High-throughput screening discovers arginine-depleted peptides for improved DMD antisense therapy delivery
Researchers developed a high-throughput chromatographic screening platform that identified novel 'arginine-depleted' cell-penetrating peptides capable of delivering antisense therapeutics more effectively and with lower toxicity in Duchenne muscular dystrophy models. Current approved PMO therapies for DMD suffer from poor muscle uptake, requiring frequent high doses, while existing peptide carriers cause kidney damage that limits their clinical use. The new lead peptide, CXP1, outperformed standard carriers in both cellular and animal models, suggesting a path toward safer and more effective DMD treatments.
Phosphorodiamidate morpholino oligomers (PMOs) are FDA-approved exon-skipping therapies for Duchenne muscular dystrophy, but their limited uptake in muscle tissue forces patients to undergo frequent high-dose treatments. Cell-penetrating peptides (CPPs) can improve PMO delivery into cells, but conventional arginine-rich CPPs cause dose-limiting renal toxicity that has blocked their clinical adoption. To overcome this, scientists created a charge-based chromatographic enrichment platform capable of screening more than 15,000 synthetic peptides, including those containing noncanonical amino acids not found in nature. This screen identified four lead arginine-depleted CPP candidates that delivered PMOs to cell nuclei with approximately 10-fold lower toxicity than standard CPPs like penetratin. The top candidate, CXP1, demonstrated strong splice-switching activity — the mechanism by which exon skipping is achieved — and was well tolerated in both cell and mouse models. In dystrophic mdx mice, CXP1-PMO conjugates produced greater exon skipping than a benchmark arginine-rich carrier at equivalent doses, and tissue drug levels correlated with therapeutic effect, establishing a clear pharmacokinetic-pharmacodynamic relationship. The authors argue this platform represents a broadly applicable strategy for discovering improved peptide-based delivery vehicles for antisense therapies in DMD and other neuromuscular diseases.
What's missing
The study was conducted in mdx mice, a standard but imperfect model of DMD; it remains unknown whether CXP1-PMO conjugates will achieve sufficient efficacy and tolerability in larger animal models or humans. Long-term safety data, including chronic renal and systemic toxicity profiles of CXP1, are not reported. The mechanism by which arginine depletion reduces toxicity while preserving cell-penetrating activity is not fully elucidated. The study does not address manufacturing scalability or cost of peptides incorporating noncanonical amino acids.
What different sources said
- bioRxivCenter
High-throughput discovery of arginine-depleted peptides enables effective antisense delivery for Duchenne muscular dystrophy
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