Immune microenvironment of premenopausal estrogen receptor-positive/HER2-negative advanced breast cancer in response to treatment of Pembrolizumab, exemestane, and leuprolide

We evaluated the efficacy of combining pembrolizumab (anti-PD1 antibody), exemestane (nonsteroidal aromatase inhibitor), and leuprolide (gonadotropin-releasing hormone agonist) for 15 patients with ER+/HER2− premenopausal MBC who had failed one to two lines of hormone therapy without chemotherapy. We profiled the immune-related genes from pre- and post-treatment samples.