development of new therapies occurred one disease at a time. With >10,000 rare genetic diseases, this approach is not feasible. Diagnosis of genetic disorders has already transcended old paradigms as whole exome and genome sequencing have allowed expedient interrogation of all relevant genes in a single test. The growth of newborn screening has allowed identification of diseases in presymptomatic babies. Similarly, the ability to develop therapies is rapidly expanding due to technologies that leverage platform technology that address multiple diseases. However, movement from the basic science laboratory to clinical trials is still hampered by a regulatory system rooted in traditional trial design, requiring a fresh assessment of safe ways to obtain approval for new drugs. Ultimately, the number of nucleic acid-based therapies will challenge the ability of clinics focused on rare diseases to deliver them safely with appropriate evaluation and long-term follow-up. This manuscript summarizes discussions arising from a recent National Institutes of Health conference on nucleic acid therapy, with a focus on scaling technologies for diagnosis of rare disorders and provision of therapies across the age and disease spectrum.

Characteristics of BAY 2599023 in the Current Treatment Landscape of Hemophilia A Gene Therapy

Hemophilia A, a single gene disorder leading to deficient Factor VIII (FVIII), is a suitable candidate for gene therapy. The aspiration is for single administration of a genetic therapy that would allow the production of endogenous FVIII sufficient to restore hemostasis and other biological processes. This would potentially result in reliable protection from bleeding and its associated physical and emotional impacts. Gene therapy offers the possibility of a clinically relevant improvement in disease phenotype and transformational improvement in quality of life, including an opportunity to engage in physical activities more confidently. Gene therapy products for hemophilia A in advanced clinical development use adeno-associated viral (AAV) vectors and a codon-optimized B-domain deleted FVIII transgene. However, the different AAV-based gene therapies have distinct design features, such as choice of vector capsid, enhancer and promoter regions, FVIII transgene sequence and manufacturing processes. These, in turn, impact patient eligibility, safety and efficacy. Ideally, gene therapy technology for hemophilia A should offer bleed protection, durable FVIII expression, broad eligibility and limited response variability between patients, and long-term safety. However, several limitations and challenges must be overcome. Here, we introduce the characteristics of the BAY 2599023 (AAVhu37.hFVIIIco, DTX 201) gene therapy product, including the low prevalence in the general population of anti-AAV-hu37 antibodies, as well as other gene therapy AAV products and approaches. We will examine how these can potentially meet the challenges of gene therapy, with the ultimate aim of improving the lives of patients with hemophilia A.

Gene therapy in haemophilia: literature review and regional perspectives for Turkey

Haemophilia is an X-linked lifelong congenital bleeding disorder that is caused by insufficient levels of factor VIII (FVIII; haemophilia A) or factor IX (FIX; haemophilia B) and characterized by spontaneous and trauma-related bleeding episodes. The cornerstone of the treatment, factor replacement, constitutes several difficulties, including frequent injections due to the short half-life of recombinant factors, intravenous administration and the risk of inhibitor development. While extended half-life factors and subcutaneous novel molecules enhanced the quality of life, initial successes with gene therapy offer a significant hope for cure. Although adeno-associated viral (AAV)-based gene therapy is one of the most emerging approaches for treatment of haemophilia, there are still challenges in vector immunogenicity, potency and efficacy, genotoxicity and persistence. As the approval for the first gene therapy product is coming closer, eligibility criteria for patient selection, multidisciplinary approach for optimal delivery and follow-up and development of new pricing policies and reimbursement models should be concerned. Therefore, this review addresses the unmet needs of current haemophilia treatment and explains the rationale and principles of gene therapy. Limitations and challenges are discussed from a global and national perspective and recommendations are provided to adopt the gene therapies faster and more sufficient for the haemophilia patients in developing countries like Turkey.

Gene therapy - are we ready now?

Introduction

Haemophilia therapy has evolved from rudimentary transfusion‐based approaches to an unprecedented level of innovation with glimmers of functional cure brought by gene therapy. After decades of misfires, gene therapy has normalized factor (F)VIII and factor (F)IX levels in some individuals in the long term. Several clinical programmes testing adeno‐associated viral (AAV) vector gene therapy are approaching completion with imminent regulatory approvals.

Discussion

Phase 3 studies along with multiyear follow‐up in earlier phase investigations raised questions about efficacy as well as short‐ and long‐term safety, prompting a reappraisal of AAV vector gene therapy. Liver toxicities, albeit mostly low‐grade, occur in the first year in at least some individuals in all haemophilia A and B trials and are poorly understood. Extreme variability and unpredictability of outcome, as well as a slow decline in factor expression (seemingly unique to FVIII gene therapy), are vexing because immune responses to AAV vectors preclude repeat dosing, which could increase suboptimal or restore declining expression, while overexpression may result in phenotoxicity. The long‐term safety will need lifelong monitoring because AAV vectors, contrary to conventional wisdom, integrate into chromosomes at the rate that calls for vigilance.

