PDCD1 and breast cancer: One of the arms evaluated the benefit from the addition of the programmed cell death protein 1 (PD-1) inhibitor, pembrolizumab to weekly paclitaxel (for 12 weeks) followed by four cycles of doxorubicin and cyclophosphamide every 3 weeks, in patients with TNBC or hormone-receptor-positive, HER2-negative, early-stage breast cancer.