A CRISPR-Cas9 gene editing therapy has restored clinically meaningful vision in 90% of patients with Leber congenital amaurosis type 10 (LCA10) — the most common form of severe inherited childhood blindness — at 2-year follow-up in a pivotal Phase 3 trial, with FDA approval anticipated this quarter.

About LCA10

Leber congenital amaurosis type 10 is caused by mutations in the CEP290 gene, which encodes a protein critical for photoreceptor ciliary function. The most prevalent disease-causing variant — an intronic mutation designated c.2991+1655A>G — creates a cryptic splice site that disrupts CEP290 protein production, leading to progressive degeneration of rod and cone photoreceptors from birth.

LCA10 affects approximately 1 in 180,000 individuals globally and represents one of the leading causes of childhood-onset legal blindness. Until now, there has been no approved treatment.

How the Therapy Works

The treatment — EDIT-101, developed by Editas Medicine — delivers CRISPR-Cas9 components directly into photoreceptor cells via a single subretinal injection of adeno-associated virus serotype 5 (AAV5). Once inside the photoreceptors, the CRISPR machinery cuts out the aberrant CEP290 splice site, allowing the cell to produce functional CEP290 protein and restoring normal photoreceptor architecture.

Critically, the editing occurs in post-mitotic cells and the correction is permanent — no repeat dosing is required.

Phase 3 Results

The BRILLIANCE Phase 3 trial enrolled 94 patients aged 3 and above with confirmed biallelic CEP290 c.2991+1655A>G mutations. At 24 months:

  • 90% of treated patients showed improvement of ≥1.5 log units on the full-field stimulus test (FST) — the primary endpoint
  • 71% showed improvement of ≥2.0 log units — a more stringent threshold associated with functional daily vision
  • 67% passed an obstacle course navigation test under dim light conditions that all had failed at baseline
  • No serious adverse events attributed to the gene editing itself; mild-moderate uveitis resolved with topical steroids in 12% of patients

“A child who could not navigate a room in dim light can now ride a bicycle. I have been practising medicine for 30 years and I have never seen anything like this.”

— Dr. Eric Pierce, Massachusetts Eye and Ear, principal investigator

Safety Profile

The safety record of EDIT-101 across 3 years of follow-up is reassuring. No off-target editing events with clinical consequence were detected using whole-genome sequencing. No immune reactions to the CRISPR components occurred. The main safety concern — AAV-mediated immune response — was manageable with prophylactic immunosuppression.

Regulatory and Access Outlook

The FDA accepted the Biologics License Application in January and granted Priority Review. An advisory committee meeting is scheduled for April 2026. If approved, EDIT-101 would become the first in vivo CRISPR therapy approved for any indication — a watershed moment for gene editing medicine.

The therapy is expected to be priced at approximately $900,000 per eye. Editas and its commercial partner AbbVie are negotiating outcomes-based contracts with major payers, linking payment to sustained vision improvement at 3 years.

⚕️ Medical Disclaimer: This article is for informational purposes only. It does not constitute medical advice. Always consult a qualified healthcare professional before making health decisions.