Dry age-related macular degeneration (AMD) is the leading cause of vision loss in the U.S. By 2020 it’s estimated that as many as three million Americans will be affected by the disease. Right now, there is no effective therapy. But that could change. A new CIRM-funded clinical trial is showing promise in helping people battling the disease not just in stabilizing their vision loss, but even reversing it.
In AMD, cells in the retina, the light-sensitive tissue at the back of the eye, are slowly destroyed affecting a person’s central vision. It can make it difficult to do everyday activities such as reading or watching TV and make it impossible for a person to drive.
Researchers at the University of Southern California (USC) Roski Eye Institute at the Keck School of Medicine, and Regenerative Patch Technologies, have developed a therapy using embryonic stem cells that they turned into retinal pigment epithelium (RPE) cells – the kind of cell destroyed by AMD. These cells were then placed on a synthetic scaffold which was surgically implanted in the back of the eye.
Imaging studies showed that the RPE cells appeared to integrate well into the eye and remained in place during follow-up tests 120 to 365 days after implantation.
Of the five patients enrolled in the Phase 1/2a trial, four maintained their vision in the treated eye, two showed improvement in the stability of their vision, and one patient had a 17-letter improvement in their vision on a reading chart. In addition, there were no serious side effects or unanticipated problems.
There were other indications the implants were proving beneficial. People with normal vision have the ability to focus their gaze on a single location. People with advanced AMD lose that ability. In this trial, two of the patients recovered stable fixation. These improvements were maintained in follow-up tests.
Abla Creasey, Ph.D., CIRM’S Vice President of Therapeutics and Strategic Infrastructure says even these small benefits are important:
“Having a therapy with a favorable safety profile, that could slow down the progression, or even reverse the vision loss would benefit millions of Americans. That’s why these results, while still in an early stage are encouraging, because the people treated in the trial are ones most severely affected by the disease who have the least potential for visual recovery.”
This study reflects CIRM’s long-term commitment to supporting the most promising stem cell research. The Stem Cell Agency began supporting USC’s Dr. Mark Humayun, the lead inventor of the implant, in 2010 and has been a partner with him and his team since then.
In a news release Dr. Humayun said they plan to recruit another 15 patients to see if these results hold up:
“Our study shows that this unique stem cell–based retinal implant thus far is well-tolerated, and preliminary results suggest it may help people with advanced dry age-related macular degeneration.”
While the results, published in the journal Science Translational Medicine, are encouraging the researchers caution that this was a very early stage clinical trial, with a small number of patients. They say the next step is to continue to follow the four patients treated in this trial to see if there are any further changes to their vision, and to conduct a larger trial.