On modeling the synergy of cancer immunotherapy with radiotherapy

The release of tumor antigens during traditional cancer treatments (such as chemo- or radiotherapy) can lead to a stimulation of the immune response which provides synergistic effects these treatments have when combined with immunotherapies (e.g., based on check-point blockade). Based on a classical model for tumor-immune system interactions, a minimally parameterized mathematical model is formulated that incorporates such synergistic features. It is shown that the resulting dynamics exhibits the wide range of behaviors that encompass the variety of medically realistic scenarios often termed the three E’s (elimination, equilibrium and tumor escape) of immunoediting. The model is used to formulate an optimal control problem for a combination therapy. •A model for the synergy of immuno- and radiotherapy is formulated and analyzed•The model is a low-dimensional system of ODEs with a small number of parameters.•The dynamics exhibits elimination, equilibrium, and tumor escape•An optimal control problem for the transfer of malignant into benign states is set up