Eye On the Cure Research News

Jul 21, 2016

Stem-Cell Therapy for Retinitis Pigmentosa Safe Thus Far in Early Human Study

The trial is one of the first-ever for a stem-cell-derived therapy for RP.

Photo of researchers in a laboratory.

An emerging stem-cell-derived treatment designed to preserve and potentially restore vision in people with retinitis pigmentosa (RP) has demonstrated a favorable safety profile in an ongoing Phase I/II clinical trial at the University of California, Irvine. The therapy is being developed by the regenerative medicine company jCyte with trial funding from the California Institute for Regenerative Medicine. Earlier research funded by the Foundation Fighting Blindness helped advance this therapeutic approach toward a human study.

Given this trial is one of the first-ever for a stem-cell-derived therapy for RP, this safety report is good news and an important step in the right direction. We at the Foundation look forward to additional reports from this study in the coming years as the trial advances.

The therapy involves the injection of retinal progenitors — stem cells that are in the process of becoming retinal cells — into the vitreous, the gel-like substance in the middle of the eye. Researchers believe the cells will release proteins that will keep the patient's existing photoreceptors healthy, preventing their degeneration and preserving vision. Investigators also believe the proteins might rescue cones that have stopped processing light, but haven't fully degenerated. Cones are the photoreceptors that provide the ability to read, recognize faces, and see in lighted conditions.

The company reported interim safety results for the first nine trial participants, the first of which was treated one year ago. All nine participants have had at least six months follow up. The trial has successfully gone through four reviews from a Data Safety Monitoring Board, a group of independent experts who monitor clinical outcomes for safety.

Henry Klassen, M.D. Ph.D., jCyte co-founder and the trial's principal investigator, is pleased with the results thus far. He cautions that it is too early in the study to address treatment efficacy.

Dr. Klassen says that the therapy has two potential advantages over other stem-cell therapies for the retina. First, patients are not receiving immunosuppressive treatment to prevent rejection of the therapeutic cells. Preclinical studies showed that cells of this type did not elicit an adverse response (i.e., rejection) from the recipient's immune system. Second, the injection of cells into the vitreous is simple to perform and less likely to cause complications than an injection of cells underneath the retina, which may be performed to deliver other stem-cell-derived treatments.