Priority Review for Rare Vision-Loss Disorder Drug

FDA has accepted for priority review a Chiesi NDA for idebenone and its use in treating Leber hereditary optic neuropathy (LHON), a rare inherited condition that causes sudden and severe central vision loss. LHON is a mitochondrial disorder that damages retinal ganglion cells, leading to rapid vision decline, typically beginning in one eye before affecting the other, according to the company. The agency set 2/28/2026 as the user fee review action target date.

The submission is based on data from the Phase 3 RHODOS trial and the Phase 4 LEROS study, which demonstrated that idebenone can improve or stabilize visual acuity in patients with the most common mitochondrial DNA mutations linked to LHON, Chiesi says. Data also suggested that earlier treatment—within a year of symptom onset—was associated with greater clinical benefit. Across studies, the therapy showed a favorable safety profile, with most side effects mild to moderate, it adds.