ERBB2 and salivary duct carcinoma: For example, the amplification of Erb-B2 receptor tyrosine kinase 2 (ERBB2/HER2) protein overexpression is seen in 20–30% of cases of salivary duct carcinoma [13] and there is trial data to support the efficacy of HER2-targeting therapy with either trastuzumab and docetaxel [11], trastuzumab and pertuzumab [12] or trastuzumab-emtansine [10] in recurrent or metastatic ERBB2-amplified/HER2-overexpressing disease.