[Combining radiotherapy with immunotherapy for urological malignancies]

Photon radiotherapy has repeatedly been described to elicit effects beyond mere inhibition of tumor cell clonogenicity: immunomodulatory phenomena including radiation-induced expression of tumor-associated antigens, increased recruitment and functioning of immunocompetent cells and secretion of immunomodulatory messengers have been described to explain the radiation responses of tumor lesions outside of irradiated volumes ("abscopal effect") in both preclinical models and clinical cases. With radiotherapy only, the abscopal effect is only rarely observed, but several trials have suggested combining modern immunotherapy with radiation to increase both frequency and intensity of the abscopal effect. Urological malignancies are commonly described as immunogenic malignancies. Both radiotherapy and immunotherapy are typical components of modern treatment regimes. Combining both modalities is expected to result in increased efficacy within and beyond irradiated lesions. However, prospective clinical trials have not yet provided mature results for oncological efficacy and toxicity of combined modality treatments in urological malignancies. This review details the preclinical rationale for combining photon radiotherapy with immunotherapy, summarizes early clinical experience, and provides a perspective for potential, future innovative combination treatments.