ERBB2 and breast cancer: To evaluate the effect of metixene on a panel of various metastatic breast cancer cell lines, the IC50 was determined in 2 HER2-positive cell lines (BT-474Br and HCC1954) and 5 triple-negative breast cancer cell lines (MDA-MB-231Br, HCC1806, HS578T, HCC3153, and SUM159) after 72 hours of treatment.