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ObjectivesThis study aimed to evaluate the suitability of the National Eye Institute Visual Function Questionnaire (NEI-VFQ-25) for measuring vision-related quality of life (VRQoL) in patients with Leber hereditary optic neuropathy receiving lenadogene nolparvovec gene therapy in three Phase III randomised controlled clinical trials.MethodsVRQoL was assessed using the NEI-VFQ-25 at baseline (n=174) and 2 years after treatment (n=152). All participants received lenadogene nolparvovec in at least one eye. The scoring structure of the original NEI-VFQ-25 was evaluated for fit to the Rasch model, and a post hoc revision was created and psychometrically reevaluated. Stacked analysis was conducted to compare Rasch-revised scores at baseline and 2 years after treatment.ResultsThe original NEI-VFQ-25 exhibited multiple issues including limitations in response functioning and scale dimensionality. These issues were rectified by revising the NEI-VFQ25 into two separate unidimensional scales measuring ‘Vision-related Activity Limitation’ (VAL) and ‘Socioemotional Functioning’ (SEF). Participants’ mean VAL score at baseline on a Rasch-transformed 0–100 scale was 46.1 (11.7), improving to 48.4 (13.7) after treatment (F(1, 324) = 2.67, p=0.103). On the SEF scale, there was a significant difference 2 years after treatment, with participants improving from a mean score of 40.1 (14.1) at baseline to 49.6 (17.6) (F(1, 324) = 29.1, p<0.001).ConclusionsThe scoring structure of the original NEI-VFQ-25 has limitations that undermine its psychometric validity as a measure of VRQoL. Using the Rasch-revised NEI-VFQ-25, we determined that improvement in VRQoL after treatment with lenadogene nolparvovec was driven predominantly by an improvement in socioemotional functioning.

Leber congenital amaurosis due to CEP290 ciliopathy is being explored by treatment with the antisense oligonucleotide (AON) sepofarsen. One patient who was part of a larger cohort (ClinicalTrials.gov NCT03140969 ) was studied for 15 months after a single intravitreal sepofarsen injection. Concordant measures of visual function and retinal structure reached a substantial efficacy peak near 3 months after injection. At 15 months, there was sustained efficacy, even though there was evidence of reduction from peak response. Efficacy kinetics can be explained by the balance of AON-driven new CEP290 protein synthesis and a slow natural rate of CEP290 protein degradation in human foveal cone photoreceptors. Post hoc analyses and follow-up of a patient with Leber congenital amaurosis treated with the antisense oligonucleotide sepofarsen as part of a clinical trial indicates sustained improvement of vision 15 months after receiving a single dose of the drug.

Leber congenital amaurosis type 10 is a severe retinal dystrophy caused by mutations in the CEP290 gene1,2. We developed EDIT-101, a candidate genome-editing therapeutic, to remove the aberrant splice donor created by the IVS26 mutation in the CEP290 gene and restore normal CEP290 expression. Key to this therapeutic, we identified a pair of Staphylococcus aureus Cas9 guide RNAs that were highly active and specific to the human CEP290 target sequence. In vitro experiments in human cells and retinal explants demonstrated the molecular mechanism of action and nuclease specificity. Subretinal delivery of EDIT-101 in humanized CEP290 mice showed rapid and sustained CEP290 gene editing. A comparable surrogate non-human primate (NHP) vector also achieved productive editing of the NHP CEP290 gene at levels that met the target therapeutic threshold, and demonstrated the ability of CRISPR/Cas9 to edit somatic primate cells in vivo. These results support further development of EDIT-101 for LCA10 and additional CRISPR-based medicines for other inherited retinal disorders.In human cells, a humanized mouse model and non-human primates, CRISPR/Cas9 corrects the splicing defect in a gene associated with congenital blindness.

