Treatment Efficacy of PD-1 Inhibitor Therapy in Patients With Recurrent and/or Metastatic Salivary Gland Carcinoma

The efficacy of programmed cell death 1 (PD-1) inhibitor therapy for patients with recurrent and/or metastatic salivary gland carcinoma (R/M SGC) remains unclear.We retrospectively analyzed 36 patients with R/M SGC treated with PD-1 inhibitor. The expression of programmed cell death ligand 1 (PD-L1) and mismatch repair (MMR) proteins was also analyzed.The objective response rate (ORR) was 11.1%. The histopathological subtypes of patients who achieved complete response or partial response were salivary duct carcinoma (SDC) in three patients and poorly differentiated carcinoma in one patient, all of whom showed a positive PD-L1 expression. The expression of MMR proteins was not associated with the efficacy of PD-1 inhibitors.Although the efficacy of PD-1 inhibitor therapy in R/M SGC is limited, certain patients may respond and achieve long-term disease control. There is a potential therapeutic effect in SDC patients with positive PD-L1 expression.