Poziotinib(NOV120101; HM781-36B) is an irreversible Pan-HER inhibitor with IC50s of 3/5/23 nM for HER1/HER2/HER4 respectively.Poziotinib(NOV120101; HM781-36B) is an irreversible Pan-HER inhibitor with IC50s of 3/5/23 nM for HER1/HER2/HER4 respectively. IC50 value: 3/5/23 nM(HER1/HER2/HER4)  Target: pan-HER inhibitor in vitro: The IC50 levels of HM781-36B for N87 and SNU216 were 0.001 and 0.004 μmol/L, respectively, which was 10–1000 fold lower than the IC50 levels of other HER family TKIs. HM781-36B more potently inhibited the phosphorylation of HER family and downstream proteins, and induced apoptosis and G1 arrest compared to gefitinib or lapatinib . HM781-36B is a potent inhibitor of EGFR in vitro, including the EGFR-acquired resistance mutation (T790M), as well as HER-2 and HER-4, compared with other EGFR tyrosine kinases inhibitors (erlotinib, lapatinib and BIBW2992). HM781-36B treatment of EGFR DelE746_A750-harboring erlotinib-sensitive HCC827 and EGFR L858R/T790M-harboring erlotinib-resistant NCI-H1975 NSCLC cells results in the inhibition of EGFR phosphorylation and the subsequent deactivation of downstream signaling proteins . The addition of HM781-36B induced potent growth inhibition in both DiFi cells with EGFR overexpression and SNU-175 cells (IC50 = 0.003 and 0.005 μM, respectively). Furthermore, HM781-36B induced G1 arrest of the cell cycle and apoptosis, and reduced the levels of HER family and downstream signaling molecules, pERK and pAKT, as well as nonreceptor/cytoplasmic tyrosine kinase, BMX . in vivo: The growth of tumors in mice treated with HM781-36B alone or in combination with 5-FU was significantly inhibited compared with control mice, and tumor volume in mice receiving coadministraion of HM781-36B and 5-FU was smaller than tumor volume in mice receiving HM781-36B only .