A model of tumor-immune system interactions with healthy cells and immunotherapies

A mathematical model of the tumor–immune system interactions is presented. The model includes the primary cell populations involved in CD4⁺ T cells mediated regression of the tumor, that is, tumor cells, CD4⁺ T cells, anti-tumor cytokines, CTLA-4 molecules, and normal cells. Our study reveals that host cells together with cytokines are key features in driving tumor dynamics. The malignant tumor can be completely suppressed if the tumor growth rate is small and the host cells are more competitive. No treatments are needed in this scenario as tumor cells are driven to extinction by host cells. We examine various immunotherapies of either T cells, anti-tumor cytokines, anti-CTLA-4, or a combination of these to study their effectiveness. For the tumor with a medium growth rate and a moderate competitive ability to host cells, numerical simulations show that the host cells impel the tumor cells to demise due to battle with the normal cells and the effective jointed treatment strategy.