Skylark Bio has dosed the first patient in SONIX, its Phase I/II trial of SKY-GJB2 for GJB2-related pediatric hearing loss. The multi-site study will assess safety, tolerability, PK/PD and preliminary efficacy after a single unilateral intracochlear injection in children aged 9 months to 7 years. Initial results are expected by the end of 2026, with additional data planned during 2027. SKY-GJB2 delivers a functional GJB2 gene to cochlear supporting cells to restore connexin 26 and the gap-junction network required for hearing.
Skylark Bio Doses First Patient in SONIX Phase I/II Trial of SKY-GJB2 Gene Therapy
Mutations in the GJB2 gene disrupt the protein’s function and impact the gap-junction network crucial for hearing. Credit: R Photography Background/Shutterstock.com.
Skylark Bio has dosed the first patient in its multi-site SONIX Phase I/II study testing SKY-GJB2, an investigational gene therapy for children with hearing loss caused by GJB2 gene alterations. The milestone advances the company’s effort to develop a targeted inner-ear treatment for inherited, GJB2-related deafness.
Trial Design and Objectives
The SONIX study will evaluate safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of SKY-GJB2 after a single unilateral intracochlear injection. The trial is enrolling pediatric participants aged 9 months to 7 years across multiple clinical sites and will also collect preliminary efficacy data.
Skylark expects initial study readouts by the end of 2026, with additional data releases planned during 2027.
How SKY-GJB2 Works
SKY-GJB2 is engineered to deliver a functional copy of the GJB2 gene directly to supporting cells in the cochlea. These supporting cells are responsible for producing connexin 26, a protein essential for maintaining the gap-junction network and the ionic environment required for normal hearing. Mutations in GJB2 disrupt connexin 26 function and impair inner-ear physiology, leading to hearing loss.
Skylark Bio CEO Jodi Cook commented: “Dosing the first patient in SONIX brings us one step closer to a future where children born with genetic hearing loss have new treatment options that could meaningfully change the trajectory of their lives. The recent approval of a targeted AAV-delivered inner-ear therapy validates this approach and reinforces our confidence in developing precision genetic medicines for hearing loss.”
Broader Development Programme
In addition to SKY-GJB2, Skylark Bio is developing gene therapy candidates targeting SLC26A4-related hearing loss and advancing investigational programmes in the central nervous system. The company says ongoing work aims to broaden genetic medicine options for monogenic disorders.
As the SONIX trial progresses, safety and early efficacy data will be closely monitored and shared in planned readouts across 2026–2027.
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