The first retinal gene therapy in human blindness from RPE65 mutations has focused on safety and efficacy, as defined by improved vision. The disease component not studied, however, has been the fate of photoreceptors in this progressive retinal degeneration. We show that gene therapy improves vision for at least 3 y, but photoreceptor degeneration progresses unabated in humans. In the canine model, the same result occurs when treatment is at the disease stage equivalent to humans. The study shows the need for combinatorial therapy to improve vision in the short term but also slow retinal degeneration in the long term. Leber congenital amaurosis (LCA) associated with retinal pigment epithelium-specific protein 65 kDa ( RPE65 ) mutations is a severe hereditary blindness resulting from both dysfunction and degeneration of photoreceptors. Clinical trials with gene augmentation therapy have shown partial reversal of the dysfunction, but the effects on the degeneration are not known. We evaluated the consequences of gene therapy on retinal degeneration in patients with RPE65 -LCA and its canine model. In untreated RPE65 -LCA patients, there was dysfunction and degeneration of photoreceptors, even at the earliest ages. Examined serially over years, the outer photoreceptor nuclear layer showed progressive thinning. Treated RPE65 -LCA showed substantial visual improvement in the short term and no detectable decline from this new level over the long term. However, retinal degeneration continued to progress unabated. In RPE65 -mutant dogs, the first one-quarter of their lifespan showed only dysfunction, and there was normal outer photoreceptor nuclear layer thickness retina-wide. Dogs treated during the earlier dysfunction-only stage showed improved visual function and dramatic protection of treated photoreceptors from degeneration when measured 5–11 y later. Dogs treated later during the combined dysfunction and degeneration stage also showed visual function improvement, but photoreceptor loss continued unabated, the same as in human RPE65 -LCA. The results suggest that, in RPE65 disease treatment, protection from visual function deterioration cannot be assumed to imply protection from degeneration. The effects of gene augmentation therapy are complex and suggest a need for a combinatorial strategy in RPE65 -LCA to not only improve function in the short term but also slow retinal degeneration in the long term.

Abstract PurposeTo investigate real-world safety and efficacy of voretigene neparvovec gene therapy administration in pediatric patients with biallelic RPE65 disease-causing variants.MethodsA retrospective study of 27 eyes of 14 patients with RPE65-associated Leber congenital amaurosis examined postoperative complications and longitudinal changes in photoreceptor function following treatment with subretinal injection of voretigene neparvovec. Full-field stimulus threshold testing (FST), Goldmann visual fields (GVF), best-corrected visual acuity (BCVA), and central subfield thickness (CST) on optical coherence tomography (OCT) scans were collected preoperatively and up to 12 months posttreatment.ResultsBaseline through 6–12 month follow-up FST and GVF data were obtained for 13 eyes of 7 patients. FST improved for each eye after treatment with a mean improvement of 2.1 log-units (P < 0.001) and GVF improved for each eye with a mean improvement of 221 sum degrees (P < 0.001). BCVA improved from logMAR 0.98 at baseline to logMAR 0.83 at last follow-up (P < 0.001). Across 19 eyes of 10 patients included in CST analysis, there was a small but statistically significant 9-μ decrease in mean CST from baseline to last follow-up (P < 0.001). The most common postoperative issues included elevation in intraocular pressure (59%), persistent intraocular inflammation (15%), and vitreous opacities (26%) that resolved over a period of months.ConclusionsThis report provides some of the earliest longitudinal real-world evidence of the pediatric safety and efficacy of voretigene neparvovec using multiple functional and structural measures of the retina. Outcomes demonstrate significant improvements in visual function consistent with clinical trial results.

Leber congenital amaurosis (LCA) is a severe inherited retinal disorder manifesting at birth or in early infancy, with a subset of cases linked to mutations in the aryl hydrocarbon receptor-interacting protein-like 1 (AIPL1) gene. Initially identified as the disease locus for LCA4, AIPL1 exhibits a retina-specific expression pattern. Its protein product is a unique member of the FKBP family, distinguished by its specific structural features and specialized functions. A wide spectrum of mutations in AIPL1 is associated with varying severities of retinal degeneration, implicating diverse pathogenic mechanisms. While the early onset and rapid progression of AIPL1-related disorders pose a therapeutic challenge, significant progress in gene therapy has unlocked promising avenues for effective treatment. This comprehensive review summarizes current findings to spark interest and pave the way for further studies in the therapy of AIPL1-caused retinal diseases.

A long-term study, conducted over approximately 5.5 years, involving three patients treated with gene therapy for Leber's congenital amaurosis shows that visual sensitivity initially improved and then declined. Leber’s congenital amaurosis, a childhood-onset autosomal recessive blindness that is known to be caused by mutations in at least 19 different genes, was considered to be untreatable and incurable until 2008, when gene therapy was successfully developed for patients with the disease caused by mutated RPE65 . The gene encoding RPE65 (retinal pigment epithelium–specific protein 65 kDa), a key enzyme of the retinoid cycle of vision, was introduced into the retina of patients with RPE65 -associated Leber’s congenital amaurosis in three independent but contemporaneously conducted clinical trials. In all the trials, the safety and efficacy of the treatment was announced . . .

