Does Subretinal Gene Therapy for Achromatopsia Improve Vision?

In patients with CNGA3-linked achromatopsia blindness, poor visual acuity, and photophobia are common.

In this open-label, exploratory nonrandomized controlled trial, 9 patients with CNGA3-linked achromatopsia were treated with a single unilateral injection of 1.0 × 1010, 5.0 × 1010, or 1.0 × 1011 total vector genomes of adeno-associated virus (AAV) encoding CNGA3 (AAV8.CNGA3). During the 12-month follow-up period no substantial safety problems were observed.

All patients had some level of improvement in visual function including a change in visual acuity of 2.9 letters. Contrast sensitivity also improved by a mean of 0.33 log.

The authors concluded that, “Subretinal gene therapy with AAV8.CNGA3 was not associated with substantial safety problems and was associated with cone photoreceptor activation in adult patients, as reflected by visual acuity and contrast sensitivity gains.”

Reference:

Fischer MD, Michalakis S, Wilhelm B, et al. Safety and Vision Outcomes of Subretinal Gene Therapy Targeting Cone Photoreceptors in Achromatopsia: A Nonrandomized Controlled Trial. JAMA Ophthalmol. Published online April 30, 2020. doi:10.1001/jamaophthalmol.2020.1032