The efficacy of PD‐1 inhibitors in patients with salivary gland carcinoma: A retrospective observational study

Objective Immune checkpoint inhibitors (ICIs) have been considered as novel therapeutic approaches for various cancers. ICIs were reportedly efficacious against rare cancers, including salivary gland carcinoma (SGC). We aimed to analyze the efficacy and safety of ICIs in patients with SGC. Methods We retrospectively analyzed the oncologic outcomes and immune‐related adverse events (irAEs) in patients with SGC treated with at least one cycle of nivolumab or pembrolizumab. Results Among 12 patients, there were two with a complete response (CR), two with a partial response, five with stable diseases, and three with progressive diseases. The overall response rate was 33.3%. A CR was achieved in patients with poorly differentiated carcinoma (carcinoma ex pleomorphic adenoma) and salivary duct carcinoma. The progression‐free survival ranged between 1 and 18 months (median, 4 months), while the overall survival ranged between 2 and 25 months (median, 13.5 months). An irAE was observed in only one patient who developed grade 3 erythema multiforme, and this patient's condition improved with withdrawal of pembrolizumab alone. Conclusion Programmed death‐1 blockade was an effective therapy for patients with SGC, including aggressive histologic types. Computed tomography (CT) showing tumor disappearance of a right lung metastasis in a patient with salivary duct carcinoma. Plain CT of the lung tumor after administrating 17 cycles of pembrolizumab.