PD-L1 expression in tumor lesions and soluble PD-L1 serum levels in patients with breast cancer: TNBC versus TPBC.

Background: Block of programmed cell death protein 1 (PD-1) interaction with its ligand, PD-L1, enhances anti-tumor activity.

Objectives: We aimed to assess the association between PD-L1 expression in tumor cells and CD8+ tumor infiltrating T cells (TILs) as well as soluble (s)PD-L1 serum levels in patients with triple negative breast cancer (TNBC) compared to triple positive (TPBC).

Methods: A total of 113 tumor sections and 133 serum samples were available from 144 patients with breast cancer (72 TNBC and 72 TPBC).