Landmark gene therapy for hereditary blindness closes in on FDA approval
Back in August, the FDA approved the first gene therapy for general use in the United States. That particulartreatment, for cancer, was beset by controversy due to its exorbitantprice tag and potential side effects. Now another gene therapy is onthe cusp of approval, this time to treat a form of hereditaryblindness. If given the tick by the FDA, this therapy could pave the way for a wholehost of treatments for genetically-based vision problems.
The gene therapy focuses on a rareinherited retinal disease called Leber congenital amaurosis (LCA), which is caused by a mutation in one of 19 particular genes.The therapy focuses in one specific gene called RPE65. A healthyversion of that gene is attached to a genetically modified harmlessvirus and injected into a patient's eyes.
The treatment is currently undergoingfinal phase 3 clinical trials after nearly a decade of research and the early results have beenexcitingly positive. Data from the first phase 3 trial showed 93percent of subjects (27 out of 29) displayed "meaningfulimprovements in their vision."
"These are kids who could not walkthrough a room in normal light, and who were absolutely paralyzed indim light," says study leader Stephen Russell. "Now they'rewalking around markedly better."
The final FDA approval decision ishoped to come by January 2018, and back in October an advisory panelunanimously endorsed the efficacy of the treatment. The FDAdoesn't have to follow the advice of this expert panel, but ittraditionally does.
While this particular therapy is not acomplete cure, and it is targeted at a rare genetic disease, manyhope it is the first in a new wave of gene therapies directed at awide variety of occular diseases. There are over 225 known geneticmutations that cause blindness, and the genetically modified virusused in this particular treatment can likely be used as a deliverymechanism in treatments for a great majority of those conditions.
If this therapy is ultimately approvedit will certainly be a landmark for modern gene therapy. Unlike theprior cancer therapy approved in August, which concentrates ongenetically modifying immune cells, this treatment will be the firstto replace, or essentially fix, specific missing and mutated genesthat directly cause disease.
The early trial results were publishedin the journal The Lancet.