A Gene Therapy Improves Vision For Retinitis Pigmentosa

As reported in Biospace; the clinical-stage biotech company Nanoscope Therapeutics, Inc. has announced a resonating gene therapy success: all participants with advanced retinitis pigmentosa (RP) maintained vision improvements a year after the Phase 1/2a clinical trials. This is big news — never before have patients with RP had access to a treatment to improve their inherited disease, that over time, progresses into blindness.
There are plans to begin the next phase of the trial this summer. It will be a Phase 2b, multi-center, optogenetic trial run in the United States, meant to further prove the efficacy of the drug. Researchers and patients are hopeful that this trial will be successful, as it would become the first restorative drug formulated for retinitis pigmentosa.

Retinitis Pigmentosa

Retinitis Pigmentosa is the umbrella term for a group of genetic diseases that causes degeneration of the retina, the tissue lining the back of the eye that converts light into messages the brain understands as vision. The disorder causes patients to lose their vision over time. The progression depends on whether the patient’s rods or cones are first affected. Usually, a person’s rods are first eroded, causing a dimming of light and difficulty with peripheral and night vision. As the cones diminish, the person also loses their color perception, central vision, and visual acuity. The genetic disorder is progressive, and while the rate and degree of visual erosion vary, most patients have totally lost their vision by age 40. There are symptomatic treatments, but no cure.

The Lab Improves Vision

The trial included 11 patients, three of whom received a low dose of the single intravitreal injection, and eight others received a higher dose. The gene therapy administers the MCO genes in a single injection into the person’s eye using a proprietary AAV2 vector, which has been designated an orphan drug by the FDA.
They found that regardless of which mutation was responsible for the patient’s conditions, all participants experienced improvements in both their objective and subjective vision. They also found the participants improved by >90% in their accuracy in shape discrimination. They also measured mobility, finding patients reduced their reaction time in touching a light panel by 50%. The patients’ reports of improvements were correlated to these measures.
In fact, patients reported lasting improvements in performing their daily tasks and sensitivity to outdoor light. Some patients could even attend their follow-up appointment without any assistance. Even more exciting, a number of study participants have regained the ability to use a cell phone, read letters on a wall or the title of a newspaper, watch TV, and even thread a needle.
The lab’s results are the first meaningful clinical findings that provide real functional visual improvements using optogenetic therapy. They’ve resulted in significant improvements in the quality of life for patients, mobility, and their ability to connect with the world. The team hopes as their gene begins its Phase 2b trial this summer, it will continue onto FDA approval, and become the first therapy of its kind available to patients with RP.
Nanoscope’s president and the technology’s inventor, Dr. Samarendra Mohanty, said,
“Optogenetics is a powerful research tool, but had limited scope of clinical benefit because the opsins had a narrow band of activation, unlike natural light environment. MCO is sensitive to broadband light and activatable by ambient light, thus eliminating the risk of photo-toxicity from long-term continuous use of external intense light stimulation devices.”

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