PDCD1 and neoplasm: Considering that PD-1 is highly upregulated on tumor-derived NK-cells (Fig. 3B) and effector T-cells31, IL-2 antibody fusion proteins, such as IL-2variant-anti-PD-1 mAb fusion proteins, might also be attractive candidates to enhance T- and NK-cell mediated anti-tumor immunity in GBM45.