Key Findings
Sonpiretigene isteparvovec (son-vec) demonstrated the ability to improve visual acuity in patients with Stargardt disease and enhance retinal electrical responses in nonhuman primate models of geographic atrophy (GA). In an open-label phase 2 study of Stargardt patients with visual acuity of 20/200 or worse, those with atrophy limited to the macula gained an average of 12 ETDRS letters. Additionally, the STARLIGHT trial involving 6 adults showed a mean best-corrected visual acuity (BCVA) improvement of 5.5 letters at 48 weeks, while use of a wearable magnifier improved acuity by 13.3 letters.
Technical Details
Unlike gene replacement, son-vec utilizes optogenetics. An adeno-associated viral vector delivers a gene encoding a multi-characteristic opsin to ON bipolar cells. Because these cells often survive after photoreceptors degenerate, they can be engineered to respond directly to light. This “mutation agnostic” approach is administered via a single intravitreal injection. In preclinical dose-ranging studies using laser-induced lesions in nonhuman primates, treated eyes expressed the opsin in retinal neurons and showed significantly stronger responses on multifocal electroretinography compared to untreated eyes.
Background & Context
GA affects approximately 1 million people in the US. While the FDA has approved two complement inhibitors—pegcetacoplan (Syfovre) and avacincaptad pegol (Izervay)—these only slow lesion growth and do not restore lost vision. Son-vec is most advanced in treating retinitis pigmentosa (RP); the FDA accepted a Biologics License Application (BLA) for the brand name Mogenry in September 2026. The therapy also holds RMAT and orphan drug designations for Stargardt disease.
Significance & Outlook
The transition to a randomized phase 2 trial in GA patients seeks to determine if the benefits seen in inherited diseases and animal models translate to the larger AMD population. If positive, the investigators plan phase 2b/3a trials for regulatory approval. However, caution is noted as current human data is limited to small, open-label cohorts of patients with inherited diseases rather than older adults with AMD.
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