Funded Grants FY24

DAVID BRINT TRANSLATIONAL RESEARCH AWARDS

Ben Yerxa, PhD - $1,050,165
Opus Genetics

“IND-Enabling Study to Assess the Tolerability and Efficacy of a Mutation-Independent Rhodopsin Knockdown and Replacement Gene therapy in a Canine Model of RHO-adRP”

Opus Genetics has developed OPGx-RHO, a novel gene therapy to address the challenges with speficic mutations in the rhodopsin (RHO) gene associated with autosomal dominant RP (adRP). This genetic therapy employs a mutation-independent strategy, involving knocking down both mutated and wild-type alleles (copies) of the RHO gene and replacing them with healthy copies.

In collaboration with William Beltran from the University of Pennsylvania School of Veterinary Medicine, Opus Genetics will assess OPGx-RHO's effectiveness and safety in an adRP canine model. This study will involve therapeutic subretinal injections at various doses with untreated eyes serving as controls. Opus will use outcomes like retinal thickness and function using advanced imaging techniques and assess overall health through clinical observations and pathology. The study will last six months, aligning with FDA recommendations, and will provide crucial data for advancing OPGx-RHO towards a clinical trial.

Vadim Arshavsky, PhD - $900,000
Duke University

"Gene-Agnostic Therapy for Retinal Degenerations"

Supported by the Diana Davis Spencer Foundation

The goal of this research effort is to reduce large amounts of harmful misfolded or mistargeted proteins (proteasomal overload) formed because of disease-causing mutations in retinal diseases. To mitigate proteasomal overload, the team will evaluate enhanced protein degradation as a therapeutic neuroprotectant. Specifically, the researchers will overexpress the 11S proteasome subunits in mutant photoreceptors via AAV to lower the proteasomal overload. 

Dr. Arshavsky’s team will: 1) compare AAV constructs encoding 11S proteasome caps subunits to select the best candidate for further development; 2) assess long-term efficacy of the treatment in rhodopsin (RHO) P23H knock-in mice with the optimized 11S-AAV; 3) and identify candidate IRD mutations whose consequences could be addressed using this therapy. Results of this study will be particularly valuable for selecting participants for future clinical trials.

Denise Montell, PhD - $900,000
University of California, Santa Barbara

"Development of a New Gene Therapy for Autosomal Dominant Retinitis Pigmentosa"

Dr. Montell and her team aim to develop a novel therapy to enhance the clearance of misfolded proteins found in retinal disease due to disease-causing genetic variants such as RHO-P23H. Treatments that promote degradation of misfolded proteins and alleviate cellular stress are emerging as a promising approach to preventing the progression of RHO-associated autosomal dominant retinitis pigmentosa (adRP). 

The researchers will develop a novel gene therapy to overexpress ZIP7 (Zinc transporter SLC39A7) to promote degradation of misfolded RHO, thereby slowing retinal degeneration. Previous research suggests ZIP7 can promote misfolded protein degradation as well as other beneficial biological activities. The team will test: 1) ZIP7 overexpression for its ability to relieve cellular stress and prevent photoreceptor cell death in a human retinal organoid model of adRP; 2) ZIP7 overexpression for suppression of RHO-P23H in a mouse model of adRP; 3) ZIP7 overexpression against multiple RHO mutations in flies, mammalian cells, and transgenic mice.

Ashley Winslow, PhD - $1,500,000
Odylia Therapeutics

"AAV-Anc80 Gene Therapy Platform to Treat Vision Loss Caused by RPGRIP1 Mutations"

Odylia Therapeutics is developing a gene therapy for Leber congenital amaurosis (LCA6) resulting from RPGRIP1 mutations. The therapy employs the Anc80 AAV capsid (viral container) to deliver a functional RPGRIP1 gene to photoreceptors. RPGRIP1 is responsible for producing a protein needed for proper vision. Previous research shows that Anc80 is more efficient and safer than AAV8 and AAV9 in both small and large animal eyes. 

The grant will also support AAV vector production for toxicology studies, assessment of vector biodistribution and transgene expression in a large animal, and evaluation of vector safety in a 90-day toxicology study. Three doses will be evaluated to determine a dosing strategy for a future clinical trial.

