Retinal Pigment Epithelium-specific 65kDa Research Articles

Surgical Observations From the First 120 Cases of Subretinal Gene Therapy for Inherited Retinal Diseases.

To report surgical observations formulated during the first 120 cases of subretinal gene therapy in patients with inherited retinal degenerations (IRDs). A two-surgeon team compiled surgical observations and formulated surgical pearls based on the consecutive cases of subretinal viral vector injection in patients enrolled in clinical trials focusing on choroideremia, achromatopsia, and RP GTPase regulator associated retinitis pigmentosa, as well as patients with retinal pigment epithelium-specific-65-kDa (RPE65) associated Leber congenital amaurosis receiving Food and Drug Administration-approved voretigene neparvovec-rzyl therapy. One hundred twenty subretinal surgeries were performed by a two-surgeon team. Key anatomical features pertinent to surgical management were noted and are described in this article. Surgical decision making for successful subretinal administration of viral vectors and management of potential surgical challenges were formulated. Lessons learned during subretinal gene therapy cases may be helpful to other surgeons entering clinical trials or performing postapproval gene therapy administration. Surgical pearls outlined in this article may also be helpful for other targeted subretinal therapies, such as cellular transplantation or retinal prosthesis implantation.

Voretigene Neparvovec: A Review in RPE65 Mutation-Associated Inherited Retinal Dystrophy.

Voretigene neparvovec (Luxturna®), a recombinant adeno-associated virus vector-based gene therapy, delivers a functioning copy of the human retinal pigment epithelium-specific 65kDa (RPE65) gene into retinal cells of patients with reduced or absent levels of RPE65 protein, providing the potential to restore the visual cycle. A single-dose subretinal injection of voretigene neparvovec administered in each eye is approved in several countries worldwide for the treatment of vision loss in adult and paediatric patients with confirmed biallelic RPE65 mutation-associated inherited retinal dystrophy (IRD) and with sufficient viable retinal cells. In the pivotal phase III trial, significant improvements from baseline were seen in the mean bilateral multi-luminance mobility test scores in the voretigene neparvovec group compared with the control group at 1year. The beneficial effects of voretigene neparvovec treatment were maintained after up to 4years of follow-up (with follow-up continuing for 15years). Control recipients were eligible to receive voretigene neparvovec at 1year, and showed improvements at subsequent follow-ups (≤ 3years post injection) consistent with those in patients who received voretigene neparvovec at baseline. Most adverse reactions in voretigene neparvovec recipients were transient, asymptomatic and non-serious, and resolved without sequelae (may have been related to voretigene neparvovec, the subretinal injection procedure, concomitant corticosteroid use or a combination thereof). Retinal detachment occurred in one patient at year 4. Although ongoing additional long-term efficacy and safety data are required, voretigene neparvovec is an important novel gene therapy for patients with RPE65 mutation-associated IRD and sufficient viable retinal cells.

Impacts of deletion and ichthyosis prematurity syndrome-associated mutations in fatty acid transport protein 4 on the function of RPE65.

The retinal pigment epithelium-specific 65kDa (RPE65) isomerase plays a pivotal role in photoreceptor survival and function. RPE65-catalyzed synthesis of 11-cis-retinol from all-trans-retinyl esters in the visual cycle is negatively regulated, through a heretofore unknown mechanism, by the fatty acid transport protein FATP4, mutations in which are associated with ichthyosis prematurity syndrome (IPS). Here, we analyzed the interaction between deletion mutants of FATP4 and RPE65 and the impacts of IPS-associated FATP4 mutations on RPE65 expression, 11-cis-retinol synthesis, and all-trans-retinyl ester synthesis. Our results suggest that the interaction between FATP4 and RPE65 contributes to the inhibition of RPE65 function and that IPS-associated nonsense and missense mutations in FATP4 have different effects on the visual cycle.

Treatment of Leber Congenital Amaurosis Due toRPE65Mutations by Ocular Subretinal Injection of Adeno-Associated Virus Gene Vector: Short-Term Results of a Phase I Trial

Leber congenital amaurosis (LCA) is a group of autosomal recessive blinding retinal diseases that are incurable. One molecular form is caused by mutations in the RPE65 (retinal pigment epithelium-specific 65-kDa) gene. A recombinant adeno-associated virus serotype 2 (rAAV2) vector, altered to carry the human RPE65 gene (rAAV2-CBSB-hRPE65), restored vision in animal models with RPE65 deficiency. A clinical trial was designed to assess the safety of rAAV2-CBSB-hRPE65 in subjects with RPE65-LCA. Three young adults (ages 21-24 years) with RPE65-LCA received a uniocular subretinal injection of 5.96 x 10(10) vector genomes in 150 microl and were studied with follow-up examinations for 90 days. Ocular safety, the primary outcome, was assessed by clinical eye examination. Visual function was measured by visual acuity and dark-adapted full-field sensitivity testing (FST); central retinal structure was monitored by optical coherence tomography (OCT). Neither vector-related serious adverse events nor systemic toxicities were detected. Visual acuity was not significantly different from baseline; one patient showed retinal thinning at the fovea by OCT. All patients self-reported increased visual sensitivity in the study eye compared with their control eye, especially noticeable under reduced ambient light conditions. The dark-adapted FST results were compared between baseline and 30-90 days after treatment. For study eyes, sensitivity increases from mean baseline were highly significant (p < 0.001); whereas, for control eyes, sensitivity changes were not significant (p = 0.99). Comparisons are drawn between the present work and two other studies of ocular gene therapy for RPE65-LCA that were carried out contemporaneously and reported.