Figure 1.
BT‐474/KR cells are resistant to trastuzumab‐emtansine (T‐DM1) both in vitro and in vivo. A, BT‐474 and BT‐474/KR cells were treated with different concentrations of T‐DM1 for 120 h, and cell survival was measured using sulforhodamine B assay. Data represent mean ± SD of 3 independent experiments. B, Nude mice bearing BT‐474 or BT‐474/KR xenograft tumors were treated with vehicle or 5 mg/kg T‐DM1 weekly for 21 days. Tumor volume was measured on the indicated days, and tumor growth inhibition (TGI) was calculated. IC50, 50% inhibitory concentration