ERBB2 and ductal breast carcinoma in situ: T-DM1 combines the anti-HER2 properties of trastuzumab with the anti-microtubule cytotoxic activities of DM1.30–32 Mice bearing SUM225 DCIS-like tumors were randomized into one of two treatment groups (n = 5 mice per group): single agent T-DM1 (10 mg/kg/1 × week i.p. 2 weeks) or vehicle.