Expression of PD-L1 and NY-ESO-1 in early and advanced triple-negative breast cancer.

1110 Background: Advanced triple negative breast cancer (TNBC) is a poor prognosis disease to which no targeted therapies are available. PD-L1 is a key player in tumor immune escape, and significant responses have been obtained inhibiting this pathway in various malignancies. NY-ESO-1 is a tumor-specific antigen and represents a possible target for vaccine therapy. Here we evaluate PD-L1 and NY-ESO-1 expression in early and advanced TNBC patients. Methods: 26 metastatic TNBC patients who underwent both primary surgery and distant lesion biopsy were selected. From representative paraffin-embedded block, we obtained 3 tissue-cores of 1.5 mm diameter for the construction of a tissue microarray, which was evaluated by immunohistochemistry. Results: In primary and metastatic lesions NY-ESO-1 was expressed in 12% and 24% of the samples respectively (30.8% overall positivity). PD-L1 was expressed in 100% of early TNBC and in 92% of corresponding metastatic lesions. Two patients lost PD-L1 expression in the dista...