Safety of Intravitreal Gene Therapy for Treatment of Subjects with Leber Hereditary Optic Neuropathy due to Mutations in the Mitochondrial ND4 Gene: The REVEAL Study

Rodent Models of Retinal Degeneration: From Purified Cells in Culture to Living Animals

Rodent models of retinal degeneration are essential for the development of therapeutic strategies. In addition to living animal models, we here also discuss models based on rodent cell cultures, such as purified retinal ganglion cells and retinal explants. These ex vivo models extend the possibilities for investigating pathological mechanisms and assessing the neuroprotective effect of pharmacological agents by eliminating questions on drug pharmacokinetics and bioavailability. The number of living rodent models has greatly increased with the possibilities to achieve transgenic modifications in animals for knocking in and out genes and mutations. The Cre-lox system has further enabled investigators to target specific genes or mutations in specific cells at specific stages. However, chemically or physically induced models can provide alternatives to such targeted gene modifications. The increased diversity of rodent models has widened our possibility to address most ocular pathologies for providing initial proof of concept of innovative therapeutic strategies.

Leber's hereditary optic neuropathy: Update on the novel genes and therapeutic options

A maternal inheritance disorder called Leber's hereditary optic neuropathy (LHON) is the most common primary mitochondrial deoxyribonucleic acid (DNA) disorder. In most studies, there are more male patients than female patients, which contradicts the usual pattern in mitochondrial hereditary diseases. This suggests that nuclear DNA (nDNA) may influence the degeneration of retinal ganglion cells (RGCs) in LHON. The primary cause of this is dysfunction in complex I of the electron transport chain, leading to ineffective adenosine triphosphate (ATP) production. In addition to MT-ND4 or MT-ND1 mutations, genes such as PRICKLE3 , YARS2 , and DNAJC30 , which come from nDNA, also play a role in LHON. These three genes affect the electron chain transport differently. PRICKLE3 interacts with ATP synthase (complex V) at Xp11.23, while YARS2 is a tyrosyl-tRNA synthetase 2 involved in mitochondria . DNAJC30 mutations result in autosomal recessive LHON (arLHON). Understanding how genes impact the disease is crucial for developing new treatments. Idebenone has been approved for treating LHON and has shown safety and efficacy in clinical trials. Mesenchymal stem cell-based therapy has also emerged as a potential treatment for LHON by transferring mitochondria into target cells. Gene therapy research focuses on specific gene mutations, and the wild-type ND4 gene target in the adeno-associated viruses (AAV) vector has shown promise in clinical trials as a potential treatment for LHON.

Mitochondrially Targeted Gene Therapy Rescues Visual Loss in a Mouse Model of Leber's Hereditary Optic Neuropathy

Leber's hereditary optic neuropathy (LHON) is a common mitochondrial genetic disease, causing irreversible blindness in young individuals. Current treatments are inadequate, and there is no definitive cure. This study evaluates the effectiveness of delivering wildtype human NADH ubiquinone oxidoreductase subunit 4 (hND4) gene using mito-targeted AAV(MTSAAV) to rescue LHOH mice. We observed a declining pattern in electroretinograms amplitudes as mice aged across all groups (p < 0.001), with significant differences among groups (p = 0.023; Control vs. LHON, p = 0.008; Control vs. Rescue, p = 0.228). Inner retinal thickness and intraocular pressure did not change significantly with age or groups. Compared to LHON mice, those rescued with wildtype hND4 exhibited improved retinal visual acuity (0.29 ± 0.1 cy/deg vs. 0.15 ± 0.1 cy/deg) and increased functional hyperemia response (effect of flicker, p < 0.001, effect of Group, p = 0.004; Interaction Flicker × Group, p < 0.001). Postmortem analysis shows a marked reduction in retinal ganglion cell density in the LHON group compared to the other groups (Effect of Group, p < 0.001, Control vs. LHON, p < 0.001, Control vs. Rescue, p = 0.106). These results suggest that MTSAAV-delivered wildtype hND4 gene rescues, at least in part, visual impairment in an LHON mouse model and has the therapeutic potential to treat this disease.