David Corey, PhD - $1,206,669
Harvard Medical School

"Development of Mini-Gene Therapy for Usher Syndrome Type 1F Blindness"

Dr. Corey and his team are developing a mini-gene genetic therapy for Usher 1F syndrome caused by genetic variants in the PCDH15 gene. A challenge in delivering a PCDH15 genetic therapy is that the gene is too big to fit into standard viral vectors like AAV. To address this challenge, the team created smaller versions of PCDH15 gene that still make a functional protein, but which can fit into an AAV vector. Through previous screens, the researchers identified one mini-PCDH15 that works well in the inner ear and improves hearing an Usher 1F mouse model. The team will evaluate mini-PCDH15 gene therapies in zebrafish, mice, and human retinal organoids and explants.

Yvan Arsenijevic, PhD - $900,000
Fondation Asile des aveugles, University of Lausanne (Switzerland)

"Gene Augmentation Therapy for FAM161A-Associated Retinal degeneration: IND-Enabling Studies Toward a Phase 1/2a Clinical Trial"

The team will perform Investigational New Drug (IND)-enabling studies in preparation for launch of a regulatory toxicology study in large animals followed by a Phase 1/2a clinical trial for people with RP caused by mutations in FAM161A. The researchers previously identified FAM161A genetic variants that lead to the development of retinitis pigmentosa-28 (RP28). Aberrant FAM161A protein leads to abnormal formation of the photoreceptor connecting cilium, degeneration of photoreceptors, and progressive loss of vision. Their activities will include: selection of a lead vector, identification of an optimal gene therapy dose, and evaluation of the vector in human retinal organoids.

Yuanyuan Chen, PhD - $900,000
University of Pittsburgh

"Nuclear Speckle Rejuvenation to Treat Retinitis Pigmentosa"

Dr. Chen and her team are developing a pharmacotherapy — pyrvinium pamoate (PP]) — to improve photoreceptor protein regulation for the treatment of RP. They believe the drug can induce nuclear speckle rejuvenation to slow degeneration. Speckles are subnuclear structures that contain pre-messenger RNA splicing factors and other proteins that are involved in RNA transcription. (RNA are the genetic messages that cells read to make proteins.)

The group hypothesize that invigorating nuclear speckle dynamics could amplify the entire protein balance pathway, potentially reversing aberrant protein-related neurodegeneration in RP. The approach has the potential to rescue rod cells by identifying an upstream regulator of cellular proteins. The approach may be effective for multiple RP-causing gene mutations. The researchers will determine the efficacy and safety of PP and/or its analogues in ameliorating RP in a mouse model (RHO-P23H).

Shigemi Matsuyama, PhD - $1,500,000
Case Western Reserve University

"Prevention of Blindness Using an Oral Cell Death Inhibitor"

This research team previously developed an oral bioactive cell death inhibitor (M109S) that protected photoreceptors from death in four different mouse models of IRDs. They believe it can serve as the basis of an oral medicine to prevent or delay blindness in RP patients regardless of the underlying gene mutation.  

M109S is a novel inhibitor of the Bax protein, an evolutionary conserved cell death-inducing protein that is ubiquitously expressed in human cells. Pharmacological inhibition of Bax has therapeutic potential to prevent retinal cell death in RP patients. The researchers will select a drug candidate from the M109S series of small compounds (M109S and its backup compounds), followed by optimizing a formulation for lead candidate development. This group also wants to develop the lead candidate into an eye drop formulation. Both oral and eye drop formulations will be evaluated in an RP mouse model.

PRPH2 AND ASSOCIATED RETINAL DISEASES (PARD) SCIENCE AWARD

Sheldon Rowan, PhD and Debasish Sinha, PhD - $599,972
Tufts University, Nutrition and Vision Laboratory
Johns Hopkins School of Medicine

"Diet, Microbiome, and Genetic Therapies to Target Drusenogenic Pathways in an Atrophic AMD Model"

The hallmark of all forms of age-related macular degeneration (AMD) is the accumulation of drusen deposits in a critical, supportive layer of cells called the retinal pigment epithelium (RPE). Drusen can be destructive, causing degeneration of the RPE and subsequently photoreceptors, the cells that make vision possible.

