QR-110 Treatment for Leber’s Congenital Amaurosis Type 10: Restoration of CEP290 mRNA Levels and Ciliation in LCA10 iPSC-Derived Optic Cups

Abstract

Purpose : The p.Cys998X mutation (known as c.2991+1655A>G) in the human CEP290 gene is associated with Leber’s congenital amaurosis Type 10 (LCA10) when present in homozygosity or compound heterozygosity. These genotypes result in an early childhood blindness associated with loss of photoreceptors. QR-110 is an antisense, single stranded, fully phosphorothioated and 2'-O-methyl modified RNA oligonucleotide designed as a disease modifying therapy for patients with LCA10 due to the CEP290 p.Cys998X mutation. QR-110 targets the splicing mutation of CEP290 through a mechanism of RNA modulation, by which it skips the inclusion of the cryptic exon-X and thus restores the open reading frame of CEP290.

Methods : LCA10 patient fibroblasts were first reprogrammed into induced pluripotent stem cells (iPSC) and then differentiated into optic cups for 96 days. These optic cups were treated with different doses of QR-110 for 28 days. CEP290 wild-type and mutant transcript levels were quantified using ddPCR analysis. Percentage of ciliated cells and length of cilia were assessed by microscopy.

Results : We have previously shown that QR-110, in LCA10 fibroblasts, increases wild-type CEP290 mRNA and protein levels in a dose dependent manner with concurrent decrease of mutant levels. Levels in p.Cys998X homozygous fibroblasts increased to approximately 100% and to approximately 50% in compound heterozygous cells, as is expected when there is only one p.Cys998X allele. We now show that in optic cups, three dimensional organoids mimicking the retinal structure and containing all major retinal cell types, QR-110 increases wild-type transcript levels and CEP290 function, as measured by percentage of ciliated cells and length of the cilia, in a dose dependent manner .

Conclusions : Efficacy of QR-110 is demonstrated in a three dimensional LCA10 organoid model with all major retinal cell types.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.