  Achieving effective synergy between radiotherapy and immunotherapy is
critical for optimizing tumor control and treatment outcomes. To explore the
underlying mechanisms of this synergy, we have investigated a novel treatment
approach known as personalized ultra-fractionated stereotactic adaptive
radiation therapy (PULSAR), which emphasizes the impact of radiation timing on
treatment efficacy. However, the precise mechanism remains unclear. Building on
insights from small animal PULSAR studies, we developed a mathematical
framework consisting of multiple ordinary differential equations to elucidate
the temporal dynamics of tumor control resulting from radiation and the
adaptive immune response. The model accounts for the migration and infiltration
of T-cells within the tumor microenvironment. This proposed model establishes a
causal and quantitative link between radiation therapy and immunotherapy,
providing a valuable in-silico analysis tool for designing future PULSAR
trials.