Drusen contain various debris and substances, mainly lipids. In early stages of AMD, the RPE produces too many lipids and struggles to properly break them down in a process called lipophagy.

Drs. Rowan and Sinha’s project aims to understand how lipophagy can be enhanced and whether doing so can prevent the formation of drusen deposits and slow AMD progression. Their teams will use genetic, gene-therapy, and dietary tools to activate lipophagy in their AMD mouse model.

The team will also test an FDA-approved drug, acarbose, that has been identified as a potential anti-AMD and pro-lipophagy compound.  Acarbose works in the small intestine to slow starch breakdown.  In doing so, it dramatically alters the gut microbiome to encourage growth of bacteria that are associated with improved metabolic and eye health. Acarbose also lowers blood glucose and prevents lipid synthesis pathways, analogous to a low glycemic index diet.

INDIVIDUAL INVESTIGATOR RESEARCH AWARD

David M. Gamm, MD, Ph.D. - $300,000
University of Wisconsin-Madison

"Elucidating the Human MYO7A Interactome to Improve Understanding of Usher Syndrome Type 1B and Develop Potency Assays"

Supported by Save Sight Now

Dr. Gamm’s goal is to better understand the underlying molecular cause(s) of Usher syndrome type 1B (USH1B) and to develop an FDA-acceptable potency assay (test) that will assist therapeutic development and evaluation.

Genetic variations in the MYO7A gene cause USH1B. The majority of USH1B therapies in development focus on restoring MYO7A function in photoreceptor (PR) cells; therefore, an in-depth understanding of MYO7A’s role in PR structure and function is important for therapeutic development. The study will involve three specific aims: 1) confirm the location of the MYO7A protein in human retinal organoid-derived PRs; 2) determine what other proteins interact with the MYO7A protein in human retinal organoid-derived PRs; and 3) develop a versatile, robust, and reproducible potency/release MYO7A Proximity Ligation Assay (PLA) for quality control testing of gene, genome, and RNA-based therapeutics.

Brian A. Link, PhD - $300,000
Medical College of Wisconsin

"Investigating Cell-Type Specific MYO7A Functions and Protein Interactions Using Zebrafish"

Supported by Save Sight Now

Dr. Link and his team will uncover the vital roles of MYO7A in various retinal cell types to better understand Usher syndrome type 1B (USH1B). This research team has developed a pioneering zebrafish model that mirrors the retinal degeneration seen in USH1B patients. This model enables the study of the functions of MYO7A in maintaining healthy photoreceptors and exploration of potential therapeutic approaches. The specific aims of this project are to determine which retinal cells rely on MYO7A to maintain photoreceptor health and identify specific interactions between MYO7A and other proteins within different cell types. Results will provide crucial insights into MYO7A's role in retinal health, potentially guiding the development of therapies for USH1B.

Qin Liu, MD, PhD - $300,000
Mass Eye and Ear

"Development of Precise Correction of the c.2299delG Mutation in the USH2A Gene"

Dr. Liu and her team will investigate the potential of a novel gene-editing system (prime editing) to correct the c.2299delG mutation in the USH2A gene that impacts 3–6 in 100,000 people globally. Traditional gene therapy is difficult due to the large size of the USH2A gene and the limitations of delivery systems (viruses). Prime editing offers a precise method to correct single gene mutations.

This research effort will focus on the feasibility of delivering prime editing components via an adeno-associated virus (AAV) to repair this mutation in a humanized mouse model of USH2A disease. The specific aims are to identify and optimize prime editing components to efficiently correct the c.2299delG mutation in cells and evaluate the efficacy of these prime editors in a mutant USH2A humanized mouse model through AAV-mediated delivery. If successful, the gene correction will halt or slow the degenerative processes in photoreceptor and inner-ear hair cells in the humanized mouse model. The findings could significantly impact the development of precision therapies for USH2A and offer new hope to thousands of patients worldwide.

