We have written about jCyte many times on The Stem Cellar. For one reason, they are showing really encouraging results in their treatment for retinitis pigmentosa (RP). And now they have taken an even deeper dive into those results and identified which patients may be most likely to benefit from the therapy.

RP is a rare genetic disorder that slowly destroys the rods and cones, the light sensing cells in the back of the eye. If you look at the image below the one on the left shows normal vision, the one on the right shows what happens with RP. At first you start to lose night vision, then other parts of your vision are slowly eroded until you are legally blind.

RP starts early, often people are diagnosed in their teens and are legally blind by middle age. There is no treatment, no cure. It’s estimated that as many as 100,000 people in the US have RP, as many as two million worldwide.

That’s where jCyte comes in. They developed jCell, a therapy using adult stem cells that have been changed into human retinal progenitor cells (hRPCs). These are injected into the back of the eye where they secrete small proteins called neurotrophic factors.

Dr. Henry Klassen, one of the founders of jCyte, says jCell works by preserving the remaining photoreceptors in the eye, and helping them bounce back.

“Typically, people think about the disease as a narrowing of this peripheral vision in a very nice granular way, but that’s actually not what happens. What happens in the disease is that patients lose like islands of vision. So, what we’re doing in our tests is actually measuring […] islands that the patients have at baseline, and then what we’re seeing after treatment is that the islands are expanding. It’s similar to the way that one would track, let’s say a tumor, in oncology of course we’re looking for the opposite effect. We’re looking for the islands of vision to expand.”

And in patients treated with jCell those islands of vision did expand. The team followed patients for one-year post treatment and found that patients given the highest dose, six million cells, experienced the biggest improvement and were able to read, on average, 16 more letters on a standard eye chart than they had been before treatment. In comparison people given a sham or placebo treatment only had an improvement of less than two letters.

This group also experienced improvements in their peripheral vision, their ability to distinguish objects in the foreground from the background and were better able to get around in low light.

But that’s not all. Dr. Sunil Srivastava, with the Cleveland Clinic Cole Eye Institute, did a detailed analysis of patients treated in the trial and identified central foveal thickness (CFT- the part of the eye located in the center of the retina) as an important marker for who would be most likely to benefit from jCell. People who started out with a higher CFT score were most likely to get the biggest benefits.

In a news release, jCyte CEO Dr. Shannon Blalock said the findings are really encouraging: “We look forward to working closely with our scientific advisory board and principal investigators to apply these key learnings to our upcoming pivotal study of jCell to optimize its probability of success in an effort to advance the clinical development program of our RMAT designated therapy for RP patients who currently have no treatment options.”