The constraints of allotopic expression

Allotopic expression is the functional transfer of an organellar gene to the nucleus, followed by synthesis of the gene product in the cytosol and import into the appropriate organellar sub compartment. Here, we focus on mitochondrial genes encoding OXPHOS subunits that were naturally transferred to the nucleus, and critically review experimental evidence that claim their allotopic expression. We emphasize aspects that may have been overlooked before, i.e., when modifying a mitochondrial gene for allotopic expression━besides adapting the codon usage and including sequences encoding mitochondrial targeting signals━three additional constraints should be considered: (i) the average apparent free energy of membrane insertion (μΔGapp) of the transmembrane stretches (TMS) in proteins earmarked for the inner mitochondrial membrane, (ii) the final, functional topology attained by each membrane-bound OXPHOS subunit; and (iii) the defined mechanism by which the protein translocator TIM23 sorts cytosol-synthesized precursors. The mechanistic constraints imposed by TIM23 dictate the operation of two pathways through which alpha-helices in TMS are sorted, that eventually determine the final topology of membrane proteins. We used the biological hydrophobicity scale to assign an average apparent free energy of membrane insertion (μΔGapp) and a "traffic light" color code to all TMS of OXPHOS membrane proteins, thereby predicting which are more likely to be internalized into mitochondria if allotopically produced. We propose that the design of proteins for allotopic expression must make allowance for μΔGapp maximization of highly hydrophobic TMS in polypeptides whose corresponding genes have not been transferred to the nucleus in some organisms.

Safety and Efficacy of Adeno-Associated Viral Gene Therapy in Patients With Retinal Degeneration: A Systematic Review and Meta-Analysis

Purpose

This systematic review evaluates the safety and efficacy of ocular gene therapy using adeno-associated virus (AAV).

Methods

MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov were searched systematically for controlled or non-controlled interventional gene therapy studies using key words related to retinal diseases, gene therapy, and AAV vectors. The primary outcome measure was safety, based on ocular severe adverse events (SAEs). Secondary outcome measures evaluated efficacy of the therapy based on best corrected visual acuity (BCVA) and improvements in visual sensitivity and systemic involvement following ocular delivery. Pooling was done using a DerSimonian Laird random effects model. Risk of bias was assessed using the Cochrane Risk of Bias Tool, version 1.

Results

Our search identified 3548 records. Of these, 80 publications met eligibility criteria, representing 28 registered clinical trials and 5 postmarket surveillance studies involving AAV gene therapy for Leber congenital amaurosis (LCA), choroideremia, Leber hereditary optic neuropathy (LHON), age-related macular degeneration (AMD), retinitis pigmentosa (RP), X-linked retinoschisis, and achromatopsia. Overall, AAV therapy vectors were associated with a cumulative incidence of at least one SAE of 8% (95% confidence intervals [CIs] of 5% to 12%). SAEs were often associated with the surgical procedure rather than the therapeutic vector itself. Poor or inconsistent reporting of adverse events (AEs) were a limitation for the meta-analysis. The proportion of patients with any improvement in BCVA and visual sensitivity was 41% (95% CIs of 31% to 51%) and 51% (95% CIs of 31% to 70%), respectively. Systemic immune involvement was associated with a cumulative incidence of 31% (95% CI = 21% to 42%).

Conclusions

AAV gene therapy vectors appear to be safe but the surgical procedure required to deliver them is associated with some risk. The large variability in efficacy can be attributed to the small number of patients treated, the heterogeneity of the population and the variability in dosage, volume, and follow-up.

Translational Relevance

This systematic review will help to inform and guide future clinical trials.

