Otarmeni™ (lunsotogene parvec) Receives EMA Filing Acceptance for Genetic Hearing Loss

EMA Accepts Regeneron's Otarmeni for Accelerated Review

Regeneron Pharmaceuticals announced that the European Medicines Agency (EMA) has accepted for review under Accelerated Assessment the Marketing Authorization Application (MAA) for Otarmeni (lunsotogene parvec). This gene therapy targets biallelic OTOF variant-associated hearing loss, an ultra-rare condition affecting approximately 46 newborns annually in the EU. The MAA is supported by data from the pivotal CHORD Phase 1/2 clinical trial, which involved 24 participants aged 10 months to 16 years. Otarmeni previously received Orphan Designation from the EMA and was granted accelerated approval by the U.S. FDA in April 2026. If approved, it would be the first gene therapy for OTOF-related hearing loss in the EU.

• Otarmeni has achieved significant regulatory progress, including EMA's acceptance for Accelerated Assessment of its Marketing Authorization Application (MAA) and prior Orphan Designation. This follows its accelerated approval by the U.S. FDA in April 2026, positioning it as a potential first-in-class gene therapy for OTOF-related hearing loss in the European Union.
• The MAA is underpinned by data from the ongoing pivotal CHORD Phase 1/2 trial. This open-label, multicenter study evaluated Otarmeni's safety, tolerability, and efficacy in 24 participants, ranging from 10 months to 16 years old, with OTOF-related hearing loss. The therapy was administered via intracochlear infusion, either unilaterally or bilaterally.
• Otarmeni (lunsotogene parvec) is an in vivo dual adeno-associated virus serotype 1 (AAV1) vector-based gene therapy. It is designed to restore durable, physiological hearing by delivering a working copy of the OTOF gene to hair cells, thereby addressing the lack of functional otoferlin protein caused by biallelic OTOF variants, which leads to profound sensorineural hearing loss.

The Unmet Need in OTOF-Related Hearing Loss

Biallelic OTOF variant-associated hearing loss presents significant therapeutic challenges that have historically limited treatment options to prosthetic devices. While emerging gene therapy approaches show promise, several critical limitations persist in current treatment paradigms.

Historical Treatment Limitations:
• Clinical options were restricted to external devices like hearing aids and cochlear implants, which improve audibility but do not restore native cochlear biology
• These prosthetic devices produce artificial hearing via electric stimulation rather than biological restoration of function
• Treatment approaches failed to address the underlying genetic etiology of DFNB9 auditory neuropathy

Gene Therapy Technical Constraints:
• Limited genetic capacity (~4.5 kB) of adeno-associated viral vectors (AAV) creates delivery challenges for the ~6 kB otoferlin coding sequence
• Variations in transduction efficiency among different inner ear cell types targeted by AAV vectors
• Complex inner ear anatomy and diverse nature of deafness genes require precision approaches tailored to specific genetic forms

Variable Clinical Outcomes and Knowledge Gaps:
• Individual treatment responses vary dramatically from restored normal audibility (≤20 dB HL) to severe hearing loss (≥80 dB HL) despite substantial average improvements
• Understanding of temporal processing restoration and comparative efficacy with cochlear implantation remains limited
• Standardized frameworks to guide emerging therapies are lacking, with preclinical optimization remaining an urgent developmental need

Uncertain Therapeutic Parameters:
• The therapeutic time window for DFNB9 treatment remains largely unknown based on current clinical experience
• Long-term efficacy, specificity, and durability of novel inner ear gene therapies require further characterization
• Individual variability in treatment outcomes complicates patient counseling and treatment planning

Otarmeni's Pivotal CHORD Data and EMA Review

Current clinical development for biallelic OTOF variant-associated hearing loss shows promising early-stage progress, with eight clinical trials registered across 51 centers in eight countries. These studies primarily utilize adeno-associated virus (AAV) vectors delivered via single local injection to target DFNB9, with initial results demonstrating partial hearing restoration in several pediatric patients.

