The identification of selective, high-affinity ligands for membrane receptors and other protein targets is a critical step in the development of novel therapeutics. For small-molecule drug discovery, high-throughput screening (HTS) enables the rapid evaluation of 10⁵–10⁶ compounds per day through automated platforms. In contrast, for biologics such as peptides, proteins, and nucleic acids, selection technologies like phage, mRNA, ribosome, and yeast display offer significantly higher diversity, routinely screening libraries ranging from 10⁹ to 10¹³ variants. By implementing smart selection and deselection strategies, ligands with affinities in the low nanomolar range can often be identified.
Previously, we developed a synthetic strategy for the generation of multicyclic peptides [2]. We have now integrated this platform with mRNA display to enable the discovery of bioactive multicyclic peptides. In this presentation, we share initial findings on potent and selective multicyclic peptide binders targeting Frizzled-5 (FZD-5) and an anti-CCR7 monoclonal antibody, with affinities in the double-digit nanomolar range. Control experiments highlight the critical role of each individual peptide loop in target engagement. Furthermore, the multicyclic peptides exhibit markedly enhanced proteolytic stability compared to their linear or monocyclic counterparts. Together, these results demonstrate the readiness of this multicyclic peptide platform for broader application in the discovery of next-generation peptide therapeutics.
