Tumor-infiltrating lymphocyte abundance and programmed death-ligand 1 expression in metaplastic breast carcinoma: implications for distinct immune microenvironments in different metaplastic components

AbstractBoth stromal tumor –infiltrating lymphocytes (sTILs) and programmed death-ligand 1 (PD-L1) affect responses to immunotherapy; however, the extent of sTIL and PD-L1 expression within various metaplastic components in metaplastic breast carcinoma (MBC), which are critical for the characterization of immune microenviro nments, remains unreported. We profiled sTIL infiltration and PD-L1 expression in different metaplastic components of specimens from 82 MBC patients. The overall positivity for high or intermediate (H/I) sTIL, immune cell-PD-L1 (IcPD-L1), and tumor cell-PD-L1 (TcPD-L1) was 34.1%, 47.6%, and 17.1%, r espectively, but differences specific to MBC subtypes and each metaplastic component existed. Squamous cell carcinoma exhibited the highest positivity rates of sTIL(H/I) (50.0%) and IcPD-L1 (66.7%), while matrix-producing carcinoma had the lowest respective rates (14.3% and 28.6%). The positivity ra tes of sTIL(H/I) and IcPD-L1 were the highest in squamous component (Sq) and the lowest in chondroid component (Ch). All cases that had discordant sTIL categories between carcinoma of no special type (NST) and metaplastic components showed sTIL(H/I) positivity higher in Sq, but lower in spindled com ponent (Sp) and Ch. While there was no pattern of higher IcPD-L1-positivity in Sp, six of the seven cases that were TcPD-L1-discordant between NST and Sp were TcPD-L1-positive in Sp, suggesting a trend for higher TcPD-L1 in Sp. The diagnostic predictability of total tu...
Source: Virchows Archiv - Category: Pathology Source Type: research