Jillian N. Pearring, Ph.D. - $300,000
University of Michigan

"Investigate Whether Sequestering Overly Active Arl3-GTP can Rescue Photoreceptor Defects in a Mouse Model of RP2"

This lab discovered that dominant mutations in the ARL3 gene lead to a developmental defect in photoreceptors. Adenosine diphosphate Ribosylation Factor-Like 3 (Arl3)- Guanosine triphosphate (GTP) is involved in several biological processes, most notably cilium assembly which is critical for photoreceptors’ structure and function. However, mutations that lead to overactive Arl3-GTP can cause retinal degeneration.

This project aims to determine whether gene therapies sequestering overactive Arl3-GTP can restore photoreceptor function (i.e., nuclear migration) as well as determine the therapeutic window of treatment to restore visual function in an inherited retinal disease mouse model (RP2null) which exhibits overactive Arl3-GTP. This research will provide insights on a shared photoreceptor pathology caused by mutations in either ARL3 or RP2 genes linked to autosomal dominant and X-linked retinitis pigmentosa, respectively. Completing these aims will provide insights into the impact of photoreceptor nuclear mislocalization on retinal health, advance knowledge of RP2 and ARL3 mutation pathobiology, and identify potential therapeutic targets for inherited blindness.

Janet Sparrow, Ph.D. - $300,000
Columbia University

"Vitamins E, C and Zinc: Therapeutics for ABCA4-disease (STGD1)"

Dr. Sparrow and her team will conduct preclinical (mouse) studies to test the effectiveness of the AREDS2 antioxidant formula to treat ABCA4-associated disease (Stargardt disease or STGD1). The AREDS2 supplement formula is frequently prescribed for people with age-related macular degeneration. The project explores the potential for repurposing safe and effective supplements, which could proceed quickly to clinical trials, be administered at any disease stage, and complement other therapies like gene or cell therapy. The anticipated outcomes include demonstrating the protective effect of the AREDS2 formula on photoreceptor cell loss, reducing toxic protein accumulation, and attenuating the production of toxic compounds.

CLINICAL INNOVATION AWARDS

Alessia Amato, MD - $291,940
IRCCS Ospedale Pediatrico Bambino Gesù (Rome, Italy)

"Full-field Two-Color Dark-Adapted Perimetry as a Clinical Trial Endpoint"

This project addresses the need for rod-specific endpoints for conducting evaluations and studies of disease progression and therapy efficacy in people with retinitis pigmentosa and related conditions. The investigators will use 2-color dark-adapted perimetry (2cDAP), a test that utilizes red and blue stimuli to evaluate the function of rods and cones.

A widely available testing device (Octopus 900), yet to be validated for clinical application, will be used. Historically, the use of 2cDAP has been limited by the need for modified equipment, hindering reproducibility across study sites. A major

breakthrough came with the recent introduction of red and blue stimulus tests on the Octopus 900, a perimeter available at virtually every inherited retinal disease clinical center. 2cDAP on the Octopus 900 offers a promising approach for measuring rod function in a standardized way, but validation of this method in a large cohort of patients is a critical step before regulatory agencies can accept it as an outcome measure.

Artur Cideciyan, PhD - $300,000
University of Pennsylvania

"Multi-Luminance Chromatic Visual Acuity (MLCVA) as a Clinical Trial Endpoint"

Visual acuity (VA) is widely known to be an insensitive measure of changes in vision for people with a variety of retinal degenerative diseases including retinitis pigmentosa and dry age-related macular degeneration. The high light levels and high contrast used in ETDRS charts (a commonly used eye chart for measuring VA) create a ceiling effect.

To improve the relationship between VA and functional deficits perceived by patients, low-luminance VA (LLVA) was developed more than a decade ago. LLVA can solve the ceiling effect in some cases but not in general and not with the protocol often used. As a result, LLVA remains uninformative for evaluating the functional vision provided by different photoreceptor populations (e.g., diseased, treated).

Dr. Cideciyan and his team will completely re-evaluate the photoreceptor origins of VA measurements in a wide range of inherited retinal disease and disease stages, as well as in intermediate dry AMD. They will develop a multi-luminance chromatic visual acuity (MLCVA) protocol that can be used in the clinic with a combination of commercially available equipment and publicly available tools.

