Research in Medicine

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khastar S, ghaffari-nazari H, Jalali S A. Immunotherapy and radiotherapy: An effective combination therapy against cancer. Research in Medicine 2021; 45 (2) :72-81
URL: http://pejouhesh.sbmu.ac.ir/article-1-2172-en.html

Background: Radiotherapy (RT) is an effective treatment in the field of cancer. Since the potential effect of RT is heavily dependent on the patient's immune system, using the immunotherapy to enhance the radiotherapy effects seems to be a positive step in the treatment of cancer.
Materials and Methods: In order to write the present review article, keywords including radiotherapy, immunotherapy, combination therapy, and immune-checkpoint inhibitors antibodies were searched in reliable databases, including Google Scholar, PubMed, Scopus, and Elsevier. Among potential candidates, those which were the most relevant to the purpose of the study and evaluated the combination of radiotherapy and immunotherapy with immune-checkpoint inhibitors antibodies were selected.
Conclusion: RT has distinct effects on the tumor microenvironment which can either inhibit or promote tumor growth. By inducing immunogenic cell death results in releasing danger signals, RT increases in cytokine/chemokine secretion, recruits immune cells, and alters the expression of CTLA-4, PD-1, and PD-L1 molecules on tumor and immune cells. Previous studies showed that the combination of immunotherapy and RT (radio-immunotherapy) induces the synergic effects on stimulation of anti-tumor immune response. Due to the change in the expression of immune-checkpoint molecules, including CTLA-4 and PD-1 on tumor and immune cells, and the impact on anti-tumor immune function in controlling tumor growth as a result of radiotherapy, it seems that a rational solution to overcome the inhibitory effects and to enhance the anti-tumor effects of RT is anti-checkpoint antibodies (anti-CTLA-4 and anti-PD-1). However, some factors including dose, type of radiation, and the timing of RT in relation to administration of checkpoint inhibitors are some of the challenges along this way.