Systemic benefit of radiation therapy via abscopal effect

Abstract

Evidence of a systemic response related to localized radiation therapy (RT) in cancer management is rare. However, enhancing the immune responseviaimmunotherapy followed by localized RT has shown evidence of tumor shrinkage to non-irradiated metastatic disease thereby inducing an “abscopal effect.” Combined induction of the cGAS-STING pathway and activation of IFN-gamma signaling cascade related to RT within an activated immune environment promotes neoantigen presentation and expansion of cytotoxic effector cells enabling enhancement of systemic immune response. A proposed mechanism, case examples, and clinical trial evidence of “abscopal effect” benefit are reviewed. Results support strategic therapeutic testing to enhance “abscopal effect.”