Stem-Cell-Derived Treatment for Retinal Diseases Safe Thus Far in Human Study
Widely reported research published last week in the medical journal The Lancet spells good news for the Massachusetts-based Advanced Cell Technology (ACT) and its emerging retinal-disease treatment. Results from two early clinical trials indicate there were no serious adverse events associated with its stem-cell-derived therapy. Also, it appeared to improve vision in some patients with two kinds of macular degeneration which affect central vision and can lead to blindness.
"The most important message we can take away at this juncture is that the treatment did not cause any serious safety issues. Safety is the primary goal of these early-stage trials,” says Stephen Rose, Ph.D., chief research officer of the Foundation Fighting Blindness. “The fact that there are some vision improvements for some patients warrants cautious optimism, but we need to see how ACT’s therapy performs in more people over a longer period of time before we can make reliable assessments of efficacy.”
The Foundation funded earlier, groundbreaking research of Ray Lund, Ph.D., who developed the types of cells being used in ACT’s clinical trials. The Foundation is also supporting several other studies for innovative stem-cell therapies for a wide range of retinal diseases.
ACT launched these first-ever human studies for a stem-cell-derived treatment for retinal diseases in 2011. One study is for people with dry age-related macular degeneration (AMD), a leading cause of blindness in people over 55 years of age living in developed countries. The other is for those with Stargardt disease, an early-onset, genetic form of macular degeneration, which affects about 30,000 people in the United States and tens of thousands more around the world. Nine people with vision no better than 20/200 were treated in each study.
One year after cell transplantation, the vision of seven patients with dry AMD was evaluated. ACT reported that three had vision improvement of at least three lines on an eye chart. One had improvements of two to three lines. Three patients had stable vision.
In the Stargardt disease study, the vision of seven patients was evaluated at one year. Three were reported to have had vision improvement of at least three lines. Three had stable vision. One patient lost two lines of vision.
To grant approval for a therapy, the U.S. Food and Drug Administration often requires vision improvement of three or more lines.
The treatment involves transplantation of retinal pigment epithelial (RPE) cells derived from embryonic stem cells. RPE play an essential supportive role in the retina, providing nutrition and waste removal for photoreceptors, the cells that make vision possible. In both dry AMD and Stargardt disease, accumulation of waste products cause RPE to degenerate. Ultimately, photoreceptors are lost as well.
“The questions that remain are: What are the transplanted RPE cells actually doing? Are they performing like bona fide RPE? Are they producing factors that help keep the retina healthy? Perhaps they are having a placebo effect,” says Dr. Rose. “We just don’t know yet, but we hope to learn much more as the study proceeds and more patients are treated.”