Phage Display as a Promising Platform for Peptide Drug Discovery.

Peptides have attracted increasing popularity in modern drug discovery, with the potential to address unmet clinical needs that lie beyond the reach of small molecules and antibodies. By offering "best-of-both-worlds" features, peptides are emerging as powerful tools for targeting disease-associated, challenging proteins. Combinatorial peptide libraries have played a crucial role in the development of peptide drugs. Phage display is one of the most widely adopted combinatorial frameworks for pharmaceutical exploration, ushering in a new paradigm in peptide drug discovery over the past few decades. Phage display libraries provide a vast repertoire of ligands that can be searched through biopanning to identify peptides with high specificity and affinity for a diverse range of biologically relevant targets. Although biopanning has demonstrated great potential in identifying target-specific ligands, many peptides identified by phage display still suffer from poor pharmacological properties, creating hurdles in translating initial hits from phage display selections into therapeutic molecules. To achieve improved pharmacological characteristics, various modifications can be introduced into peptides, such as cyclization, the incorporation of non-canonical amino acids, the introduction of D-amino acids, oligomerization, conjugation/fusion, and stapling. Optimizing peptide properties through these strategies has laid a solid groundwork for a significant number of phage display-derived peptides to progress from fundamental research and preclinical studies into various phases of clinical evaluations, with several peptide drugs already receiving regulatory approval for routine clinical applications. These achievements raise hopes for peptide phage display to remain a promising platform for drug discovery in the years ahead.