TNFRSF18 and melanoma: Therefore, an agonistic human anti-GITR mAb (TRX-518, TolerxR), which blocks the interaction of GITR with its ligand and also co-stimulates T cells and enhances the cytotoxicity of NK cells, is currently under clinical investigation for the treatment of melanoma [(Schaer et al., 2010) and clinicaltrials.gov].