Inflammation after voretigene neparvovec administration in patients with RPE65-related retinal dystrophy

A morphometric analysis of the retinal arterioles with adaptive optics imaging in RPE65-associated retinal dystrophy after treatment with voretigene neparvovec

PURPOSE

To investigate the changes in retinal arterial architecture after treatment with voretigene neparvovec in patients with retinal dystrophy caused by bi-allelic mutations in the RPE65 gene.

METHODS

Sixteen eyes treated with voretigene neparvovec at the University Eye Clinic in Tuebingen, Germany, underwent adaptive optics ophthalmoscopy (AO) imaging at baseline and 2 weeks, 1, 3, 6 and 12 months after treatment. Follow-up was performed in six eyes of four patients. For each eye, five different positions at arterial vessels were selected and the wall-to-lumen ratio (WLR), the lumen diameter (LD) and the wall cross-sectional area (WCSA) were measured by the manufacturer's software over the observational period.

RESULTS

Vast retinal atrophy dominated all gained AO images. WLR fluctuated in the observation period without statistically significant change. LD and WCSA changed significantly after 2 weeks from the baseline examination and returned to values similar to baseline thereafter. There were no signs of inflammation such as macrophages or perivascular accumulated fluid visible.

CONCLUSION

AO imaging of the retinal vessels in RPE65-associated retinal dystrophies (IRD) is challenging. There was no change in the retinal arterial vasculature over the observation period of 12 months that would indicate inflammatory changes. Decrease of the LD and WCSA shortly after treatment might be caused by the perioperative prednisolone intake. AO of retinal vessels can be used as a diagnostic module to complement monitoring the disease and effects of genetic treatments if the acquisition is possible in selected cases.

Objective Outcomes to Evaluate Voretigene Neparvovec Treatment Effects in Clinical Practice

PURPOSE

To assess the efficacy of voretigene neparvovec (VN) treatment by objective fixation stability and chromatic pupillometry testing in clinical practice.

DESIGN

Retrospective cohort study with longitudinal follow-up.

SUBJECTS

Twelve patients (aged 7-34 years) with RPE65-related inherited retinal dystrophies were treated at the same center with VN in both eyes.

METHODS

Patients treated at the same center with VN were evaluated over a 12-month posttreatment follow-up by subjective and objective tests. Furthermore, patients treated with VN who developed atrophy were compared with those who did not.

MAIN OUTCOME MEASURES

Best-corrected visual acuity (BCVA), full-field stimulus threshold test (FST), semiautomated kinetic visual field (SKVF), microperimetry, and chromatic pupillometry over a 12-month follow-up.

RESULTS

Significant improvements of BCVA (P < 0.001), SKVF (P < 0.05), and FST (P < 0.001) were already observed 45 days after treatment and were maintained at the 12-month timepoint. Fixation stability, assessed by microperimetry, improved significantly (P < 0.05) after treatment. Chromatic pupillometry showed significant improvements (P < 0.05) at the 6- and 12-month timepoints. The increase in maximum pupillary constriction significantly (P < 0.001) correlated with higher retinal sensitivity in FST. Four patients developed multifocal retinal atrophy in both eyes, detected at the 6-month timepoint, but this atrophy was not generally associated with worse visual function outcomes.

CONCLUSIONS

This study explores objective outcomes in order to demonstrate the efficacy of VN treatment in addition to the tests normally performed in clinical practice. Our findings show a significant improvement of retinal function both in subjective assessments, such as BCVA, SKVF, and FST, and in objective measurements of fixation stability and maximum pupillary constriction. Moreover, the significant correlation between maximum pupillary constriction and light sensitivity thresholds corroborates the introduction of chromatic pupillometry as an objective test to better assess treatment outcomes in patients with inherited retinal dystrophies.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references in the Footnotes and Disclosures at the end of this article.

