Toward a Novel Drug To Target the EGF–EGFR Interaction: Design of Metabolically Stable Bicyclic Peptides

Abstract

In cancer, proliferation of malignant cells is driven by overactivation of growth‐signalling mechanisms, such as the epidermal growth factor receptor (EGFR) pathway. Despite its therapeutic relevance, the EGF–EGFR interaction has remained elusive to inhibition by synthetic molecules, mostly as a result of its large size and lack of binding pockets and cavities. Designed peptides, featuring cyclic motifs and other structural constraints, have the potential to modulate such challenging protein–protein interactions (PPIs). Herein, we present the structure‐based design of a series of bicyclic constrained peptides that mimic an interface domain of EGFR and inhibit the EGF–EGFR interaction by targeting the smaller partner (i.e., EGF). This design process was guided by the integrated use of in silico methods and biophysical techniques, such as NMR spectroscopy and surface acoustic wave. The best analogues were able to reduce selectively the viability of EGFR+ human cancer cells. In addition to their efficacy, these bicyclic peptides are endowed with exceptional stability and metabolic resistance—two features that make them suitable candidates for in vivo applications.

Blocking EGFR Activation with Anti‐EGF Nanobodies via Two Distinct Molecular Recognition Mechanisms

“…[9] From astructural point of view,EGF is a6kDa globular and highly flexible protein with no defined cavities and binding pockets.T hese challenging features would explain why it has remained largely undrugged by conventional strategies. [12,13] However,given these encouraging precedents,w ee nvisioned applying the same EGFfocused approach to discover more potent ligands with potential applications in clinical settings. [12,13] However,given these encouraging precedents,w ee nvisioned applying the same EGFfocused approach to discover more potent ligands with potential applications in clinical settings.…”

Protein Chemical Synthesis Combined with Mirror‐Image Phage Display Yields d‐Peptide EGF Ligands that Block the EGF–EGFR Interaction

“…Four out of the nine sequences interacted with EGF with micromolar affinities (Tables and S5, Figures A and S11). Peptides d ‐PI_1 and d ‐PI_4 displayed higher affinities ( K D =115±12 and 54±2 μ m , respectively) with a slightly lower K D than cp23G, the best binder reported so far …”

“…However, so far, only a limited number of small molecules and peptides (suramin, cp23G and d (CVRAC)) have been reported and they have limited success. This scarcity might be related with the absence of grooves and cavities on the flat surface of EGF, a feature that hinders the identification of binders.…”

Blocking EGFR Activation with Anti‐EGF Nanobodies via Two Distinct Molecular Recognition Mechanisms

“…These challenging features would explain why it has remained largely undrugged by conventional strategies . Recently, we designed a series of cyclic and bicyclic constrained peptides that targeted EGF and decreased cancer cell proliferation, although high peptide concentrations were required to reach efficacy . However, given these encouraging precedents, we envisioned applying the same EGF‐focused approach to discover more potent ligands with potential applications in clinical settings.…”