Improving the View: Treatment reverses macular degeneration
People with a relentless eye disease now have a better-than-average prospect of recovering some vision, thanks to a new drug that takes a lesson from an anticancer strategy, two studies show.
Age-related macular degeneration is the leading cause of blindness in the elderly. In the less common, wet form of the disease, rogue blood vessels escape normal growth control and leak fluid into the macula, the area at the center of the retina that enables a person to see fine detail.
As a result of fluid disrupting their sight, people with the condition often see straight lines as crooked. This form of macular degeneration can lead to legal blindness within months.
Cancer researchers have developed a drug to stop the similarly aberrant blood vessel growth that’s often present in tumors. The new eye studies showcase a drug called ranibizumab, which is a fragment of the cancer drug. Both drugs inhibit a protein essential to blood vessel growth, says David M. Brown, a retina surgeon at Methodist Hospital in Houston who worked on both trials.
Preliminary studies of ranibizumab convinced the Food and Drug Administration in June to approve the drug to treat wet macular degeneration. The two new large trials, reported in the Oct. 5 New England Journal of Medicine, establish that ranibizumab reverses the disease in many patients.
“This is a huge breakthrough,” says Frederick Ferris, clinical director of the National Eye Institute in Bethesda, Md. “This treatment is remarkably different from other treatments.” He likened it to the added power that penicillin contributed to the fight against infections.
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One wet macular degeneration trial enrolled 716 patients, and the other followed 423. Two-thirds of the participants in each study were randomly assigned to receive a monthly ranibizumab injection in their affected eye, and one-third got an inert injection. In the smaller study, the control group also received a standard treatment—the drug verteporfin followed by laser light, which activates verteporfin. That treatment also combats abnormal vessel growth.
After 2 years, patients getting ranibizumab in the larger study could see an average of one additional line on an eye chart. More than one-fourth of them had regained three lines. After 1 year in the smaller trial, patients getting ranibizumab had recovered one to two lines of visual acuity.
In contrast, patients getting the sham injections in both trials had, on average, lost acuity and could see two fewer lines—whether or not they got the verteporfin treatment.
Ranibizumab isn’t a sure cure, however. Some patients getting the drug in each trial still showed considerable vision loss. And even when the drug is successful, patients might need to continue receiving the monthly injections indefinitely.
Nevertheless, the effect in most patients is dramatic, says ophthalmologist Edwin M. Stone of the University of Iowa Hospitals and Clinics in Iowa City, who was not on the research team for the trials. He’s observed that the rogue blood vessels in the eye wither and stop leaking shortly after contact with ranibizumab. The vision of one of his patients improved from significantly impaired, 20/100, to near perfect.
“We’re finally getting medical treatments in which we figure out the underlying mechanisms [of a disease] and design elegant ways to counteract them, as opposed to trial and error,” Brown says.
Ranibizumab is marketed under the name Lucentis by its maker Genentech of South San Francisco, Calif.