Antisense oligonucleotide therapy for the common Stargardt disease type 1-causing variant in ABCA4

The c.5461-10T>C p.[Thr1821Aspfs*6,Thr1821Valfs*13] variant has been identified as the most common severe Stargardt disease type 1 (STGD1)-associated variant in ABCA4. STGD1 is the most recurrent hereditary form of maculopathy and so far, no treatment is available for STGD1. In STGD1 patients homozygous for this variant, the onset of the disease typically is in childhood and patients are legally blind by early adulthood. The variant leads to exon skipping and generates out-of-frame ABCA4 transcripts that prevent the translation of functional ABCA4 protein. We applied antisense oligonucleotides (AONs) to restore the wild-type RNA splicing in ABCA4 c.5461-10T>C. The effect of AONs was investigated in vitro using an ABCA4 midigene model and 3D human retinal organoids (ROs) homozygous for the ABCA4 c.5461-10T>C variant. The mRNA in untreated ROs contained only disease-associated isoforms, whereas the organoids treated with the lead AON sequence showed 53% splicing correction and restoration of ABCA4 protein. Collectively, these data identified the lead candidate QR-1011 as a potent splice-correcting AON to be further developed as therapeutic intervention for patients harboring the severe ABCA4 c.5461-10T>C variant.