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News Tips from the Eyes of Innovation, 2008 Annual Meeting of The Association for Research in Vision and Ophthalmology (ARVO)
April 27 - May 1, 2008, at The Greater Fort Lauderdale/Broward County Convention Center in Fort Lauderdale, Florida
DRUG THERAPY MORE EFFECTIVE THAN STANDARD TREAMENT IN FIGHT AGAINST DIABETES RETINAL SWELLING
Researchers at the Johns Hopkins Wilmer Eye Institute and 14 clinical centers around the United States have shown that the drug ranibizumab can reduce retinal thickness and improve the visual acuity of patients with diabetic macular edema (DME) better than the current standard treatment, laser photocoagulation.
“The READ-2 study results are promising and show that ranibizumab injection into the eyes improves vision by resolving retinal thickening much better than laser photocoagulation,” says Quan Dong Nguyen, M.D., M.Sc., an assistant professor of ophthalmology at Hopkins’ Wilmer Eye Institute.
Macular edema, one of the most common causes of blindness among working-age people, occurs when fluid and protein deposits collect on or under the macula of the eye, a yellow central area of the retina, causing it to thicken and swell.
The READ-2 (Ranibizumab for Edema of the mAcula in Diabetes phase 2) Study examined 126 diabetic patients with an average age of 62 years. The majority of participants had chronic DME with 20/80 vision. Patients were randomly assigned to one of three groups: ranibizumab injection alone, focal laser photocoagulation alone, or a combination of ranibizumab injection plus focal laser photocoagulation. At each visit over the course of six months, patients were evaluated for vision, retinal thickening and general eye health. Although the study ended at 6 months, patients will be followed for two years.
Eyes treated with ranibizumab had a mean visual acuity of 20/63+3 at month six compared to a mean visual acuity of 20/80+2 in the laser group and 20/80+3 in the combination treatment group. In addition, eyes treated with ranibizumab had a 56 percent reduction in excess retinal thickness compared to only an 11 percent reduction in laser treated eyes.
“Although the results of this study are promising, a several-year long phase 3 randomized trial is needed to determine the ultimate value of ranibizumab for patients with DME,” says Nguyen. Two phase 3 trials currently are underway.
PROMISING TREATMENT FOR RETINAL THICKENING
Johns Hopkins researchers have found that injections of the drug ranibizumab, which binds the protein VEGF, can rapidly improve vision and reduce macular swelling caused by blockages in the retinal vein, suggesting that VEGF is a major contributor to macular edema.
“Some patients stabilize after only a few injections and some require several injections, but the results are very encouraging,” says Peter A. Campochiaro, M.D., the George S. and Dolores Doré Eccles Professor of ophthalmology and neuroscience at the Johns Hopkins Wilmer Eye Institute.
Twenty patients with macular edema due to central retinal vein occlusion and 20 patients with macular edema due to branch retinal vein occlusion were randomized to receive 3 monthly injections of ranibizumab. One month after the third injection, patients were evaluated for vision improvement and the average improvement was a doubling of the visual angle. “This was a substantial improvement,” says Campochiaro. “Higher doses led to faster recovery that lasted somewhat longer, but had no effect on improving vision,” he adds.
The VEGF protein-vascular endothelial growth factor-long has been suspected as a culprit behind blood vessel leakage and macular edema, according to Campochiaro. Since ranibizumab is known to bind VEGF, these results strongly suggest that VEGF is a major contributor to retinal vein occlusion-induced edema, he says.
The results of the three month end point of this study appeared in April issue of Molecular Therapy, but the FDA has allowed continued treatment and additional follow up will be reported at the Association of Research in Vision and Ophthalmology meeting. Two phase 3 trials currently are underway.
Both research projects are funded in part by Genentech; Nguyen and Campochiaro are not paid consultants.
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