Taking aim at macular degeneration.
To learn more about the emerging therapies under investigation, MU spoke with ophthalmologist Dr. Thomas A. Ciulla, a highly regarded expert and author on macular degeneration.
"We're on the cusp of many exciting breakthroughs with a host of new drugs on the horizon," says Dr. Ciulla, who is also an assistant professor at Indiana University School of Medicine. "Previously, we used treatments that were 'destructive' to treat MD. For example, we would laser a patient's retina to stop wet macular degeneration from progressing to the center of the retina. Laser is a fancy way of cauterizing or destroying tissue. Often, laser causes a blinding scar and in at least half the patients, it didn't work; blood vessels would continue to grow, sometimes more vigorously. Recently we've learned that certain growth factors, such as vascular endothelial growth factor (VEGF), are responsible for the new blood vessels under the patient's retina. We're now developing several drugs that target VEGF to prevent blood vessels from growing or expanding. Within the next few years, several drugs will hopefully be approved and available for general use.
Three new drugs are currently in final phase III testing. In general, patients with recent onset of wet macular degeneration may be eligible for one of these studies.
"One drug made by Genentec is called Lucentis (ranibizumab), an antibody fragment injected in the eye that is designed to bind to and inhibit VEGF," explains Dr. Ciulla.
"Another medication in phase III trials is Macugen from Eyetech and Pfizer. Macugen is an anti-VEGF aptamer that binds to and thus inhibits the activity of VEGF when injected in the eye.
"Finally, Retaane (anecortave acetate) made by Alcon, also in phase III trials, is a steroidal compound that is injected around the eye."
The drugs might also someday be used to treat other eye disorders, such as diabetic retinopathy and venous occlusions.
"VEGF is potentially the key growth factor in macular degeneration, because it mediates the growth of abnormal blood vessels," notes Dr. Ciulla. "Many other eye diseases involve abnormal blood vessel growth in and under the retina. Diabetic retinopathy, for example, involves the growth of blood vessels not under the retina, as is the case in MD, but on the surface of the retina and into the vitreous cavity. When blood vessels are pulled, they can tear. As they fracture, blood is released into the vitreous cavity, and many diabetics will have hemorrhage into the eye. These drugs may be beneficial for diabetic retinopathy.
"Another common cause of blindness is venous occlusion, which involves a very similar process to diabetic retinopathy, where blood vessels can grow on the surface of the retina and into the vitreous cavity and cause bleeding. In addition, because the vein is blocked, the blood flow in the eye is backed up and the retina will swell, a condition called macular edema that causes symptoms very similar to MD. We are starting a trial using Macugen to investigate its potential for macular edema induced by vein occlusions."
"When I started eight years ago, retinal and vitreous diseases were largely surgical disorders," concludes Dr. Ciulla. "Many of these diseases had poor prognoses, and many patients lost vision regardless of what we did.
"Now we're on the horizon of a very exciting time with many novel drugs to potentially treat MD, diabetic retinopathy, and venous occlusions."
People interested in learning more about ongoing trials may visit alconlabs.com for Retaane; genentech.com for Lucentis; and eyetech.com for Macugen.
Foods High in Lutein/Zeaxanthin
Green peas (pod)
Summer (yellow) squash
Peach, orange, tangerine, avocado, kiwi fruit, rhubarb.
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|Date:||Sep 1, 2004|
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