Cyclic peptides are among the most diverse architectures
for current
drug discovery efforts. Their size, stability, and ease of synthesis
provide attractive scaffolds to engage and modulate some of the most
challenging targets, including protein–protein interactions
and those considered to be “undruggable”. With a variety
of sophisticated screening technologies to produce libraries of cyclic
peptides, including phage display, mRNA display, split intein circular
ligation of peptides, and in silico screening, a
new era of cyclic peptide drug discovery is at the forefront of modern
medicine. In this perspective, we begin by discussing cyclic peptides
approved for clinical use in the past two decades. Particular focus
is placed around synthetic chemistries to generate de novo libraries of cyclic peptides and novel methods to screen them. The
perspective culminates with future prospects for generating cyclic
peptides as viable therapeutic options and discusses the advantages
and disadvantages currently being faced with bringing them to market.