Significant and durable clinical benefit from trastuzumab in 2 patients with HER2‐amplified salivary gland cancer and a review of the literature

Background Salivary ductal carcinoma and carcinoma ex pleomorphic adenoma (CEPA) are aggressive salivary gland cancers with poor prognosis. The standard of care is resection with or without radiotherapy, and there are no established systemic therapy options. Methods We describe 1 patient with metastatic CEPA and 1 patient with metastatic recurrent salivary duct carcinoma whose tumors were evaluated by comprehensive genomic profiling. Testing identified human epidermal growth factor receptor 2 (HER2) amplification in both patients, and an additional activating HER2 mutation in the CEPA case. Results Both patients were treated with the HER2‐targeting monoclonal antibody trastuzumab (herceptin) plus chemotherapy and experienced rapid responses. Subsequently, both patients were given single‐agent maintenance trastuzumab and continue to experience durable disease control. Conclusion Given the poor prognosis for salivary gland cancers and the limited treatment options upon recurrence or metastasis, patients should be tested for all classes of HER2 alterations. In cases with HER2 overexpression or activation, targeted therapies, such as trastuzumab are promising. © 2016 Wiley Periodicals, Inc. Head Neck 39: E40–E44, 2017