IRX4204 treatment alone inhibited the growth of HER2-overexpressing cell lines, SkBr3, AU565, HCC1419 and ZR75-1 in vitro , but not the growth of HER2-normal cell lines MCF7, MDA-MB-231, or HCC1143. When combined with trastuzumab, tucatinib, neratinib or T-DM1, additive or synergistic effects were observed in all of the drug-sensitive cell lines...