Promising results for the treatment of this rare genetic eye disease when associated with mutations on both copies of the RPE65 gene
Gene therapy is also beginning to be successfully applied in the treatment of eye diseases. the case of Leber’s congenital amaurosis, a rare hereditary disease that generally begins to show signs of yes already in the first years of life. Sufferers experience an almost total loss of vision from an early age with initial night blindness and a progressive narrowing of the visual field up to severe low vision by the age of 30. But thanks to a new gene therapy (voretigene naparvovec), studied for the proportion of patients who present mutations on both copies of the RPE65 gene, it is now possible to block the evolution of the disease, restore sensitivity in night vision and recover in less advanced cases. also some central vision. Recently in Milan, a team from the Sacco Hospital treated their first patient, a boy, almost two years after the start of preparations to equip themselves and comply with all safety regulations. It is estimated that at least 300 patients, ie 600 eyes, have already been treated in the world to date.
Leber and gene therapy
For now, the Italian Medicines Agency has approved the use of the new therapy in patients with low vision, around three tenths, but the hope is to be able to treat individuals at a very early stage, before the retina has undergone important and irreparable damages – points out Professor Giovanni Staurenghi, director of the ophthalmology clinic of the Luigi Sacco Hospital, University of Milan -. With a single injection, we prevent problems for the rest of our life and this should allow for the high cost of treatment to be amortized. Not to mention that there are no more than forty patients with this particular form of Leber’s congenital amaurosis in Italy. So far, at least twenty genes have been identified which, if mutated, are responsible for the development of the disease, which in only about 10 percent of cases is linked to mutations on both copies of the RPE65 gene.
How does it work
Gene therapy is based on the use of associated adenoviral vectors (viruses that are not associated with any pathology in humans), modified to eliminate the genes that produce viral replication proteins, replaced with the gene of interest, which in the case of Leber’s congenital amaurosis, precisely the RPE65 gene. The next step is to infect the target cells, bringing in them a working copy of the gene that begins to produce the missing protein. This approach works all the better the more conserved the anatomy of the target cells, that is photoreceptors and cells of the retinal pigment epithelium, explains Anna Paola Salvetti, consultant on retina and ocular genetics at the University Ophthalmology Clinic of the Sacco Hospital in Milan. The procedure involves the vitrectomy, the temporary detachment of the retina in its central part, the injection of the viral vector in direct contact with the cells of the pigment epithelium and then the repositioning of the raised retina. It is a delicate intervention, but controlled thanks to the help of technology such as intraoperative OCT, with which, with a single injection, it is possible to block the evolution of the disease, with visible results as early as one month, points out Staurenghi.
New prospectives
If up to a few years the parents of young patients had to resign themselves to an ineluctable fate of blindness for their sick children, today we can offer hope, also because there are many ongoing trials. Gene therapy is the future of medical therapies, the prospects are exciting conclude Anna Paola Salvetti and Professor Staurenghi.
November 20, 2021 (change November 20, 2021 | 10:25)
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