PDCD1 and neoplasm: Additionally, co-expression of PD-1 and LAG-3 indicates a higher level of exhaustion in CD8+ TILs, with dual blockade of these checkpoints leading to tumor regression.177 In ovarian cancer, LAG-3 + PD-1 + CD8+ T cells showed significantly reduced IFN-γ and TNF-α production compared to their single-positive counterparts.178 Moreover, antigen presentation and recognition are essential for the immune system to identify and eliminate abnormal cells.