Resumen de Dynamic Analysis of a Model on Tumor-Immune System with Regulation of PD-1/PD-L1 and Stimulation Delay of Tumor Antigen

Jianquan Li, Fang Liu, Yuming Chen, Dian Zhang

• We propose and investigate a mathematical model on interaction between tumor and the immune system, where the regulation of PD-1/PD-L1 and the stimulation delay of tumor antigen for the immune system are considered. Though delay will not change the structure of equilibria, the global dynamics in the case without delay is simple compared with that in the case with delay. Theoretic analysis and numerical simulations show that the incorporation of delay leads to complex dynamics, including the appearance of oscillating solutions, periodic solutions from Hopf bifurcation, and homoclinic orbits, etc. The effect of the immunotherapy including anti-PD-1/PD-L1 inhibitor and tumor vaccine is also discussed.