A high-content biosensor-based screen identifies cell-permeable activators and inhibitors of EGFR function: implications in drug discovery.

Early success of kinase inhibitors has validated their use as drugs. However, discovery efforts have also suffered from high attrition rates due to lack of cellular activity. We reasoned that screening for such candidates in live cells would identify novel cell-permeable modulators for development. For this purpose, we have used our recently optimized epidermal growth factor receptor (EGFR) biosensor assay to screen for modulators of EGFR activity. Here, we report on its validation under high-throughput screening (HTS) conditions displaying a signal-to-noise ratio of 21 and a Z' value of 0.56-attributes of a robust cell-based assay. We performed a pilot screen against a library of 6912 compounds demonstrating good reproducibility and identifying 82 inhibitors and 66 activators with initial hit rates of 1.2% and 0.95%, respectively. Follow-up dose-response studies revealed that 12 of the 13 known EGFR inhibitors in the library were confirmed as hits. ZM-306416, a vascular endothelial growth factor receptor (VEGFR) antagonist, was identified as a potent inhibitor of EGFR function. Flurandrenolide, beclomethasone, and ebastine were confirmed as activators of EGFR function. Taken together, our results validate this novel approach and demonstrate its utility in the discovery of novel kinase modulators with potential use in the clinic.