Abstract IA-028: Interaction of radiotherapy and immunotherapy: Maybe not what you think

Abstract

Abstract Immunotherapy has altered the cancer therapy landscape and has engendered significant investigative interest in the context of the basic mechanisms and clinical applications of radiotherapy/immunotherapy combinations from accomplished investigators, many of whom have presented at this conference. Despite high quality preclinical data and some intriguing hints of efficacy, most of the clinical trials to date have failed to show a benefit to radiotherapy/immunotherapy combinations except for small subsets of patients treated in phase 1 clinical trials. The often cited “PACIFIC” trial in stage 3 lung cancer shows that immunotherapy can safely be given after chemoradiotherapy and provides significant patient benefit in terms of progression free and overall survival but does not demonstrate a positive dependent interaction between radiotherapy and immunotherapy. I will critically review select clinical trials and present data from our (and other) laboratories that may in part explain the discrepancies between the encouraging preclinical data and the somewhat disappointing clinical results. Citation Format: Ralph R. Weichselbaum. Interaction of radiotherapy and immunotherapy: Maybe not what you think [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr IA-028.