Peptide-conjugated oligonucleotides evoke long-lasting myotonic dystrophy correction in patient-derived cells and mice

Antisense oligonucleotides (ASOs) strategies for DM1 can abolish the toxic RNA gain-of-function mechanism caused by nuclear-retained mutant DMPK transcripts containing CUG expansions (CUGexp). However, systemic use of ASOs for this muscular disease remains challenging due to poor drug distribution to skeletal muscle. To overcome this limitation, we test an arginine-rich Pip6a cell-penetrating peptide and show that Pip6a-conjugated PMO dramatically enhanced ASO delivery into striated muscles of DM1 mice following systemic administration in comparison to unconjugated PMO and other ASO strategies. Thus, low dose treatment of Pip6a-PMO-CAG targeting pathologic expansions is sufficient to reverse both splicing defects and myotonia in DM1 mice and normalizes the overall disease-transcriptome. Examination of HSA-LR DM1 mice treated with Pip6a-CAG7-PMO compared to non-treated HSA-LR mice and WT mice.