放疗联合免疫治疗的生物学基础及研究进展

研究发现放疗能促进肿瘤细胞免疫原性死亡，并经肿瘤抗原呈递和特异性T细胞免疫应答过程来杀伤肿瘤，甚至产生系统性抗肿瘤免疫反应，引起照射野外肿瘤缩小，上述现象被称为放疗远位效应。尽管放疗的临床远位效应已有报道，许多基础及转化性研究也证实其发生存在一定的生物学基础，但放疗远位效应更多地表现为亚临床效应，难以达到临床客观疗效。目前，抗PD-1/PD-L1抗体免疫治疗在临床肿瘤研究中展示出明显而确切的疗效，是临床中局部放疗联合免疫治疗的新治疗模式。但是，这种新治疗模式的临床实践，应当基于能够产生远位效应的放疗分割模式以及最佳的联合时机，最终达到全身抗肿瘤免疫反应的协同疗效。 

Biological foundation and research progress on radiotherapy combined with immunotherapy

Numerous studies revealed that radiation can promote the immunogenic cell death, enhance the immune response of tumor-antigen-specific T cells, and induce systematic antitumor immunity, which may result in abscopal effect. Abscopal effect refers to the regression of non-irradiated metastatic lesions distant from the primary tumor site that is directly subjected to irradiation. Despite that abscopal effect has been clinically reported and that many preclinical studies have confirmed its biological basis, abscopal effect remains a subclinical phenomenon, in which objective efficacy is difficult to obtain. Currently, the anti-PD-1/PD-L1 therapy in clinical applications shows a clear and definite curative effect, thereby making local radiotherapy combined with immunotherapy a new treatment pattern. However, the clinical practice of this new mode should be based on appropriate dose and fraction and the most suitable temporal combination to achieve the synergic antitumor immune response.