First human test of optogenetics highlights its clinical potential

RetroSense Therapeutics, a startup based in Ann Arbor, Michigan, will soon begin the first clinical trial of an optogenetics-based therapy in humans.

Optogenetics has caused a revolution in neuroscience research over the last decade or so, and now looks set to transform the world of gene therapy too.

Restoring vision

In August 2015, the company received FDA approval for human trials of their lead gene therapy candidate to treat blindness due to retinitis pigmentosa (RP) and advanced dry age-related macular degeneration (advanced dry-AMD).

In these conditions, the retina’s photoreceptors gradually die off causing a loss of visual acuity and the ability to see in low-light environments. This progressive degeneration eventually leads to blindness.

RetroSense’s therapy, RST-001, uses a genetically modified virus that has been engineered to contain a gene for a light-sensitive protein from algae (Channelrhodopsin-2 (ChR2)).

This virus will be injected into the eye of up to 15 legally blind patients at the Retina Foundation of the Southwest in Dallas, Texas, in the hope that ChR2 will become expressed on the retinal cells that it infects. These cells will then be light-sensitive and should let the patients see again, although only in blurry black and white.

Previous studies in animal models suggest that blind mice treated with RST-001 have some form of vision restored, but because it is so difficult to assess what the mice are seeing, only the results of the clinical trial will reveal how well the therapy works, if at all.

RetroSense, founded in 2009, was set up to help commercialise research from Zhuo-Hua Pan of Wayne State University. To Pan, the eye seemed like the easiest place to use optogenetics as a therapeutic tool. No expensive, specialised hardware is required as light shines directly on the retina.

Clinical Potential

RetroSense is not the only firm looking to develop therapies based on optogenetics.

Circuit Therapeutics, founded in 2010, wants to begin clinical trials for an optogenetics therapy to treat chronic pain. The treatment functions by modifying neurons that sense pain so they can be controlled by light.

Circuit Therapeutics and other companies are also interested in developing optogenetics for epilepsy, Parkinson’s disease and other neurological conditions.

As the technological hurdles preventing the use of optogenetics in humans are overcome and optogenetic techniques advance to have more control over neurons, therapies based on this breakthrough technology will begin to emerge in the clinic.

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