UNC research points to promising treatment for macular degeneration
Researchers at the University of North Carolina School of Medicine today published new findings in the hunt for a better treatment for macular degeneration. In studies using mice, a class of drugs known as MDM2 inhibitors proved highly effective at regressing the abnormal blood vessels responsible for the vision loss associated with the disease.
“We believe we may have found an optimized treatment for macular degeneration,” said senior study author Sai Chavala, MD, director of the Laboratory for Retinal Rehabilitation and assistant professor of Ophthalmology and Cell Biology & Physiology at the UNC School of Medicine. “Our hope is that MDM2 inhibitors would reduce the treatment burden on both patients and physicians.”
The research appeared Sept. 9, 2013 in the Journal of Clinical Investigation.
As many as 11 million Americans have some form of macular degeneration, which is the most common cause of central vision loss in the western world. Those with the disease find many daily activities such as driving, reading and watching TV increasingly difficult.
Currently, the best available treatment for macular degeneration is an antibody called anti-VEGF that is injected into the eye. Patients must visit their doctor for a new injection every 4-8 weeks, adding up to significant time and cost.
“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.” Chavala practices at the Kittner Eye Center at UNC Health Care in Chapel Hill and New Bern.
The Facts on Macular Degeneration
The macula is a tiny circle in the middle of the retina, a light-sensitive membrane that lines the inside of the back of the eye. In older people, it sometimes begins to deteriorate or degenerate for unknown reasons. Women are believed to be more at risk than men. Macular degeneration is the leading cause of legal blindness in Canada, accounting for 34% of cases. However, macular degeneration rarely leaves you totally unable to see.
There are two types of this disease:
Dry macular degeneration accounts for about 90% of cases. The tissue of the retina shrinks and pigments accumulate inside of it. Dry macular degeneration can progress to the wet form.
In wet macular degeneration, new blood vessels grow around and behind the macula. There’s sometimes bleeding in or behind the macula. Material seeps into the retina and settles in the macula. This is called an exudate. Eventually the exudate disappears, but a scar takes its place. All people who have wet macular degeneration had dry macular degeneration first.
All patients with age-related macular degeneration start out with the “dry” form of the disease, which can cause blurred vision or blind spots. In about 20 percent of patients, the disease progresses to its “wet” form, in which abnormal blood vessels form in the eye and begin to leak fluid or blood, causing vision loss.
While anti-VEGF works by targeting the growth factors that lead to leaky blood vessels, MDM2 inhibitors target the abnormal blood vessels themselves causing them to regress - potentially leading to a lasting effect.
Wet macular degeneration can’t be cured. If diagnosed early, treatment may help slow progress of wet macular degeneration and reduce the amount of vision lost.
Medications to stop growth of abnormal blood vessels
Medications may help stop growth of new blood vessels by blocking the effects of growth signals the body sends to generate new blood vessels. These drugs are considered the first-line treatment for all stages of wet macular degeneration.
Medications used to treat wet macular degeneration include:
Bevacizumab (Avastin)
Ranibizumab (Lucentis)
Pegaptanib (Macugen)
Aflibercept (Eylea)
Your doctor injects these medications directly into your eye. You may undergo repeat injections every four weeks to maintain the beneficial effect of the medication. In some instances, you may partially recover vision as the blood vessels shrink and the fluid under the retina absorbs, allowing retinal cells to regain some function.
Some of these medications may increase the risk of stroke.
Chavala and his colleagues investigated the effects of MDM2 inhibitors in cell culture and in a mouse model of macular degeneration. They found that the drug abolishes the problematic blood vessels associated with wet macular degeneration by activating a protein known as 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 conceivable advantages over another treatment that is currently being investigated in several clinical trials: the use of low-dose radiation for wet macular degeneration. Radiation works by causing DNA damage in cells leading to an increase in p53 and cell death. MDM2 inhibitors activate p53 without causing DNA damage. Also, MDM2 inhibitors can be given by eye injection, which is advantageous over some forms of radiation treatment that require surgery to administer.
Co-authors include Younghee Kim, Nagaraj Kerur and Jayakrishna Ambati of the University of Kentucky; Laura Tudisco, Valeria Cicatiello and Sandro De Falco of the Institute of Genetics and Biophysics in Napoli, Italy; Till Milde, Nidia Claros and Shahin Rafii of Weill Medical College of Cornell University; Susan Yanni and John S. Penn of Vanderbilt University; Victor H. Guaiquil of the Hospital for Special Surgery in New York, N.Y.; William W. Hauswirth of the University of Florida; and Thomas C. Lee of Children’s Hospital Los Angeles.
Disclosure Statement: Dr. Chavala has filed a patent for the use of MDM2 inhibitors for treating ocular conditions and is founder of Serrata, LLC, which plans to commercialize novel treatments for ocular disease.
###
Media Contact: Tom Hughes, .(JavaScript must be enabled to view this email address), 919-966-6047