Drug for RP and LCA Continues to Perform Well in Clinical Trial
A drug designed to save and restore vision in people with
retinitis pigmentosa (RP) and Leber congenital amaurosis (LCA) caused by
defects in the RPE65 or LRAT genes continues to show positive preliminary
results in a Phase Ib clinical trial taking place in several locations
worldwide. The study, which began in 2010 and was made possible by earlier
studies funded by the Foundation, is evaluating both safety and effectiveness
of the oral treatment.
QLT, Inc., the maker of the drug, reported on March 1, 2012, that visual field improved on average by 22 percent for 17 people with RP after they took a seven-day course of the treatment. Nine of the 17 subjects also had improvement in visual acuity of at least one line on an eye chart.
In spring 2011, QLT announced positive preliminary trial results for 12 people with LCA. All patients responded well, reporting some gains in acuity and/or sizes of their visual fields. The investigators were encouraged that the effect of the week-long oral treatment persisted for several months.
Known as QLT091001, the drug replaces a retinoid, a form of vitamin A, which is necessary for vision, but is missing in people with RP or LCA caused by RPE65 or LRAT mutations.
“Vitamin A is an essential ingredient in the visual cycle, the biochemical process that makes vision possible. But for it to work, it needs to get processed and recycled into different forms called retinoids, including the retinoid 11-cis-retinal,” says Dr. Stephen Rose, the Foundation’s chief research officer. “QLT’s drug replaces the 11-cis-retinal that’s missing in certain forms of RP and LCA. And early study results show that it’s working.”
Scientists funded by the Foundation have conducted extensive research to understand the role of LRAT and RPE65 mutations in LCA and RP, giving targets for related treatments to companies such as QLT.
QLT is evaluating increased and longer term dosing of the drug for both safety and effectiveness. The company continues to recruit participants for the trial, which it hopes to conclude before the end of 2012. Seven clinical research centers are conducting the trial for autosomal recessive forms of RP and LCA. The Montreal Children’s Hospital is also recruiting patients with the autosomal dominant form of RP caused by RPE65 mutations.