Yi-Zhong Wang, PhD - $300,000
Retina Foundation of the Southwest

"Deep-Learning Assisted Measurements of Retinal Layer Metrics as Biomarkers for Progression in Retinitis Pigmentosa"

Previously, the investigators developed deep learning models for automatic, accurate, and time-cost effective identification of outer retinal layers. They also developed models for the measurements of photoreceptor outer segment metrics using optical coherence tomography (OCT) in people with retinitis pigmentosa (RP). (Outer segments are the light-sensing extensions of photoreceptors.) The outer segments can serve as precise and sensitive biomarkers for disease progression and visual function. The limitation of the team’s previous work was that OCT measurements came from a single site and a limited sample size.

In the new study, the investigators will expand the datasets and machine learning by employing federated learning, gathering data from multiple sites. Next, they will conduct both cross-sectional and longitudinal studies on the relationship between visual field sensitivity and retinal layer (e.g., outer segment) metrics from 50 patients with RP. They will then develop a new, more robust deep learning model to predict visual field sensitivity from OCT scans and other types of retinal images. The models will be valuable for reducing the variability of outcome measures in inherited retinal disease clinical trials, thereby reducing the number of patients needed, and duration of trials required, to determine a therapeutic effect.

ENHANCED CAREER DEVELOPMENT AWARD

Ajoy Vincent, MBBS, MS, FRCSC - $509,924
Hospital for Sick Children‚ Toronto     

"A Transgenic Mouse Model for an Orphan Hereditary Macular Dystrophy"  

Dr. Vincent is leveraging a gene discovery that resulted in the creation of a new IRD mouse model from an earlier Foundation award. His group discovered a genetic variant in ALOX15, a gene that breaks down fatty acids including docosahexaenoic acid (DHA).  DHA is an important component of photoreceptor disc membranes and function. Also, lipid metabolism is important in retinal function. Dr. Vincent also identified a family affected by hereditary macular dystrophy caused by mutations in ALOX15.

The mouse model is expected to show a reduction in protective omega-3 fatty acids and buildup of toxic byproducts. He will follow disease progression in the model to understand mechanisms of retinal degeneration. Also, Dr. Vincent will evaluate a treatment approach using different dietary supplements to improve retinal health and prevent or slow disease progression. This work will be an important proof-of-principle that will pave the way for the next steps towards developing a therapy for people with hereditary macular dystrophy.

CAREER DEVELOPMENT AWARDS

Jason Miller MD, PhD - $375,000
Kellogg Eye Center, University of Michigan

"Regulation and Role of RPE Beta-Oxidation in AMD-Relevant Pathology"

Dr. Miller will explore the role of retinal pigment epithelium (RPE), a single layer of cells that supports photoreceptors, and its ability to degrade the toxic fatty deposits known as drusen. Drusen accumulation outside the RPE leads to RPE death, as well as photoreceptor death, and causes central vision loss in advanced dry AMD. Dr. Miller will use a genetically engineered mouse model and dish-grown RPE cells to determine whether the RPE’s ability to degrade fat is important in preventing drusen buildup outside the RPE. This study will provide insights on the role of RPE fat degradation in AMD, providing feasibility data for a novel therapeutic pathway for dry AMD.

Christopher Toomey MD, PhD - $375,000
Shiley Eye Institute and Viterbi Family Department of Ophthalmology

"Heparan Sulfate and Lipoprotein Interactions in Bruch's Membrane in the Early Stages of AMD"

Dr. Toomey will investigate whether age-related heparan sulfate (HS) changes contribute to lipoprotein (fat) retention in Bruch’s Membrane during early AMD. HS is a kind of sugar molecule found in the Bruch's membrane (thin layer between the retinal pigment epithelium and choroid) which normally holds onto important nutrients and proteins, but as we age, changes in HS can cause it to hold onto harmful fats. This can lead to more drusen and retinal degeneration. This work will further understanding of the causes of early dry AMD that may lead to novel therapeutic targets.

Thomas Mendel, MD, PhD - $375,000
The Ohio State University Wexner Medical Center

"Surgical and Adjuvant-Assisted Retinal Gene Therapy"

Dr. Mendel will use a pig model to test a novel gene therapy administration approach that combines both administration on top of the retina (rather than under the retina) with insulin added to accelerate gene therapy uptake into retinal cells. Dr. Mendel hypothesizes this approach will limit inflammation and deliver the gene therapy faster without retinal function degradation. This effort has the potential to improve gene therapy delivery for a variety of retinal diseases.

