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Replies to post #189206 on Biotech Values
03/26/15 10:51 AM
On Wednesday, Avalanche Biotechnologies in Menlo Park and the University of Washington in Seattle announced a licensing agreement to develop the first treatment for colorblindness. The deal brings together a gene therapy technique developed by Avalanche with the expertise of vision researchers at the University of Washington.
"Our goal is to be treating colorblindness in clinical trials in patients in the next one to two years," says Thomas Chalberg, the founder and CEO of Avalanche.
The agreement has its roots in a scientific breakthrough that occurred six years ago. That's when two vision researchers at the University of Washington used gene therapy to cure a common form of colorblindness in squirrel monkeys.
"This opened the possibility of ultimately getting this to cure colorblindness in humans," says Jay Neitz, who runs the Color Vision Lab at UW along with his wife, Maureen Neitz.
The couple knew that transferring their success from monkey to man would be a challenge. But they were determined, says Maureen Neitz. "We've spent our entire careers writing NIH grants where we say our goal is to improve human health."
Colorblindness is usually a genetic disorder. About 8 percent of men inherit a mutation on the X chromosome that makes it hard for them to distinguish between red and green. The condition affects only about 0.5 percent of women, who have two X chromosomes.
And color vision problems can be disabling. Emails arrive every day at Neitz lab with subject lines saying things like "colorblindness ruined my life," says Jay Neitz.
The stories often come from people who say they are unable to pursue careers as pilots or fire fighters or even electricians, whose work involves a lot of color-coded wires.
Colorblindness can also make it hard to do things like drive after dark, says Maureen Neitz. That became a big problem for her brother, who is colorblind, after his community switched from mercury street lamps, which give off bluish light, to sodium street lamps, which produce orange light.
"He came home and he was shaking," Maureen Neitz says. "He said everything was just a sea of lights, it was all the same colors. (He) could not tell the street lights from the brake lights from the stoplights."
Neitz and his colleagues introduced the human form of the red-detecting opsin gene into a viral vector, and injected the virus behind the retina of two male squirrel monkeys — one named Dalton in honour of the British chemist, John Dalton, who was the first to describe his own colour blindness in 1794, and the other named Sam. The researchers then assessed the monkeys' ability to find coloured patches of dots on a background of grey dots by training them to touch coloured patches on a screen with their heads, and then rewarding them with grape juice. The test is a modified version of the standard 'Cambridge Colour Test' where people must identify numbers or other specific patterns in a field of coloured dots.
Colour coded
After 20 weeks, the monkeys' colour skills improved dramatically, indicating that Dalton and Sam had acquired the ability to see in three shades (see video). Both monkeys have retained this skill for more than two years with no apparent side effects, the researchers report in Nature1.
Adding the missing gene was sufficient to restore full colour vision without further rewiring of the brain even though the monkeys had been colour blind since birth. "There is this plasticity still in the brain and it is possible to treat cone defects with gene therapy," says Alexander Smith, a molecular biologist and vision researcher at University College London, who did not contribute to the study.
"It doesn't seem like new neural connections have to be formed," says Komáromy. "You can add an additional cone opsin pigment and the neural circuitry and visual pathways can deal with it."
