CD8A and neoplasm: The efficient depletion of Treg cells in tumors but not in spleen or lymph node can be explained by the much higher expression of CTLA-4 on tumor infiltrated Treg cells (Supplementary information, Figure S6B and C), which is also reported by previous studies.9–11 As a result of Treg cell depletion, the ratio of CD8 T cells over Treg cells was selectively increased in the tumor (Fig. 7e).