PD (L) 1-Inhibitors and Radiation: A Good Combination for Local and Systemic Effects?

Abstract

Radiation therapy is an important component in treatment of solid tumours, in a locally advanced situation and also in a metastatic situation. Indications for using PD- (L) -1 inhibitors increase especially in the metastatic situation, but also in locally advanced solid tumours. Preclinical data show local and systemically effective synergies between local irradiation and an application of checkpoint inhibitors. In the metastatic situation, a possible abscopal effect is of particular interest. This abscopal effect can be achieved especially in concurrent approaches of PD-(L)-1-inhibitors and stereotactic radiation with higher single doses like 3 x 8 Gy or 4 x 12,5 Gy. In locally advanced tumours a local enhancement of the radiation effect, and also an abscopal effect to eliminate potential micrometastases to is of great interest to achieve healing. In this treatment situation promising results are seen in the application of PD-(L)-1-inhibitors as maintenance after concurrent chemoradiation especially in non-small cell lung cancer, as well as in concurrent applications of conventionally fractionated radiotherapy and PD-(L)-1 inhibitors. These approaches and results are considered from the clinician’s point of view.