PDCD1 and neoplasm: LAG-3 regulates T-cell responses through major histocompatibility (MHC) class II interaction, facilitating tumor immune evasion similar to PD-1, while anti-LAG-3 medicines like ieramilimab demonstrate limited efficacy as monotherapy but exhibit enhanced responses (e.g., 10.7% overall response rate [ORR]) when combined with anti-PD-1 mAbs such as spartalizumab in advanced solid tumors.