Current and Future Landscape in Genetic Therapies for Leber Hereditary Optic Neuropathy

Leber hereditary optic neuropathy (LHON) is the most common primary mitochondrial genetic disease that causes blindness in young adults. Over 50 inherited mitochondrial DNA (mtDNA) variations are associated with LHON; however, more than 95% of cases are caused by one of three missense variations (m.11778 G > A, m.3460 G > A, and m.14484 T > C) encoding for subunits ND4, ND1, and ND6 of the respiration complex I, respectively. These variants remain silent until further and currently poorly understood genetic and environmental factors precipitate the visual loss. The clinical course that ensues is variable, and a convincing treatment for LHON has yet to emerge. In 2015, an antioxidant idebenone (Raxone) received European marketing authorisation to treat visual impairment in patients with LHON, and since then it was introduced into clinical practice in several European countries. Alternative therapeutic strategies, including gene therapy and gene editing, antioxidant and neurotrophic agents, mitochondrial biogenesis, mitochondrial replacement, and stem cell therapies are being investigated in how effective they might be in altering the course of the disease. Allotopic gene therapies are in the most advanced stage of development (phase III clinical trials) whilst most other agents are in phase I or II trials or at pre-clinical stages. This manuscript discusses the phenotype and genotype of the LHON disease with complexities and peculiarities such as incomplete penetrance and gender bias, which have challenged the therapies in development emphasising the most recent use of gene therapy. Furthermore, we review the latest results of the three clinical trials based on adeno-associated viral (AAV) vector-mediated delivery of NADH dehydrogenase subunit 4 (ND4) with mitochondrial targeting sequence, highlighting the differences in the vector design and the rationale behind their use in the allotopic transfer.

Ocular stress enhances contralateral transfer of lenadogene nolparvovec gene therapy through astrocyte networks

Lenadogene nolparvovec (GS010) was developed to treat a point mutation in mitochondrial ND4 that causes Leber hereditary optic neuropathy. GS010 delivers human cDNA encoding wild-type ND4 packaged into an rAAV2/2 vector that transduces retinal ganglion cells, to induce allotopic expression of hybrid mitochondrial ND4. GS010 clinical trials improved best-corrected visual acuity (BCVA) up to 5 years after treatment. Interestingly, unilateral treatment improved BCVA bilaterally. Subsequent studies revealed GS010 DNA in visual tissues contralateral to the injected eye, suggesting migration. Here we tested whether unilateral intraocular pressure (IOP) elevation could influence the transfer of viral ND4 RNA in contralateral tissues after GS010 delivery to the IOP-elevated eye and probed a potential mechanism mediating translocation in mice. We found IOP elevation enhanced viral ND4 RNA transcripts in contralateral visual tissues, including retinas. Using conditional transgenic mice, we depleted astrocytic gap junction connexin 43 (Cx43), required for distant redistribution of metabolic resources between astrocytes during stress. After unilateral IOP elevation and GS010 injection, Cx43 knockdown eradicated ND4 RNA transcript detection in contralateral retinal tissues, while transcript was still detectable in optic nerves. Overall, our study indicates long-range migration of GS010 product to contralateral visual tissues is enhanced by Cx43-linked astrocyte networks.

The Role of Citicoline and Coenzyme Q10 in Retinal Pathology

Ocular neurodegenerative diseases such as glaucoma, diabetic retinopathy, and age-related macular degeneration are common retinal diseases responsible for most of the blindness causes in the working-age and elderly populations in developed countries. Many of the current treatments used in these pathologies fail to stop or slow the progression of the disease. Therefore, other types of treatments with neuroprotective characteristics may be necessary to allow a more satisfactory management of the disease. Citicoline and coenzyme Q10 are molecules that have neuroprotective, antioxidant, and anti-inflammatory properties, and their use could have a beneficial effect in ocular neurodegenerative pathologies. This review provides a compilation, mainly from the last 10 years, of the main studies that have been published on the use of these drugs in these neurodegenerative diseases of the retina, analyzing the usefulness of these drugs in these pathologies.

