Allosteric Inhibition of the Epidermal Growth Factor Receptor

Tackling Undruggable Targets with Designer Peptidomimetics and Synthetic Biologics

The development of potent, specific, and pharmacologically viable chemical probes and therapeutics is a central focus of chemical biology and therapeutic development. However, a significant portion of predicted disease-causal proteins have proven resistant to targeting by traditional small molecule and biologic modalities. Many of these so-called "undruggable" targets feature extended, dynamic protein-protein and protein-nucleic acid interfaces that are central to their roles in normal and diseased signaling pathways. Here, we discuss the development of synthetically stabilized peptide and protein mimetics as an ever-expanding and powerful region of chemical space to tackle undruggable targets. These molecules aim to combine the synthetic tunability and pharmacologic properties typically associated with small molecules with the binding footprints, affinities and specificities of biologics. In this review, we discuss the historical and emerging platforms and approaches to design, screen, select and optimize synthetic "designer" peptidomimetics and synthetic biologics. We examine the inspiration and design of different classes of designer peptidomimetics: (i) macrocyclic peptides, (ii) side chain stabilized peptides, (iii) non-natural peptidomimetics, and (iv) synthetic proteomimetics, and notable examples of their application to challenging biomolecules. Finally, we summarize key learnings and remaining challenges for these molecules to become useful chemical probes and therapeutics for historically undruggable targets.

Wandering beyond small molecules: peptides as allosteric protein modulators

Recent years have seen the rise of allosteric modulation as an innovative approach for drug design and discovery, efforts which culminated in the development of several clinical candidates. Allosteric modulation of many drug targets, including mainly membrane-embedded receptors, have been vastly explored through small molecule screening campaigns, but much less attention has been paid to peptide-based allosteric modulators. However, peptides have a significant impact on the pharmaceutical industry due to the typically higher potency and selectivity for their targets, as compared with small molecule therapeutics. Therefore, peptides represent one of the most promising classes of molecules that can modulate key biological pathways. Here, we report on the allosteric modulation of proteins (ranging from G protein-coupled receptors to specific protein-protein interactions) by peptides for applications in drug discovery.