ERBB2 and ductal breast carcinoma in situ: For patients with HER2+ DCIS, treatment with Trastuzumab modestly reduces risk of disease recurrence.79 Resistance to Trastuzumab is associated with MET expression.80 Therefore, patients with HER2+ breast cancers might benefit from MET and/or CCR2 targeted therapy to enhance efficacy of Trastuzumab.