by Gail Brashers-Krug
Researchers are finding that two related drugs can stop and even reverse vision loss caused by diabetic retinopathy and age-related macular degeneration (also called AMD), the two leading causes of blindness in America. The two drugs, Lucentis and its chemically similar cousin, a cancer drug called Avastin, are produced by San Francisco-based pharmaceutical Genentech. But one of them—Avastin—is much less expensive.
Genentech’s two drugs, Lucentis and Avastin, work by stopping the growth of new blood vessels. Both are injected directly into the eye, which is a lot less painful than it sounds. Both drugs target wet AMD and proliferative diabetic retinopathy—the forms of the diseases that lead to severe loss of vision, eventually leading to total blindness. Both diseases occur when lots of tiny blood vessels begin growing uncontrollably around the retina, which contains the light-sensitive cells essential to vision. By stopping the growth of new blood vessels and sometimes even destroying some of the excess blood vessels, Lucentis and Avastin can stop wet AMD and proliferative diabetic retinopathy in their tracks.
Lucentis Offers Dramatic Success
Only one of the drugs, Lucentis, is approved by the FDA for use in treating AMD. Approved for use last June, Lucentis has already become the treatment of choice for wet AMD. Lucentis not only stops AMD in many patients, it also reverses the damage, dramatically improving vision in most cases.
Although the FDA has not yet approved Lucentis for treating proliferative diabetic retinopathy, the drug is proving extremely effective in clinical studies. Recently researchers at the Johns Hopkins Wilmer Eye Institute began treating 10 patients, all with early stages of proliferative diabetic retinopathy, with Lucentis injections. After several months of treatment, all 10 patients experienced vision improvement of at least two lines on a standard eye chart. In fact, patients saw dramatic improvements after just one week, according to study investigator and ophthalmology professor Peter Campochiaro, M.D.
Lucentis vs. Avastin: What’s the Difference?
There is no question that Lucentis is an effective treatment for AMD. So why are researchers looking for alternatives to Lucentis? The problem with Lucentis is its cost. A single dose of the drug costs more than $2,000, whereas a single injectible dose of Avastin costs about $150. Even the typical Medicare copayment of 20 percent, or $400, is more than twice as costly as the full price of an injection of Avastin.
Chemically, Lucentis and Avastin are very similar. Lucentis is a small fragment of the much-larger Avastin molecule. To be effective, the drugs must penetrate the tiny vessels of the retina. Genentech researchers originally thought the large Avastin molecule would be too big to do so. But doctors across the country are finding that, when injected directly into the eye, Avastin does its job and reverses the growth of new blood vessels.
The success of Avastin in treating AMD is well documented. Doctors across the country widely use Avastin to treat AMD with great success. Less is known about Avastin’s effectiveness in treating diabetic retinopathy, but medical researchers in Birmingham, Alabama, recently reported that Avastin totally reversed early-stage diabetic retinopathy in only three weeks in a very small study.
The question is whether Avastin, the cheaper drug, is just as safe and effective as Lucentis. Avastin’s manufacturer, Genentech, has no plans to find out. Genentech officials say that they spent millions developing Lucentis as a macular degeneration treatment, and in funding clinical trials proving the drug’s safety and effectiveness. Therefore, Genentech officials say they have no intention of also funding clinical trials for Avastin to treat eye diseases, now that Lucentis has FDA approval.
Instead, the National Eye Institute (NEI) officials announced in October 2006 that they will pay for trials to compare effectiveness and safety of the two drugs as treatment for AMD. So far, the NEI researchers do not plan to study treatment of diabetic retinopathy by the two drugs. They expect to publish results in 2009.
Although the FDA has only approved Avastin for treatment of cancer, it can still be legally used to treat eye diseases. Once a drug is approved by the FDA, physicians may use it “off-label”—that is, for conditions other than the one it was approved for—if they are well-informed about the product, base its use on firm scientific method and sound medical evidence, and maintain records of its use and effects. As a result, ophthalmologists around the country are using Avastin “off-label” to treat AMD and diabetic retinopathy.