Long-Term Gene Therapy Safety in Retinal Disease: Insights from the EXTEND Study

The EXTEND five-year update shows a single intravitreal injection of MCO-010 is safe and durable through five years, supporting its potential role in managing advanced retinitis pigmentosa and informing long-term patient planning.

EXTEND extends earlier gene-therapy reports by confirming durability beyond the typical 1–3 year window and documenting sustained effect after a single in-office dose.

No serious ocular adverse events were reported, and the safety profile remained consistent between the initial trial and long-term follow-up.

Higher-dose recipients had statistically significant visual-acuity gains at one year and maintained vision-related quality measures thereafter, with the investigational agent MCO-010 demonstrating the effect. The evidence indicates a dose-related visual benefit without new safety trade-offs through five years.