Gene Editing for CEP290-Associated Retinal Degeneration.

BACKGROUND: CEP290-associated inherited retinal degeneration causes severe early-onset vision loss due to pathogenic variants in CEP290. EDIT-101 is a clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) gene-editing complex designed to treat inherited retinal degeneration caused by a specific damaging variant in intron 26 of CEP290 (IVS26 variant). METHODS: We performed a phase 1-2, open-label, single-ascending-dose study in which persons 3 years of age or older with CEP290-associated inherited retinal degeneration caused by a homozygous or compound heterozygous IVS26 variant received a subretinal injection of EDIT-101 in the worse (study) eye. The primary outcome was safety, which included adverse events and dose-limiting toxic effects. Key secondary efficacy outcomes were the change from baseline in the best corrected visual acuity, the retinal sensitivity detected with the use of full-field stimulus testing (FST), the score on the Ora-Visual Navigation Challenge mobility test, and the vision-related quality-of-life score on the National Eye Institute Visual Function Questionnaire-25 (in adults) or the Children's Visual Function Questionnaire (in children). RESULTS: EDIT-101 was injected in 12 adults 17 to 63 years of age (median, 37 years) at a low dose (in 2 participants), an intermediate dose (in 5), or a high dose (in 5) and in 2 children 9 and 14 years of age at the intermediate dose. At baseline, the median best corrected visual acuity in the study eye was 2.4 log10 of the minimum angle of resolution (range, 3.9 to 0.6). No serious adverse events related to the treatment or procedure and no dose-limiting toxic effects were recorded. Six participants had a meaningful improvement from baseline in cone-mediated vision as assessed with the use of FST, of whom 5 had improvement in at least one other key secondary outcome. Nine participants (64%) had a meaningful improvement from baseline in the best corrected visual acuity, the sensitivity to red light as measured with FST, or the score on the mobility test. Six participants had a meaningful improvement from baseline in the vision-related quality-of-life score. CONCLUSIONS: The safety profile and improvements in photoreceptor function after EDIT-101 treatment in this small phase 1-2 study support further research of in vivo CRISPR-Cas9 gene editing to treat inherited retinal degenerations due to the IVS26 variant of CEP290 and other genetic causes. (Funded by Editas Medicine and others; BRILLIANCE ClinicalTrials.gov number, NCT03872479.).

Adeno-Associated Virus Serotype 2-hCHM Subretinal Delivery to the Macula in Choroideremia: Two-Year Interim Results of an Ongoing Phase I/II Gene Therapy Trial.

PURPOSE: To assess the safety of the subretinal delivery of a recombinant adeno-associated virus serotype 2 (AAV2) vector carrying a human choroideremia (CHM)-encoding cDNA in CHM. DESIGN: Prospective, open-label, nonrandomized, dose-escalation, phase I/II clinical trial. PARTICIPANTS: Fifteen CHM patients (ages 20-57 years at dosing). METHODS: Patients received uniocular subfoveal injections of low-dose (up to 5 × 1010 vector genome [vg] per eye, n = 5) or high-dose (up to 1 × 1011 vg per eye, n = 10) of a recombinant adeno-associated virus serotype 2 (AAV2) vector carrying a human CHM-encoding cDNA (AAV2-hCHM). Patients were evaluated preoperatively and postoperatively for 2 years with ophthalmic examinations, multimodal retinal imaging, and psychophysical testing. MAIN OUTCOME MEASURES: Visual acuity, perimetry (10-2 protocol), spectral-domain OCT (SD-OCT), and short-wavelength fundus autofluorescence (SW-FAF). RESULTS: We detected no vector-related or systemic toxicities. Visual acuity returned to within 15 letters of baseline in all but 2 patients (1 developed acute foveal thinning, and 1 developed a macular hole); the rest showed no gross changes in foveal structure at 2 years. There were no significant differences between intervention and control eyes in mean light-adapted sensitivity by perimetry or in the lateral extent of retinal pigment epithelium relative preservation by SD-OCT and SW-FAF. Microperimetry showed nonsignificant (< 3 standard deviations of the intervisit variability) gains in sensitivity in some locations and participants in the intervention eye. There were no obvious dose-dependent relationships. CONCLUSIONS: Visual acuity was within 15 letters of baseline after the subfoveal AAV2-hCHM injections in 13 of 15 patients. Acute foveal thinning with unchanged perifoveal function in 1 patient and macular hole in 1 patient suggest foveal vulnerability to the subretinal injections. Longer observation intervals will help establish the significance of the minor differences in sensitivities and rate of disease progression observed between intervention and control eyes.

