BI-4020 is a fourth-generation, orally active, and non-covalent EGFR tyrosine kinase inhibitor. BI-4020 inhibits not only the triple mutant EGFR del19 T790M C797S variant (IC50=0.2 nM in BaF3 cell lines) but also the double mutant EGFR del19 T790M and primary mutant EGFR del19 (IC50=1 nM). BI-4020 also shows activity against EGFR wt (IC50=190 nM). BI-4020 shows high kinome selectivity and good DMPK properties.