The tumor immune contexture of salivary duct carcinoma.

Abstract

Salivary duct carcinoma (SDC) is a rare and aggressive malignancy. Recently, biomarker studies found promising targetable alterations. In this study, we provide a descriptive analysis of tumor and immune biomarkers and survival associations. We extracted clinical data and performed immunohistochemistry for AR, AR-V7, HER-2, PD-L1, LAG-3, and tumor-infiltrating immune cells. We included 17 patients. Age ranged from 42 to 85 years old; HER-2 was overexpressed or amplified in 65%. AR was positive in 88% of patients, while AR-V7 was positive in 13% by IHC. We found low scores of immune infiltration and a PD-L1 expression in 53%. We found no clinically significant association between biomarkers and survival outcomes. In this small series of SDC, biomarkers do not seem to correlate with disease biology, although they provide additional treatment options. SDC may harbor a different immune profile compared to other subtypes, with an indication of T-cell dysfunction.