Codon optimised gene therapy for RPGR-linked retinitis pigmentosa

Session Details

Session Title: Free Paper Session 18: New Drug & Treatment Technology

Session Date/Time: Saturday 09/09/2017 | 14:30-16:00

Paper Time: 14:42

Venue: Room 120

First Author: : M.Fischer GERMANY

Co Author(s): :    M. McClements   C. Martinez de la Camara   D. Dauletbekov   S. Ramsden   A. Barnard   R. MacLaren              

Abstract Details

Purpose:

RPGR is a hotspot for mutations responsible for one in five cases of retinitis pigmentosa. It's genetic instability also leads to unpredictable recombination errors during development of gene therapy. Here, we describe a solution through a codon optimised RPGR gene replacement therapy for clinical use in human XLRP disease.

Setting:

This research was performed at the Nuffield Laboratory of Ophthalmology (University of Oxford) in collaboration with the Centre for Ophthalmology Tuebingen.

Methods:

Codons of the human RPGR coding sequence (CDS) were optimized and tested for expression efficiency and sequence stability in vitro using immunohistochemistry, flow cytometry, and western blotting. Recombinant RPGR was characterized by western, mass spectrometry and glutamylation assays. Codon optimised RPGR was tested in vivo in two relevant animal models (Rpgr-/y and C57BL/6JRd9/Boc) and in C57BL6/J wild-type mice. Electroretinography, scanning laser ophthalmoscopy and immunohistochemistry were used to assess safety and efficacy.

Results:

Codon optimised RPGR shows superior sequence stability and expression levels in vitro. After subretinal delivery via the AAV8 vector, the codon-optimised RPGR rescues the disease phenotype in two relevant animal models and shows good safety in wild-type mice.

Conclusions:

Optimising the CDS of human RPGR overcomes the inherent sequence instability of therapeutic transgenes developed for XLRP gene therapy. While maintaining post- translational characteristics and increasing expression levels, RPGR based gene therapy shows excellent safety in wild-type mice and efficacy in two relevant animal models of human XLRP disease. This work provides the basis for clinical trial development to treat patients with XLRP due to RPGR mutations.

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