Toward low-cost gene therapy: mRNA-based therapeutics for treatment of inherited retinal diseases

Inherited retinal diseases (IRDs) stem from genetic mutations that result in vision impairment. Gene therapy shows promising therapeutic potential, exemplified by the encouraging initial results with voretigene neparvovec. Nevertheless, the associated costs impede widespread access, particularly in low-to-middle income countries. The primary challenge remains: how can we make these therapies globally affordable? Leveraging advancements in mRNA therapies might offer a more economically viable alternative. Furthermore, transitioning to nonviral delivery systems could provide a dual benefit of reduced costs and increased scalability. Relevant stakeholders must collaboratively devise and implement a research agenda to realize the potential of mRNA strategies in equitable access to treatments to prevent vision loss.

Chorioretinal Atrophy Growth After Voretigene Neparvovec Retinotopically Is Connected to Retinal Functional Rescue

Purpose

Chorioretinal atrophy growth after voretigene neparvovec has been reported recently with its positive correlation with successful treatment. This finding raised the question on long-term effects and the etiology of the chorioretinal atrophy.

Methods

Using local retinal functional diagnostics, we tested whether the atrophy growth is connected to the initial local functional improvement after the therapy.

Results

The results describe factors predicting the development of atrophy. First, the atrophy emerges after approximately 3 months in an area with local functional rescue before. The areas of the greatest gain in the number of functionally rescued rods are prone to be the initial spots of atrophy growth in almost one-half of the cases and the retinotopy corresponds with the area of a high number of post-treatment functioning rods. Second, the dark-adapted perimetry shows that the atrophy growth is in the area with functioning rescued rods. However, the rods with the greatest sensitivity gain are not the parts of the growing atrophy in the first 2 years after intervention. This preservation of rods with the greatest sensitivity seems to explain the excellent profile of rods rescue over the long term measured by full-field stimulus threshold and reported earlier.

Conclusions

A disbalance between the increase of functional rods and their threshold shortly after treatment could be an indicator for a metabolic origin of chorioretinal atrophy after voretigene neparvovec.

Translational Relevance

A basic understanding of the photoreceptor rescue aspects after gene therapy can demonstrate a metabolic causal influence of the efficacy on the development of side effects, such as chorioretinal atrophy.

Single Center Experience with Voretigene Neparvovec Gene Augmentation Therapy in RPE65 Mutation-Associated Inherited Retinal Degeneration in a Clinical Setting

PURPOSE

To assess the impact of baseline data on psychophysical and morphological outcomes of subretinal voretigene neparvovec (VN) (Luxturna, Spark Therapeutics, Inc.) treatment.

DESIGN

Single-center, retrospective, longitudinal, consecutive case series.

PARTICIPANTS

Patients with RPE65-biallelic mutation-associated inherited retinal degeneration (RPE65-IRD) treated between February 2020 and March 2022 with VN and oral immunosuppression according to the manufacturer's recommendation by one surgeon (F.G.H.).

METHODS

Retrospective analysis of surgical and clinical records, ancillary testing, and retinal imaging after VN therapy for RPE65-IRD. Descriptive statistics compared data at baseline up to 32 months post-treatment.

MAIN OUTCOME MEASURES

Best-corrected visual acuity (BCVA), low-luminance VA (LLVA), Goldmann visual fields (GVFs), chromatic full-field stimulus threshold (FST) testing (FST), scotopic and photopic 2-color threshold perimetry (2CTP), and multimodal retinal imaging.

