Researchers in the Casey Eye Institute at Oregon Health & Science University (OHSU) will begin participation this week in a gene therapy trial for people with age-related macular degeneration (AMD). The disease involves abnormal growth of blood vessels in the eye. AMD affects approximately 8 million Americans and is the leading cause of adult blindness in the United States.
The multicenter clinical trial involves a gene called the Pigment Epithelium-Derived Factor (PEDF) gene. The gene produces PEDF protein, which regulates the formation of blood vessels. In patients with AMD, it appears this protein does not exist in sufficient amounts to prevent uncontrolled blood vessel growth, often resulting in vision loss.
To introduce the PEDF gene into the eye, researchers will inject an adenovirus carrying the gene. While the virus is unable to replicate, it acts as a vehicle to incorporate the gene into the diseased eye. Researchers hope this will result in increased PEDF protein levels, slowing or halting the progression of AMD. Animal research involving the PEDF gene has led to increased PEDF protein levels in the eye without side effects.
"Currently there is only one Food and Drug Administration-approved treatment for macular degeneration. Gene therapy holds the possibility of becoming a powerful treatment for AMD," explained Timothy Stout, M.D., Ph.D., an associate professor of ophthalmology in the OHSU School of Medicine and co-principal investigator of the study.
"This research is a phase-one clinical trial, meaning we're primarily testing for the safety of this treatment," explained Michael Klein, M.D., director of the OHSU Macular Degeneration Center and co-principal investigator. "This is a very important first step. However, years of research will be necessary to determine whether this type of therapy is effective and if it can be made available for use by patients with AMD."