TAS0728 is a potent, selective, orally active, irreversible and covalent-binding HER2 inhibitor, with an IC50 of 13 nM. TAS0728 also shows IC50s of 4.9, 8.5, 31, 65, 33, 25 and 86 nM for BMX,HER4,BLK,EGFR,JAK3,SLK and LOK respectively. Furthermore, TAS0728 exhibits robust and sustained inhibition of the phosphorylation of HER2, HER3, and downstream effectors[1].