ESMO-ESTRO consensus statements on the safety of combining radiotherapy with immune checkpoint inhibitors, VEGF(R) inhibitors, or multitargeted tyrosine kinase inhibitors

Background: The combination of radiotherapy (RT) with targeted agents or immunotherapy may result in improved outcomes, but it can also increase toxicity. However, there is a paucity of high-quality toxicity data, leading to an absence of evidence-based guidelines. Design: To address this, European Society for Medical Oncology (ESMO) and European SocieTy for Radiotherapy and Oncology (ESTRO) initiated a series of systematic reviews followed by a Delphi consensus process to develop multidisciplinary, evidence-based consensus statements regarding the safety of combining RT with such agents. The current publication describes the combination of RT with immune checkpoint inhibitors (ICIs), vascular endothelial growth factor (receptor) [VEGF(R)] inhibitors, or multitargeted tyrosine kinase inhibitors (TKIs). By systematically covering different drug classes and irradiated areas, 76 clinical scenarios were evaluated during two Delphi rounds with 20 international experts. Safety statements were developed for each scenario, based on the systematic literature reviews. Results: A total of 5921 records were screened during the systematic literature review process for ICIs, VEGF(R) inhibitors, and multitargeted TKIs, and 159 reports were selected for inclusion in the final literature reviews and the database. During the two Delphi rounds, agreement was reached regarding the safety statements for 74 clinical scenarios. Conclusions: Generally, the expected toxicity of combining RT with ICIs is low, particularly for programmed death(-ligand) 1 inhibitors. For most combinations with VEGF(R) inhibitors and multitargeted TKIs, exercising caution is recommended. The evidence-based safety statements developed during this comprehensive project provide practical guidance on combining RT with targeted cancer therapies and immunotherapy.