Latest Update: Gene Therapy Restores Significant Vision to Children with LCA
Drs. Albert Maguire, Katherine High and Jean Bennett of CHOP have successfully reversed blindness in twelve LCA patients.
CHOP researchers began the study two years ago and, in 2008, reported vision improvement for their first three participants, all of whom were young adults. The results of these first participants were heralded worldwide as one of the greatest breakthroughs in medical research.
Over the past 18 months, CHOP researchers have treated nine more individuals, ranging in age from 8 to 44. Just two weeks following treatment, all of the patients reported improved vision in dimly lit environments. Since treatment, each of these participants has demonstrated improvements in visual acuity, peripheral vision, and light sensitivity in the treated eye.
Leber congenital amaurosis is a form of retinitis pigmentosa that can cause blindness or severe vision loss at birth. Patients involved in the trial have LCA2, a form of the disease caused by a defect in a gene, called RPE65. Treatment involved injecting a normal version of the gene into one eye -- their worst-seeing eye.
The most dramatic vision improvements occurred in the youngest patients, whose retinal degeneration was less advanced than that of older participants. All four children in the study, ages 8 to 11 when treated, demonstrated a significantly improved ability to navigate an obstacle course after treatment.
“Children who were treated with gene therapy are now able to walk and play just like any normally sighted child,” said Albert M. Maguire, M.D., a lead investigator in the trial. “They can also carry out classroom activities without visual aides.”
The youngest patient, Corey Haas, who was treated 13 months ago and is now 9 years old, has shown the greatest improvement. While his vision is not perfect, his visual acuity is vastly improved and his field of vision is now comparable to that of someone with normal vision. When asked what he thinks is the biggest difference, he says that colors are now much brighter and more vibrant. Corey no longer relies on his white cane to navigate rooms and can now read large print books.
On the other end of the age spectrum, the oldest patient, a 44 year old woman, has also experienced remarkable improvement in her vision. She can now walk down the street, unassisted, to meet her children after school. Going into the trial, she said that her personal goal was to see her daughter hit a home run in a softball game. As a result of gene therapy, that goal has become a reality.
“The Foundation began funding the research leading to this successful gene therapy more than two decades ago when it was still just a concept, and we have been a key funding resource for the project virtually every step of the way,” says William T. Schmidt, chief executive officer, Foundation Fighting Blindness. “We are delighted to see that our sustained support of this effort has led to such dramatic and life-changing results.”
All 12 patients continue to experience some level of sustained improvement in their vision. Investigators do not know when the continued vision improvement will level out, nor do they know how long the effects of the treatment will last. Past studies indicate that improved vision may last for many years to come; dogs that received gene therapy treatment over nine years ago continue to maintain their vision today. Researchers will continue to monitor these patients for the next 15 years to ensure safety and to determine whether this treatment stops the progression of the degeneration.
“These results are outstanding. We are delighted by not only the restoration of vision, but also that vision improvement has been sustained,” says Stephen Rose, Ph.D., chief research officer, Foundation Fighting Blindness. “The success of this groundbreaking effort is paving the way to use gene therapy to treat a wide range of retinal degenerative diseases. Recently, more and more companies and institutions have begun developing gene therapies for retinal diseases such as Stargardt disease, Usher syndrome, retinoschisis, and age-related macular degeneration, because of this early success.”