PDCD1 and neoplasm: Indeed, when we consider the aforementioned studies and the results obtained by us, we can hypothesize that higher PD-L1 IHC scores found in TCs may interfere with the cytokine pathway of chemoattraction, an adaptive resistance mechanism of immune escape, suggesting that the PD-1/PD-L1/PD-L2 axis can play a leading role in tumor progression.