Beyond functional invalidation of Treg cells, if of appropriate isotype, anti-OX-40 mAbs can further eliminate infiltrating Treg by Antibody-Dependent Cellular Cytotoxicity (ADCC), as reported for several malignancies such as MCA303 sarcoma, CT26 colon carcinoma and SM1 breast cancer (14, 15). Here, TNFRSF4 is linked to breast cancer.