Safety of Lenadogene Nolparvovec Gene Therapy Over 5 Years in 189 Patients With Leber Hereditary Optic Neuropathy

AAV2-mediated ABD-FGF21 gene delivery produces a sustained anti-hyperglycemic effect in type 2 diabetic mouse

BACKGROUND

Fibroblast Growth Factor 21 (FGF21) is a naturally occurring peptide hormone involved in the regulation of glycolipid metabolism, and it shows promise as a potential treatment for type 2 diabetes mellitus (T2DM). However, the short half-life and poor pharmacokinetics of native FGF21 limit its efficacy in reducing hyperglycemia in vivo. Therefore, maintaining stable and sustained blood concentrations of FGF21 is crucial for its role as an effective regulator of glycolipid metabolism in vivo. In this study, we developed an AAV2-mediated gene delivery system incorporating an Albumin-binding domain (ABD) fused to FGF21, and we evaluated its effects in a type 2 diabetic mouse model.

METHODS

The plasmids pAAV-FGF21-Luciferase, pHelper, and the capsid plasmid were transfected into HEK293T cells to generate recombinant AAV (rAAV) virus. A type 2 diabetes mellitus (T2DM) mouse model was established for evaluation. The rAAV was administered via tail vein injection into the mice. The effects of rAAV injection on various parameters were assessed using commercial kits. Histological changes in the liver and adipose tissue of T2DM mice were examined using hematoxylin and eosin (H&E) staining.

RESULTS

The data showed that the inclusion of ABD significantly prolonged the half-life of FGF21 in the serum of mice. Additionally, AAV2-mediated delivery of ABD-FGF21 to the liver resulted in sustained gene expression and a significant increase in circulating FGF21 levels in mice. Treatment with AAV2-ABD-FGF21 led to several benefits, including reduced fasting glucose, improved insulin sensitivity, decreased triglyceride and total cholesterol levels, and improved body weight in T2DM mice. Furthermore, serum analysis and histological examination showed no significant liver damage at the study endpoint after seven weeks.

CONCLUSION

In conclusion, we have developed a novel strategy for producing long-acting FGF21 using the AAV vector, and AAV2-ABD-FGF21 shows promise as a therapeutic approach for type 2 diabetes mellitus and other glycolipid metabolic disorders.

Five-Year Outcomes of Lenadogene Nolparvovec Gene Therapy in Leber Hereditary Optic Neuropathy

Importance

Limited studies have assessed the long-term benefit/risk of gene therapy for Leber hereditary optic neuropathy (LHON).

Objective

To determine the safety and efficacy of lenadogene nolparvovec in patients with LHON due to the MT-ND4 gene variant for up to 5 years after administration.

Design, Setting, and Participants

The RESCUE and REVERSE Long-Term Follow-up Study (RESTORE), conducted from 2018 to 2022, is the 5-year follow-up study of the 2 phase 3 clinical studies RESCUE (Efficacy Study of Lenadogene Nolparvovec for the Treatment of Vision Loss Up to 6 Months From Onset in LHON Due to the MT-ND4 Mutation) and REVERSE (Efficacy Study of Lenadogene Nolparvovec for the Treatment of Vision Loss From 7 Months to 1 Year From Onset in LHON Due to the MT-ND4 Mutation). At the end of each study, ie, 2 years after gene therapy administration, patients were offered enrollment in the RESTORE trial, a multinational, multicenter, prospective study, for an additional 3 years of follow-up. Patients with LHON due to the MT-ND4 gene variant received lenadogene nolparvovec in 1 eye and a sham injection in the other eye.

Intervention

Lenadogene nolparvovec was administered as a single intravitreal injection in the RESCUE/REVERSE studies.

Main Outcomes and Measures

Measures included best-corrected visual acuity (BCVA), quality of life using the National Eye Institute visual functioning questionnaire 25 (NEI VFQ-25), and adverse events.

Results

Among the 76 patients who received gene therapy in the RESCUE (n = 39) and REVERSE (n = 37) studies, 72 (94.7%) completed these studies; 62 patients (81.6%) participated in the RESTORE trial, and 55 patients (72.4%) completed the 5-year follow-up. Participants were mostly male (49 [79.0%]) with a mean (SD) age of 35.9 (15.3) years at treatment. At baseline, the mean (SD) BCVA was 1.5 (0.5) logMAR (20/600 Snellen) in eyes to be treated with lenadogene nolparvovec and 1.4 (0.5) logMAR (20/500) in sham eyes. At the end of the RESCUE/REVERSE trials, ie, 2 years after treatment, eyes treated with lenadogene nolparvovec and eyes treated with sham reached a mean BCVA value of 1.4 (0.6) logMAR (20/500). The mean (SD) change from baseline to year 2 was -0.05 (0.6) logMAR (+1 line) and 0.01 (0.6) logMAR (-0 line) in gene therapy-treated and sham eyes, respectively (difference, -0.03; 95% CI, -0.16 to 0.09; P = .60). Five years after treatment, the bilateral improvement from nadir was similar to that observed at 2 years, with a mean (SD) change in BCVA of -0.4 (0.5) logMAR (more than +4 lines) for eyes treated with lenadogene nolparvovec and -0.4 (0.4) logMAR (+4 lines) for eyes treated with sham (difference, -0.05; 95% CI, -0.15 to 0.04; P = .27). An improvement of at least -0.3 logMAR (+3 lines) from the nadir in at least 1 eye was observed in 66.1% of participants (41 of 62). Between 2 and 5 years, intraocular inflammation was noted in 4 participants with 8 events in eyes treated with lenadogene nolparvovec and 1 event in an eye treated with sham.

