SEATTLE – The latest data from a phase 3 clinical trial shows that gene therapy can counter visual degeneration associated with Leber hereditary optic neuropathy (LHON). The therapy, delivered by intravitreal injection, uses an adeno-associated virus vector to deliver a corrected copy of the mutated ND4 mitochondrial gene.
LHON is a rare, maternally inherited mitochondrial mutation that can cause blindness, most commonly in young men, though it does not happen in all individuals with the mutation. The condition often starts with blindness in one eye, accompanied or followed shortly by blindness in the second eye. Researchers believe that the injected viral vector gets taken up retinal ganglion cells, where the mutated gene interferes with vision. Once synthesized, a mitochondria-targeting sequence facilitates transport of the protein to the mitochondria.
The study protocol called for injection of the therapy into one eye and a placebo into the other, using the patient as his or own placebo control. The results in the treated eye were encouraging, though modest. "This is not hitting it out of the ballpark. But for people whose vision is devastated by this disease, it certainly is a first step," said Nancy J. Newman, MD, during a press conference held March 29 in advance of the 2022 annual meeting of the American Academy of Neurology.
