Gene therapy for wet age-related macular degeneration
Status: Phase I trial complete
Wet age-related macular degeneration (AMD)
AMD is a common cause of vision loss. It affects an estimated 25 - 30 million people worldwide with the incidence expected to triple by 2025. The “wet” form of the condition accounts for 10 – 15% of all cases, and 90% of those with severe loss of vision.
OXB-201 is a gene-based treatment for neo-vascular wet AMD and potentially diabetic retinopathy. It aims to preserve and improve patients’ vision through anti-angiogenesis, the process of blocking the formation of new blood vessels. The product uses Oxford BioMedica’s LentiVector® technology to deliver two genes encoding the anti-angiogenic proteins endostatin and angiostatin. Following a single administration to the retina, OXB-201 creates genetically modified cells that produce the two proteins, preventing vascularisation.
Proof of concept
OXB-201 has demonstrated clear proof-of-concept in industry standard models of wet AMD. Results from a long-term Phase I clinical study show a positive safety profile up to four years post-treatment. The data also show a successful and sustained increase in endostatin and angiostatin expression and secretion, with dose escalation yielding a proportional increase in average expression.
In the Phase I dose escalation study, OXB-201 met its safety and tolerability primary end point six months post-treatment. In addition, patients showed signs of clinical benefit, with visual acuity stabilisation and a reduction in vascular leakage consistent with the action of endostatin and angiostatin. The study, in subjects with highly fibrotic retinas who were refractory to current standard therapy following prior responsiveness, is the first time a lentiviral based vector has been administered to the human eye. Importantly, therapeutic gene expression was dose-dependent and maintained for up to 4 years in some subjects. The initial study data were published in the journal Human Gene Therapy.
Current standard treatments for wet AMD and other related ocular conditions achieved global sales of more than approximately US$7 billion. These require frequent repeated dosing, and as OXB-201 is designed as a single administration this would provide a significant market opportunity for the gene therapy.