LDRT combined with anti-PD-1 promotes tumor regression in head and neck squamous cell carcinoma through tumor metaprogram evolution and immune cell reprogramming

作者：Guanjun Li, Xiangdi Yang, Linxuan Huang, Yannan Zheng, Liangfu Xu, Zhaoyuan Zhang, Junyan Li, Tingting Li, Yutong Zhang, Yongqin Yang, Yifei Li, Zhigang Liu · 发表于：Journal of Experimental & Clinical Cancer Research · 年份：2026 · DOI：10.1186/s13046-026-03660-3 · 被引用次数：1 · 研究领域：Cancer Immunotherapy and Biomarkers、Single-cell and spatial transcriptomics、CAR-T cell therapy research

BACKGROUND: Anti–PD-1 (αPD-1) therapy shows limited efficacy in head and neck squamous cell carcinoma (HNSCC), partly due to an immunosuppressive tumor microenvironment (TME) and insufficient infiltration of effector T cells. Low-dose radiotherapy (LDRT) has been suggested to modify the TME, potentially enhancing the effects of αPD-1. METHODS: We profiled murine HNSCC treated with LDRT (1 Gy) and/or αPD-1 using single-cell RNA sequencing (scRNA-seq) and single-cell TCR sequencing (scTCR-seq), complemented by orthogonal functional assays and in situ validation (spatial transcriptomics and multiplex immunofluorescence). RESULTS: LDRT and αPD-1 synergistically suppressed tumor growth and remodeled the TME. Single-cell analyses showed malignant programs shifting from proliferative states toward stress- and interferon (IFN)-responsive states. Integrated scTCR-seq analysis revealed enhanced clonal expansion of tumor-reactive CD8⁺ T-cell subsets and reduced the frequency of CD4⁺ Treg-Ctla4 under combination therapy. TCR-based metrics (including STARTRAC) indicated higher migration potential and limited intratumoral clonal overlap for CD4⁺ Treg-Ctla4. An Isg15high macrophage state (Macro-Isg15) was positively associated with CD4⁺ Treg-Ctla4 frequency and was more prominent under αPD-1 monotherapy. Ligand–receptor inference highlighted a Macro-Isg15–associated CXCL14–CXCR4 chemokine axis enriched under αPD-1 monotherapy and attenuated in LDRT-containing regimens, suggesting reduced ch...