Novel EGFR tyrosine kinase inhibitors exhibiting intrinsic fluorescence

ErbB proteins have been extensively studied. Mutations in the EGFR gene that lead to the formation of mutant proteins such as EGFR vIII or EGFR L858R/T790M occur only in cancer cells [ 1 , 2 , 3 , 4 ]. Additionally, as demonstrated in our earlier studies, some ErbB mutants, e.g., the abovementioned EGFR vIII and EGFR L858R/T790M , are resistant to ligand-induced degradation or undergo degradation much more slowly than normal ErbB proteins [ 5 , 6 ]. These studies indicate that these mutants enhance cell proliferation and hinder programmed cell death [ 7 , 8 ]. Further investigation of these phenomena and processes could benefit from a molecule that covalently binds to ErbB proteins and simultaneously exhibits fluorescence. Covalent fluorescent EGFR kinase blockers can also be used for diagnostic purposes, e.g., during cytological examination. Assessment of the stability or high expression of these proteins may contribute to therapy selection. Chemical entities with these properties could also support the development of a new type of photodynamic therapy. To date, no molecule that can act as a covalent inhibitor of EGFR while simultaneously exhibiting fluorescence has been described. These findings inspired us to design a diagnostic and research tool that was not only an irreversible fluorescent EGFR TKI but also capable of recognizing the most commonly mutated variants. Herein, we describe the design, docking studies, and utility of this novel afatinib analog against various mutants of EGFR. Moreover, we present the in vitro fluorescence performance of these compounds.