A Phase I clinical trial, led by Prof. Pete Coffey of The London Project to Cure Blindness, ORBIT, Institute of Ophthalmology, University College London (UCL), and Prof. Lyndon da Cruz, consultant ophthalmic surgeon, also of UCL and Moorfields, have published the 12 month results of an innovative experimental study to deliver stem-cell derived RPE cells on a synthetic membrane, or “patch”, for the treatment of AMD. The study paper, published in Nature Biotechnology (doi:10.1038/nbt.4114), reported the clinical outcome for two patients 12 months following the surgical implantation of a fully differentiated, human embryonic stem cell (hESC)–derived RPE monolayer on a coated, synthetic basement membrane. Both patients showed improved BCVA recordings over 12 months, increasing from 10 to 39 letters in “patient 1”, and from 8 to 29 letters in “patient 2”. Reading speed on the University of Minnesota MNRead test improved from 1.7 to 82.8 and from 0 to 47.8 words/min in patients 1 and 2, respectively, over the 12 month period. In addition, micro-perimetry testing showed visual fixation at the center of the patch and vision over the patch in both patients at the 12 months time-point. The results mark a significant milestone and achievement for the UK based research and clinical teams. Perseverance and dedication were undoubtedly key ingredients required to overcome multiple challenges ranging from cell biology to engineering, surgery, surgical tool innovation, animal study design the development of clinical grade hESC-RPE patches, manufacturing, regulatory and the design and execution of a full phase I clinical trial.
While clinical trial studies using stem-cell derived RPE cells have been attempted previously, a key distinction in the current study, as highlighted in the Nature Biotechnology article, was that, “[i]n contrast to RPE suspensions, cells on the patch are delivered fully differentiated, polarized, and with the tight junction barrier formed, that is, in a form close to their native configuration.” The delivery of such fully differentiated cells in a physiologically functioning manner appears to be a significant component to the success of the study. While the development of the membrane and cell biology techniques comprised a significant volume of work allowing for more robust handling of the therapy prior to surgical delivery, a more specialized surgical procedure and surgical tool was required to insure safe insertion of the treatment. According to the research team, “[t]he results presented here provide an early indication of the safety and feasibility of manufacturing an hESC-RPE monolayer on a synthetic basement membrane and delivering the patch into the subretinal space as a potential treatment for AMD. Our data suggest early efficacy, stability, and safety of the RPE patch for up to 12 months in two patients with severe vision loss from very severe wet AMD.”
The clinical trial, designed as a phase 1, open-label, safety and feasibility study of implantation of an hESC-RPE patch in subjects with acute wet AMD and recent rapid vision decline, was approved by the UK MHRA and was solely funded by Pfizer Inc. According to a press release from UCL, Douglas Waters, 86 years of age, from Croydon, London, was one of the two patients treated at Moorfields Eye Hospital. Mr. Waters developed severe wet AMD in July 2015 and received the experimental treatment three months later in his right eye. Commenting on his experience of the therapy, UCL reported Mr Waters stating that: “In the months before the operation my sight was really poor and I couldn’t see anything out of my right eye. I was struggling to see things clearly, even when up-close. After the surgery my eye sight improved to the point where I can now read the newspaper and help my wife out with the gardening. It’s brilliant what the team have done and I feel so lucky to have been given my sight back.”