Phase 2a study shows improved vision with stem cell therapy for retinitis pigmentosa

VANCOUVER, British Columbia — Human retinal progenitor cell therapy from ReNeuron Group is showing positive preliminary results in the company’s ongoing phase 1/2a clinical trial involving patients with retinitis pigmentosa.

ReNeuron chief medical officer Richard Beckman, MD, told Healio.com/OSN here at the Association for Research in Vision and Ophthalmology meeting that the three subjects in the current trial have shown subjective improvement in their visual acuity that has persisted for at least 2 months.

Study results were presented by researcher Jason Comander, MD, PhD, at the Retinal Cell and Gene Therapy Innovation Summit, held just before ARVO.

Beckman told Healio that the phase 1 portion was a dose-escalation study involving 12 patients that showed “excellent safety. We didn’t expect efficacy because these patients all had very poor vision and very little remaining retinal function.”

He noted that in phase 1, “the highest dose was transitioned into a cryopreserved formulation that’s much more commercially viable than the original fresh formulation. We now have a 9-month shelf life, and it can be shipped wherever we need it in a cryoshipper.”

The current study is being overseen at Massachusetts Eye and Ear by Comander and at the Retinal Research Institute in Phoenix by Pravin U. Dugel, MD.

The three patients with retinitis pigmentosa (RP) in this phase of the study, two in their 70s and one in their 50s, “have a little remaining visual acuity, and we’ve seen a rather remarkable, very early improvement in best corrected visual acuity on the order of about four lines of vision,” Beckman said.

He noted that they received one subretinal injection of a reformulated version of the cryopreserved stem cells.

“It’s unlike gene therapy,” Beckman said. “It’s agnostic to genotype. It should work in patients with any type of RP.”

The next cohorts will involve nine patients with even better baseline vision, he said.

“Without any remaining retinal function, we don’t anticipate that you’ll see any effect because these retinas are burned out,” Beckman said. “When you have some remaining function, you still have some cellular architecture, cells that are available to provide support to, and we may indeed be seeing engraftment.

“If the pattern continues, it will be transformational for people with RP,” he said. – by Nancy Hemphill, ELS, FAAO

Disclosure: Beckman reports he is employed by ReNeuron.