Investigation of the Timely-coordinated Therapy of Patients With Metastatic Cancer by Radiotherapy Together With Immune Checkpoint Inhibition

Immunotherapy for the treatment of several cancer entities steadily increased during the last years. The data from the finalized and ongoing studies show the tremendous impact of immune checkpoint inhibition (ICI) also for advanced metastatic patients. Especially the ICI with pembrolizumab and nivolumab have an increasing number of first line treatment approvals. However, in particular metastatic patients which receive ICI therapy are often irradiated for immediate palliation of several metastases. Preclinical work revealed that radiotherapy (RT) is capable to modulate the tumor phenotype, its microenvironment in a way that systemic anti-tumor immune responses are induced. However, radiation has also immune suppressive properties as e.g. the expression of immune checkpoint molecules is increased following radiotherapy. So the ICI therapy in combination with the RT has the potential to overcome the immunotolerance of the tumor and the metastases. More and more reports therefore describe a so-called systemic immune-modulating effect of radiotherapy (former and still often named as abscopal effect). However the timely application of ICI and RT is often randomly and depends on the clinical need for the palliative RT. The aim of this trial is therefore to standardize the chronology of RT in combination with ICI, to evaluate the effects of radio-immunotherapy with a stratified and comparable patient cohort. The ST-ICI study is a prospective and observational study not influencing the standard therapeutic scheme and will provide hints how the radio-immune therapy drives systemic anti tumor responses.