The Barcelona Macula Foundation, committed to progress on Retinitis Pigmentosa

Retinitis Pigmentosa describes the most frequent group of hereditary retinal diseases. It appears slowly and silently, normally between the ages of 25 and 40. Now the leading cause of complete blindness, central and peripheral, it affects one in every 4,000 people. World Retinitis Pigmentosa Day (September 29th) aims to raise awareness in the general public and inform them about the disease.

At present, there is no treatment for Retinitis Pigmentosa and therefore research is vital. Dr Jordi Monés MD, PhD, the Medical Director of the Barcelona Macula Foundation, is part of the research team conducting the phase I/IIa clinical trial with human retinal progenitor cells (hRPC) led by the ReNeuron company.

Pre-clinical studies have demonstrated that retinal implantation of hRPC has the potential to preserve existing photoreceptors, potentially reducing or halting further deterioration of vision. In addition, the hRPC mature into functional photoreceptors, enabling them to be grafted into the photoreceptor layer.

This clinical trial, which is being conducted in the US, is a study to assess the safety, tolerability and preliminary efficiency of a sub-retinal injection of the therapy with hRPC stem cells in patients with advanced Retinitis Pigmentosa.

The main objective of the study is safety, with a follow-up of patients over the 12 months after treatment, which includes measurements of visual acuity. The progression of this study to phase IIa will involve the inclusion of patients with a degree of retinal functionality, unlike the phase I patients, who have very low vision.

The initial results are very promising, with three patients and a follow-up time of 2 to 4 months, as a sustained and additional improvement in vision is being demonstrated compared to the starting point prior to treatment.

In the most recent follow-up, the results obtained showed an improvement in mean visual acuity of +23 letters in the treated eye, while the untreated eye hardly showed any significant improvement. An improvement of +23 letters is the equivalent of reading four additional lines of letters in the ETDRS eye chart, the standard used to measure visual acuity in clinical trials. It should be noted that any improvement of at least +15 letters from the pre-treatment starting point is considered clinically significant.