The Vision Thing: Update on LCA

Last year's "big ticket" item at ASGT was results from the first three patients in two gene transfer trials testing nearly identical products against a rare form of congenital blindness, Leber's Congenital Amaurosis (LCA). I previously blogged (here and here and here and elsewhere) on the controversial decision to move the intervention into children, given the novelty of the intervention, that the trial is primarily a safety study, and that blindness is not a fatal condition.

Today, Jean Bennett of University of Pennsylvania presented an update on the first three patients (previously reported in New England Journal of Medicine) plus results on the next three patients. Here's a synopsis. The first three patients continue to show dramatic improvement in objective measures like pupillometry (that is, their pupils are responding to flashes of light in a way that does not normally occur in patients with this form of blindness), and they show signs of improved vision.

The next three patients were children eight years or a bit older. Bennett showed dramatic footage of a child unable to find his way through a maze when using the uncorrected eye, and navigating a maze with relative ease with the corrected eye. She also showed data indicating retinal function in regions of the eye receiving vector. Improvements in vision were greater with the children than in the previous cohort- which she chalked up to the fact that retinal tissue was not as degenerated in younger patient-volunteers. The team did not observe any gene transfer-related adverse events.

The other two LCA trials were conspicuously missing from the meeting. Rumor has it that the Penn team has been far more successful recruiting patients with this rare disorder. Bennett flashed a slide at the beginning of her presentation showing that patients had been accrued from several continents- North America, Africa, Europe, and elsewhere. Patients in the second cohort, according to Bennett, are begging to have their second eye dosed. (photo credit: Ferran 2009).