Radiotherapy supports protective tumor-specific immunity

Abstract

Radiotherapy is an important therapeutic option for the treatment of cancer. Growing evidence indicates that, besides inducing an irreversible DNA damage, radiotherapy promotes tumor-specific immune response, which significantly contribute to therapeutic efficacy. We postulate that radiotherapy activates tumor-associated dendritic cells, thus changing the tolerogenic tumor environment into an immunogenic one.

Figure 1. Radiotherapy supports tumor-specific immunity at multiple tumor-intrinsic and tumor-extrinsic levels. Radiotherapy (1) induces the death of tumor cells, resulting in the release of tumor-associated antigens and presumably in their cross-presentation by DCs, which is further promoted by radiation-induced Type I interferon; (2) induces the upregulation of MHC Class I molecules and CTAs, which makes cancer cells better targets for the immune system; (3) disturbs immune homeostasis in a way that results in DC maturation; and (4) supports the survival, proliferation and maintenance of effector functions of tumor-infiltrating T cells, resulting in a qualitatively and quantitatively improved T-cell infiltrate.