Clinical Perspective: Treating RPE65-Associated Retinal Dystrophy.

Until recently, there was no approved treatment for a retinal degenerative disease. Subretinal injection of a recombinant adeno-associated virus (AAV) delivering the normal copy of the human RPE65 cDNA led to reversal of blindness first in animal models and then in humans. This led to the first US Food and Drug Administration (FDA)-approved gene therapy product for a genetic disease, voretigene neparvovec-rzyl (Luxturna). Luxturna was then approved by the European Medicines Association and is now available in the US through Spark Therapeutics and worldwide through Novartis. Not only has treatment with Luxturna changed the lives of people previously destined to live a life of blindness, but it has fueled interest in developing additional gene therapy reagents targeting numerous other genetic forms of inherited retinal disease. This review describes many of the considerations for administration of Luxturna and describes how lessons from experience with Luxturna could lead to additional gene-based treatments of blindness.

Durability of Voretigene Neparvovec for Biallelic RPE65-Mediated Inherited Retinal Disease: Phase 3 Results at 3 and 4 Years.

PURPOSE: To determine whether functional vision and visual function improvements after voretigene neparvovec (VN; Luxturna [Spark Therapeutics, Inc]) administration in patients with biallelic RPE65 mutation-associated inherited retinal disease are maintained at 3 to 4 years and to review safety outcomes. DESIGN: Open-label, randomized, controlled phase 3 trial. PARTICIPANTS: Thirty-one individuals were enrolled and randomized 2:1 to intervention (n = 21) or control (n = 10). One participant from each group withdrew before, or at, randomization. METHODS: Patients in the original intervention (OI) group received bilateral subretinal VN injections. Delayed intervention (DI) patients served as control participants for 1 year then received VN. MAIN OUTCOME MEASURES: Change from injection baseline in bilateral performance on the multiluminance mobility test (MLMT), a measure of ambulatory navigation, and change from injection baseline in full-field light sensitivity threshold white light, visual field (VF), and visual acuity (VA). RESULTS: Mean bilateral MLMT change scores at year 4 for OI patients and year 3 for DI patients were 1.7 and 2.4, respectively, with 71% of patients with a year 3 visit able to pass MLMT at the lowest light level. Mean change in full-field light sensitivity threshold white light, averaged over both eyes at year 4 for OI patients and year 3 for DI patients, was -1.90 log10(cd.s/m2) and -2.91 log10(cd.s/m2), respectively. Mean change in Goldmann kinetic VF III4e sum total degrees, averaged across both eyes, was 197.7 at year 4 for OI patients and 157.9 at year 3 for DI patients. Mean change in VA (Holladay scale), averaged across both eyes, was -0.003 logarithm of the minimum angle of resolution (logMAR) at year 4 for OI patients and -0.06 logMAR at year 3 for DI patients. One OI patient experienced retinal detachment at approximately year 4 that impacted VA for the OI group. No product-related serious adverse events (AEs) occurred, nor did any deleterious immune responses. CONCLUSIONS: Improvements in ambulatory navigation, light sensitivity, and VF were consistent in both intervention groups. Overall, improvements were maintained up to 3 to 4 years, with ongoing observation. The safety profile of VN was consistent with vitrectomy and the subretinal injection procedure and was similar between intervention groups, with no product-related serious AEs reported.

Efficacy, Safety, and Durability of Voretigene Neparvovec-rzyl in RPE65 Mutation-Associated Inherited Retinal Dystrophy: Results of Phase 1 and 3 Trials.

