The combined presence of CD20 + B cells and PD-L1 + tumor-infiltrating lymphocytes in inflammatory breast cancer is prognostic of improved patient outcome

Purpose The purpose of the study was to evaluate protein expression of PD-L1 and CD20 as prognostic biomarkers of patient outcome in inflammatory breast cancer (IBC) samples. Methods PD-L1 and CD20 protein expression was measured by immunohistochemistry in 221 pretreatment IBC biopsies. PD-L1 was assessed in tumor cells (PD-L1 + tumor cells) and tumor stromal infiltrating lymphocytes (PD-L1 + TILs); CD20 was scored in tumor-infiltrating B cells. Kaplan–Meier curves and Cox proportional hazard models were used for survival analysis. Results PD-L1 + tumor cells, PD-L1 + TILs, and CD20 + TILs were found in 8%, 66%, and 62% of IBC, respectively. PD-L1 + tumor cells strongly correlated with high TILs, pathological complete response (pCR), CD20 + TILs, but marginally with breast cancer-specific survival (BCSS, P = 0.057). PD-L1 + TILs strongly correlated with high TILs, CD20 + TILs, and longer disease-free survival (DFS) in all IBC and in triple-negative (TN) IBC ( P