Understanding the molecular basis and pathogenesis of hereditary optic neuropathies: towards improved diagnosis and management

Hereditary optic neuropathies result from defects in the human genome, both nuclear and mitochondrial. The two main and most recognised phenotypes are dominant optic atrophy and Leber hereditary optic neuropathy. Advances in modern molecular diagnosis have expanded our knowledge of genotypes and phenotypes of inherited disorders that affect the optic nerve, either alone or in combination, with various forms of neurological and systemic degeneration. A unifying feature in the pathophysiology of these disorders appears to involve mitochondrial dysfunction, suggesting that the retinal ganglion cells and their axons are especially susceptible to perturbations in mitochondrial homoeostasis. As we better understand the pathogenesis behind these genetic diseases, aetiologically targeted therapies are emerging and entering into clinical trials, including treatments aimed at halting the cascade of neurodegeneration, replacing or editing the defective genes or their protein products, and potentially regenerating damaged optic nerves, as well as preventing generational disease transmission.

Indirect Comparison of Lenadogene Nolparvovec Gene Therapy Versus Natural History in Patients with Leber Hereditary Optic Neuropathy Carrying the m.11778G>A MT-ND4 Mutation

INTRODUCTION

Lenadogene nolparvovec is a promising novel gene therapy for patients with Leber hereditary optic neuropathy (LHON) carrying the m.11778G>A ND4 mutation (MT-ND4). A previous pooled analysis of phase 3 studies showed an improvement in visual acuity of patients injected with lenadogene nolparvovec compared to natural history. Here, we report updated results by incorporating data from the latest phase 3 trial REFLECT in the pool, increasing the number of treated patients from 76 to 174.

METHODS

The visual acuity of 174 MT-ND4-carrying patients with LHON injected in one or both eyes with lenadogene nolparvovec from four pooled phase 3 studies (REVERSE, RESCUE and their long-term extension trial RESTORE; and REFLECT trial) was compared to the spontaneous evolution of an external control group of 208 matched patients from 11 natural history studies.

RESULTS

Treated patients showed a clinically relevant and sustained improvement in their visual acuity when compared to natural history. Mean improvement versus natural history was - 0.30 logMAR (+ 15 ETDRS letters equivalent) at last observation (P < 0.01) with a maximal follow-up of 3.9 years after injection. Most treated eyes were on-chart as compared to less than half of natural history eyes at 48 months after vision loss (89.6% versus 48.1%; P < 0.01) and at last observation (76.1% versus 44.4%; P < 0.01). When we adjusted for covariates of interest (gender, age of onset, ethnicity, and duration of follow-up), the estimated mean gain was - 0.43 logMAR (+ 21.5 ETDRS letters equivalent) versus natural history at last observation (P < 0.0001). Treatment effect was consistent across all phase 3 clinical trials. Analyses from REFLECT suggest a larger treatment effect in patients receiving bilateral injection compared to unilateral injection.

CONCLUSION

The efficacy of lenadogene nolparvovec in improving visual acuity in MT-ND4 LHON was confirmed in a large cohort of patients, compared to the spontaneous natural history decline. Bilateral injection of gene therapy may offer added benefits over unilateral injection.

TRIAL REGISTRATION NUMBERS

NCT02652780 (REVERSE); NCT02652767 (RESCUE); NCT03406104 (RESTORE); NCT03293524 (REFLECT); NCT03295071 (REALITY).

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

PURPOSE

To evaluate the safety profile of lenadogene nolparvovec (Lumevoq) in patients with Leber hereditary optic neuropathy.

DESIGN

Pooled analysis of safety data from 5 clinical studies.

METHODS

A total of 189 patients received single unilateral or bilateral intravitreal injections of a recombinant adeno-associated virus 2 (rAAV2/2) vector encoding the human wild-type ND4 gene. Adverse events (AEs) were collected throughout the studies, up to 5 years. Intraocular inflammation and increased intraocular pressure (IOP) were ocular AEs of special interest. Other assessments included ocular examinations, vector bio-dissemination, and systemic immune responses against rAAV2/2.

