ReNeuron trial FAQs

Posted on: Wednesday 9 February 2022



UPDATE 14 February 2022

ReNeuron has announced that it is discontinuing the phase 2a clinical trial of its retinal progenitor cell therapy. This follows disappointing results due to surgical complications and limited evidence of efficacy. The company has stated that it can no longer justify continued investment in its RP programme, although it will look to out-license the technology so that another company can potentially build on the learnings of these trials and further investigate the treatment. Read the more detailed statement from ReNeuron.


You may have heard that a cell-based treatment approach (sometimes referred to as a “stem cell treatment”), developed by a company called ReNeuron, is being tested in a clinical trial at Oxford Eye Hospital and other centres in the US and Europe. This page provides more information about the trial and next steps. Please note that the Oxford team is not currently recruiting participants for the trial.

What is the treatment?

The treatment is a preparation of retinal photoreceptor progenitor cells (RPC) developed by the biotechnology company ReNeuron. RPC are cells that have only just started on the path towards developing into mature, fully differentiated retinal cells; you would find them in a developing human eye and they are basically very “young” retinal cells. The ReNeuron treatment is injected into the back of the retina (subretinal injection), usually under general anaesthetic. ReNeuron has yet to establish whether this will be a one-off treatment, or if the injections will be repeated.

How does the treatment work?

Following encouraging results from animal studies, ReNeuron is hopeful that the RPC will integrate into the retina, where they could provide nourishment and support to improve survival of existing retinal cells, or even develop into photoreceptors to replace cells that have already degenerated. Clinical trials will help ReNeuron understand exactly how the treatment works in the human eye.

Who is this treatment for?

The ReNeuron treatment is currently being tested in people with classic retinitis pigmentosa (RP). It does not target a specific genetic fault, so could be suitable for any genetic diagnosis. However, the trial is recruiting people who do have a genetic test result to help inform the researchers’ understanding.

The clinical trials will help to establish the stage of sight loss at which treatment is most useful. The current trial involves people with reasonably advanced RP, whose central vision has started to deteriorate. This enables the researchers to measure the impact of the treatment on visual acuity. ReNeuron may move to testing in people with less advanced sight loss later in the trials process.

Where is the clinical trial taking place and can I take part?

This is a phase 2a clinical trial to build on the safety and efficacy data gathered from an earlier phase 1 / 2 trial.  The current trial will involve just nine people with retinitis pigmentosa across four trial sites: two sites in the USA, one in Spain and one here in the UK at Oxford Eye Hospital. The Oxford work is supported by the research arm of the NHS, so is currently only open to UK residents.

Oxford has so far enrolled three trial participants and is not actively recruiting anyone else at the moment. There is a possibility that more people could take part at Oxford in future phases of the study, but the centre is confident that they are likely to be able to identify any further participants they need from their existing database. Please do not contact Oxford at the moment.

How long will this trial take, and when might the treatment be more widely available?

ReNeuron expects to report data from the current trial within the first half of 2022. If this trial is successful, ReNeuron will run a phase 3 trial involving a greater number of participants, who could be enrolled in late 2022 or early 2023. We do not yet know where the phase 3 trial centres might be or what the inclusion criteria will be.

Each participant in the phase 3 trial will be monitored for up to two years to enable ReNeuron to get a clear picture of efficacy and long term safety of the treatment. It is only once ReNeuron has robust and positive data from the phase 3 trial that the company can begin applying to regulatory authorities such as the MHRA to license the treatment for general use.


Another stem cell treatment for RP, developed by the company jCyte, is also being tested in clinical trials in the USA. For more information on recent developments with the jCyte treatment, see https://retinauk.org.uk/research-news/jcyte-update/