PDCD1 and neoplasm: On the other hand, among the 3 tumor-infiltrating CD8 T-cell clusters (C0, C9, C6), both C9 and C6 were marked by signature genes of exhausted T cells (Texs), such as PDCD1 and LAG378,79 (Fig. 5B), whereas C0 cells highly expressed the marker of T-cell activation CD16080, suggesting that C0 was an activated tumor-infiltrating Teff cell cluster.