Eradicating gross tumor disease: a prerequisite for efficient radioimmunotherapy?

Radiation therapy may induce off-target antitumor "abscopal" immunostimulatory and immunosuppressive effects. Several preclinical and early clinical studies revealed promising results when combining radiation therapy with immunostimulatory agents. Most radioimmunotherapy randomized trials showed disappointing results in patients with advanced tumors. In contrast, outcomes were encouraging when immunotherapy was delivered on top of gross disease elimination with curative-intent radiation therapy. In this review, we highlight available results from randomized trials and discuss the potential impact of overall tumor burden on the observed efficacy of radioimmunotherapy.