RESULTS

Thirty eyes of 19 patients were analyzed (10 pediatric patients < 20 years; 20 adult patients > 20 years of age; overall range: 8-40 years) with a median follow-up of 15 months (range, 1-32). The fovea was completely or partially detached in 16 eyes, attached in 12 eyes, and not assessable in 2 eyes on intraoperative imaging. Median BCVA at baseline was better in the pediatric group (P < 0.05) and did not change significantly independent of age. Meaningful loss of BCVA (≥ 0.3 logarithm of the minimal angle of resolution [logMAR]) occurred in 5 of 18 adult eyes, and a meaningful gain (≥-0.3 logMAR) occurred in 2 of 18 adult and 2 of 8 pediatric eyes. The LLVA and scotopic 2CTP improved considerably in pediatric patients. Scotopic blue FST improved at all ages but more in pediatric patients (8/8 eyes gained ≥ 10 decibels [dB]; P < 0.05). In pediatric patients, median GVF improved by 20% for target V4e and by 50% for target III4e (target I4e not detected). Novel atrophy developed in 13 of 26 eyes at the site of the bleb or peripheral of vascular arcades. Improvements in FST did not correlate with development of chorioretinal atrophy at 12 months. Mean central retinal thickness was 165.87 μm (± 26.26) at baseline (30 eyes) and 157.69 μm (± 30.3) at 12 months (26 eyes). Eight adult patients were treated unilaterally. The untreated eyes did not show meaningful changes during follow-up.

CONCLUSIONS

These data in a clinical setting show the effectiveness of VN therapy with stable median BCVA and mean retinal thickness and improvements of LLVA, FST, and 2CTP up to 32 months. Treatment effects were superior in the pediatric group. We observed new chorioretinal atrophy in 50% of the treated eyes.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Real-World Safety and Effectiveness of Voretigene Neparvovec: Results up to 2 Years from the Prospective, Registry-Based PERCEIVE Study

Voretigene neparvovec (VN) is the first available gene therapy for patients with biallelic RPE65-mediated inherited retinal dystrophy who have sufficient viable retinal cells. PERCEIVE is an ongoing, post-authorization, prospective, multicenter, registry-based observational study and is the largest study assessing the real-world, long-term safety and effectiveness of VN. Here, we present the outcomes of 103 patients treated with VN according to local prescribing information. The mean (SD) age was 19.5 (10.85) years, 52 (50.5%) were female, and the mean (SD) duration of the follow up was 0.8 (0.64) years (maximum: 2.3 years). Thirty-five patients (34%) experienced ocular treatment-emergent adverse events (TEAEs), most frequently related to chorioretinal atrophy (n = 13 [12.6%]). Eighteen patients (17.5%; 24 eyes [13.1%]) experienced ocular TEAEs of special interest, including intraocular inflammation and/or infection related to the procedure (n = 7). The mean (SD) changes from baseline in full-field light-sensitivity threshold testing (white light) at month 1, month 6, year 1, and year 2 were -16.59 (13.48) dB (51 eyes), -18.24 (14.62) dB (42 eyes), -15.84 (14.10) dB (10 eyes), and -13.67 (22.62) dB (13 eyes), respectively. The change in visual acuity from baseline was not clinically significant. Overall, the outcomes of the PERCEIVE study are consistent with the findings of VN pivotal clinical trials.

Gene therapy for RAB28: What can we learn from zebrafish?

The eye is particularly suited to gene therapy due to its accessibility, immunoprivileged state and compartmentalised structure. Indeed, many clinical trials are underway for therapeutic gene strategies for inherited retinal degenerations (IRDs). However, as there are currently 281 genes associated with IRD, there is still a large unmet need for effective therapies for the majority of IRD-causing genes. In humans, RAB28 null and hypomorphic alleles cause autosomal recessive cone-rod dystrophy (arCORD). Previous work demonstrated that restoring wild type zebrafish Rab28 via germline transgenesis, specifically in cone photoreceptors, is sufficient to rescue the defects in outer segment phagocytosis (OSP) observed in zebrafish rab28-/- knockouts (KO). This rescue suggests that gene therapy for RAB28-associated CORD may be successful by RAB28 gene restoration to cones. It also inspired us to critically consider the scenarios in which zebrafish can provide informative preclinical data for development of gene therapies. Thus, this review focuses on RAB28 biology and disease, and delves into both the opportunities and limitations of using zebrafish as a model for both gene therapy development and as a diagnostic tool for patient variants of unknown significance (VUS).

Bilateral Hypopyon in a Young Woman

A 28-year-old woman presented to the emergency department with a 5-day history of bilateral blurry vision, eye redness, discharge, photophobia, and pain. There were more than 20 cells per high-power field of 1 mm × 1 mm beam, with fibrin bilaterally and 2.5-mm hypopyon in the right eye and 2.7-mm hypopyon in the left eye. What would you do next?

