AZ5104, the demethylated metabolite of AZD-9291, is a potent EGFR inhibitor with IC50 of <1 nM, 6 nM, 1 nM, and 25 nM for EGFR (L858R/T790M), EGFR (L858R), EGFR (L861Q), and EGFR (wildtype), respectively. Phase 1.