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Drug Fixes Vision Birth Defect in Lab Tests, Trial Planned

Cheryl Gregory-Evans

Cheryl Gregory-Evans (University of British Columbia)

Medical researchers at University of British Columbia in Vancouver, Canada adapted a new drug as a treatment for aniridia, a rare eye disease caused by a birth defect, with tests on mice showing the drug’s potential effectiveness in treating the disorder. The team from UBC and the affiliated Vancouver Coastal Health, led by UBC ophthalmology professor Cheryl Gregory-Evans, published its findings online today in the Journal of Clinical Investigation. A small-scale clinical trial of the therapy is planned for next year.

Aniridia is characterized by a complete or partial absence of the iris, the colored part of the eye, that can result in damage to the pupils, and lead to reduced visual sharpness and increased sensitivity to light. People with aniridia often develop more serious eye diseases, such as glaucoma, later in life, and become legally blind. The disorder occurs in 1 in 50,000 to 100,000 newborns, affecting some 5,000 people in North America.

A mutation in the Pax6 gene is believed to cause aniridia, resulting from signals generated by the mutation that interrupt production of a protein needed for normal formation of the eyes. This type of mutation, called a nonsense mutation, prevents the full translation of genetic code into functional proteins, and is implicated in a number of genetic disorders.

In her research, Gregory-Evans came across Ataluren, a drug in development by PTC Therapeutics in South Plainfield, New Jersey. PTC Therapeutics is developing the drug as an oral compound to treat genetic conditions resulting from nonsense mutations, such as Duchenne muscular dystrophy and cystic fibrosis. Both the U.S. Food and Drug Administration and European Medicines Agency granted Ataluren orphan drug status.

The UBC/VCH team tested the ability of Ataluren, formulated as eyedrops, to limit progressive damage to the eyes of newborn mice. Converting the compound into eyedrops required the help of colleagues in UBC’s pharmacy school that ground Ataluren into a fine powder, which in a solution adheres better to the eyes than in earlier versions.

The researchers applied the treatments to the eyes of two-week old mice with aniridia. The results showed that the treatments not only stop progression of the damage, but they also reverse the damage, fixing defects in the mice’s corneas, lenses, and retinas. “We were amazed to see how malleable the eye is after birth,” says Gregory-Evans.

A small-scale clinical trial of the treatments is planned for next year in Vancouver, the U.K., and the U.S. The trial is expected to enroll some 30 patients, and is supported by the Vision for Tomorrow Foundation in Deerfield, Illinois.

Gregory-Evans tells more about the research in the following video.

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