Why PhosphoSens for EGFR [N771-P772insH]?

EGFR drug discovery presents distinct assay challenges including the need to accurately characterize covalent inhibitors such as osimertinib and afatinib, where traditional endpoint assays like ADP-Glo and HTRF fail to capture the time-dependent kinact/KI parameters essential for covalent mechanism characterization. Radiometric assays offer sensitivity but generate radioactive waste and provide only single-timepoint snapshots. PhosphoSens continuous fluorescent kinase assays monitor EGFR substrate phosphorylation in real time using physiological ATP concentrations, generating complete progress curves that directly reveal covalent inhibitor kinetics, competitive binding modes, and subtle mechanistic differences between first-, second-, and third-generation inhibitors. This real-time approach eliminates endpoint artifacts from product inhibition or enzyme instability, enables accurate IC50 and Ki determination under near-physiological conditions, and is readily adaptable for high-throughput profiling of mutant EGFR variants including L858R, T790M, and C797S resistance mutations.