ReNeuron upbeat on early data from retinitis pigmentosa trials

Cell-based therapeutics developer ReNeuron Group announced updated positive preliminary data in its ongoing phase 1 and 2a clinical trial of its human retinal progenitor cell (hRPC) therapy candidate in the blindness-causing disease, retinitis pigmentosa (RP), on Friday.

The AIM-traded company said all three subjects in the first cohort of the phase 2a element of the study had demonstrated a sustained and further improvement in vision, compared with their pretreatment baseline.

At the most recent follow-up, subjects in the study showed a mean improvement from baseline in visual acuity of 23 letters in the treated eye, while the untreated control eyes did not show meaningful improvement.

An improvement of 23 letters was equivalent to reading an additional four lines of letters on the ETDRS eye chart - the standardised eye chart used to measure visual acuity in clinical trials - the ReNeuron board explained.

It said an improvement of at least 15 letters from baseline on the ETDRS chart was considered to be “clinically meaningful” by the US Food and Drug Administration (FDA), as stated in their recent guidance on gene therapy for retinal disorders.

As a comparator, the difference between a patient with 20/20 vision and 20/200 vision - the latter being the legal definition for blindness in terms of central visual acuity - would be the equivalent of being able to read an extra ten lines on the ETDRS chart.

In addition to those objective measurements, all three subjects reportedly also noted a subjective improvement in vision in their treated eye.

“I am excited that the rapid and remarkable visual improvement in these RP patients has been sustained and even improved upon at 60 and 120 days,” said Pravin Dugel, managing partner at Retinal Consultants of Arizona and study investigator.

“It is especially gratifying to feel the excitement and joy in my patients where this objective and subjective improvement in their vision has been a source of hope following years of slow but steady progression towards blindness.”

ReNeuron said RP was a group of hereditary diseases of the eye that led to progressive loss of sight due to cells in the retina becoming damaged and eventually dying.

Its RP clinical programme had been granted orphan drug designation in both Europe and the US, as well as ‘fast track’ designation from the FDA.

The Phase 1 and 2a clinical trial was described as an open-label study to evaluate the safety, tolerability and preliminary efficacy of ReNeuron's hRPC stem cell therapy candidate in patients with advanced RP.

It said the Phase 2a element of the study, which used a cryopreserved hRPC formulation, enrolled subjects with some remaining retinal function, and was being conducted at two clinical sites in the US -- Massachusetts Eye and Ear in Boston and Retinal Research Institute in Phoenix, Arizona.

The company noted that the data remained early, adding it would continue to generate further data including regular ongoing monitoring of the treated subjects, to continue to assess durability of effect and efficacy over a longer period of time and in a larger number of patients.

“The extent of vision improvement observed in this patient cohort demonstrates the potential for our hRPC cell therapy candidate to make an enormous difference in the lives of patients with RP,” said ReNeuron chief executive officer Olav Hellebø.

“Treatment has already begun in the next cohort of patients, who have a greater baseline level of visual acuity than those treated so far.

“The results from this cohort will be presented in due course.”