Conclusions

AAV transduction and transgene expression engage the host immune system, cellular DNA processing, transcription and translation machineries in ways that have been only cursorily studied in the clinic. Delineating those mechanisms will be key to finding mitigants and solutions to the remaining problems, and including individuals who cannot avail of gene therapy at this time.

Gene therapy: Practical aspects of implementation

The first wave of gene therapies for haemophilia submitted for regulatory review utilize a liver-directed approach in which a functional gene copy of factor VIII (FVIII) or factor IX (FIX) is packaged inside a recombinant adeno-associated viral vector (rAAV). Following a single treatment event, these particles are taken up into liver cells, where the rAAV uncoats and delivers the DNA to the nucleus of the cell, where genetic elements that accompany the gene allow for efficient expression and secretion of FVIII or FIX protein into the plasma. An immune response to the vector capsid has been manifest by elevations in common liver enzymes that must be diligently followed postinfusion for weeks and months afterward and if signs of toxicity appear, will trigger a course of immunosuppression. Despite this, the studies have shown that this works in the great majority of individuals and the immunosuppression course is either avoided or short-lived for many. Optimal outcomes in the haemophilia population will be dependent on proper screening assessment and maintenance of liver health prior to consideration of gene therapy, close short-term follow up and implementation of immunomodulatory strategies to identify and manage liver toxicity and preserve durable transgene expression. This review proposes best practices to assist clinical teams with overcoming the challenges this platform of therapy poses to the traditional clinical care models and infrastructure within the haemophilia treatment centres (HTCs) who will be coordinating the patient's journey through this potentially transformative therapy.

Preparing for tomorrow: Defining a future agenda

Gene therapy will be the first long-term therapy with potential to produce a functional cure for haemophilia. As a single dose ('once-and-done') therapy with significant uncertainties regarding impact and duration of factor expression, flexibility and adaptability of (1) value framework, (2) health technology assessment (HTA) methodology, and (3) development of alternative payment models will be needed for adoption of this new technology and to facilitate transparent decision-making to support its implementation. The responsibility for each of these currently lies with distinct entities, underscoring a need for enhanced collaboration between all stakeholders, as expanded engagement by key stakeholders will be critical to optimizing the assessment of value, enabling an optimised approach to HTA, and opening receptivity to new and innovative payment models. This supplement issue describes important considerations for a gene therapy 'toolkit', highlighting key considerations for each of the aforementioned tools, which will be useful for guiding decision-making regarding gene therapy as a novel treatment modality. In this article, we outline how the tools presented in this supplement can be applied as part of a framework to address the requirements of the relevant stakeholders, including payers, manufacturers, treaters, and patients. The paper also provides an illustrative example of how to understand the features of alternative payment models depending on the organization of and payment for healthcare.

Immunotherapy and Gene Therapy: New Challenges in the Diagnosis and Management of Drug-Induced Liver Injury

In the last 5 years, the landscape of oncologic treatment has been deeply modified with the development and use of immune checkpoint inhibitors (ICIs) that exert their antitumoral effect by reverting the exhausted phenotype of tumor-infiltrating lymphocytes. This innovative therapeutic strategy has widely changed the prognosis of some advanced neoplastic diseases such as melanoma and lung cancer, providing durable remission for a significant number of patients. Unfortunately, immune-related adverse events (irAEs), especially ICI-induced hepatitis, may be very severe in some cases, impairing the prognosis of the patient. Guidelines available today on the diagnosis and management of ICI-induced hepatitis are mainly based on expert opinions and case series. This lack of large data is explained not only by the low incidence of hepatic adverse events but also by their clinical heterogeneity and variable severity. In this article, we will review the clinical, biological, and histological characteristics of ICI-induced liver injury. We will discuss the current knowledge on their pathological mechanisms and their therapeutic strategy based on immunosuppressive treatment for more severe cases. Regarding severity assessment, we will discuss the gap between the oncologist and the hepatologist's point of view, highlighting the need for multidisciplinary management. While initially developed for notably less frequent diseases than neoplastic ones, gene therapy is going to be a revolution for the treatment of diseases not responding to pharmacological therapy. Limited but growing data describe liver injury after the administration of such therapy whose exact physiopathology remains unknown. In this article, we will discuss the available data supporting the role of gene therapies in the onset of drug-induced liver injury and related mechanisms. We will describe the clinical context, the biological and histological features, and the management currently proposed.

