Immune checkpoint inhibitors (ICI) are effective in cancer treatment. A pre-existing immune response demonstrated by significant pretreatment tumor lymphocytic infiltration is a prerequisite for response. Within such infiltrated tumors, referred to as ‘hot’ tumors, ICI rescue the activity of antitumor T cells. By contrast, ‘cold’ tumors lack lymphocytic infiltration and are refractory to immunotherapy. Preclinical data show that radiotherapy sensitizes refractory tumors to ICI by recruiting antitumor T cells. Despite the growing number of clinical studies testing the ability of radiation to enhance immunotherapy, clinical evidence that it converts cold tumors into responsive ones remains elusive. Here, we review evidence that radiotherapy is not only an occasional enhancer of the effects of immunotherapy, but also a ‘game changer’, and propose a blueprint to test this.

免疫检查点抑制剂（ICI）在癌症治疗中有效。通过显着的预处理肿瘤淋巴细胞浸润证明预先存在的免疫应答是应答的前提。在这种浸润的肿瘤（称为“热”肿瘤）中，ICI可以挽救抗肿瘤T细胞的活性。相比之下，“冷”肿瘤缺乏淋巴细胞浸润并且对免疫治疗是难治的。临床前数据表明，放疗通过募集抗肿瘤T细胞使难治性肿瘤对ICI敏感。尽管越来越多的临床研究测试放射线增强免疫疗法的能力，但仍无法将其将冷肿瘤转化为反应性肿瘤的临床证据。在这里，我们回顾了证据，放射疗法不仅是免疫疗法效果的偶然增强剂，而且还是“游戏规则改变者”，