PDCD1 and neoplasm: Indeed, the anti-tumor activity of combined GARP:TGF-β1/PD-1 blockade: i) occurred without Treg depletion, ii) was observed using anti-GARP:TGF-β1 incapable of binding Fcg receptors, and iii) was lost in MC38 tumor-bearing mice carrying a Treg-specific deletion of the Garp gene.