The Hemophilia Gene Therapy Patient Journey: Questions and Answers for Shared Decision-Making

PURPOSE

The anticipated emergence of hemophilia gene therapy will present people with hemophilia (PWH) and treating clinicians with increasingly complex treatment options. It will be critical that PWH and their families be empowered to participate fully in decision-making through transparent communication and the development of targeted educational resources.

METHODS

The Council of Hemophilia Community (CHC) convened across a series of roundtable meetings to define the patient journey for hemophilia gene therapy, and to develop a question-and-answer style resource to guide discussion between healthcare professionals (HCPs) and their patients. Patient groups were also consulted during the development of this tool.

RESULTS

The CHC defined 5 key stages in the hemophilia gene therapy patient journey: pre-gene therapy (information-seeking and decision-making), treatment initiation, short- and long-term post-gene therapy follow-up. PWH will have different questions and concerns at each stage of their journey, which should be discussed with their HCP to aid decision-making. The resulting patient journey infographic and Q&A resource (see Supplementary Materials) has been developed for HCPs and PWH to provide a novel and practical roadmap of key issues and considerations throughout all stages.

CONCLUSION

These resources support a collaborative, patient-centric, shared decision-making approach to inform treatment decision discussions between HCPs and PWH. The value of such discussions will be influenced by the language adopted; health literacy is a particularly important consideration, and these discussions should be accessible and tailored to PWH. HCPs and PWH can benefit from awareness of the common questions and uncertainties as they progress together along the patient journey. While the contents of this article are specific to hemophilia gene therapy, the concepts developed here could be adapted to aid patients in other disease states.

The Clinical Genetics of Hemophilia B (Factor IX Deficiency)

Hemophilia B (HB) is a bleeding disorder caused by deficiency of or defect in blood coagulation factor IX (FIX) inherited in an X-linked manner. It results from one of over 1000 known pathogenic variants in the FIX gene, F9; missense and frameshift changes predominate. Although primarily males are affected with HB, heterozygous females may have excessive bleeding due to random or non-random X chromosome inactivation; in addition, homozygous, compound heterozygous, and hemizygous females have been reported. Somatic and germinal mosaicism for F9 variants has been observed. Development of antibodies to FIX treatment products (inhibitors) is rare and related to the type of causative variant present. Treatment is with products produced by recombinant DNA technology, and gene therapy is in clinical trials. Genetic counseling with up-to-date information is warranted for heterozygotes, potential heterozygotes, and men and women affected with HB.

Health insurance coverage and switching among people with hemophilia A in the United States

BACKGROUND: Hemophilia A (HA) is marked by substantial economic burden, including costs of ongoing treatment, increased monitoring, bleed events, and other health care utilization associated with managing the disease and comorbidities related to the disease. Gene therapies and other anticipated breakthrough treatments hold potential to substantially offset long-term traditional factor VIII (FVIII) prophylaxis in specific populations. Fragmentation of the US insurance system, however, may impact payers' approaches to coverage of new treatments, given concerns about patients "switching" insurance and the payer's ability to offset costs over time. OBJECTIVE: To assess insurance coverage and switching across payers among people with severe HA (SHA) using real-world data. METHODS: Adult men with SHA (FVIII measuring < 1%) in the American Thrombosis and Hemostasis Network dataset between January 2013 and September 2019 were identified. Patients' primary insurance category (ie, commercial, Medicaid, Medicare) and insurance switching over time were described. Outcomes included distribution of current primary insurance coverage by category and mean years of coverage per payer for commercially insured patients, including those with 2 or more commercial payers, and for those who switched insurance categories (eg, coverage by a commercial payer and government payer). RESULTS: Among the cohort of patients with SHA (N = 3,677), 51.9% had commercial primary insurance and 29.0% had coverage by Medicaid (including state-funded programs). The mean duration of follow-up in the database was 6.3 years for patients with at least 1 year of follow-up. Among patients who had ever been commercially insured, 74.9% had the same commercial payer for the entire follow-up period. The mean time covered by the same commercial insurance was 4.8 years. Only 7.5% of patients switched insurance categories (eg, from commercial to Medicaid). Among those who switched categories, patients averaged 3.9 years of commercial coverage, 4.0 years of Medicaid coverage, and 4.8 years of Medicare coverage during the follow-up period. CONCLUSIONS: Both commercially and government-insured patients with SHA typically maintain continuous coverage for extended periods, with limited switching between payers and insurance categories over time. These findings suggest that should breakthrough treatments be approved, payers would likely be able to realize substantial cost savings associated with avoiding long-term prophylactic therapies during the several years after treatment. DISCLOSURES: This study was funded by BioMarin Pharmaceutical Inc. Hinds, Chen, and Sammon are employees of BioMarin Pharmaceutical Inc. and own stock/stock options. Solari was an employee of BioMarin Pharmaceutical Inc. at the time of the study. Pezalla is CEO of Enlightenment Bioconsult, LLC. He, Cheng, and Recht are, or were at the time of this study, employees of American Thrombosis and Hemostasis Network (ATHN), which has received ATHNdataset licensing and other fees from BioMarin Pharmaceutical Inc. Research funding to Recht's employers has come from Bayer, BioMarin Pharmaceutical Inc., CSL Behring, Genentech, Grifols, Hema Biologics, LFB, Novo Nordisk, Octapharma, Pfizer, Sanofi, Spark, Takeda, and uniQure. Recht has also worked as a consultant for Catalyst Biosciences, CSL Behring, Genentech, Hema Biologics, Kedrion, Novo Nordisk, Pfizer, Sanofi, Takeda, and uniQure; sits on the board of directors of the Foundation for Women and Girls with Blood Disorders and of Partners in Bleeding Disorders; and is an employee of the Oregon Health & Science University. Data from this study were presented as a poster at AMCP Nexus 2021; October 18-21, 2021; Denver, CO.