PURPOSE: To report the durability of voretigene neparvovec-rzyl (VN) adeno-associated viral vector-based gene therapy for RPE65 mutation-associated inherited retinal dystrophy (IRD), including results of a phase 1 follow-on study at year 4 and phase 3 study at year 2. DESIGN: Open-label phase 1 follow-on clinical trial and open-label, randomized, controlled phase 3 clinical trial. PARTICIPANTS: Forty subjects who received 1.5×1011 vector genomes (vg) of VN per eye in at least 1 eye during the trials, including 11 phase 1 follow-on subjects and 29 phase 3 subjects (20 original intervention [OI] and 9 control/intervention [CI]). METHODS: Subretinal injection of VN in the second eye of phase 1 follow-on subjects and in both eyes of phase 3 subjects. MAIN OUTCOME MEASURES: End points common to the phase 1 and phase 3 studies included change in performance on the Multi-Luminance Mobility Test (MLMT) within the illuminance range evaluated, full-field light sensitivity threshold (FST) testing, and best-corrected visual acuity (BCVA). Safety end points included adverse event reporting, ophthalmic examination, physical examination, and laboratory testing. RESULTS: Mean (standard deviation) MLMT lux score change was 2.4 (1.3) at 4 years compared with 2.6 (1.6) at 1 year after administration in phase 1 follow-on subjects (n = 8), 1.9 (1.1) at 2 years, and 1.9 (1.0) at 1 year post-administration in OI subjects (n = 20), and 2.1 (1.6) at 1 year post-administration in CI subjects (n = 9). All 3 groups maintained an average improvement in FST, reflecting more than a 2 log10(cd.s/m2) improvement in light sensitivity at 1 year and subsequent available follow-up visits. The safety profile was consistent with vitrectomy and the subretinal injection procedure, and no deleterious immune responses occurred. CONCLUSIONS: After VN gene augmentation therapy, there was a favorable benefit-to-risk profile with similar improvement demonstrated in navigational ability and light sensitivity among 3 groups of subjects with RPE65 mutation-associated IRD, a degenerative disease that progresses to complete blindness. The safety profile is consistent with the administration procedure. These data suggest that this effect, which is nearly maximal by 30 days after VN administration, is durable for 4 years, with observation ongoing.

Amelioration of Neurosensory Structure and Function in Animal and Cellular Models of a Congenital Blindness.

Most genetically distinct inherited retinal degenerations are primary photoreceptor degenerations. We selected a severe early onset form of Leber congenital amaurosis (LCA), caused by mutations in the gene LCA5, in order to test the efficacy of gene augmentation therapy for a ciliopathy. The LCA5-encoded protein, Lebercilin, is essential for the trafficking of proteins and vesicles to the photoreceptor outer segment. Using the AAV serotype AAV7m8 to deliver a human LCA5 cDNA into an Lca5 null mouse model of LCA5, we show partial rescue of retinal structure and visual function. Specifically, we observed restoration of rod-and-cone-driven electroretinograms in about 25% of injected eyes, restoration of pupillary light responses in the majority of treated eyes, an ∼20-fold decrease in target luminance necessary for visually guided behavior, and improved retinal architecture following gene transfer. Using LCA5 patient-derived iPSC-RPEs, we show that delivery of the LCA5 cDNA restores lebercilin protein and rescues cilia quantity. The results presented in this study support a path forward aiming to develop safety and efficacy trials for gene augmentation therapy in human subjects with LCA5 mutations. They also provide the framework for measuring the effects of intervention in ciliopathies and other severe, early-onset blinding conditions.

Efficacy and safety of voretigene neparvovec (AAV2-hRPE65v2) in patients with RPE65-mediated inherited retinal dystrophy: a randomised, controlled, open-label, phase 3 trial.

