Computationally guided design of N4-(2-methyl-2H-indazol-6-yl)-N2-phenylpyrimidine-2,4-diamine inhibitors of EGFR kinase targeting Cys797.

The epidermal growth factor receptor kinase (EGFR) is a tyrosine kinase (TK) implicated in the uncontrolled growth of non-small cell lung cancer. EGFR-TK inhibitors have been used extensively, however inhibitor resistance often develops leading to disease progression. In this work, we report the computationally guided design and preparation of novel covalent 2,4-diaminopyrimidine EGFR-TK inhibitors, inspired by Osimertinib. Molecular dynamics simulations and quantum mechanical (QM) calculations were performed on novel designs incorporating a 2-methyl-2H-indazol-6-amine at the 4-position of pyrimidine as well as various linkers and electrophiles. Calculations suggested swapping the 5-pyrimidine H atom for Cl would lead to a preferential "out" ligand conformation that favored T790M enzyme which was later confirmed experimentally. Compound 19 was the most potent inhibitor of WT EGFR (3.0 nM) observed, more potent than the EGFR WT inhibitor Erlotinib (5.9 nM). Compounds 48 and 49 demonstrated better activity for the double-mutant EGFR (3.0 & 2.0 nM, respectively) than Osimertinib (12.8 nM). The selectivity of these compounds for the DM was found to be comparable to Osimertinib (∼20 fold) while their phosphate buffer solubilities were > 50-fold better than both marketed drugs. Kinetic evaluation of 48 (propenamide moiety) vs 49 (acrylamide electrophile) confirms kinact/Ki values consistent with a covalent mode of action for the latter, but not the former. 2009 Elsevier Ltd. All rights reserved.