Iterative Optimization Yields Stapled Peptides with Superior Pharmacokinetics and Potency for Renal Fibrosis Treatment

Renal fibrosis, resulting from myofibroblast-mediated
excessive
extracellular matrix (ECM) deposition, lacks effective treatments.
Novel peptide DR3penA developed by our group showed therapeutic potential
for fibrotic diseases; however, its application was hindered by poor
stability and bioavailability. To address this unmet need, we implemented
stepwise optimization of DR3penA. The conformationally restricted
analogs designed via structural predictions enhanced both activity
and stability. Through structure–activity relationship analysis
and cleavage site mapping, introducing unnatural amino acids improved
stability. Fatty acid modifications conferred fibroblast-selective
cytotoxicity and improved pharmacokinetics. After several rounds of
progressive modification, peptide 27 exhibited remarkable
stability, with a 5.68-fold extended half-life compared to DR3penA.
Following profibrotic stimuli, peptide 27 effectively
inhibited myofibroblast activation, epithelial–mesenchymal
transition, and ECM synthesis. It also attenuated renal fibrosis in
a unilateral ureteral obstruction model. Our study leverages multiple
modifications that integrate cell and animal models to identify peptide 27 as a promising candidate for renal fibrosis therapy.