BACKGROUND: Phase 1 studies have shown potential benefit of gene replacement in RPE65-mediated inherited retinal dystrophy. This phase 3 study assessed the efficacy and safety of voretigene neparvovec in participants whose inherited retinal dystrophy would otherwise progress to complete blindness. METHODS: In this open-label, randomised, controlled phase 3 trial done at two sites in the USA, individuals aged 3 years or older with, in each eye, best corrected visual acuity of 20/60 or worse, or visual field less than 20 degrees in any meridian, or both, with confirmed genetic diagnosis of biallelic RPE65 mutations, sufficient viable retina, and ability to perform standardised multi-luminance mobility testing (MLMT) within the luminance range evaluated, were eligible. Participants were randomly assigned (2:1) to intervention or control using a permuted block design, stratified by age (<10 years and ≥10 years) and baseline mobility testing passing level (pass at ≥125 lux vs <125 lux). Graders assessing primary outcome were masked to treatment group. Intervention was bilateral, subretinal injection of 1·5 × 1011 vector genomes of voretigene neparvovec in 0·3 mL total volume. The primary efficacy endpoint was 1-year change in MLMT performance, measuring functional vision at specified light levels. The intention-to-treat (ITT) and modified ITT populations were included in primary and safety analyses. This trial is registered with ClinicalTrials.gov, number NCT00999609, and enrolment is complete. FINDINGS: Between Nov 15, 2012, and Nov 21, 2013, 31 individuals were enrolled and randomly assigned to intervention (n=21) or control (n=10). One participant from each group withdrew after consent, before intervention, leaving an mITT population of 20 intervention and nine control participants. At 1 year, mean bilateral MLMT change score was 1·8 (SD 1·1) light levels in the intervention group versus 0·2 (1·0) in the control group (difference of 1·6, 95% CI 0·72-2·41, p=0·0013). 13 (65%) of 20 intervention participants, but no control participants, passed MLMT at the lowest luminance level tested (1 lux), demonstrating maximum possible improvement. No product-related serious adverse events or deleterious immune responses occurred. Two intervention participants, one with a pre-existing complex seizure disorder and another who experienced oral surgery complications, had serious adverse events unrelated to study participation. Most ocular events were mild in severity. INTERPRETATION: Voretigene neparvovec gene replacement improved functional vision in RPE65-mediated inherited retinal dystrophy previously medically untreatable. FUNDING: Spark Therapeutics.

Safety and durability of effect of contralateral-eye administration of AAV2 gene therapy in patients with childhood-onset blindness caused by RPE65 mutations: a follow-on phase 1 trial.

BACKGROUND: Safety and efficacy have been shown in a phase 1 dose-escalation study involving a unilateral subretinal injection of a recombinant adeno-associated virus (AAV) vector containing the RPE65 gene (AAV2-hRPE65v2) in individuals with inherited retinal dystrophy caused by RPE65 mutations. This finding, along with the bilateral nature of the disease and intended use in treatment, prompted us to determine the safety of administration of AAV2-hRPE65v2 to the contralateral eye in patients enrolled in the phase 1 study. METHODS: In this follow-on phase 1 trial, one dose of AAV2-hRPE65v2 (1.5 × 10(11) vector genomes) in a total volume of 300 µL was subretinally injected into the contralateral, previously uninjected, eyes of 11 children and adults (aged 11-46 years at second administration) with inherited retinal dystrophy caused by RPE65 mutations, 1.71-4.58 years after the initial subretinal injection. We assessed safety, immune response, retinal and visual function, functional vision, and activation of the visual cortex from baseline until 3 year follow-up, with observations ongoing. This study is registered with ClinicalTrials.gov, number NCT01208389. FINDINGS: No adverse events related to the AAV were reported, and those related to the procedure were mostly mild (dellen formation in three patients and cataracts in two). One patient developed bacterial endophthalmitis and was excluded from analyses. We noted improvements in efficacy outcomes in most patients without significant immunogenicity. Compared with baseline, pooled analysis of ten participants showed improvements in mean mobility and full-field light sensitivity in the injected eye by day 30 that persisted to year 3 (mobility p=0.0003, white light full-field sensitivity p<0.0001), but no significant change was seen in the previously injected eyes over the same time period (mobility p=0.7398, white light full-field sensitivity p=0.6709). Changes in visual acuity from baseline to year 3 were not significant in pooled analysis in the second eyes or the previously injected eyes (p>0.49 for all time-points compared with baseline). INTERPRETATION: To our knowledge, AAV2-hRPE65v2 is the first successful gene therapy administered to the contralateral eye. The results highlight the use of several outcome measures and help to delineate the variables that contribute to maximal benefit from gene augmentation therapy in this disease. FUNDING: Center for Cellular and Molecular Therapeutics at The Children's Hospital of Philadelphia, Spark Therapeutics, US National Institutes of Health, Foundation Fighting Blindness, Institute for Translational Medicine and Therapeutics, Research to Prevent Blindness, Center for Advanced Retinal and Ocular Therapeutics, Mackall Foundation Trust, F M Kirby Foundation, and The Research Foundation-Flanders.

The Role of the Human Visual Cortex in Assessment of the Long-Term Durability of Retinal Gene Therapy in Follow-on RPE65 Clinical Trial Patients.