RESULTS

Almost all patients (95.2%) received 9 × 10¹⁰ viral genomes and 87.8% had at least 2 years of follow-up. Most patients (75.1%) experienced at least one systemic AE, but systemic treatment-related AEs occurred in 3 patients; none were serious. Intraocular inflammation was reported in 75.6% of lenadogene nolparvovec-treated eyes. Almost all intraocular inflammations occurred in the anterior chamber (58.8%) or in the vitreous (40.3%), and were of mild (90.3%) or moderate (8.8%) intensity; most resolved with topical corticosteroids alone. All IOP increases were mild to moderate in intensity. No AE led to study discontinuation. Bio-dissemination of lenadogene nolparvovec and systemic immune response were limited. The safety profile was comparable for patients treated bilaterally and unilaterally.

CONCLUSIONS

Lenadogene nolparvovec had a good overall safety profile with excellent systemic tolerability, consistent with limited bio-dissemination. The product was well tolerated, with mostly mild ocular side effects responsive to conventional ophthalmologic treatments.

Developments in the Treatment of Leber Hereditary Optic Neuropathy

PURPOSEOF REVIEW

To outline the current landscape of treatments for Leber hereditary optic neuropathy (LHON) along the therapeutic delivery pipeline, exploring the mechanisms of action and evidence for these therapeutic approaches.

RECENT FINDINGS

Treatments for LHON can be broadly classified as either mutation-specific or mutation-independent. Mutation-specific therapies aim to correct the underlying mutation through the use of a gene-editing platform or replace the faulty mitochondrial DNA-encoded protein by delivering the wild-type gene using a suitable vector. Recent gene therapy clinical trials assessing the efficacy of allotopically expressed MT-ND4 for the treatment of LHON due to the m.11778G > A mutation in MT-ND4 have shown positive results when treated within 12 months of symptom onset. Mutation-independent therapies can have various downstream targets that aim to improve mitochondrial respiration, reduce mitochondrial stress, inhibit or delay retinal ganglion cell apoptosis, and/or promote retinal ganglion cell survival. Idebenone, a synthetic hydrosoluble analogue of co-enzyme Q10 (ubiquinone), is the only approved treatment for LHON. Mutation-independent approaches to gene therapy under pre-clinical investigation for other neurodegenerative disorders may have the potential to benefit patients with LHON. Although approved treatments are presently limited, innovations in gene therapy and editing are driving the expansion of the therapeutic delivery pipeline for LHON.

Randomized trial of bilateral gene therapy injection for m.11778G > A MT-ND4 Leber optic neuropathy

Leber hereditary optic neuropathy (LHON) is an important example of mitochondrial blindness with the m.11778G > A mutation in the MT-ND4 gene being the most common disease-causing mitochondrial DNA (mtDNA) variant worldwide. The REFLECT phase 3 pivotal study is a randomized, double-masked, placebo-controlled trial investigating the efficacy and safety of bilateral intravitreal injection of lenadogene nolparvovec in patients with a confirmed m.11778G > A mutation, using a recombinant adeno-associated virus vector 2, serotype 2 (rAAV2/2-ND4). The first-affected eye received gene therapy; the fellow (affected/not-yet-affected) eye was randomly injected with gene therapy or placebo. The primary endpoint was the difference in change from baseline of best-corrected visual acuity (BCVA) in second-affected/not-yet-affected eyes treated with lenadogene nolparvovec versus placebo at 1.5 years post-treatment, expressed in logarithm of the minimal angle of resolution (LogMAR). Forty-eight patients were treated bilaterally and 50 unilaterally. At 1.5 years, the change from baseline in BCVA was not statistically different between second-affected/not-yet-affected eyes receiving lenadogene nolparvovec and placebo (primary endpoint). A statistically significant improvement in BCVA was reported from baseline to 1.5 years in lenadogene nolparvovec-treated eyes: -0.23 LogMAR for the first-affected eyes of bilaterally treated patients (p < 0.01); and -0.15 LogMAR for second-affected/not-yet-affected eyes of bilaterally treated patients and the first-affected eyes of unilaterally treated patients (p < 0.05). The mean improvement in BCVA from nadir to 1.5 years was -0.38 (0.052) LogMAR and -0.33 (0.052) LogMAR in first-affected and second-affected/not-yet-affected eyes treated with lenadogene nolparvovec, respectively (bilateral treatment group). A mean improvement of -0.33 (0.051) LogMAR and -0.26 (0.051) LogMAR was observed in first-affected lenadogene nolparvovec-treated eyes and second-affected/not-yet-affected placebo-treated eyes, respectively (unilateral treatment group). The proportion of patients with one or both eyes on-chart at 1.5 years was 85.4% and 72.0% for bilaterally and unilaterally treated patients, respectively. The gene therapy was well tolerated, with no systemic issues. Intraocular inflammation, which was mostly mild and well controlled with topical corticosteroids, occurred in 70.7% of lenadogene nolparvovec-treated eyes versus 10.2% of placebo-treated eyes. Among eyes treated with lenadogene nolparvovec, there was no difference in the incidence of intraocular inflammation between bilaterally and unilaterally treated patients. Overall, the REFLECT trial demonstrated an improvement of BCVA in LHON eyes carrying the m.11778G > A mtDNA mutation treated with lenadogene nolparvovec or placebo to a degree not reported in natural history studies and supports an improved benefit/risk profile for bilateral injections of lenadogene nolparvovec relative to unilateral injections.

