AGTC Reports Promising Interim Results for XLRP and Achromatopsia Gene Therapy Trials

Applied Genetic Technologies Corporation (AGTC), a biotech company developing gene therapies for retinal diseases and other conditions, has reported favorable safety profiles and evidence of efficacy for participants in its gene therapy clinical trials for X-linked retinitis pigmentosa (XLRP) caused by mutations in the RPGR gene and achromatopsia caused by mutations in the CNGA3 or CNGB3 genes.

“Evaluating safety is always the primary goal in these early studies, and we are pleased that AGTC has reported its emerging gene therapies appear so far to be well-tolerated in patients,” says Brian Mansfield, PhD, vice president of research, interim chief scientific officer, Foundation Fighting Blindness. “The reports of vision improvements are also encouraging. We look forward to more data from these trials as they progress.”

Dr. Mansfield says that AGTC used the Foundation’s My Retina Tracker patient registry and genetic testing study to identify and recruit patients for the XLRP and achromatopsia studies.

XLRP

For its Phase 1/2 dose escalation trial for XLRP, the company reported results for two groups: eight patients who had the gene therapy administered to the peripheral region of their retinas and nine who had the treatment delivered to their central retinas. A total of 22 patients have been dosed thus far (not all were enrolled long enough to be included in the interim reports).

The eight reported patients who were dosed peripherally showed stable visual function at six months as measured by visual fields and best corrected visual acuity.

Preliminary data from the nine centrally dosed patients at the three-month time point (seven who have completed three-month evaluation and two who have completed six-month evaluation) showed evidence of improvement in visual acuity and sensitivity.

Some participants in the XLRP study also reported, anecdotally, improvements in reading, side vision, and the ability to see in dim settings.

AGTC plans to report additional data from the XLRP trial in the fourth quarter of 2019 and first half of 2020. The company is in ongoing discussions with the US Food and Drug Administration (FDA) about a potential Phase 3 (pivotal) trial.

XLRP affects approximately 20,000 people in the US and EU. The condition causes constriction of vision, reduced vision in dark settings, and central vision loss, especially in later stages. Most people with XLRP are legally blind by the age of 45.

The Foundation Fighting Blindness funded successful canine studies of XLRP gene therapy at the University of Pennsylvania School of Veterinary Medicine that helped make AGTC’s XLRP gene therapy clinical trial possible.

Achromatopsia (CNGA3, CNGB3)

Early data suggest benefit from treatment for patients in both CNGA3 and CNGB3 Phase 1/2 dose escalation clinical trials. One of three patients at the middle dose level in each trial and two of three patients at the high dose level in the CNGB3 trial have shown clinically meaningful improvements in light discomfort, defined as change from baseline at three months.

AGTC plans to report six-month data for both trials.

The hallmarks for people with achromatopsia are debilitating light sensitivity, loss of color perception, and poor visual acuity. Approximately 28,000 people in the US and EU are affected by achromatopsia.

The Foundation funded lab studies that helped make the achromatopsia gene therapy clinical trials possible.

Preclinical projects for dry AMD and optogenetic treatment

AGTC is also advancing a dry age-related macular degeneration (AMD) gene therapy and an optogenetic therapy toward clinical trials. Optogenetics is an emerging gene therapy approach for bestowing light sensitivity (some vision) to people with the most advanced retinal disease, regardless of the gene mutation causing their condition.