PURPOSE: Gene therapy (GT) has offered immense hope to individuals who are visually impaired because of RPE65 mutations. Although GT has shown great success in clinical trials enrolling these individuals, evidence for stability and durability of this treatment over time is still unknown. Herein we explored the value of functional magnetic resonance imaging (fMRI) as an objective measure to assess independently the longevity of retinal GT. DESIGN: Individuals with RPE65 mutations who underwent GT in their worse-seeing eye in a phase 1 clinical trial received a second subretinal injection in their contralateral eye in a follow-on clinical trial. Functional magnetic resonance imaging (MRI) was performed longitudinally to assess brain responses of patients with RPE65 mutations after stimulation of their most recently treated eye before and 1 to 3 years after GT. PARTICIPANTS: Seven participants with RPE65 mutations who were part of the follow-on clinical trial gave informed consent to participate in a longitudinal neuroimaging fMRI study. METHODS: All participants underwent fMRI using a 3-Tesla MRI system and a 32-channel head coil. Participants' cortical activations were assessed using a block design paradigm of contrast reversing checkerboard stimuli delivered using an MRI-compatible video system. MAIN OUTCOME MEASURES: The primary parameters being measured in this study were the qualitative and quantitative fMRI cortical activations produced by our population in response to the visual task. RESULTS: Functional MRI results showed minimal or no cortical responses before GT. Significant increase in cortical activation lasting at least 3 years after GT was observed for all participants. Repeated measures analysis showed significant associations between cortical activations and clinical measures such as full-field light sensitivity threshold for white, red, and blue colors; visual field; and pupillary light reflex. CONCLUSIONS: Participants with RPE65 mutations showed intact visual pathways, which became responsive and strengthened after treatment. Functional MRI results independently revealed the efficacy and durability of a 1-time subretinal injection. The fMRI results paralleled those recently reported during the long-term clinical evaluations of the same patients. Results from this study demonstrated that fMRI may play an important role in providing complementary information to patients' ophthalmic clinical evaluation and has usefulness as an outcome measure for future retinal intervention studies.

Natural History of the Central Structural Abnormalities in Choroideremia: A Prospective Cross-Sectional Study.

PURPOSE: To describe in detail the central retinal structure of a large group of patients with choroideremia (CHM). DESIGN: A prospective, cross-sectional, descriptive study. PARTICIPANTS: Patients (n = 97, age 6-71 years) with CHM and subjects with normal vision (n = 44; ages 10-50 years) were included. METHODS: Subjects were examined with spectral-domain optical coherence tomography (SD OCT) and near-infrared reflectance imaging. Visual acuity (VA) was measured during their encounter or obtained from recent ophthalmic examinations. Visual thresholds were measured in a subset of patients (n = 24) with automated static perimetry within the central regions (±15°) examined with SD OCT. MAIN OUTCOME MEASURES: Visual acuity and visual thresholds; total nuclear layer, inner nuclear layer (INL), and outer nuclear layer (ONL) thicknesses; and horizontal extent of the ONL and the photoreceptor outer segment (POS) interdigitation zone (IZ). RESULTS: Earliest abnormalities in regions with normally appearing retinal pigment epithelium (RPE) were the loss of the POS and ellipsoid zone associated with rod dysfunction. Transition zones (TZs) from relatively preserved retina to severe ONL thinning and inner retinal thickening moved centripetally with age. Most patients (88%) retained VAs better than 20/40 until their fifth decade of life. The VA decline coincided with migration of the TZ near the foveal center. There were outer retinal tubulations in degenerated, nonatrophic retina in the majority (69%) of patients. In general, RPE abnormalities paralleled photoreceptor degeneration, although there were regions with detectable but abnormally thin ONL co-localizing with severe RPE depigmentation and choroidal thinning. CONCLUSIONS: Abnormalities of the POS and rod dysfunction are the earliest central abnormalities observed in CHM. Foveal function is relatively preserved until the fifth decade of life. Migration of the TZs to the foveal center with foveal thinning and structural disorganization heralded central VA loss. The relationships established may help outline the eligibility criteria and outcome measures for clinical trials for CHM.

Evaluation of Ocular Gene Therapy in an Italian Patient Affected by Congenital Leber Amaurosis Type 2 Treated in Both Eyes.

