Radiation therapy for cancer has systemic consequences that are mediated through danger signaling in irradiated tissues and tumors and that engage the immune system. This proposal aims to understand how different dose-fractionation schedules in radiation therapy shape the immune system. Recent technological advances in physical dose delivery have encouraged innovative use of higher than conventional doses/fraction given over a shorter time. The optimal dose per fraction that generates anti-tumor as opposed to pro-tumor immune responses in humans is not known but preclinical data suggest that doses around 8Gy may be superior. This is the question addressed here by immune monitoring prostate cancer patients receiving hypofractionated and conventional regimens. The study is designed in a longitudinal fashion to detect changes in individual patients over time before, during and after treatment and to probe multiple aspects of their immune responses. Composing immune profiles with time for each patient circumvents some of the problems of individual variation. An additional benefit of this study comes from the fact that both dose-fractionation schedules will be compared side-by-side in one institution, which minimizes potential biases. The methods employed will be based on cutting-edge, sophisticated immune monitoring technologies to track the frequency, phenotype, and function of effector and suppressor lymphoid and myeloid-derived cells as well as humoral responses. They include Dextramer assay, ELISpot, multi-color flow cytometry, ELISA and multiplex technology.
The aim i s to paint a global immune picture that includes tumor-specific responses - qualitative as well as quantitative - for each patient as they undergo radiation treatment. The study will have high impact. It may provide data for a new paradigm for re-thinking radiation fractionation, the release of danger signals, and the development of tumor-specific immune responses. Knowing how different radiation dose delivery schedules affect the balance between pro- and anti-tumor immune responses is crucial if we are to engage the immune system in the context of cancer treatment, especially if we are to integrate it with other more systemic therapies, including chemo- (CT) and immunotherapy (IT). This study also has the potential to have an enormous impact as a fast-track translational application because it will ultimately allow us to harness the power of the immune system with an innovative approach that takes radiation oncology to the 21st century.

Public Health Relevance

Cancer patients undergoing radiation therapy respond with changes in their immune system that can influence overall treatment success but our understanding of how this works for different treatment options is still very limited. This proposa aims to follow individual prostate cancer patients as they undergo a less conventional schedule of high radiation doses given over a shorter time and to monitor their immune response. This will be compared to standard radiation therapy and it will ultimately tell us if, how and when we need to intervene with the immune system so as to maximize therapeutic benefit, all of which has immense potential to assist the cancer community.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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Radiation Therapeutics and Biology Study Section (RTB)
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Ahmed, Mansoor M
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University of California Los Angeles
Schools of Medicine
Los Angeles
United States
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Formenti, Silvia C; Lee, Percy; Adams, Sylvia et al. (2018) Focal Irradiation and Systemic TGF? Blockade in Metastatic Breast Cancer. Clin Cancer Res 24:2493-2504
McBride, William H; Ganapathy, Ekambaram; Lee, Mi-Heon et al. (2017) A perspective on the impact of radiation therapy on the immune rheostat. Br J Radiol 90:20170272
Schaue, Dörthe (2017) A Century of Radiation Therapy and Adaptive Immunity. Front Immunol 8:431