CEP290-associated Leber congenital amaurosis type 10 (LCA10) is a retinal disease resulting in childhood blindness. Sepofarsen is an RNA antisense oligonucleotide targeting the c.2991+1655A>G variant in the CEP290 gene to treat LCA10. In this open-label, phase 1b/2 ( NCT03140969 ), 12-month, multicenter, multiple-dose, dose-escalation trial, six adult patients and five pediatric patients received ≤4 doses of intravitreal sepofarsen into the worse-seeing eye. The primary objective was to evaluate sepofarsen safety and tolerability via the frequency and severity of ocular adverse events (AEs); secondary objectives were to evaluate pharmacokinetics and efficacy via changes in functional outcomes. Six patients received sepofarsen 160 µg/80 µg, and five patients received sepofarsen 320 µg/160 µg. Ten of 11 (90.9%) patients developed ocular AEs in the treated eye (5/6 with 160 µg/80 µg; 5/5 with 320 µg/160 µg) versus one of 11 (9.1%) in the untreated eye; most were mild in severity and dose dependent. Eight patients developed cataracts, of which six (75.0%) were categorized as serious (2/3 with 160 µg/80 µg; 4/5 with 320 µg/160 µg), as lens replacement was required. As the 160-µg/80-µg group showed a better benefit–risk profile, higher doses were discontinued or not initiated. Statistically significant improvements in visual acuity and retinal sensitivity were reported (post hoc analysis). The manageable safety profile and improvements reported in this trial support the continuation of sepofarsen development. Intravitreal administration of the antisense oligonucleotide sepofarsen in patients with Leber congenital amaurosis type 10 showed a manageable safety profile, ocular adverse events being dose dependent, and achieved meaningful improvements of visual function.

Leber congenital amaurosis, caused by mutations in RPE65 and LRAT, is a severe form of inherited retinal degeneration leading to blindness. We aimed to assess replacement of the missing chromophore 11-cis retinal with oral QLT091001 (synthetic 9-cis-retinyl acetate) in these patients. In our open-label, prospective, phase 1b trial, we enrolled patients (aged ≥6 years) with Leber congenital amaurosis and RPE65 or LRAT mutations at McGill University's Montreal Children's Hospital. Patients received 7 days of oral QLT091001 (10–40 mg/m2 per day). We assessed patients at baseline and days 7, 9, 14, and 30, and then 2 months and every 2 months thereafter for up to 2·2 years for safety outcomes and visual function endpoints including Goldmann visual fields (GVF), visual acuity, and functional MRI assessment. We regarded patients as having an improvement in vision if we noted at least a 20% improvement in retinal area on GVF compared with baseline or a visual acuity improvement of five or more letters compared with baseline in two consecutive study visits (or any improvement from no vision at baseline). This study is registered with ClinicalTrials.gov, number NCT01014052. Between December, 2009, and June, 2011, we enrolled and treated 14 patients aged 6–38 years who were followed up until March, 2012. Ten (71%) of 14 patients had an improvement in GVF areas (mean increase in retinal area of 28–683%). Six (43%) patients had an improvement in visual acuity (mean increase of 2–30 letters). Self-reported or parent-reported improvements in activities of daily living supported these findings. After 2 years, 11 (79%) patients had returned to their baseline GVF retinal area and ten (71%) had returned to baseline visual acuity letter values. Thus, three (21%) patients had a sustained GVF response and four (30%) had a sustained visual acuity response. Four patients had functional MRI scans, which correlated with visual response or absence of response to treatment. No serious adverse events occurred, although we noted transient headaches (11 patients), photophobia (11 patients), reduction in serum HDL concentrations (four patients), and increases in serum triglycerides (eight patients) and aspartate aminotransferase concentrations (two patients). Non-invasive oral QLT091001 therapy is well tolerated, and can rapidly improve visual function in some patients with Leber congenital amaurosis and RPE65 and LRAT mutations. QLT, Foundation Fighting Blindness Canada, CIHR, FRSQ, Reseau Vision.

Inherited retinal diseases (IRDs) comprise a clinically and genetically heterogeneous group of disorders that can ultimately result in photoreceptor dysfunction/death and vision loss. With over 270 genes known to be involved in IRDs, translation of treatment strategies into clinical applications has been historically difficult. However, in recent years there have been significant advances in basic research findings as well as translational studies, culminating in an increasing number of clinical trials with the ultimate goal of reducing vision loss and associated morbidities. The recent approval of Luxturna ® (voretigene neparvovec-rzyl) for Leber congenital amaurosis type 2 (LCA2) prompts a review of the current clinical trials for IRDs, with a particular focus on the importance of adeno-associated virus (AAV)-based gene therapies. The present article reviews the current state of AAV use in gene therapy clinical trials for IRDs, with a brief background on AAV and the reasons behind its dominance in ocular gene therapy. It will also discuss pre-clinical progress in AAV-based therapies aimed at treating other ocular conditions that can have hereditable links, and what alternative technologies are progressing in the same therapeutic space.