Gene therapy clinical trials with gene augmentation therapy for Leber Congenital Amaurosis have shown partial reversal of retinal dysfunction. Most studies described the effect of treatment in a single eye and limited evidence is reported in literature about patients treated in both eyes. In this chapter, we present the findings of a young patient treated in both eyes. Efficacy of the treatment was assessed with Best Corrected Visual Acuity, Goldman Visual Field testing, Esterman computerized binocular visual field and Microperimetric testing. Post-treatment results showed improvement of visual function in both eyes, in particular, a strong amelioration was observed after the first injection, by using conventional monocular tests. Moreover, the treatment in the second eye resulted in a further improvement of binocular visual functionality, as easily detected by computerized binocular visual field. In conclusion, our data suggest that gene therapy can inhibit retinal degeneration and can be safe and effective in restoring visual functionality in young subjects treated in both eyes. Finally, new outcome measurements, in particular binocular computerized visual field parameters, can therefore be useful to quantify overall visual gain in patients undergoing gene therapy in both eyes.

Adeno-associated virus 8-mediated gene therapy for choroideremia: preclinical studies in in vitro and in vivo models.

BACKGROUND: Choroideremia (CHM) is a slowly progressive X-linked retinal degeneration that results in a loss of photoreceptors, retinal pigment epithelium and choroid. CHM, the gene implicated in choroideremia, encodes Rab escort protein-1 (REP-1), which is involved in the post-translational activation via prenylation of Rab proteins. METHODS: We evaluated AAV8.CBA.hCHM, a recombinant adeno-associated virus serotype 8 (rAAV8) vector, which targets retinal cells efficiently, for both therapeutic effect and safety in vitro and in vivo in a murine model. In vitro studies included western blot analyses and prenylation assays. In vivo studies included ophthalmoscopy, pupillometry, histology and immunofluorescence analysis. RESULTS: Infection with AAV8.CBA.hCHM induced the expression of REP-1 protein in a dose-responsive fashion. Transduction with AAV8.CBA.hCHM reverses the biochemical and pathogenetic defects in CHM both in vitro and in vivo and showed no safety concerns in the in vivo investigations performed in the present study. CONCLUSIONS: AAV8 is a promising vector for human clinical gene therapy trials for choroideremia.

Detailed phenotype and long-term follow-up of RAB28-associated cone-rod dystrophy.

PURPOSE: To gain an insight into the pathophysiology of RAB28-associated inherited retinal degeneration through detailed phenotyping and long-term longitudinal follow-up. METHODS: The patient underwent complete ophthalmic examinations. Visual function was assessed with microperimetry, full-field electroretinography (ffERG), imaging with optical coherence tomography (OCT), short-wave (SW), and near-infrared (NIR) fundus autofluorescence (FAF). RESULTS: A healthy Haitian woman with homozygous pathogenic variants (c.68C > T; p.Ser23Phe) in RAB28 presented at 16 years of age with a four-year history of blurred vision. Visual acuities were 20/125 in each eye, which remained relatively stable since. At age 27, cone ffERGs were non-detectable and borderline for rod-mediated responses. Kinetic fields were full to a V-4e target, undetectable to a small I-4e stimulus. Microperimetry showed an absolute central scotoma surrounded by a pericentral relative scotoma. SD-OCT showed an undetectable or barely detectable foveal and parafoveal photoreceptor outer nuclear layer (ONL), photoreceptor outer segment (POS), and retinal pigment epithelium (RPE) signals and loss of the SW- and NIR-FAF signals. This atrophic region was separated from a normally laminated retina by a narrow transition zone (TZ) of hyper SW- and NIR-FAF that co-localized with preserved ONL but abnormally thinned POS and RPE. There was minimal centrifugal (<100 µm) expansion over a six-year period. CONCLUSION: The cone-rod dystrophy phenotype documented herein supports a critical role of RAB28 for cone function and POS maintenance. Severe central photoreceptor and RPE loss with a predilection for POS loss in TZs suggests possible disruptions of complex mechanisms that maintain central cone photoreceptor and RPE homeostasis.

Three-year follow-up after unilateral subretinal delivery of adeno-associated virus in patients with Leber congenital Amaurosis type 2.

