Sustained response of HER2-positive metastatic salivary adenocarcinoma, not otherwise specified, treated with trastuzumab

Objective Adenocarcinoma–not otherwise specified (AD-NOS) is an aggressive salivary gland carcinoma subtype with poor prognosis. Her2/neu-targeted therapy may be beneficial in cases of overexpression (20% of AD-NOS). Here, a case of metastatic AD-NOS of the submandibular gland showing sustained complete response to trastuzumab is reported, and the existing literature is reviewed. Study Design and Results A 68-year-old male with poorly differentiated AD-NOS of the submandibular gland with multiple metastases (T3 N2 bM1) underwent radical surgery and adjuvant radiation. The primary lesion demonstrated Her2/neu overexpression, and treatment with trastuzumab was initiated. The patient remains alive without evidence of disease at 36-months after treatment (three cycles of trastuzumab). Literature review of all published trastuzumab-based therapy studies (1990–2015) for salivary gland carcinoma is included. Conclusions Definitive clinical trials of trastuzumab-based interventions are challenging to undertake in rare tumors. This report adds to increasing evidence for trastuzumab-based therapy in salivary carcinomas, where sustained partial response at 36-months is achievable.