SPP1 and neoplasm: In contrast, immunosuppressive populations such as regulatory T cells (Tregs), M2-polarized macrophages, myeloid-derived suppressor cells (MDSCs), and SPP1+ tumor-associated macrophages (TAMs) support tumor immune evasion and are linked to poor prognosis (Davis et al., 2016; Binnewies et al., 2018; Liu et al., 2025).