Gene therapy dosing needs more research

[caption id="attachment_16374" align="alignleft" width="1024"] Robert E. MacLaren[/caption] Professor Robert E. MacLaren, University of Oxford, UK, presented “Gene Therapy of Choroideremia & X-Linked Retinitis Pigmentosa”, an update on the current areas of focus in the field at the 19th Annual EURETINA Congress in Paris. He first reviewed the technique of gene delivery, which involves vitrectomy, intraoperative OCT-guided subretinal injection of balanced salt solution (BSS) to detach the retina and subsequent injection of 0.1ml of viral vector suspension into the BSS-bleb. But how high should the vector concentration be? “The dosing of gene therapy is still relatively unexplored,” said Prof MacLaren. “A subtotal dose of the vector leads to insufficient numbers of transfused cells, which will expire due to the natural history of the disease. However, a toxic dose can lead to cell death and even more visual loss as compared to controls.” Dosing strategies will be the focus of later studies. In the meantime, “finding patients can be challenging, because the genetics aren’t always very straightforward”, he said. One must be certain that the phenotype observed in the clinic is caused by the genetic abnormality discovered in the lab. Considering the success of the current studies, however, Prof MacLaren was rightfully optimistic about the future of gene therapy for chorioretinal disease.

Tags: choroideremia, gene therapy, retinitis pigmentosa