PDCD1 and melanoma: LAG-3 has thus become one of the most critical new targets of cancer immunotherapy and is considered a major development direction after PD-1 with great application prospects.171,177,178 Relatlimab, the first inhibitor of LAG-3 to enter the clinic, blocks the interaction of LAG-3 with MHC II.179 RELATIVITY 047 (CA224-047), a phase II/III clinical study, was designed to evaluate a fixed-dose combination of relatlimab combined with nivolumab versus nivolumab monotherapy in patients with previously untreated metastatic or unresectable melanoma.