CD274 and neoplasm: In the 40 TNBC patients who had both serum and tumor tissue available, we found a negative correlation between serum IRGPI and tissue PD-L1 expression, as well as between serum CCL25 levels and tissue PD-L1 expression, although the correlation was not statistically significant (r = −0.302; p = 0.058) (Table 4 and Table 5).