Choroideremia is an incurable genetic disease that causes blindness in men, and affects approximately one in 50,000 people. It is caused by a genetic fault in the CHM gene which plays a key role in the metabolism of the cells making up the retina. Sight loss in choroideremia begins with ‘night blindness’ (i.e. loss of night vision) in adolescence, followed by a gradual loss of peripheral vision which results in progressively worsening ‘tunnel vision’, and consequent loss of vision. The new technique involves putting normal copies of the affected gene back into the cells of the retina to help them to function normally. In order to do this, we need to use a vector (i.e. carrier) of the normal gene that can safely bring the normal genes back into the retinal cells without harming them. This technique we believe may help to slow or even stop the degeneration.
Phase 1: Clinical Trial This Phase 1 clinical trial was designed to test the safety and efficacy of the choroideremia gene therapy A total of 14 choroideremia patients were treated.
Phase 2: Clinical Trial REGENERATE (REP1 Gene Replacement Therapy) The REGENERATE study is ongoing, with patients being treated at the John Radcliffe Hospital in Oxford and the Moorfields Eye Hospital in London. Professor Robert MacLaren and his team have started a Phase II trial enrolling 30 patients. The first patient in the UK to undergo gene therapy surgery using an operating microscope with integrated optical coherence tomography (OCT) was operated on 1st Sept 2016. This state-of-the-art operating microscope has a built-in OCT scanner which uses a laser to define the retinal layers, and these are projected into the microscope field through an internal image enabling the surgeon to see a cross-sectional scan of the retina in real time. This permits very delicate, complex surgical procedures to be conducted with an unprecedented level of precision.