HOXD13 and cancer: PD-L1 decreased the excitability of neurons and increased the mechanical pain threshold.[29–31] On the other hand, sPD-1 can neutralize PD-L1, increase the excitability of neurons and cause tactile pain.[30] However, the relationship between the expression of sPD-1 and cancer pain still remains unclear, which does not take the advantages of the further development of future researches.