CLINICAL RESEARCH FELLOWSHIP AWARDS

Kirk Stephenson, MD - $65,000
Hospital for Sick Children‚ Toronto     

"Assessment of Potential Clinical Trial Endpoints Part 1: For PRPF31-Related IRDs, Part 2: Finalizing the First PROM for Children with an IRD"

Dr. Stephenson will study the natural history of vision change in PRPF31-related autosomal dominant retinitis pigmentosa (RP) patients. He will also administer a questionnaire of patient reported outcome measures to children affected with inherited retinal diseases (IRDs). These activities will provide valuable information on the impact of IRDs on visual structure and daily life, which are key for the selection of outcome measures in clinical trials.

Kirill Zaslavsky, MD, PhD - $65,000
Massachusetts Eye and Ear

“Leveraging Large Cohorts of Genetically Characterized Individuals to Mitigate Phenotypic Ascertainment Bias”

Dr. Zaslavsky will use genetic data and health records from volunteer biobanks to better understand the link between genotype (genetic profile) and phenotype (disease presentation) in dominant pathogenic variants associated with IRDs. He will reverse search wider data sets by genotype to learn more about the likelihood of known genetic variants to cause disease in those with IRDs and the general population.

Ahmad Al-Moujahed, MD, PhD, MPH - $65,000    
Massachusetts Eye and Ear

“Assessing the Impact of Retinitis Pigmentosa Genotype on the Prevalence and Clinical Features of Cystoid Macular Edema”     

Dr. Al-Moujahed will investigate the genetics of cystoid macular edema (CME) in RP patients to determine which genes are causing their RP and whether these genes are associated with their CME. This may help to better understand the causes of CME and lead to earlier treatment. CME is an accumulation of fluid in the retina that occurs for some RP patients. It can cause additional vision loss and can be difficult to treat in some cases.

NON-RODENT LARGE ANIMAL MODELS

Yannis Paulus, MD - $498,060
Johns Hopkins University

"Development of Rabbit Models of Eyes Shut Homolog-Associated Retinal Degeneration"

Rabbits have been used frequently as models for clinical, morphological (structural), and mechanistic studies of common ocular diseases. Rabbits, easily handled and laboratory friendly, share many features with humans, including eyeball size, internal structure, optical system, biomechanics, and biochemical features. Rabbit retinae have a visual streak with a high density of rod and cone photoreceptors, which shares some similarities with the human macula.

Dr. Paulus’ research team has developed a rabbit genome editing platform and previously generated rabbit models for USH2A, USH3A, and RHO genes that show retinal degeneration. They will develop two rabbit models of EYS each with a common mutation found in patients. (Mutations in EYS are a common cause of RP.) They propose to do so using gene and base editing tools to create two lines of mutant rabbits that will be phenotypically characterized by using non-invasive functional and imaging methods that are already in place in their labs. The EYS rabbit model is expected to be a resource for basic and translational studies for EYS associated RP.

Erwin van Wijk, PhD - $499,376
Radboud University Medical School

"Generation and Characterization of a Porcine Model for Usher Type 2C"

The porcine (pig) retina is comparable to the human retina in terms of anatomy, structure, and function. Recently, the first porcine model for Usher syndrome (type 1c) was generated and showed a similar phenotype as seen in patients. The goal of this project is to generate a multifunctional humanized knockout pig model for Usher syndrome type 2C (USH2C) that can be used for basic and translational research.  A humanized porcine model for USH2C can enable the assessment of therapeutic strategies currently under development. The model will help identify the optimal delivery routes and dosing (interval) and can enable toxicological assessment of therapeutic compounds prior to entering clinical trials. The availability of this model will benefit researchers, pharmaceutical industry, and funding bodies to develop, assess, and fund treatments for individuals with USH2C.

Bhanu Telugu, PhD - $499,759
University of Missouri

"Generation and Characterization of a Novel Porcine Model of Choroideremia"

This project is focused on creating a novel porcine model for choroideremia. The study aims to replicate the pathogenesis of human choroideremia by inactivating the CHM gene in pigs. Among the pig breeds for modeling inherited retinal disease, minipigs are especially appealing for widespread distribution. Most researchers, including those in medical schools and land grant universities in the US, have infrastructure to house the minipigs for long-term studies. A clinically relevant minipig model will aid in the development of validated, reproducible, safe, and effective treatments for human patients.

