This was shown in patients with metastatic melanoma, NSCLC, RCC, and urothelial cancer, treated with anti-programmed cell death 1 (anti-PD-1) monotherapy or anti-PD-1 in combination with anti-cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA-4), where the presence of liver metastases was associated with a lower response and a shorter progression-free and overall survival [4,5,13,53,55]. This evidence concerns the gene PDCD1 and metastatic melanoma.