State of clinical research of radiotherapy/chemoradiotherapy and immune checkpoint inhibitor therapy combinations in solid tumours-a German radiation oncology survey.

Combinations of immune checkpoint inhibitors (ICIs) with radiotherapy and/or chemoradiotherapy are currently under investigation in many cancer types and clinical settings. In this survey, we solicited members of the German Radiation Oncology Society and young DEGRO (working group of DEGRO e.V.) to review the current status of research in this field and underline critical issues such as oncological benefit, treatment toxicity and obstacles in clinical research. The responses represent 14 different departments of radiation oncology at German university hospitals. Respondents of the same department were analysed for congruence. Sixty-one percent of all respondents perform radiotherapy/chemoradiotherapy and ICI therapy combination studies at their institutions and participate in multicentre studies. Combinations were investigated mainly in head and neck tumours (95%), lung cancer (57%), malignant melanoma (48%) and tumours of the upper gastrointestinal tract (9%). Combination of chemoradiotherapy with checkpoint inhibitors was only tested in head and neck cancers (52%), non-small-cell lung cancer (NSCLC) (8.70%) and malignant melanoma (4%). A combination of radiotherapy/chemoradiotherapy with ICIs is assumed to be effective or very effective by >85% of all respondents. The treatment of intracranial metastatic disease by this combination is assumed to be very effective by most respondents (61%). The present survey shows great acceptance of new combined modality treatment paradigm. ICIs with radiotherapy and/or chemoradiotherapy are under investigation at >75% of all participating centres. Head and neck tumours, NSCLC and malignant melanoma are the most frequently tested cancer types.