FREE FAMILY FOUNDATION AMD AWARD

Yoshikazu Imanishi, PhD - $500,000
Indiana University

"Elucidating Pathophysiological Mechanisms and Advancing High-Throughput Drug Discovery in PRPH2-Related Retinal Dystrophies"

Supported by the Nixon’s Vision Foundation

Mutations in the gene PRPH2 cause several dominantly inherited retinal diseases, including RP, macular dystrophies, and central areolar choroidal dystrophy.  Some mutations interfere with the ability of the PRPH2 protein to traffic (i.e., move) to photoreceptor outer segments where it carries out critical functions. This proposal hypothesizes that a better understanding of PRPH2 trafficking and incorporation into outer segment disks will improve our understanding of disease processes and aid in the identification of new therapies. Dr. Imanishi will conduct studies to identify compounds (drugs) that may improve PRPH2 trafficking in cells and in frogs.

Andrew Goldberg, PhD - $433,729
Oakland University

"Natural History and AAV-Mediated Intervention for Dominant Negative and Haploinsufficient Mouse Models of PRPH2-Associated Disease"

Supported by the Nixon’s Vision Foundation

Mutations in the gene PRPH2 that cause dominantly inherited retinal diseases are thought to affect the retina in two different ways. Some mutations decrease the total amount of PRPH2 protein present to levels insufficient for maintaining photoreceptor structure (called loss-of-function, leading to haploinsufficiency), while others interfere with the ability of PRPH2 to interact with other proteins and carry out normal function (called dominant negative).

This proposal will conduct a careful and rigorous natural history study of two mouse strains—one with a loss-of-function mutation and one with a dominant negative mutation. Following thorough characterization of these two strains, the researchers will test whether adeno-associated virus (AAV)-mediated delivery of PRPH2 can stop or slow disease progression. If successful, these studies will provide two characterized lines for other researchers to test therapies in and provide proof-of-concept for gene therapy for PRPH2 mutations.

Krzysztof Palczewski, PhD - $500,000
University of California, Irvine

"Precision Genome Editing in Humanized Mice Expressing Mutant Peripherin-2"

Dr. Palczewski and his team will create and characterize two “humanized” PRPH2 mouse models — models in which the mouse PRPH2 gene is replaced by a wildtype (healthy) or a mutant human PRPH2 gene. Once these mice have been generated and characterized, the researchers propose to use them to test the ability of prime editing to correct a specific PRPH2 mutation. The prime editing machinery is too large to be delivered by AAV, so the researchers propose to use lipid nanoparticles for delivery.  This study will also generate the tools to use prime editing to replace each of the three exons (protein coding regions) of PRPH2, potentially enabling many different PRPH2 mutations to be corrected.

Muayyad Al-Ubaidi, PhD - $481,269
University of Houston

"Mutation-Independent Therapeutic Strategy for Peripherin 2-Associated Diseases"

The goal of this project is to demonstrate proof-of-concept for a “knock-down and replace” therapeutic strategy for PRPH2-associated retinopathies. Mutations in PRPH2 lead to autosomal dominant retinal diseases. PRPH2 mutations often cause the mutant PRPH2 protein to interfere with the ability of unaffected PRPH2 or its binding partners to carry out their normal function. (These are called dominant negative mutations.)  Therapeutic strategies must therefore stop production of mutant PRPH2 and add back a wild-type copy of PRPH2.

In this study, the researchers will use ‘mirtrons’ to knock down PRPH2. Mirtrons are small RNA molecules that interact with machinery already present in cells to either cut target RNA or prevent it from being translated into protein.  To test the feasibility of their strategy, the project will determine: 1) if wild-type mouse PRPH2, delivered by nanospheres, can rescue retinal defects in a PRPH2 mouse model; 2) if delivery of a mirtron and mirtron-resistant copy of mouse PRPH2 can rescue retinal defects in a mouse model of a dominant negative PRPH2 mutation; 3) and if a mirtron can knock down human PRPH2 but not a mirtron-resistant copy of human PRPH2 in wild type mice.

