TAS0728 (TPC 107) is a potent, selective, orally active, irreversible and covalent-binding inhibitor of HER2 (human epidermal growth factor receptor 2) with IC50 of 13 nM. TAS0728 inihibits BMX, HER4, BLK, EGFR, JAK3, SLK, LOK and human HER2 with IC50 of 4.9 nM, 8.5 nM, 31 nM, 65 nM, 33 nM, 25 nM, 86 nM and 36 nM, respectively. TAS0728 shows antitumor activity.