Emerging drugs for hemophilia A: insights into phase II and III clinical trials

INTRODUCTION

Hemophilia is a lifelong, genetic-bleeding disorder, which inadequately treated results in permanent joint damage. It is characterized by spontaneous and trauma-related bleeding episodes. In the last 50 years, treatment has seen dramatic improvements which have improved the quality of life of persons with hemophilia.

AREAS COVERED

This review will provide a summary of current pharmacological approaches for hemophilia A as well as discuss novel agents which are either approved recently or in phase II-III clinical trials, plasma-derived and recombinant factor VIII (FVIII) products, extended half-life FVIII products, bypassing agents and non-replacement therapies.

EXPERT OPINION

Novel therapies are already changing the way that hemophilia A is managed, and as more new therapies get approved, there will be a revolution in the management of this serious condition. Clinicians will have both the opportunities as well as the challenges of incorporating such new technologies into clinical practice.

Gene Therapy for Inherited Bleeding Disorders

Decades of preclinical and clinical studies developing gene therapy for hemophilia are poised to bear fruit with current promising pivotal studies likely to lead to regulatory approval. However, this recent success should not obscure the multiple challenges that were overcome to reach this destination. Gene therapy for hemophilia A and B benefited from advancements in the general gene therapy field, such as the development of adeno-associated viral vectors, as well as disease-specific breakthroughs, like the identification of B-domain deleted factor VIII and hyperactive factor IX Padua. The gene therapy field has also benefited from hemophilia B clinical studies, which revealed for the first time critical safety concerns related to immune responses to the vector capsid not anticipated in preclinical models. Preclinical studies have also investigated gene transfer approaches for other rare inherited bleeding disorders, including factor VII deficiency, von Willebrand disease, and Glanzmann thrombasthenia. Here we review the successful gene therapy journey for hemophilia and pose some unanswered questions. We then discuss the current state of gene therapy for these other rare inherited bleeding disorders and how the lessons of hemophilia gene therapy may guide clinical development.

Linking the Expression of Therapeutic Genes to Unfolded Protein Response: A New Option for Anti-Hepatitis B Virus Gene Therapy

Tight control of transgene expression is key to ensure the efficacy of a wide range of gene therapy interventions, in which the magnitude and duration of gene expression have to be adjusted to therapeutic needs, thereby limiting secondary effects. The development of upgraded strategies to link transgene expression to pathological stress episodes is an unmet need in gene therapy. Here, we propose an expression strategy that associates transgene expression to an intracellular stress coping mechanism, the unfolded protein response. Specifically, we harnessed the cis elements required to sustain the noncanonical splicing of X-box binding protein 1 (XBP1) messenger RNA (mRNA) in response to the dysfunction of the endoplasmic reticulum (ER), a situation commonly known as ER stress, to drive the expression of heterologous genes. Since ER stress features a wide variety of pathological conditions, including viral infections, cancer, or metabolic disorders, this new expression module stimulates the synthesis of therapeutic genes as a response to cellular damage, and ensures their expression only when necessary. Validation of this inducible expression system was performed in vitro and in vivo, and its potential to limit/inhibit viral infections has been shown in proof-of principle experiments.

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.