Otarmeni: Reshaping the OTOF Hearing Loss Landscape

The treatment landscape for biallelic OTOF variant-associated hearing loss has undergone a dramatic transformation over the past five years, marked by the emergence of gene therapy as a viable therapeutic option alongside traditional cochlear implantation. Five international groups are now conducting human clinical trials using AAV1-mediated gene therapy: Eye and ENT Hospital Fudan University (China), Lilly-Akouos (USA), Otovia (China), Regeneron (USA), and Sensorion (France). All employ a dual vector approach to reconstitute full-length otoferlin, with eight clinical trials now registered across 51 centers in eight countries. The most significant clinical milestone came from a bilateral gene therapy trial in five pediatric patients with DFNB9, where all subjects achieved bilateral hearing restoration from baseline auditory brainstem response thresholds exceeding 95 dB to functional levels ranging from 50-85 dB, accompanied by restored speech perception and sound localization capabilities.

The safety profile of OTOF gene therapy has proven favorable across published trials, with 21 DFNB9 patients experiencing only 244 grade I/II adverse events, 2 grade III events, and no serious adverse events. The most common side effects were transient increases in lymphocyte counts and cholesterol levels. Efficacy data demonstrates substantial therapeutic impact, with an average improvement of 52.4 dB from baseline complete deafness, rapid onset with a 0.74-month time constant, and sustained effects over the initial six months. Individual outcomes vary considerably, ranging from restored normal audibility (≤20 dB HL) to residual severe hearing loss (≥80 dB HL), though treatment benefits extend beyond young children to include adolescents and young adults in some cases.

The field has also advanced through the establishment of the first international consensus framework for clinical application of gene therapy in hereditary hearing loss, with 30 expert-derived statements covering patient selection, diagnosis, drug delivery, and follow-up protocols. Complementing gene replacement strategies, innovative approaches including DNA base editing using Nme2ABE8e adenine base editors have demonstrated superior on-target editing efficiency for correcting pathogenic OTOF mutations in preclinical models. This therapeutic evolution positions gene therapy as an emerging alternative to cochlear implantation for monogenic deafness, offering biological restoration of native cochlear function rather than artificial electrical stimulation of the auditory nerve.

Otarmeni's European Review: A New Horizon for Genetic Hearing Loss

The European Medicines Agency's decision to grant Accelerated Assessment to Regeneron's Otarmeni for biallelic OTOF variant-associated hearing loss marks a significant milestone, signaling a potential transformation in how we approach congenital deafness. For decades, the primary interventions for hearing loss have been prosthetic devices like hearing aids and cochlear implants, which, while effective, improve audibility rather than restoring the ear's natural biological function. Otarmeni, as a gene therapy, offers the promise of a restorative approach, directly addressing the genetic root cause of this specific form of hearing loss.

Research has consistently shown that over half of all congenital hearing loss cases have a genetic origin, and the success of AAV-OTOF gene therapy in restoring hearing in congenitally deaf children with DFNB9 is a testament to this therapeutic avenue. This development not only offers hope for the approximately 46 newborns annually in the EU affected by this ultra-rare condition but also validates the broader potential of gene therapy for other monogenic sensory disorders.

However, the path forward is not without its complexities. A critical challenge lies in patient identification. Studies indicate that even with awareness of genetic causes, clinicians do not uniformly refer children with Auditory Neuropathy Spectrum Disorder (ANSD) for OTOF pathogenic variant testing. This highlights the urgent need to integrate comprehensive genetic screening into early hearing detection and intervention programs to ensure eligible patients are identified promptly. Furthermore, as with any groundbreaking therapy, particularly in a pediatric population, the long-term efficacy and safety of Otarmeni will require continuous, rigorous monitoring. Finally, navigating the diverse reimbursement landscapes across Europe for an ultra-rare disease therapy, while potentially having a low overall budget impact due to small patient numbers, will be crucial for ensuring equitable access.