Study design and baseline characteristics for the reflect gene therapy trial ofm.11778g>A/ND4-LHON

Objective

REFLECT is the first randomised, double-masked, placebo-controlled multicentre phase 3 clinical trial that evaluated the efficacy and safety of bilateral intravitreal (IVT) injection of lenadogene nolparvovec in subjects with Leber hereditary optic neuropathy carrying the m.11778G>A mutation.

Methods and analysis

A total of 98 subjects were enrolled with vision loss of ≤12 months. The subjects were randomised to one of two treatment arms with all subjects receiving an intravitreal (IVT) injection of lenadogene nolparvovec in their first affected eye and the second-affected eye randomised to receive IVT of either lenadogene nolparvovec or placebo.

Results

The majority of subjects were male with a mean duration of vision loss of 8.3 months. All but one subject experienced bilateral loss of vision at the time of injection. The mean best-corrected visual acuity of first-affected eyes was worse compared with second/not-yet-affected eyes. Analysis of retinal anatomical parameters showed increased thinning in the first-affected eyes when compared with the second/not-yet-affected eyes with both treatment arms showing significant changes compared with unaffected individuals.

Conclusion

The REFLECT trial is the third and the largest phase 3 clinical study evaluating lenadogene nolparvovec in m.11778G>A Leber hereditary optic neuropathy (LHON) subjects. The observed demographics in REFLECT are consistent with previous reports in LHON subjects in the acute and dynamic phases of LHON disease. Combined with the visual function and anatomical parameters obtained in the previous RESCUE and REVERSE trials, REFLECT has provided a uniformly collected data set that should help direct future LHON clinical trials.

Leber Hereditary Optic Neuropathy: Molecular Pathophysiology and Updates on Gene Therapy

Molecular pathophysiology of LHON was reviewed and the current status of gene therapy for LHON is updated.

From Bench to Bedside-Delivering Gene Therapy for Leber Hereditary Optic Neuropathy

Leber hereditary optic neuropathy (LHON) is a rare, maternally inherited mitochondrial disorder that presents with severe bilateral sequential vision loss, due to the selective degeneration of retinal ganglion cells (RGCs). Since the mitochondrial genetic basis for LHON was uncovered in 1988, considerable progress has been made in understanding the pathogenetic mechanisms driving RGC loss, which has enabled the development of therapeutic approaches aimed at mitigating the underlying mitochondrial dysfunction. In this review, we explore the genetics of LHON, from bench to bedside, focusing on the pathogenetic mechanisms and how these have informed the development of different gene therapy approaches, in particular the technique of allotopic expression with adeno-associated viral vectors. Finally, we provide an overview of the recent gene therapy clinical trials and consider the unanswered questions, challenges, and future prospects.