Conclusions and Relevance

In this analysis of the RESTORE trial, follow-up of patients with LHON due to the MT-ND4 gene variant unilaterally treated with lenadogene nolparvovec demonstrated a sustained bilateral improvement in BCVA and a good safety profile up to 5 years after treatment. This evidence of persistent benefit over time is promising for the use of gene therapy in these patients.

Trial Registration

ClinicalTrials.gov Identifier: NCT03406104.

Recent advances in neuro-ophthalmology

This review article represents a collaborative effort across continents, bringing together the latest developments in neuro-ophthalmology with a focus on innovative diagnostic and therapeutic modalities that are shaping the future of the field. Among the most significant advancements is the rise of optical coherence tomography (OCT), now recognized as an indispensable tool in neuro-ophthalmological research, providing unparalleled insights into optic nerve and central nervous system pathologies. Gene therapy, particularly for conditions such as Leber's hereditary optic neuropathy, marks a new frontier in personalized medicine, offering hope for previously untreatable conditions. The article also examines the transformative role of telemedicine and artificial intelligence (AI) in clinical practice, which are revolutionizing patient care and enhancing diagnostic precision. Furthermore, it highlights the impact of novel serological biomarkers on the understanding and management of immune-mediated optic neuritis, and discusses the introduction of new therapeutic agents like Tocilizumab and Teprotumumab, which are redefining treatment paradigms. Collectively, these advancements reflect the profound influence of modern medicine on neuro-ophthalmology, paving the way for improved patient outcomes and fostering new avenues for research and clinical practice.

Mitochondria in Retinal Ganglion Cells: Unraveling the Metabolic Nexus and Oxidative Stress

This review explored the role of mitochondria in retinal ganglion cells (RGCs), which are essential for visual processing. Mitochondrial dysfunction is a key factor in the pathogenesis of various vision-related disorders, including glaucoma, hereditary optic neuropathy, and age-related macular degeneration. This review highlighted the critical role of mitochondria in RGCs, which provide metabolic support, regulate cellular health, and respond to cellular stress while also producing reactive oxygen species (ROS) that can damage cellular components. Maintaining mitochondrial function is essential for meeting RGCs' high metabolic demands and ensuring redox homeostasis, which is crucial for their proper function and visual health. Oxidative stress, exacerbated by factors like elevated intraocular pressure and environmental factors, contributes to diseases such as glaucoma and age-related vision loss by triggering cellular damage pathways. Strategies targeting mitochondrial function or bolstering antioxidant defenses include mitochondrial-based therapies, gene therapies, and mitochondrial transplantation. These advances can offer potential strategies for addressing mitochondrial dysfunction in the retina, with implications that extend beyond ocular diseases.

Gene therapy for Leber hereditary optic neuropathy

INTRODUCTION

Leber hereditary optic neuropathy (LHON) is among the most frequent inherited mitochondrial disease, causing a severe visual impairment, mostly in young-adult males. The causative mtDNA variants (the three common are m.11778 G>A/MT-ND4, m.3460 G>A/MT-ND1, and m.14484T>C/MT-ND6) by affecting complex I impair oxidative phosphorylation in retinal ganglion cells, ultimately leading to irreversible cell death and consequent functional loss. The gene therapy based on allotopic expression of a wild-type transgene carried by adeno-associated viral vectors (AVV-based) appears a promising approach in mitochondrial disease and its efficacy has been explored in several large clinical trials.

AREAS COVERED

The review work employed basic concepts in mitochondrial diseases, LHON, and gene therapy procedures. Reports from completed trials in LHON (i.e. RESCUE) were reviewed and critically compared.

EXPERT OPINION

New challenges, as the improvement of the contralateral untreated eye or the apparently better outcome in patients treated in later stages (6-12 months), were highlighted by the latest gene therapy trials. A better understanding of the pathogenetic mechanisms of the disease together with combined therapy (medical and gene therapy) and optimization in genetic correction approaches could improve the visual outcome of treated eyes.

Leber hereditary optic neuropathy gene therapy

PURPOSE OF REVIEW

To discuss relevant clinical outcomes, challenges, and future opportunities of gene therapy in Leber hereditary optic neuropathy (LHON).

RECENT FINDINGS

Results of G11778A LHON Phase 3 randomized clinical trials with unilateral intravitreal rAAV2/2-ND4 allotopic gene therapy show good safety and unexpected bilateral partial improvements of BCVA (best-corrected visual acuity) with mean logMAR BCVA improvements of up to near ∼0.3 logMAR (3 lines) in the treated eyes and ∼0.25 logMAR (2.5 lines) in the sham-treated or placebo-treated fellow eyes. Final mean BCVA levels after gene therapy were in the range of ∼1.3 logMAR (20/400) bilaterally.

