Protease Stability Correlates with Efficacy for High-Affinity, Cell Penetrant MDM2-Binding Stapled Peptides

Abstract

Nearly two-thirds of all disease-associated proteins are ‘undruggable’ by modern therapeutics, meaning they are inside cells, out of the reach of biologics, but lack small molecule binding pockets. Stabilized peptides have the potential to hit these targets. However, the design criteria for developing agents that can reach and disrupt their target are poorly understood. This work focuses on the physicochemical properties of three newly-developed high affinity double-click stabilized MDM2/p53 inhibiting peptides that have favorable in vitro characteristics including protease stability, cytosolic access, and target-specific cell killing. These properties are distinct fromATSP-7041, the only p53-based peptide that has led to a clinical lead compound. We highlight a promising peptide variant with an added disulfide-bond backbone modification that demonstrates sub-micromolar cell killing in the presence of serum, comparable to the published in vitro potency of ATSP-7041. Overall, these peptides help better define the landscape needed for effective intracellular biologics.