In a phase II trial (KEYNOTE-086) (51), High stromal TIL levels were associated with improved ORR in patients with metastatic TNBC receiving pembrolizumab (PD-1 inhibitor).These findings are similar to those of the phase III KEYNOTE-119 trial (124), which may indicate TILs are emerging as potentially important biomarkers of prediction of response to immunotherapeutic agents in breast cancer. Here, PDCD1 is linked to breast cancer.