ERBB2 and breast neoplasm: Globally, many immune parameters in HER2+ breast tumors (i.e., TILs, CD8+ infiltrate) are inversely correlated with ER or progesterone receptor expression (90), and it is tempting to propose a possible relationship between decreased clinical benefit of ER+ tumors to anti-HER2 mAbs and their increased resistance to NK cell-mediated ADCC.