AZD9291 (Osimertinib) is a potent inhibitor of EGFR L858R/T790M recombinant enzyme (1 nM), EGFR L858R recombinant enzyme (12 nM), EGFRvIII (<100 nM), EGFR 19Del/T790M/C797S protein (124.82 nM), WT EGFR (184 nM), EGFR 19Del/C797S protein (304.39 nM), EGFR L858R/C797S protein (573.72 nM), hERG-encoded potassium channel (Kv11.1) (690000 nM), EGFR, EGFR sensitive mutations, EGFR T790M, EGFR exon 19 deletion, MAPK-interacting kinases, eIF4E. AZD9291 (Osimertinib) exhibits the greatest inhibitory potency toward EGFR L858R/T790M recombinant enzyme (IC50 = 1 nM).