Articles

Patricia A. D'Amore, Ph.D.

Question: I have “wet” age-related macular degeneration (AMD) and have been hearing about new drugs for this disease. Can you comment on whether they work and how?

Answer: Three new drugs have recently become available for “wet” macular degeneration. This form of macular degeneration, unlike the “dry” variety, is characterized by the growth of small blood vessels known as capillaries under the retina, particularly its tiny center, the macula. The macula is responsible for central vision and activities that require visual acuity such as reading, driving and face recognition.  These fragile new blood vessels leak fluid, which collects under the macula, damaging vision.  All three new drugs work by blocking the action of a growth factor called VEGF (vascular endothelial growth factor), which has been proven by scientists to stimulate vessel growth (angiogenesis) and their tendency to leak.

Macugen was the first “anti-angiogenic” therapy for AMD and was approved by the FDA in 2004. Although some successes have been reported, it has not been as effective as ophthalmologists had hoped.

Shortly thereafter, eye doctors began treating patients with Avastin, a drug produced by Genentech that was the first anti-angiogenic therapy approved for treating colorectal cancer.  Ophthalmologists reasoned that if Avastin could block blood vessel growth in tumors, it might also affect angiogenesis in “wet” AMD. Extensive testing in what is known as “off label use” has yielded outstanding results.

Lucentis™ is the latest in this series of drugs.  Created specifically for the treatment of “wet” AMD, it is very similar in structure and action to Avastin.  In a large, two-year study, this drug stopped vision loss in more than 90 percent of patients studied and restored vision in 33 percent.  Scientists are now comparing the efficacy of Lucentis and Avastin, since Avastin is much less expensive than Lucentis.

Side effects are also of concern. For instance, my laboratory has strong evidence that VEGF in the adult also is necessary for the health and integrity of normal blood vessels. The side effects that have been seen in patients taking systemic Avastin support this idea.  So, although anti-VEGF therapies are important and effective, further study is needed to assess long-term effects.

AMD is the leading cause of legal blindness in Americans 55 and older and its numbers will jump from nine to 18 million by 2020. Thus, research into these and other medications to prevent and halt its escalation is of vital interest to us all.

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