Successful Treatment with Nivolumab in a Patient with Metastatic Salivary Duct Carcinoma

Salivary duct carcinoma (SDC) is a rare and highly aggressive malignancy. A 58-year-old man presented with a right-sided submandibular mass and metastatic lesions in the right supraclavicular and inferior internal jugular nodes. He underwent right submandibulectomy and right neck dissection followed by adjuvant chemoradiotherapy. However, relapse occurred in the hilar lymph node and lumbar spine. Although radiotherapy was performed, a second relapse appeared in the hilar lymph nodes and sacral bone. Immunohistochemical analysis revealed negativity for programmed death ligand-1 (PD-L1) in the primary tumor specimen. The patient then received the anti-programmed death-1 (PD-1) antibody nivolumab. His metastatic lesions were completely eliminated after 48 weeks of therapy. This case reveals that anti-PD-1 antibodies are effective even against PD-L1-negative SDC.