COMBINING RADIOTHERAPY AND IMMUNE CHECKPOINT INHIBITORS

ABSTRACT

Radiotherapy is a component of standard care in cancer treatment. It was conventionaly known that radiation kills cancer cells through direct interaction with DNA or via the production of free radicals. Currently, we know that radiotherapy enhances anti-tumor immune responses by increasing tumor antigen release and inducing T cell infiltration. Thus, RT can create a systemic effect defined as 'abscopal effect' with the immune response it creates against tumor cells. Similarly, immune check point inhibitors provide the induction of more effective anti-tumor immunity. Combining radiation and immunotherapy has been shown to be promising in improving treatment outcomes and reducing relapses by overcoming tumor immune tolerance. However, optimal use of combined therapy in terms of RT dose and fractionation, and immunotherapy-radiotherapy sequence is still unclear. In this review, the synergistic effect of RT and immunotherapy and the abscopal effect of combination therapy are described with review of various publications. Besides this, the optimum sequencing, effective RT dose and fractionation in the combination of RT with immune therapy were summarized.

Key words: Immunotherapy, radiotherapy, check point inhibition, abscobal effect.