CD4 and neoplasm: Importantly, though myeloid cells appear to be the major direct target cell population for E7046, in vivo anti-tumor activity of E7046 requires CD8+ cytolytic T cells but not CD4+ T cells, suggesting a unique mechanism of action of E7046 in which reduced myeloid cell-based immunosuppression facilitates a cytolytic CD8+ T cell-dependent anti-tumor activity.