Tests of a new oral medication show the drug can improve vision in children with an inherited disease that can cause complete blindness and is currently untreatable.
“This is the first time that an oral drug has improved the visual function of blind patients with LCA (Leber congenital amaurosis),” says Robert Koenekoop, professor of human genetics, pediatric surgery, and ophthalmology at McGill University. “It is giving hope to many patients who suffer from this devastating retinal degeneration.”
Published in the Lancet, the study involved 14 participants from around the world with LCA ranging in age from 6 to 38 years old. Their blindness was caused by either mutations in the genes RPE65 or LRAT, leading to a serious defect in the retinoid cycle. The retinoid cycle is one of the most important cycles in the human retina because it produces a molecule called 11-cis retinal which has the special capacity to capture light and initiate vision.
Patients with RPE65 or LRAT mutations cannot produce this crucial molecule thus the retinal cells cannot create vision, and slowly die.
“By giving patients with RPE65 or LRAT mutations an oral retinoid intermediate (QLT091001) most patients’ vision improved rapidly. We discovered that a certain portion of the retinal cells that were not working because of the lack of 11-cis retinal could be woken up,” Koenekoop says.
“Contrary to what was previously thought, children with LCA and defects in RPE65 or LRAT are not born with dead retinal cells; the cells can simply go dormant, and they can remain dormant for years before they eventually die. The oral drug we tested awakened these cells and allowed patients to see.”
Ten out of the 14 patients expanded their visual fields; others improved their visual acuity. Researchers performed special brain scans of the visual cortex, which showed marked improvements in brain activities in patients who also improved in field size and acuity. More research will now be conducted to learn more about the retinal function in blind people in relation to dosage and methodology.
Researchers from McGill University, Johns Hopkins University, and Stanford University contributed to the study, which was funded by QLT Inc, the Foundation Fighting Blindness Canada, the Canadian Institutes of Health Research, the Fonds de recherche du Québec-Santé, and the Montreal Children’s Hospital Foundation.
《Oral 9-cis retinoid for childhood blindness due to Leber congenital amaurosis caused by RPE65 or LRAT mutations: an open-label phase 1b trial》, Published on Journal 《Lancet》in July 2014.