Emerging Gene Therapy for RP Receives Fast-Track Designation

Granted by the FDA, the designation is a critical step in moving the Foundation-funded treatment toward a clinical trial.

Genable Technologies, a gene therapy development company in Ireland, has received an orphan drug designation from the U.S. Food and Drug Administration (FDA) for its gene therapy for people with autosomal dominant retinitis pigmentosa (adRP) caused by mutations in the gene rhodopsin.

The FDA’s orphan designation, granted to therapies for diseases affecting fewer than 200,000 U.S. residents, provides Genable with seven years of marketing exclusivity in the United States. The designation may also help Genable qualify for clinical research grants from the FDA. In 2011, Genable received an orphan designation for its adRP gene therapy from the European Medicines Agency.

“This is a critical step in moving this promising, vision-saving therapy into a clinical trial and out to the people who desperately need it,” says Dr. Stephen Rose, chief research officer, Foundation Fighting Blindness, which has provided significant funding for the therapy’s development. “We are excited about the treatment’s potential for halting vision loss from a devastating condition.”

Known as GT308, Genable’s treatment works by turning off the disease-causing copies of rhodopsin while delivering healthy copies of the gene. A human-engineered, adeno-associated virus delivers the therapeutic cargo to the photoreceptors, the affected retinal cells that make vision possible. Though several different mutations in the rhodopsin gene can cause adRP, GT308 will work regardless of the mutation.

“The ability for Genable’s therapy to work for all rhodopsin mutations is a huge benefit,” says Dr. Rose. “Otherwise, they would need to develop individual gene therapies for each mutation.”

Research suggests that a single GT308 treatment, which is administered by an injection underneath the retina, will last for several years, perhaps a lifetime.

Of the 100,000 people in the United States affected by RP, approximately 10 percent have adRP caused by rhodopsin mutations.