SUMMARY

Bilateral partial improvement with unilateral LHON gene therapy was unanticipated and may be due to treatment efficacy, natural history, learning effect, and other mediators. The overall efficacy is limited given the final BCVA levels. The sequential progressive visual loss and varied occurrence of spontaneous partial improvement in LHON confound trial results. Future clinical trials with randomization of patients to a group not receiving gene therapy in either eye would help to assess treatment effect. Promising future LHON gene therapy strategies include mitochondrially-targeted-sequence adeno-associated virus ('MTS-AAV') for direct delivery of the wild-type mitochondrial DNA into the mitochondria and CRISPR-free, RNA-free mitochondrial base editing systems. Signs of anatomical optic nerve damage and objective retinal ganglion cell dysfunction are evident in the asymptomatic eyes of LHON patients experiencing unilateral visual loss, indicating the therapeutic window is narrowing before onset of visual symptoms. Future treatment strategies utilizing mitochondrial base editing in LHON carriers without optic neuropathy holds the promise of a more advantageous approach to achieve optimal visual outcome by reducing disease penetrance and mitigating retinal ganglion cell loss when optic neuropathy develops.

Development of mitochondrial gene-editing strategies and their potential applications in mitochondrial hereditary diseases: a review

Mitochondrial DNA (mtDNA) is a critical genome contained within the mitochondria of eukaryotic cells, with many copies present in each mitochondrion. Mutations in mtDNA often are inherited and can lead to severe health problems, including various inherited diseases and premature aging. The lack of efficient repair mechanisms and the susceptibility of mtDNA to damage exacerbate the threat to human health. Heteroplasmy, the presence of different mtDNA genotypes within a single cell, increases the complexity of these diseases and requires an effective editing method for correction. Recently, gene-editing techniques, including programmable nucleases such as restriction endonuclease, zinc finger nuclease, transcription activator-like effector nuclease, clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeats-associated 9 and base editors, have provided new tools for editing mtDNA in mammalian cells. Base editors are particularly promising because of their high efficiency and precision in correcting mtDNA mutations. In this review, we discuss the application of these techniques in mitochondrial gene editing and their limitations. We also explore the potential of base editors for mtDNA modification and discuss the opportunities and challenges associated with their application in mitochondrial gene editing. In conclusion, this review highlights the advancements, limitations and opportunities in current mitochondrial gene-editing technologies and approaches. Our insights aim to stimulate the development of new editing strategies that can ultimately alleviate the adverse effects of mitochondrial hereditary diseases.

Gene therapy for mitochondrial disorders

In this review, we detail the current state of application of gene therapy to primary mitochondrial disorders (PMDs). Recombinant adeno-associated virus-based (rAAV) gene replacement approaches for nuclear gene disorders have been undertaken successfully in more than ten preclinical mouse models of PMDs which has been made possible by the development of novel rAAV technologies that achieve more efficient organ targeting. So far, however, the greatest progress has been made for Leber Hereditary Optic Neuropathy, for which phase 3 clinical trials of lenadogene nolparvovec demonstrated efficacy and good tolerability. Other methods of treating mitochondrial DNA (mtDNA) disorders have also had traction, including refinements to nucleases that degrade mtDNA molecules with pathogenic variants, including transcription activator-like effector nucleases, zinc-finger nucleases, and meganucleases (mitoARCUS). rAAV-based approaches have been used successfully to deliver these nucleases in vivo in mice. Exciting developments in CRISPR-Cas9 gene editing technology have achieved in vivo gene editing in mouse models of PMDs due to nuclear gene defects and new CRISPR-free gene editing approaches have shown great potential for therapeutic application in mtDNA disorders. We conclude the review by discussing the challenges of translating gene therapy in patients both from the point of view of achieving adequate organ transduction as well as clinical trial design.

Immunogenicity of Recombinant Adeno-Associated Virus (AAV) Vectors for Gene Transfer

Recombinant adeno-associated viruses (AAVs) have emerged as promising gene delivery vehicles resulting in three US Food and Drug Administration (FDA) and one European Medicines Agency (EMA)-approved AAV-based gene therapies. Despite being a leading platform for therapeutic gene transfer in several clinical trials, host immune responses against the AAV vector and transgene have hampered their widespread application. Multiple factors, including vector design, dose, and route of administration, contribute to the overall immunogenicity of AAVs. The immune responses against the AAV capsid and transgene involve an initial innate sensing. The innate immune response subsequently triggers an adaptive immune response to elicit a robust and specific response against the AAV vector. AAV gene therapy clinical trials and preclinical studies provide important information about the immune-mediated toxicities associated with AAV, yet studies suggest preclinical models fail to precisely predict the outcome of gene delivery in humans. This review discusses the contribution of the innate and adaptive immune response against AAVs, highlighting the challenges and potential strategies to mitigate these responses, thereby enhancing the therapeutic potential of AAV gene therapy.