SPP1 and head and neck squamous cell carcinoma: Two of the identified macrophage populations, SPP1 and CXCL9, recapitulate recent results that suggest the recasting of macrophage polarity along the SPP1 and CXCL9 axes rather than the traditional M1/M2 phenotypes, and associates them with worse and better survival, respectively.[34,75] We also identified a population of IL1β-positive myeloid cells not previously described in HNSCC that show both an immunosuppressive phenotype through the expression of IL1β and IL10, and an angiogenic phenotype, but lacking classical markers for M2 macrophages, and is SPP1-negative.