Abstract PL2: The role of radiotherapy combined with immunotherapy in oligometastatic cancer

In 1995 Samuel Hellman and I advanced the hypothesis that many cancers represent a spectrum of disease from purely localized to widespread, highlighting a disease state we termed “oligometastasis.” We proposed that oligometastasis represented an intermediary state between localized and widespread disease that was amenable to cure by metastasis-directed therapies. We also hypothesized that tumor clones that escape systemic therapies, now termed “oligoprogressors,” might be targets for ablation by focal treatments. I will present data supporting the basis and classification of (oligo)metastatic disease, as well as clinical trial results from patients, including those with breast cancer, that informs us regarding future clinical strategies. A decade ago our group noted that large radiation doses used in stereotactic radiotherapy employed in clinical trials of oligometastatic tumors induced immunogenic cell death, which has led us to investigations into the potential interaction between radiotherapy and immunotherapy. I will also present basic and clinical data from investigations into combined radio-immunotherapy treatment and suggest how these investigations might improve treatment of patients. Citation Format: RR Weichselbaum, S Hellman. The role of radiotherapy combined with immunotherapy in oligometastatic cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr PL2.