HER2-positive salivary duct carcinoma: durable response to targeted therapy and chemotherapy

Salivary duct carcinoma (SDC) of the parotid gland is a rare and aggressive malignancy. Conventional treatment for recurrent or metastatic disease commonly involves platinum-based chemotherapy and taxane-based regimens although treatment is increasingly informed by molecular profiling. A subset of these tumours are human epidermal growth factor receptor 2 (HER2) positive and are associated with more aggressive metastatic behaviour. Novel treatment approaches, particularly dual HER2-targeted therapies commonly used in breast cancer, are now being explored for clinical utility in this group.This case report describes a patient with recurrent metastatic SDC arising from a carcinoma ex-pleomorphic adenoma, with strong HER2 positivity. The patient was treated with a combination of monoclonal antibodies (trastuzumab and pertuzumab) and chemotherapy agents (carboplatin and paclitaxel). The patient demonstrated an excellent and sustained clinical response. This case supports the potential benefit of targeted anti-HER2 therapy in HER2-positive salivary gland tumours and suggests this strategy may be considered in future treatment protocols.