Combining Immunotherapy and Radiation for Prostate Cancer

Abstract

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.

A Case of Complete Abscopal Response in High-Grade Pleiomorphic Sarcoma Treated with Radiotherapy Alone

“…There are several unanswered questions that are being investigated to determine how to induce the native immune system to recognize and attack metastatic tumor cells, including the optimal fractionation size of local radiotherapy to induce tumor antigen expression, the timing of delivery of radiotherapy in conjunction with immunotherapy [6-7], and which drug therapies show the best promise in priming the immune system [8-10]. …”

Immunotherapy of Prostate Cancer: Facts and Hopes

“…The goal is to modify the phenotype of cancer cells, making it easier for immune cells to recognize and kill them (37). …”

Remarkable Pathologic Change in Advanced Prostate Cancer Patient Using Dendritic Cell–Cytokine-Induced Killer Combined Therapy: A Case Report

“…6,21 Recent studies have indicated that combining immunotherapy with chemotherapy, radiotherapy, or both is an effective method of prolonging patient survival and enhancing immunological responses. [22][23][24] In addition, the other study reported an immunotherapeutic strategy that combined an autologous tumor lysate-loaded DC vaccine with CIK and NK cells to treat undifferentiated embryonal sarcoma of the liver, 23 which is a rare but rapidly growing malignant spindle cell tumor, with satisfactory outcomes. 25 All these previously reported cases relieved the tumor progression and prolonged the lives of the patients; however, to our knowledge, no patients experienced pathologic remission (clinical cure).…”