How retinitis pigmentosa erodes normal vision
The failure rate for clinical trials is depressingly high. A study from Tufts University in 2010 found that for small molecules – the substances that make up more than 90 percent of the drugs on the market today – the odds of getting from a Phase 1 trial to approval by the Food and Drug Administration are just 13 percent. For stem cell therapies the odds are even lower.
That’s why, whenever a stem cell therapy shows good results it’s an encouraging sign, particularly when that therapy is one that we at CIRM are funding. So we were more than a little happy to hear that Dr. Henry Klassen and his team at jCyte and the University of California, Irvine have apparently cleared the first hurdle with their treatment for retinitis pigmentosa (RP).
jCyte has announced that the first nine patients treated for RP have shown no serious side effects, and they are now planning the next phase of their Phase 1/2a safety trial.
In a news release Klassen, the co-founder of jCyte, said:
“We are pleased with the results. Retinitis pigmentosa is an incurable retinal disease that first impacts people’s night vision and then progressively robs them of sight altogether. This is an important milestone in our effort to treat these patients.”
The therapy involves injecting human retinal progenitor cells into one eye to help save the light sensing cells that are destroyed by the disease. This enables the researchers to compare the treated eye with the untreated eye to see if there are any changes or improvements in vision.
So far, the trial has undergone four separate reviews by the Data Safety Monitoring Board (DSMB), an independent group of experts that examines data from trials to ensure they meet all safety standards and that results show patients are not in jeopardy. Results from the first nine people treated are encouraging.
The approach this RP trial is taking has a couple of advantages. Often when transplanting organs or cells from one person into another, the recipient has to undergo some kind of immunosuppression, to stop their body rejecting the transplant. But earlier studies show that transplanting these kinds of progenitor cells into the eye doesn’t appear to cause any immunological response. That means patients in the study don’t have to undergo any immunosuppression. Because of that, the procedure is relatively simple to perform and can be done in a doctor’s office rather than a hospital. For the estimated 1.5 million people worldwide who have RP that could make getting treatment relatively easy.
Of course the big question now is not only was it safe – it appears to be – but does it work? Did any of those people treated experience improvements in their vision? We will share those results with you as soon as the researchers make them available.
Next step for the clinical trial is to recruit more patients, and treat them with a higher number of cells. There’s still a long way to go before we will know if this treatment works, if it either slows down, stops, or better still helps reverse some of the effects of RP. But this is a really encouraging first step.