Although to date preclinical data supporting the use of agonistic GITR mAb for immunotherapeutic interventions in CRC are scarce, two GITR agonistic antibodies (TRX518 and MK-4166) are being investigated in a phase I setting, with or without the addition of a PD-1 inhibitor (Pembrolizumab) (Table 1). Here, TNFRSF18 is linked to colorectal carcinoma.