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Usher Syndrome

Recent research efforts aimed at curing Usher Syndrome.

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Français — Syndrome d'Usher

Usher Syndrome

Overview

Usher syndrome is a group of inherited conditions that combine hearing loss or deafness with retinitis pigmentosa (RP), a progressive disease in which light-sensitive retinal cells gradually deteriorate. Some people also have balance difficulties. The course varies by genetic subtype: type 1 usually involves profound congenital hearing loss and early balance problems, while type 2 commonly involves congenital moderate-to-severe hearing loss with RP beginning later, often in adolescence or adulthood. Vision loss typically begins with poor night vision and narrowing peripheral vision and may eventually affect central vision. National Eye Institute overview and GeneReviews: Usher syndrome type II describe this substantial variation in prognosis. (nei.nih.gov)

There is no approved cure that corrects the underlying genetic cause of Usher syndrome. Current care is therefore supportive and preventive: genetic diagnosis and regular retinal monitoring, low-vision and orientation-and-mobility services, hearing aids or cochlear implants when appropriate, communication support, and management of treatable eye complications such as cataract or cystoid macular edema. National Eye Institute guidance and GeneReviews: Usher syndrome type I emphasize early, multidisciplinary hearing, vision, balance, educational, and rehabilitation care. (nei.nih.gov)

Scope of Recent Research (2020–present)

The field has become more active and technically focused since 2020, especially around repairing or bypassing mutations in large Usher genes that do not fit inside conventional gene-therapy vectors. The most advanced curative-oriented programs now include a dual-vector gene-replacement trial for MYO7A-related Usher type 1B and an RNA exon-skipping trial for a subgroup of USH2A-related disease; meanwhile, gene editing, compact “mini-gene” constructs, and long-lasting RNA delivery remain preclinical. These are important advances, but the community is not yet close to a broadly applicable cure because treatments are subtype- and mutation-specific, must demonstrate long-term safety and durability, and generally aim first to preserve remaining retinal cells rather than replace cells already lost. LUCE-1 trial summary, LUNA ultevursen trial, and a recent review of gene-therapy challenges reflect this stage of development. (hra.nhs.uk)

Major Breakthroughs and Emerging Therapies

Dual-AAV gene replacement for large genes. A major barrier in Usher syndrome is that several key genes are too large for a standard adeno-associated virus (AAV), the most widely used eye-gene-therapy delivery vehicle. Researchers have addressed this by splitting a gene between two AAVs so that treated cells can reassemble the full instruction set. In a 2024 peer-reviewed study, dual-AAV delivery of full-length PCDH15 restored hearing and balance in mouse models of Usher type 1F and achieved correctly localized protein expression in human retinal organoids and nonhuman-primate retina, providing a strong preclinical proof of principle for treating both ear and eye disease caused by a large Usher gene. PCDH15 dual-AAV study. (jci.org)

The same strategy has reached human testing for Usher type 1B. AAVB-081 uses two subretinal AAV8 vectors to deliver the large MYO7A gene. In preliminary, company-reported data presented in 2025 from the ongoing LUCE-1 study, four participants followed for at least 180 days had more than one line of improvement in best-corrected visual acuity, with no drug-related serious adverse events or dose-limiting toxicities reported; these findings are encouraging but remain early, uncontrolled, and not a demonstration of a durable cure. AAVantgarde’s LUCE-1 update and the LUCE-1 regulatory study summary provide the available trial details. (aavantgarde.com)

Smaller replacement genes and gene editing. For Usher type 1F, investigators have engineered shortened, functional versions of PCDH15 that fit into a single AAV. In mice, an AAV-delivered mini-PCDH15 preserved hair-cell bundles and restored hearing, suggesting that rationally designed compact genes may avoid the complexity of using two vectors. Mini-PCDH15 gene therapy. (nature.com) A separate 2023 study used adenine base editing—an approach that changes one DNA letter without cutting both DNA strands—to correct the common PCDH15 R245X mutation in a humanized mouse model and restore hearing in a developmental conditional-loss model. However, it did not restore hearing in mice lacking Pcdh15 from the earliest stages, underscoring how strongly treatment timing may matter for congenital inner-ear disease. Adenine base editing for USH1F. (pubmed.ncbi.nlm.nih.gov)