Absence of lenadogene nolparvovec DNA in a brain tumor biopsy from a patient in the REVERSE clinical study, a case report

BACKGROUND

Leber Hereditary Optic Neuropathy (LHON) is a rare, maternally-inherited mitochondrial disease that primarily affects retinal ganglion cells (RGCs) and their axons in the optic nerve, leading to irreversible, bilateral severe vision loss. Lenadogene nolparvovec gene therapy was developed as a treatment for patients with vision loss from LHON caused by the most prevalent m.11778G > A mitochondrial DNA point mutation in the MT-ND4 gene. Lenadogene nolparvovec is a replication-defective recombinant adeno-associated virus vector 2 serotype 2 (AAV2/2), encoding the human wild-type MT-ND4 protein. Lenadogene nolparvovec was administered by intravitreal injection (IVT) in LHON patients harboring the m.11778G > A ND4 mutation in a clinical development program including one phase 1/2 study (REVEAL), three phase 3 pivotal studies (REVERSE, RESCUE, REFLECT), and one long-term follow-up study (RESTORE, the follow-up of REVERSE and RESCUE patients).

CASE PRESENTATION

A 67-year-old woman with MT-ND4 LHON, included in the REVERSE clinical study, received a unilateral IVT of lenadogene nolparvovec in the right eye and a sham injection in the left eye in May 2016, 11.4 months and 8.8 months after vision loss in her right and left eyes, respectively. The patient had a normal brain magnetic resonance imaging with contrast at the time of diagnosis of LHON. Two years after treatment administration, BCVA had improved in both eyes. The product was well tolerated with mild and resolutive anterior chamber inflammation in the treated eye. In May 2019, the patient was diagnosed with a right temporal lobe glioblastoma, IDH-wildtype, World Health Organization grade 4, based on histological analysis of a tumor excision. The brain tumor was assessed for the presence of vector DNA by using a sensitive validated qPCR assay targeting the ND4 sequence of the vector.

CONCLUSION

ND4 DNA was not detected (below 15.625 copies/μg of genomic DNA) in DNA extracted from the brain tumor, while a housekeeping gene DNA was detected at high levels. Taken together, this data shows the absence of detection of lenadogene nolparvovec in a brain tumor (glioblastoma) of a treated patient in the REVERSE clinical trial 3 years after gene therapy administration, supporting the long-term favorable safety of lenadogene nolparvovec.

Biodistribution of intravitreal lenadogene nolparvovec gene therapy in nonhuman primates

Lenadogene nolparvovec (Lumevoq) gene therapy was developed to treat Leber hereditary optic neuropathy (LHON) caused by the m.11778G > A in MT-ND4 that affects complex I of the mitochondrial respiratory chain. Lenadogene nolparvovec is a replication-defective, single-stranded DNA recombinant adeno-associated virus vector 2 serotype 2, containing a codon-optimized complementary DNA encoding the human wild-type MT-ND4 subunit protein. Lenadogene nolparvovec was administered by unilateral intravitreal injection in MT-ND4 LHON patients in two randomized, double-masked, and sham-controlled phase III clinical trials (REVERSE and RESCUE), resulting in bilateral improvement of visual acuity. These and other earlier results suggest that lenadogene nolparvovec may travel from the treated to the untreated eye. To investigate this possibility further, lenadogene nolparvovec was unilaterally injected into the vitreous body of the right eye of healthy, nonhuman primates. Viral vector DNA was quantifiable in all eye and optic nerve tissues of the injected eye and was detected at lower levels in some tissues of the contralateral, noninjected eye, and optic projections, at 3 and 6 months after injection. The results suggest that lenadogene nolparvovec transfers from the injected to the noninjected eye, thus providing a potential explanation for the bilateral improvement of visual function observed in the LHON patients.

Long-Term Follow-Up After Unilateral Intravitreal Gene Therapy for Leber Hereditary Optic Neuropathy: The RESTORE Study

BACKGROUND

RESCUE and REVERSE were 2 Phase 3 clinical trials that assessed the efficacy and safety of intravitreal gene therapy with lenadogene nolparvovec (rAAV2/2-ND4) for the treatment of Leber hereditary optic neuropathy (LHON). RESTORE is the long-term follow-up study of subjects treated in the RESCUE and REVERSE trials.

