FOXP3 and neoplasm: However, tumor-infiltrating CD8+ T cells presented increased expression of the exhaustion marker PD-1 and the infiltration of FoxP3+Treg cells into the tumor was unaffected (Fig. 2J and S5B), which could be responsible for lack of antitumor efficacy and provide the rationale for the combination of 7aaRGD with anti-PD-1 immune checkpoint inhibitor.