RNA therapies for USH2A. Ultevursen is an antisense oligonucleotide: a short synthetic RNA-like medicine injected into the eye to instruct cells to skip exon 13 of USH2A. For patients whose disease-causing variants are in that exon, the goal is to produce a shorter but potentially functional usherin protein. This does not repair DNA and requires repeat dosing, but it avoids the challenge of fitting the very large USH2A gene into an AAV. Sponsor-reported follow-up across 29 treated participants found no serious ocular adverse events leading to discontinuation; in the small sham-controlled STELLAR phase 1b/2 study, the treated group showed numerically better 48-week vision and structural measures than sham, though the study was too small to establish efficacy conclusively. Ultevursen STELLAR/HELIA analysis. (sepulbio.com)

Gene-agnostic retinal protection. NPI-001, an oral formulation of the antioxidant N-acetylcysteine amide, is not a genetic cure and cannot restore missing Usher proteins. It is nevertheless relevant because reducing oxidative stress could slow photoreceptor loss across Usher subtypes while gene-specific therapies mature. In a sponsor-reported randomized phase 1/2 study of 49 people with RP associated with Usher syndrome, Nacuity reported more than a 50% reduction in loss of ellipsoid-zone area—a retinal imaging marker of photoreceptor health—over two years, while the functional retinal-sensitivity endpoint did not reach statistical significance. These results need confirmation in a larger trial. NPI-001 phase 1/2 update. (nacuity.com)

Clinical Trials and Experimental Approaches

The leading gene-replacement trial is LUCE-1 (NCT06591793), a phase 1/2, open-label, dose-escalation study sponsored by AAVantgarde Bio for retinal degeneration caused by MYO7A-related Usher type 1B. It evaluates subretinal dual-AAV8 delivery of AAVB-081 at multiple doses, with safety, tolerability, and preliminary benefit as its central objectives. The early reported improvements in visual acuity and low-light vision are promising but must be interpreted cautiously because they involve very few participants, short follow-up, and no randomized control group. LUCE-1 study summary and AAVantgarde’s 2025 data release. (hra.nhs.uk)

For USH2A exon 13 disease, LUNA (NCT06627179) is a Sepul Bio-sponsored phase 2b, randomized, double-masked, sham-controlled study of repeated intravitreal ultevursen injections. The trial began in December 2024, plans to enroll 81 participants aged 8 years and older, and is expected to run through approximately July 2028; it is designed to test efficacy as well as safety rather than merely establish tolerability. LUNA trial listing. (clinicaltrials.ucsf.edu)

NPI-001 has completed a randomized, placebo-controlled phase 1/2 trial in Australia and is being positioned for confirmatory development as a mutation-independent photoreceptor-protection therapy. It should be regarded as a possible disease-modifying treatment, not a cure, because it does not correct the causative gene or regenerate lost retinal cells. NPI-001 phase 1/2 report. (nacuity.com)

Methodologies and Scientific Approaches

Usher research combines animal models, patient-derived induced pluripotent stem cells, retinal organoids, human retinal tissue, and nonhuman-primate studies to test whether a therapy reaches the appropriate retinal or inner-ear cells and produces functional protein. Dual-AAV studies assess whether both vectors enter the same target cell and successfully reassemble a full-length message; base-editing studies sequence treated DNA and examine possible unintended edits; RNA therapies measure exon skipping, protein restoration, and retinal function. The PCDH15 dual-AAV program illustrates this translational ladder by testing mice for hearing and balance rescue and human retinal organoids and primate retina for photoreceptor targeting. PCDH15 dual-AAV study. (jci.org)