OBJECTIVE: The aim of this study was to show the clinical data of long-term (3-year) follow-up of 5 patients affected by Leber congenital amaurosis type 2 (LCA2) treated with a single unilateral injection of adeno-associated virus AAV2-hRPE65v2. DESIGN: Clinical trial. PARTICIPANTS: Five LCA2 patients with RPE65 gene mutations. METHODS: After informed consent and confirmation of trial eligibility criteria, the eye with worse visual function was selected for subretinal delivery of adeno-associated virus (AAV2-hRPE65v2). Subjects were evaluated before and after surgery at designated follow-up visits (1, 2, 3, 14, 30, 60, 90, 180, 270, and 365 days, 1.5 years, and 3 years) by complete ophthalmic examination. Efficacy for each subject was monitored with best-corrected visual acuity, kinetic visual field, nystagmus testing, and pupillary light reflex. MAIN OUTCOME MEASURES: Best-corrected visual acuity, kinetic visual field, nystagmus testing, and pupillary light reflex. RESULTS: The data showed a statistically significant improvement of best-corrected visual acuity between baseline and 3 years after treatment in the treated eye (P<0.001). In all patients, an enlargement of the area of visual field was observed that remained stable until 3 years after injection (average values: baseline, 1058 deg(2) vs. 3 years after treatment, 4630 deg(2)) and a reduction of the nystagmus frequency compared with baseline at the 3-year time point. Furthermore, a statistically significant difference was observed in the pupillary constriction of the treated eye (P<0.05) compared with the untreated eye in 3 patients at 1- and 3-year time points. No patients experienced serious adverse events related to the vector in the 3-year postinjection period. CONCLUSIONS: The long-term follow-up data (3 years) on the 5-patient Italian cohort involved in the LCA2 gene therapy clinical trial clearly showed a stability of improvement in visual and retinal function that had been achieved a few months after treatment. Longitudinal data analysis showed that the maximum improvement was achieved within 6 months after treatment, and the visual improvement was stable up to the last observed time point. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Lessons Learned from the Development of the First FDA-Approved Gene Therapy Drug, Voretigene Neparvovec-rzyl.

In the 5 years following U.S. Food and Drug Administration (FDA) approval of the first gene therapy reagent approved to treat a genetic disease, voretigene neparvovec-rzyl (Luxturna), retinal disease clinics, hospital pharmacies, operating rooms, and even health insurance entities around the world have incorporated gene therapy as a standard procedure. The success of Luxturna has helped pave the way to establish a template for developing other gene therapy reagents that promise to restore sight or halt the progression of photoreceptor cell loss in both inherited and acquired retinal diseases. Here we review lessons learned from development of a gene therapy drug for RPE65 disease and how these lessons may expedite the development of additional treatments for previously untreatable blinding conditions.

Vitreoretinal lymphoma presenting as frosted branch angiitis in a patient with diffuse large B-cell lymphoma.

Purpose: To describe the evaluation, diagnosis, and treatment of vitreoretinal lymphoma presenting as frosted branch angiitis in a patient with diffuse large B-cell lymphoma (DLBCL). Observations: A 57-year-old woman with a history of non-Hodgkin lymphoma and recent DLBCL relapse presented with frosted branch angiitis that raised suspicion for an infectious retinitis but was found to be vitreoretinal lymphoma. Conclusions and Importance: This case primarily highlights the importance of considering vitreoretinal lymphoma on the differential diagnosis of etiologies of frosted branch angiitis. Despite suspicion for vitreoretinal lymphoma, it is also important to treat empirically for infectious etiologies of retinitis in cases of frosted branch angiitis. In this case where the diagnosis was ultimately vitreoretinal lymphoma, weekly alternating intravitreal injections of methotrexate and rituximab led to improvement in visual acuity and retinal infiltration.

Motion-selective areas V5/MT and MST appear resistant to deterioration in choroideremia.

