The HIPPO pathway plays a critical role in contact inhibition, a pathway that is commonly dysregulated in many human cancers (including liver, colon, ovarian, and lung). The signaling pathway culminates in the intranuclear interaction of the transcriptional co-activator YAP and the transcription factor TEAD. This is representative of a number of cancer driving pathways that have proven nearly impossible to drug, as they are mediated by intracellular protein-protein interactions. High throughput screening campaigns with small molecule libraries have failed to provide specific, high affinity binders capable of disrupting larger protein-protein interfaces (such as YAP-TEAD), while at the same time, antibodies cannot penetrate the cell membrane to access cytosolic and nuclear targets. Optides are small disulfide-knotted peptides (knottins) that are large enough to interfere with protein-protein interactions, but small enough to access compartments beyond the reach of antibodies. Examples include the calcines, activators of sarcoplasmic reticulum ryanodine receptors, and BLZ-100, a knottin-fluorophore conjugate that is capable of accumulating in a wide range of tumor types. Using the computational design software Rosetta, we created a library of Optides designed to interact with TEAD in locations that overlap YAP binding. Mammalian surface display screening against soluble TEAD yielded a candidate (Hit1) that binds TEAD with nanomolar affinity and inhibits YAP binding. Affinity maturation, using site saturation mutagenesis, produced an improved sub-nanomolar variant (IV1) with potent YAP inhibition. This variant was also found to be highly resistant to reduction and proteolysis, crucial for a disulfide-knotted peptide with a cytosolic target in the proteinase-rich tumor milieu. With this highly potent YAP inhibitor, efforts are now focused on cell penetration and biodistribution with the long-term goal of advancing a clinical development candidate.
Citation Format: Zachary R. Crook, Philip Bradley, Gregory Sevilla, Della Friend, Chris King, Andrew Mhyre, Roland Strong, David Baker, James M. Olson. A high-affinity Optide (optimized peptide) inhibitor of the Hippo pathway’s YAP-TEAD interaction [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5573. doi:10.1158/1538-7445.AM2017-5573