Radiotherapy has conventionally been viewed as immunosuppressive, which has precluded its use in combination with immunotherapy for prostate and other cancers.
However, the relationship between ionizing radiation and immune reactivity is now known to be more complex than was previously thought, and data on the use of radiotherapy and immunotherapy are accumulating. Herein, we review this topic in the light of recently available data in the prostate cancer setting. Recent research has shown no significant lymphopenia in patients undergoing radiotherapy for high-risk adenocarcinoma of the prostate. In addition, emerging evidence suggests that radiotherapy can have immunostimulatory effects, and that tumor cell death, coupled with related changes in antigen availability and inflammatory signals, can affect lymphocyte and dendritic cell activation. Initial studies have focused on combinations of tumor irradiation and immunotherapy, such as the autologous cellular immunotherapy sipuleucel-T and the monoclonal antibody ipilimumab, in metastatic castration-resistant prostate cancer. These combinations appear to have clinical promise, and further investigation of the potentially synergistic combination of radiotherapy and immunotherapy is continuing in clinical trials.
Finkelstein SE, Salenius S, Mantz CA, Shore ND, Fernandez EB, Shulman J, Myslicki FA, Agassi AM, Rotterman Y, DeVries T, Sims R. Are you the author?
21st Century Oncology Translational Research Consortium, Scottsdale, AZ; 21st Century Oncology Translational Research Consortium, Fort Myers, FL; Carolina Urologic Research Center, 21st Century Oncology, Myrtle Beach, SC; Dendreon Corporation, Seattle, WA.
Reference: Clin Genitourin Cancer. 2015 Feb;13(1):1-9.