PROGRAM PROJECT AWARD

Jeremy Kay, PhD - $2,600,000
Duke University

"Defining the Underlying Causes of Retinal Degeneration in CRB1 Disease"

Disruption of the CRB1 gene causes multiple types of inherited retinal degenerations. Most patients are diagnosed with Leber congenital amaurosis (LCA) or retinitis pigmentosa (RP). There are presently no effective treatments to prevent vision loss in CRB1-associated disease, and a significant number of patients could benefit from such a therapy, as CRB1 mutations are among the most common causes of inherited retinal disease. Researchers still do not understand why mutations in CRB1 lead to photoreceptor cell death. This impedes the creation of therapies to address the root cause(s) of CRB1-associated disease.

The central hypothesis of the CRB1 research program led by Dr. Kay is that loss of cell-cell connections in the outer retina underlies RP-like aspects of CRB1-associated disease, while loss of junctions between embryonic progenitors underlies LCA-like aspects. The project will enable researchers to better understand mechanisms of disease and provide tools and resources to advance potential treatments towards the clinic.

The primary goals of this large-scale CRB1 research effort are: 1) identification, across multiple species (mouse, pig, and human) of the primary site(s) of tissue damage caused by CRB1 dysfunction, which leads to degeneration of photoreceptors, and 2) strategies to ameliorate such damage.

The CRB1 Program Project Award includes the following four projects:

Project 1:
Jeremy Kay, PhD
Duke University

"Damage at the External Limiting Membrane as a Root Cause of CRB1 Retinal Degeneration"

This project will use a CRB1 mouse model to evaluate the hypothesis that the external limiting membrane (ELM) is the main site of retinal pathology in CRB1-associated disease and to test whether AAV-mediated delivery of a specific CRB1 isoform (CRB1-B) at different ages can restore the structural integrity of the retina. The ELM is a band of cell-to-cell contacts between photoreceptors and Muller glia that is disrupted in CRB1 mouse models.

Project 2:
Seo-Hee Cho, PhD
Thomas Jefferson University

"LCA Modeling and Pathogenic Mechanisms in Mouse and Human Cell-Based Models"

This project will determine if disrupted adhesion between retinal progenitor cells during eye development is the cause of CRB1-associated LCA symptoms. Researchers will test whether this is the case by examining the eyes of CRB1 mice before they are born and in human retinal organoids carrying CRB1 mutations. Organoids are a good model of human prenatal and early postnatal development.

Project 3:
Maureen McCall, PhD
University of Louisville

"Characterizing Retinal Development and Dystrophy in a Pig Model of CRB1 Disease"

Mouse models of CRB1 do not show all the same retinal features that are found in patients, so additional models are needed to fully understand disease pathology and to test therapies. This project will characterize the expression of CRB1 in unaffected pigs and compare this to a new pig strain that carries mutations in CRB1. The phenotype of CRB1 mutant pigs will be characterized and compared to mouse models and human patients.

Project 4:
Sina Farsiu, PhD
Duke University

"In Vivo Imaging of External Limiting Membrane Damage in Mice and CRB1 Patients"

The goal of this project is to identify an imaging biomarker of CRB1-associated disease that can be tracked in patients. The investigators believe that disruption in the external limiting membrane (ELM) can be seen on OCT and assessed as a biomarker. To test this hypothesis, they will conduct imaging on CRB1 mutant mice and patients with CRB1-associated disease.

RESOURCES

Lori Sullivan, PhD - $74,994
University of Texas Health Science Center at Houston

Dr. Sullivan is managing and curating the RetNet database (www.retnet.org), a catalogue of all the genes and loci associated with inherited retinal diseases for the research community.

Kristy Lee, MS, CGC - $150,000
University of North Carolina

Ms. Lee will continue the ABCA4 gene curation effort started by the ABCA4 Variant Curation Expert Panel, which is depositing new ABCA4 gene variants into the ClinVar database. This work will help identify individuals appropriate for clinical trial interventions as well as future, approved treatments. ABCA4 mutations are the most frequent cause of Stargardt disease.