The immunology of HR+/HER2− BC is complex, characterized by low TIL infiltration (≤10% in stromal tissue), human leukocyte antigen class I downregulation, and increased lymphocyte activation gene 3 (LAG3) and T cell immunoglobulin and mucin domain 3 expression, leading to poor recruitment of activated immune cells and increased tumor-associated macrophages (TAMs) [12]. This evidence concerns the gene LAG3 and neoplasm.