NEW YORK, Mar 27 (Reuters Health) - A topical lotion that helps sun-damaged DNA repair itself may decrease the risk of precancerous skin lesions in patients with a genetic disorder called xeroderma pigmentosum (XP).
People with XP lack the body's natural ability to undo harm to DNA caused by ultraviolet (UV) light and consequently have a much greater risk of developing various forms of skin and eye cancer, according to a report published in the March 24th issue of The Lancet.
The lotion, called T4N5, contains an enzyme known as T4 endonuclease V, which is "from bacteria that recognizes UV light damage to DNA, and starts the process of removing the damage and replacing it with newly made, undamaged DNA," lead author Dr. Daniel Yarosh of Applied Genetics Incorporated Dermatics in Freeport, New York, told Reuters Health.
In the study, the researchers gave 20 patients with XP the T4N5 lotion, while 10 patients were given an inactive (placebo) lotion. After 1 year, patients using T4N5 lotion saw a 68% decrease in their rate of sun-related skin lesions, called actinic keratoses, compared with those who used the placebo lotion. The investigators also found a 30% decrease in basal-cell carcinomas (a type of skin cancer) in the T4N5 group. No side effects from the treatment were observed.
"When DNA repair is increased by this T4 endonuclease V, the skin cancer rate goes down. This proves that DNA damage is a direct cause of skin cancer, and that we can prevent skin cancer even after sun exposure, by increasing DNA repair," Yarosh told Reuters Health.
The enzyme works by recognizing and binding to DNA that contains a specific type of damage that is only produced by UV exposure. The enzyme triggers a series of deletions and additions that correct the damaged DNA, Yarosh explained.
Could this chemical someday be used by the general public as a sunscreen?
"This is a new tool in the toolbox of sun protection. Sunscreens have their role, and we do not suggest replacing them," Yarosh said.
The "ultimate goal is to make the drug available to everyone exposed to the sun," Yarosh explained. Currently, the company is seeking approval from the US Food and Drug Administration for those most vulnerable to UV damage, such as those with XP, he added.
"This is an exciting drug and a valid study," said Dr. W. Clark Lambert of the University of Medicine and Dentistry of New Jersey in Newark. "The new treatment holds a lot of promise for people with XP and others who may be at risk (of developing skin cancer)."
The Lancet 2001 |
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