Full-field scotopic threshold improvement following voretigene neparvovec-rzyl treatment correlates with chorioretinal atrophy

PURPOSE

To analyze demographic and ophthalmologic data in patients with and without chorioretinal atrophy after voretigene neparvovec-rzyl (VN) in order to identify possible causes for this phenomenon.

DESIGN

Retrospective cohort study with longitudinal follow-up.

SUBJECTS

71 eyes of 38 patients aged 2 to 44 years with RPE65-mediated retinal dystrophy treated with VN across two large gene therapy centers in the USA and Germany.

METHODS

VN-treated patients who developed atrophy were compared to those who did not.

MAIN OUTCOME MEASURES

Gender, age, surgical center, spherical equivalent refraction, BCVA, baseline FST, and post-treatment change in full-field scotopic threshold testing (FST).

RESULTS

20 eyes of 12 patients developed atrophy following treatment with VN (28% of all eyes). There was no significant difference in gender, age, surgical center, or spherical equivalent refraction between the Atrophy group and the No Atrophy group. However, patients between school age and young adulthood were predominantly affected, whereas the youngest and the oldest patients did not develop atrophy. Baseline BCVA was better in patients who developed atrophy than those who did not (P=0.006). The postoperative improvement in FST at 1 month was significantly higher in the Atrophy than the No Atrophy group (P=0.0005), and this difference remained statistically significant at 1 year (P=0.0001). There was no correlation to baseline FST, to inflammation, or to which eye was treated first.

CONCLUSIONS

The degree of FST improvement following VN appears to be strongly correlated with the development of VN-related chorioretinal atrophy. This finding raises the possibility that atrophy may develop as a toxic or metabolic sequela of vector-mediated RPE65 expression. In light of the expanding number of retinal gene therapy clinical trials, this complication warrants further study as it may not be limited to VN.

Intravitreal gene therapy preserves retinal function in a canine model of CLN2 neuronal ceroid lipofuscinosis

CLN2 neuronal ceroid lipofuscinosis is a rare hereditary neurodegenerative disorder characterized by deleterious sequence variants in TPP1 that result in reduced or abolished function of the lysosomal enzyme tripeptidyl peptidase 1 (TPP1). Children with this disorder experience progressive neurological decline and vision loss starting around 2-4 years of age. Ocular disease is characterized by progressive retinal degeneration and impaired retinal function culminating in total loss of vision. Similar retinal pathology occurs in a canine model of CLN2 disease with a null variant in TPP1. A study using the dog model was performed to evaluate the efficacy of ocular gene therapy to provide a continuous, long-term source of human TPP1 (hTPP1) to the retina, inhibit retinal degeneration and preserve retinal function. TPP1-/- dogs received an intravitreal injection of 1 x 1012 viral genomes of AAV2.CAG.hTPP1 in one eye and AAV2.CAG.GFP in the contralateral eye at 4 months of age. Ophthalmic exams, in vivo ocular imaging and electroretinography were repeated monthly to assess retinal structure and function. Retinal morphology, hTPP1 and GFP expression in the retina, optic nerve and lateral geniculate nucleus, and hTPP1 concentrations in the vitreous were evaluated after the dogs were euthanized at end stage neurological disease at approximately 10 months of age. Intravitreal administration of AAV2.CAG.hTPP1 resulted in stable, widespread expression of hTPP1 throughout the inner retina, prevented disease-related declines in retinal function and inhibited disease-related cell loss and storage body accumulation in the retina for at least 6 months. Uveitis occurred in eyes treated with the hTPP1 vector, but this did not prevent therapeutic efficacy. The severity of the uveitis was ameliorated with anti-inflammatory treatments. These results indicate that a single intravitreal injection of AAV2.CAG.hTPP1 is an effective treatment to inhibit ocular disease progression in canine CLN2 disease.