The 15-20 National Hospital and GenSight Biologics announce the treatment of the first patient in the GS010/LUMEVOQ® REVISE Study

• First of 14 planned patients for the dose-ranging study approved by the ANSM in December 2025
• Clinical study marks continuing partnership between the 15-20 Hospital and GenSight Biologics to develop transformative treatments for rare diseases

Paris, France, February 10, 7.30 am CET – The 15-20 National Hospital (l’Hôpital national des 15-20) in Paris and GenSight Biologics (Euronext: SIGHT, ISIN: FR0013183985, PEA-PME eligible), a biopharma company focused on developing and commercializing innovative gene therapies for retinal neurodegenerative diseases and central nervous system disorders, today announced the treatment of the first patient enrolled in the REVISE dose-ranging study. The open-label, single center study aims to enroll 14 patients in France.

With REVISE now underway, the hospital is currently the only institution in Europe with a clinical study involving GS010/LUMEVOQ®, GenSight Biologics’ candidate gene therapy being developed as a treatment for Leber Hereditary Optic Neuropathy (LHON) caused by a mutated ND4 mitochondrial gene[1]. The hospital is also the sole institution in Europe authorized to perform named patient early access (AAC) treatments with GS010.

“As a leading hospital specialized in the treatment of vision disorders, 15-20 National Hospital is committed to supporting the most promising scientific advances rigorously and in the service of patients affected by rare diseases,” said Nicolas Péju, Chief Executive Officer of the 15-20 National Hospital. “The start of the REVISE study testifies to this drive and to the trust given to our clinical and research teams.”

The REVISE study will investigate two doses of GS010 for the treatment of ND4-LHON. The study was requested by the French medicines agency ANSM (Agence nationale de sécurité du medicaments et des produits de santé) during the review of the application for a named patient early access program (AAC) for GS010 and was authorized in December 2025.

Reviewed in parallel with the REVISE study, the AAC program received the authorization from the ANSM later in December 2025 and is potentially open to patients from outside of France depending on regulatory requirements in their home country. In accordance with regulations, the first named patient requests for AAC were submitted to the ANSM last week. The named patient requests, each of which resulted from a multidisciplinary consultation, will be individually evaluated by the agency. Enrollment into REVISE is prioritized for patients eligible for both programs.

“We at GenSight are gratified that two avenues are now available for patients to be treated with GS010 in France,” said Dr. Magali Taiel, Chief Medical Officer of GenSight Biologics. “The unmet medical need among ND4-LHON patients and the urgency to treat the condition continue to animate our efforts to advance the clinical development of the gene therapy, including our push to begin a new Phase III clinical study by the end of this year.”

LHON is a rare, maternally inherited mitochondrial genetic disease, characterized by the degeneration of retinal ganglion cells, which results in precipitous and usually irreversible vision loss and typically leads to legal blindness. The ND4 mitochondrial mutation is the most common of the mutations that cause LHON and is associated with the worst prognosis among the leading mutations.

[1] GS010/LUMEVOQ® has not received marketing authorization in any jurisdiction and is not commercially available.