A phase I study of anti-GITR antibody MK-4166, as monotherapy or with pembrolizumab in patients with advanced solid tumours, demonstrated an ORR of only 2.2%; however, in a melanoma expansion group, 8 out of 13 patients with immune checkpoint inhibitor (ICB)-naïve melanoma achieved a response for an ORR of 62% [108]. Here, TNFRSF18 is linked to melanoma.