September 15, 2013
New Treatment For Macular Degeneration Attacks Abnormal Blood Vessels Directly
Brett Smith for redOrbit.com - Your Universe Online
Based on experiments with laboratory mice, a group of drugs known as MDM2 inhibitors proved exceedingly effective at mitigating the abnormal blood vessels responsible for the vision loss linked to the disease.
“We believe we may have found an optimized treatment for macular degeneration,” said senior study author Dr. Sai Chavala, an assistant professor of ophthalmology at the UNC School of Medicine. “Our hope is that MDM2 inhibitors would reduce the treatment burden on both patients and physicians.”
The best treatment for macular degeneration available on the market right now is an antibody called anti-VEGF that is injected directly into the eye. Individuals with the condition must visit their doctor for a new injection every four to eight weeks, typically at a significant personal loss of time and money.
“The idea is we’d like to have a long-lasting treatment so patients wouldn’t have to receive as many injections,” said Chavala. “That would reduce their overall risk of eye infections, and also potentially lower the economic burden of this condition by reducing treatment costs.”
Macular degeneration begins as the “dry” form of the disease, which can result in blurred vision or blind spots. For about 1-in-5 patients, the disease will progress to its “wet” form, which causes abnormal blood vessels to form in the eye and start to leak fluid or blood, causing vision loss.
While anti-VEGF works by affecting the growth factors that cause leaky blood vessels, MDM2 inhibitors attack the abnormal blood vessels directly, causing them to regress. The UNC researchers said they hope to prove that the treatment can have a lasting effect.
The research team examined the effects of the novel treatment in cell cultures and in mice modeled to replicate macular degeneration. They discovered that the MDM2 inhibitors remove the problematic blood vessels that are related to wet macular degeneration by activating a protein called p53.
“p53 is a master regulator that determines if a cell lives or dies. By activating p53, we can initiate the cell death process in these abnormal blood vessels,” said Chavala.
MDM2 inhibitors also have potential advantages over another treatment that is currently being clinically tested: the use of low-dose radiation. The radiation treatment works by causing DNA damage in targeted cells, leading to an increase in p53 and cell death.
The UNC treatment activates p53 without causing DNA damage. Also, the treatment can be given by eye injection instead of radiation treatments that might require surgery to administer.
Up to 11 million Americans have some form of macular degeneration, said to be the most common cause of vision loss in the western world. Those with the condition can find driving, reading, watching TV and other activities becoming increasingly difficult. The Mayo Clinic recommends that individuals see their doctor if their central vision becomes altered or their ability to discern fine colors and detail becomes impaired.