KDR and melanoma: To our knowledge, only four preclinical studies have investigated the co-targeting of VEGF-A and PD-1,15 co-targeting of VEGFR2 plus PD-1,16 co-targeting of VEGFR2 plus PD-L1,17 as well as triple targeting of VEGF, Angiopoietin-2, and PD-118—and these have relied heavily on primary tumour models (of melanoma,18 pancreatic neuroendocrine tumours (PNETs),17 and colorectal15,16,18 and breast cancer17,18) and only utilised one metastatic model (of breast cancer18).