In the seven years since companies including Genentech/Roche and Regeneron launched new drugs to slow vision loss from an eye disorder called “wet” age-related macular degeneration, the market for those drugs has risen to an estimated $4 billion.
But that substantial market may some day be dwarfed by the revenues flowing to companies with new treatments that can thwart the earlier and much more common form of macular degeneration, dubbed the “dry” form, which also erodes vision as it progressively damages a key eye structure called the macula.
Not surprisingly, a pack of pharmaceutical giants and smaller biomedical companies are pursuing possible treatments for dry age-related macular degeneration (AMD), which afflicts an estimated 20 million to 30 million people worldwide. Competitors are testing different drug types, including antibodies and small molecules, and are targeting various biological mechanisms suspected as factors in the eye disorder.
Taking another tack, companies such as Newark, CA-based Stem Cells, Inc. (NASDAQ: [[ticker:STEM]]) are injecting preparations of live cells into the eyes of clinical trial participants with the dry version of the disorder. The hope is that these stem cells will incorporate themselves into the eye structure, and take on the work of a class of eye cells that normally maintain the health of the macula, a small but crucial spot near the center of the retina that is key to sharp central vision.
In the normal eye, maintenance cells called retinal pigment epithelium (RPE) cells help clear away waste products that can damage photoreceptor cells in the macula, says Stem Cells CEO Martin McGlynn. But if the maintenance cells malfunction, the waste buildup can cause the macula to atrophy, resulting in blind spots or blurred vision.
“The RPE layer is the main suspect in age-related macular degeneration,” McGlynn says.
Last year, the first participants in Stem Cells’ early stage trial of its experimental therapy received injections of 200,000 purified human neural stem cells beneath the retina in the back of the eye. The first goal of the trial, which began at the Retina Foundation of the Southwest in Dallas, TX, is to evaluate the safety of the company’s cell preparation, called HuCNS-SC.
Based on follow-up data from the first four trial participants, an independent safety committee late this year cleared the way for Stem Cells to begin injecting new participants with a higher dose of one million cells—the dose the company expects to use if the therapy proves successful in forestalling vision loss. Stem Cells has added the Byers Eye Institute at Stanford in Palo Alto, CA as a trial site, and has gained FDA permission to enroll participants at as many as three other US sites.
Stem Cells has also been testing its neural stem cells as treatments for other diseases. Its clinical trial in spinal cord injury, for example, started earlier than the trial in macular degeneration. But the eye studies will yield results more quickly than the programs in other diseases, McGlynn says, so the stem cell treatment for dry AMD may turn out to be the company’s first product submitted for FDA approval.
Stem Cells plans to enroll 16 participants in the current eye trial. Depending on the results,
