CCR6 and central nervous system cancer: Despite decreased frequencies of tumor-infiltrating myeloid cells in ICB R tumors, we did not observe significant differences in the frequency of circulating blood CD11b+ cells and their expression of the chemokine receptors CCR2, CCR4, CCR5, and CCR6 involved in myeloid cell recruitment to gliomas during ICB therapy (d15; Supplementary Fig. 6d, e) and response establishment (d21; Supplementary Fig. 6f, g).