GenSight Completes Enrollment Early for Phase 3 Trial of GS010 Gene Therapy

GenSight Biologics has completed full patient enrollment ahead of schedule for its ongoing Phase 3 trial assessing the safety and efficacy of GS010, the company’s gene therapy designed to improve visual acuity in patients with Leber hereditary optic neuropathy (LHON), a rare genetic mitochondrial disease that causes vision loss.

The multi-center, randomized, double-blind, placebo-controlled trial (NCT03293524), called REFLECT, is designed to evaluate the efficacy and safety of a single injection of GS010 into the eyes of patients with LHON, which is caused by a genetic mutation in the ND4 mitochondrial gene.

Eligible patients who have had vision loss up to one year have been recruited to participate in the study from clinical centers in the United States, Europe, and Taiwan.

GenSight had planned to have enrolled approximately 90 patients in the trial before September. It has now announced that the 98^th participant has been enrolled and received treatment July 2, beating its initial goal.

“The conclusion of enrollment for the REFLECT study is a milestone in the story of gene therapy for Leber Hereditary Optic Neuropathy,” Nancy J. Newman, MD, LeoDelle Jolley Professor of Ophthalmology and Neurology at the Emory University School of Medicine, and principal investigator in REFLECT, said in a press release.

“The recruitment of nearly 100 patients in less than two years is a tribute to the support of the LHON community in this partnership among researchers, clinicians and patients trying to bring therapy and hope to this blinding disease,” she added.

Patients in the trial will be randomly assigned to receive either one injection of GS010 into both eyes (treatment group), or one injection of GS010 into one eye and one injection of a placebo into the other (placebo group).

The trial’s primary endpoint will be to assess changes in the best corrected visual acuity (BCVA) from baseline until week 52 (one year after treatment) in their second affected or not-yet affected eye. Secondary endpoints will include BCVA changes from baseline until two years after treatment in their second affected or not-yet affected eye compared to placebo and their first affected eye treated with GS010, contrast sensitivity, optical coherence tomography (a non-invasive imaging test that uses light to take pictures of the retina), and quality of life.

The first patient received treatment in March 2018. According to GenSight, topline data from the first year of the study should be available by the end of 2020.

REFLECT has received a special protocol assessment (SPA) from the U.S. Food and Drug Administration (FDA), indicating that the agency has agreed that the trials’ design, clinical endpoints and analyses are adequate to support future submission of a marketing application for GS010 in the U.S.

This won’t be necessary in the European Union, as the European Medicines Agency (EMA) has considered two other Phase 3 trials — RESCUE (NCT02652767) and REVERSE (NCT02652780) — as pivotal for filing the marketing authorization application (MAA) for GS010 there.