Several studies have linked the HR+ BC immune-cold phenotype to different clinicopathological features of HR+ tumors: low mutational burden (18), low programmed cell death ligand 1 (PD-L1) expression (19), low number of tumor-infiltrating lymphocytes (TILs) (20, 21), and enrichment of immunosuppressive populations (22, 23). The gene discussed is CD274; the disease is breast cancer.