Clinical studies increasingly rely on sensitive structural and functional biomarkers because RP progresses slowly. Common measures include optical coherence tomography (OCT), particularly ellipsoid-zone area as a marker of surviving photoreceptors; fundus autofluorescence; visual fields; best-corrected visual acuity; low-luminance acuity; electroretinography; and microperimetry, which maps retinal sensitivity. Long-term natural-history work such as RUSH2A is important for determining which measurements change reliably enough to serve as clinical-trial endpoints. National Eye Institute diagnostic overview, RUSH2A endpoints study, and ultevursen biomarker analysis. (nei.nih.gov)

Leading Institutions and Funding

The Usher field is being driven by a mix of academic laboratories, specialist hospitals, charities, and biotechnology companies. Harvard Medical School’s David Corey laboratory is advancing PCDH15 mini-gene and dual-AAV strategies; the Foundation Fighting Blindness awarded the group $1,206,669 in fiscal year 2024 for development of mini-gene therapy for Usher type 1F blindness. The same funding round included $499,376 to Radboud University Medical Center for a humanized pig model of Usher type 2C, reflecting the field’s need for animal models that more closely mimic human retina. Foundation Fighting Blindness funded grants, FY2024. (fightingblindness.org)

TIGEM, the University of Campania Luigi Vanvitelli, and AAVantgarde Bio are central to the MYO7A dual-AAV clinical program, while Sepul Bio is developing ultevursen for USH2A exon 13 disease. U.S. public investment also supports model development: the National Eye Institute awarded $244,500 for a 2024–2027 project to create a new USH2A disease model. Patient-led organizations are increasingly influential; Save Sight Now reports raising more than $3 million with the Foundation Fighting Blindness for seven USH1B programs spanning assays, patient-derived cells, natural-history studies, and disease models. NEI-supported USH2A model award and Save Sight Now research strategy. (taggs.hhs.gov)

Strengths, Limitations, and Challenges

The strongest recent progress is that Usher research has moved beyond theory: large-gene delivery has produced convincing rescue in preclinical models and has entered a human MYO7A trial, while USH2A exon-skipping has generated human safety data and is now in a controlled phase 2b study. The approaches are biologically well matched to their targets: gene replacement may work across many mutations in one gene, whereas RNA exon skipping can exploit the fact that exon 13 can be omitted while retaining some usherin function. PCDH15 dual-AAV study, LUCE-1 study summary, and LUNA trial listing. (jci.org)

The limitations are equally important. Dual-vector therapies require efficient delivery of both vectors to the same cells, involve retinal surgery for subretinal administration, and can provoke inflammation; gene editing must achieve adequate editing in the correct cells without harmful unintended changes. The base-editing study in Usher type 1F also showed that correcting a mutation after early developmental damage may not restore hearing, highlighting a likely need for earlier intervention in some subtypes. Finally, ultra-rare, slowly progressive diseases make it difficult to recruit enough participants and to distinguish a real treatment effect from variable natural progression, especially when studies rely on small cohorts or surrogate imaging endpoints. Adenine base editing for USH1F, AAVB-081 preliminary safety data, and gene-therapy challenges review. (pubmed.ncbi.nlm.nih.gov)

Outlook and Future Directions

Usher syndrome is closer than ever to the first therapies that address its root genetic causes, but it is not yet close to a universal cure. The most consequential near-term milestones are durable, independently reported outcomes from the LUCE-1 dual-MYO7A program; controlled two-year results from LUNA for ultevursen; confirmation of whether NPI-001 meaningfully preserves functional vision; and evidence that preclinical dual-AAV, mini-gene, and editing approaches can safely reach enough photoreceptors and inner-ear cells in people. A realistic first generation of treatments is more likely to preserve or improve remaining vision in genetically defined subgroups than to restore vision or hearing after extensive cell loss, making early genetic diagnosis, natural-history data, and equitable access to specialized trials essential. LUCE-1 study summary, LUNA trial listing, and NPI-001 phase 1/2 report. (hra.nhs.uk)

References

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