PDCD1 and breast carcinoma: However, it has recently been demonstrated that a high abundance of PD1high/CXCL13+ CD4+ and CD8+ T cells, as observed in IE1 tumors, is predictive for increased T cell expansion upon anti-PD-1 treatment across all breast cancer subtypes15 and positively influences response to anti-PD-L1 treatment in triple-negative breast cancer75.