Interaction between Immunotherapy and Radiotherapy

Abstract

In recent years, treatment methods on immune checkpoints have emerged as promising novel therapeutic modalities against cancer as a result of studies focusing on elucidation of immune micro-environment. Immunotherapy has now become an established treatment in some cancers. ^[1-2] This has led the need for investigation of biomarkers which allow determining effectiveness of immunotherapies and patient groups which will most benefit from these therapies. In previous studies, it was suggested that programmed death receptor-1 (PD-1) and programmed death ligand-1 (PD-L1) expressions could be predictive biomarkers in cancers. PD-1 is a transmembrane protein present in macrophages, myeloid dendritic cells, B cells, epithelial cells and vascular endothelial cells, which limits and inhibits immunological activation in activated T cells. Blocking PD-1/PD-L1 interaction promises hope in the cancer treatment.  In clinical studies, it was shown that targeted PD-1/PD-L1 therapy alone or in combination with other modalities is beneficial in advanced cancers with aggressive behavior. It was shown that overexpression of PD-1 present in tumoral micro-environment is associated to poor prognosis in gastric cancer, breast cancer, ovarian cancer, kidney, pancreas and lung cancers and in melanoma. ^[1-5]