cGAS/STING-mediated γδ T cell recruitment drives radioresistance: implications for improving radioimmunotherapy outcomes

Radiotherapy is a key treatment modality in many malignancies, but radiation-induced immunosuppression can undermine its outcomes and diminish the efficacy of combinatorial strategies, like radioimmunotherapy. In this issue of the JCI, Deng et al. implicate cGAS/STING signaling in the recruitment of γδ T cells that drive downstream radioresistance. Radiation-induced microparticles containing double-stranded tumor DNA led to activation of the cGAS/STING pathway in macrophages, promoting γδ T cell recruitment through CCL20 signaling. In mouse models, γδ T cell-dependent recruitment of myeloid-derived suppressor cells and T cell suppression curbed radiotherapy efficacy and drove antitumor immunity. Ablation of γδ T cells improved the efficacy of radiotherapy alone and radiotherapy combined with immune checkpoint inhibitors in mouse models, supporting further investigation of γδ T cell targeting to improve clinical outcomes with radioimmunotherapy. The findings also add complexity to the function of the cGAS/STING pathway in setting the balance between antitumor immunity and immunosuppression.