METHODS

In RESCUE and REVERSE, 76 subjects with LHON because of the m.11778 G>A mutation in the mitochondrial gene ND4 received a single unilateral intravitreal injection of lenadogene nolparvovec. After 96 weeks, 61 subjects were enrolled in the long-term follow-up study RESTORE. The best-corrected visual acuity (BCVA) was assessed over a period of up to 52 months after onset of vision loss. A locally estimated scatterplot smoothing regression model was used to analyze changes in BCVA over time. Vision-related quality of life was reported using the visual function questionnaire-25 (VFQ-25).

RESULTS

The population of MT-ND4 subjects enrolled in RESTORE was representative of the combined cohorts of RESCUE and REVERSE for mean age (35.1 years) and gender distribution (79% males). There was a progressive and sustained improvement of BCVA up to 52 months after the onset of vision loss. The final mean BCVA was 1.26 logarithm of the minimal angle of resolution 48 months after the onset of vision loss. The mean VFQ-25 composite score increased by 7 points compared with baseline.

CONCLUSION

The treatment effect of lenadogene nolparvovec on BCVA and vision-related quality of life observed 96 weeks (2 years) after treatment in RESCUE and REVERSE was sustained at 3 years in RESTORE, with a maximum follow-up of 52 months (4.3 years) after the onset of vision loss.

Intravitreal Gene Therapy vs. Natural History in Patients With Leber Hereditary Optic Neuropathy Carrying the m.11778G>A ND4 Mutation: Systematic Review and Indirect Comparison

Objective: This work aimed to compare the evolution of visual outcomes in Leber hereditary optic neuropathy (LHON) patients treated with intravitreal gene therapy to the spontaneous evolution in prior natural history (NH) studies. Design: A combined analysis of two phase three randomized, double-masked, sham-controlled studies (REVERSE and RESCUE) and their joint long-term extension trial (CLIN06) evaluated the efficacy of rAAV2/2-ND4 vs. 11 pooled NH studies used as an external control. Subjects: The LHON subjects carried the m.11778G>A ND4 mutation and were aged ≥15 years at onset of vision loss. Methods: A total of 76 subjects received a single intravitreal rAAV2/2-ND4 injection in one eye and sham injection in the fellow eye within 1 year after vision loss in REVERSE and RESCUE. Both eyes were considered as treated due to the rAAV2/2-ND4 treatment efficacy observed in the contralateral eyes. Best corrected visual acuity (BCVA) from REVERSE, RESCUE, and CLIN06 up to 4.3 years after vision loss was compared to the visual acuity of 208 NH subjects matched for age and ND4 genotype. The NH subjects were from a LHON registry (REALITY) and from 10 NH studies. A locally estimated scatterplot smoothing (LOESS), non-parametric, local regression model was used to modelize visual acuity curves over time, and linear mixed model was used for statistical inferences. Main Outcome Measures: The main outcome measure was evolution of visual acuity from 12 months after vision loss, when REVERSE and RESCUE patients had been treated with rAAV2/2-ND4. Results: The LOESS curves showed that the BCVA of the treated patients progressively improved from month 12 to 52 after vision loss. At month 48, there was a statistically and clinically relevant difference in visual acuity of -0.33 logarithm of the minimal angle of resolution (LogMAR) (16.5 ETDRS letters equivalent) in favor of treated eyes vs. NH eyes (p < 0.01). Most treated eyes (88.7%) were on-chart at month 48 as compared to 48.1% of the NH eyes (p < 0.01). The treatment effect at last observation remained statistically and clinically significant when adjusted for age and duration of follow-up (-0.32 LogMAR, p < 0.0001). Conclusions: The m.11778G>A LHON patients treated with rAAV2/2-ND4 exhibited an improvement of visual acuity over more than 4 years after vision loss to a degree not demonstrated in NH studies. Clinical Trial Registration: NCT02652767, NCT02652780, NCT03406104, and NCT03295071.