U.S. Human Study for Choroideremia Gene Therapy Launched by Spark Therapeutics

January 27, 2015

The rapidly advancing field of vision-saving gene-therapies is taking a significant step forward with the launch of a U.S. clinical trial for a treatment for choroideremia, a blinding condition affecting males. Researchers believe a single dose of the therapy, which replaces mutated copies of the choroideremia gene, CHM, with healthy copies, will halt or possibly reverse the disease process for several years. The Foundation Fighting Blindness provided funding over two decades for lab studies that helped make the trial possible.

Spark Therapeutics, a gene-therapy development company, will conduct the 10-person study at the Children’s Hospital of Philadelphia and the University of Pennsylvania. The trial will be led by Spark co-founder Jean Bennett, M.D., Ph.D., whose groundbreaking gene-therapy study, now in its final phase, has restored vision in children and young adults affected by the retinal disease, Leber congenital amaurosis (LCA). While evaluating safety is the primary goal of the choroideremia trial, researchers will also monitor changes in vision and retinal structure. Two doses of the treatment will be evaluated.

The launch of Spark’s trial comes one year after the University of Oxford announced encouraging results for its choroideremia gene-therapy clinical trial, in which five of six participants  reported vision improvements. Nightstarx, a biopharmaceutical company spun-off from the university, is now leading clinical development of the U.K. treatment, which recently drew an investment of approximately $25 million.

In addition, a research team led by Ian MacDonald, M.D., at the University of Alberta in Edmonton, Canada, is planning to initiate a choroideremia gene-therapy human study shortly. The gene-therapy in that trial will be provided by Nightstarx.

“The momentum today behind choroideremia gene-therapy development is remarkable,” says Stephen Rose, Ph.D., chief research officer, Foundation Fighting Blindness. “We are very excited for the U.S. trial launch, because we have a tremendous need with 6,000 people in the country affected by the condition. Spark is leveraging what’s been learned in the U.K. trial, which further boosts the prospects for saving and potentially restoring functional vision.”

Both the U.S. and U.K. choroideremia clinical trials have benefitted from the Foundation’s investments in the research of Miguel Seabra, Ph.D., who played a lead role in understanding the choroideremia gene’s function, creating a mouse model of the condition, and developing a prototype version of the treatment. 

The Foundation also funded Dr. Bennett’s preclinical choroideremia work and provided extensive support for her  LCA gene therapy human study. One of the first ever for a retinal disease, that trial is paving the way for other retinal-disease, gene-therapy studies in humans.

Choroideremia leads to degeneration of the choroid, the vasculature that provides oxygen and nourishment to the retina. Photoreceptors, the cells that make vision possible, and a layer of supportive cells known as the retinal pigment epithelium, are also affected in people with the condition.

For participant recruitment information on the Spark trial, visit the clinical trials website of the National Institutes of Health.