Researchers at Bascom Palmer Eye Institute, the Department of Ophthalmology at the University of Miami Miller School of Medicine, took part in an international multi-center study titled Initial Results from a First-in-Human Gene Therapy Trial on X-linked Retinitis Pigmentosa Caused by Mutations in RPGR. This gene therapy trial represents newfound hope for those with this disease.
X-linked Retinitis Pigmentosa
Retinitis pigmentosa is a group of related eye disorders that cause progressive vision loss. These disorders impact the retina, which is the layer of light-sensitive tissue at the back of the eye. In people with retinitis pigmentosa, vision loss occurs as the light-sensing cells of the retina gradually deteriorate. X-linked Retinitis Pigmentosa is an inherited condition caused by mutations in the RPGR gene.
According to Byron L. Lam, MD, the principal investigator for Bascom Palmer, “X-linked retinitis pigmentosa related to the GTPase regulator (RPGR) gene is one of the most common and severe types of this disease.” He continued, “This gene therapy study offers hope for patients with this currently untreatable blinding disease.”
The study team recruited 18 patients to participate in the six-month Phase I/II dose escalation clinical trial for X-linked retinitis pigmentosa (RP) caused by the RPGR gene mutation, which blocks production of a protein necessary for proper functioning of the photoreceptor cells in the retina. This mutation accounts for 70% of all cases of X-linked retinitis pigmentosa, which leads to night blindness in early childhood followed by progressive daytime vision loss.
Dr. Lam reported that the initial Phase I/II study offered the foundation for the broader randomized Phase II/III clinical and continued, “Bascom Palmer is the only U.S. site participating in these trials. We now have more than 15 patients enrolled in the new study, and our team is forging ahead with gene therapy research in many types of inherited retinal diseases.”
Most of the patients treated by Bascom Palmer are men in their 20s and 30s who are experiencing serious vision problems. Patients are given genetic tests to identify the mutation so that appropriate gene therapy can be administered.
Based on the published results thus far in Nature, the authors referred to the study identifier NCT03116113. The study sponsor, NightstaRx Ltd, which was acquired by Biogen in March 2019. NightstRx focused on developing and commercializing novel one-time treatments for patients suffering from rare inherited retinal diseases that would otherwise progress to blindness.
The study team performed the RPGR gene therapy surgery using an adeno-associated viral vector on one patient in the initial study and treated 9 more participants using the optimized dosing determined from the initial trial. The results haven’t been published yet. However, one of the investigators, Dr. Janet L. Davis, reports, “The results from this initial trial showed no significant safety concerns after gene therapy surgery. “ For example, she continues, “Visual field improvements were observed in some patients, and these favorable findings support Bascom Palmer’s wide-ranging gene therapy research.”
Bascom Palmer Eye Institute: A Leader in Gene Trials
By 2018, Bascom Palmer Eye Institute of the University of Miami Health System ophthalmologists had undertaken one of the nation’s first gene therapy surgeries using Luxturna, the first ocular gene therapy drug approved by the Food and Drug Administration, to treat a child with a binding vision disease. The center has treated a number of cases thereafter. Bascom Palmer is the largest ophthalmic care, research and educational facility in the southeastern United States, treating more than 260,000 patients annually. Bascom again ranked number one U.S. News & World Report.
Byron L. Lam, MD, M.D., the Robert Z. & Nancy J. Greene Professor of Ophthalmology, and Bascom Palmer’s principal investigator
Janet L. Davis, MD Leach Distinguished Professor of Ophthalmology