Development of an exon 27-skipping antisense oligonucleotide as a targeted therapy for refractory skin ulcers in...

Werner syndrome (WS) is a rare autosomal recessive progeroid disorder caused by biallelic mutations in WRN and is frequently complicated by refractory skin ulcers for which no effective therapy exists. We developed WRN-108, a splice-switching antisense oligonucleotide (ASO) designed to induce exon 27 skipping and restore the open reading frame (ORF) disrupted by the most common WRN mutation in Japanese WS patients, c.3139-1G>C, which leads to exon 26 skipping. In WS patient-derived fibroblasts, WRN-108 efficiently induced exon 27 skipping, restored WRN protein expression, and re-established its nuclear localization. Treatment improved cell proliferation and reduced senescence-associated markers, G-quadruplex accumulation, and γH2AX signaling, consistent with partial restoration of WRN-dependent genome maintenance functions. Topical administration in a rat skin wound model resulted in effective dermal penetration and sustained tissue retention. In a cynomolgus monkey wound model, WRN-108 induced exon 27 skipping in the skin and achieved dermal exposure without local toxicity. Short-term toxicity studies in mice and miniature pigs further confirmed its favorable tolerability. These findings provide preclinical evidence that ASO-mediated exon skipping can restore WRN function, highlighting the translational potential of WRN-108 as a therapeutic approach for refractory skin ulcers in WS patients harboring the c.3139-1G>C mutation.