First Clinical Trial of an RP Stem-Cell Therapy Poised to Launch

May 06, 2015

The U.S. Food and Drug Administration (FDA) has authorized the initiation of the first human study of a stem-cell treatment for people with retinitis pigmentosa (RP). ReNeuron, a stem-cell development company in the United Kingdom, will conduct the 15-particpant, Phase I/II trial of its emerging therapy at Massachusetts Eye and Ear Infirmary (MEEI).

Eric Pierce, M.D., Ph.D., director of the Berman-Gund Laboratory at MEEI and former chairman of the Scientific Advisory Board of the Foundation Fighting Blindness, will be the study’s lead investigator. Dean Elliott, M.D., associate director of the MEEI Retina Service, will perform the surgery. The Foundation played a role in organizing the trial and funded pre-clinical research that made it possible.

The treatment is designed to save and restore vision in people with moderate to advanced RP. It involves the injection of human retinal progenitor cells (hRPCs), which are more mature than embryonic stem cells, but haven’t completely developed into photoreceptors, the cells in the retina that make vision possible. Researchers believe that once they’re injected underneath the patient’s retina, the hRPCs will develop into, and function as, normal, mature photoreceptors. In addition to integrating with the patient’s retina to potentially restore vision, the cells are expected to slow degeneration of existing photoreceptors.

“First, we need to ensure that this is a safe treatment. It involves a cell type that’s never been injected into a patient before,” says John Sinden, Ph.D., ReNeuron’s chief scientific officer. “The pre-clinical data was very clean. We didn’t see any immune reaction or tumors whatsoever.”

While evaluating safety is the primary goal of the study, clinical investigators will also be looking at changes in visual acuity, visual field, retinal sensitivity and retinal structure.

Using a strategy called dose escalation to help ensure safety, the investigators will increase the number of injected cells as patients are treated. The first three patients will receive 250,000 cells. The next three will get 500,000. The last three will receive one million. If there are no issues, the investigators will continue with the one-million-cell dose in subsequent patients.

“Based on what we observe in the first nine patients, we will consider injecting cells in areas of the retinas of the final six patients, where we may get a better effect in preserving vision,” says Dr. Sinden. “We’ll move closer to the central retina and increase the area of coverage. Ultimately we want the data to guide us in designing a pivotal, Phase III trial to demonstrate genuine efficacy.”

ReNeuron consulted with the Foundation’s Clinical Research Institute (CRI) in designing and organizing the groundbreaking clinical trial. “We were delighted to play a role in getting ReNeuron’s study off the ground,” says Patricia Zilliox, Ph.D., chief drug development officer at CRI. “While we are always cautious about our expectations at this early stage of a human study, we are nonetheless optimistic. This is a big step forward for what we hope is reversing blindness.”

The Foundation also funded decades of stem-cell research, including laboratory projects led by Michael Young, Ph.D., and Ray Lund, Ph.D., which made ReNeuron’s treatment possible. Dr. Young conducted the final preparatory study in a large animal model, also funded by the Foundation, before ReNeuron sought authorization from the FDA to initiate its clinical trial.

“This is a wonderful result for the culmination of 15 years of work,” says Dr. Young. “We are especially grateful to FFB for critical funding of the project.”