We used single cell RNA sequencing and T cell receptor (TCR) sequencing of peripheral blood mononuclear cells (for 28 samples comprising 79,284 cells) to monitor the peripheral immune dynamic of an exploratory cohort of hormone receptor positive breast cancer patients treated with neoadjuvant nab-paclitaxel+pembrolizumab with the ultimate goal of identifying potential peripheral blood predictive biomarkers. This evidence concerns the gene NR4A1 and breast cancer.