Choroideremia (CHM) is an X-linked recessive form of hereditary retinal degeneration, which preserves only small islands of central retinal tissue. Previously, we demonstrated the relationship between central vision and structure and population receptive fields (pRF) using functional magnetic resonance imaging (fMRI) in untreated CHM subjects. Here, we replicate and extend this work, providing a more in-depth analysis of the visual responses in a cohort of CHM subjects who participated in a retinal gene therapy clinical trial. fMRI was conducted in six CHM subjects and six age-matched healthy controls (HC's) while they viewed drifting contrast pattern stimuli monocularly. A single ∼3-minute fMRI run was collected for each eye. Participants also underwent ophthalmic evaluations of visual acuity and static automatic perimetry (SAP). Consistent with our previous report, a single âˆ¼ 3 min fMRI run accurately characterized ophthalmic evaluations of visual function in most CHM subjects. In-depth analyses of the cortical distribution of pRF responses revealed that the motion-selective regions V5/MT and MST appear resistant to progressive retinal degenerations in CHM subjects. This effect was restricted to V5/MT and MST and was not present in either primary visual cortex (V1), motion-selective V3A or regions within the ventral visual pathway. Motion-selective areas V5/MT and MST appear to be resistant to the continuous detrimental impact of CHM. Such resilience appears selective to these areas and may be mediated by independent retina-V5/MT anatomical connections that bypass V1. We did not observe any significant impact of gene therapy.

Optimization and Validation of a Virtual Reality Orientation and Mobility Test for Inherited Retinal Degenerations.

Purpose: To optimize a virtual reality (VR) orientation and mobility (O&M) test of functional vision in patients with inherited retinal degenerations (IRDs). Methods: We developed an O&M test using commercially available VR hardware and custom-generated software. Normally sighted subjects (n = 20, ages = 14-67 years) and patients with IRDs (n = 29, ages = 15-63 years) participated. Individuals followed a dim red arrow path to a "course exit," while trying to identify nine obstacles adjacent to, or directly in their path. Dark-adapted subjects completed 35 randomly selected VR courses at increasing luminances, twice per luminance step, binocularly, and uni-ocularly. Performance was graded automatically by the software. Patients with IRD completed a modified Visual Function Questionnaire (VFQ). Results: Normally sighted subjects identified approximately 50% of the obstacles at the dimmest course luminance. Except for two patients with IRD with poor vision, all patients were able to complete the test, although they required brighter (by >2 log units) luminances to identify 50% of the obstacles. In a single-luminance screening test in which normal subjects detected at least eight of nine objects, most patients with IRD underperformed; their performance related to disease severity, as measured by visual acuity, kinetic visual field extent, and VFQ scores. Test-retest differences in object detection were similar to the differences between the two eyes (±2 SD = ±2 objects). Conclusions: This VR-O&M test was able to distinguish subjects with IRDs from normal subjects reliably and reproducibly. Translational Relevance: This easily implemented, flexible, and objectively scored VR-O&M test promises to become a useful tool to assess the impact that IRDs and their treatments have on functional vision.

Proliferative retinopathy and retinal detachment in pediatric atypical hemolytic uremic syndrome.

We report the case of a 14-year-old boy with history of microangiopathic hemolytic crises secondary to atypical hemolytic uremic syndrome presenting with new-onset decreased vision, flashes, and floaters in his left eye. The patient had a history of chronic retinal detachment in the right eye and retinal neovascularization in the left eye treated with panretinal photocoagulation at age 5. He was now found to have a new combined tractional-rhegmatogenous retinal detachment in the left eye. Despite surgical reattachment of the retina, he had progressive retinal and optic nerve ischemia, with resultant left eye visual acuity of light perception. To our knowledge, this is the first reported case of proliferative retinopathy and tractional and rhegmatogenous retinal detachments in a pediatric patient with atypical hemolytic uremic syndrome.

Efficacy of Maribavir in Valganciclovir-Resistant Cytomegalovirus Retinitis.

PURPOSE: To determine whether maribavir is effective at treating ganciclovir-resistant cytomegalovirus retinitis. METHODS: Retrospective case report of a lung transplant patient with bilateral cytomegalovirus retinitis documented with serum and aqueous humor studies and color fundus photographs. RESULTS: A 72-year-old lung transplant patient with active ganciclovir-resistant cytomegalovirus was treated with intravitreal foscarnet therapy in one eye. Retinitis developed in the contralateral eye and was managed with systemic maribavir alone. Active retinitis regressed in both the eye treated with intravitreal foscarnet and the un-injected eye. CONCLUSIONS: This patient's results suggest that systemic maribavir is an effective treatment for treatment-resistant cytomegalovirus retinitis.