STAT3 and glioblastoma: In view of the earlier observation that the GBM stem cells trigger STAT3-mediated activation and proliferation of immunosuppressive M2 microglia/macrophages [68], anti-GBM-stem-cell and anti-STAT3 activities of CCP (Fig.5, Additional file 9: Figure S9) are likely to be pivotal in the observed CCP-evoked (i) correction of immunosuppression in the GBM microenvironment, (ii) M2➔M1 polarization of the tumor-associated microglia, and (iii) intra-tumor recruitment of M1-like macrophages and activated NK cells [10, 69].