免疫细胞的异质性已被认为决定了对癌症进展的治疗反应。新辅助化学免疫疗法（NACI）已在部分晚期头颈部鳞状细胞癌（HNSCC）患者中显示出临床效益，但其背后的临床反应机制尚不清楚。通过鉴定准确的生物标志物来预测临床反应，可以增强NACI的疗效。为此，我们尝试在晚期HNSCC中鉴定预测NACI反应的分子。我们通过结合单细胞RNA测序（scRNA-seq）和多重免疫荧光染色（mIHC）对NACI治疗的HNSCC患者的肿瘤样本进行了鉴定，发现一种新的肿瘤浸润细胞（TIL）亚型CD103+ CD8+ TILs与临床反应相关。同时，我们进行了体外和体内实验，以确定其抗肿瘤效果。通过对scRNA-seq数据的细胞相互作用分析和mIHC图像的空间分析，我们研究了CD103+ CD8+ TILs群体的调控机制。我们确定了肿瘤内CD103+ CD8+ TILs密度作为NACI在癌症中的疗效的决定因素。我们的scRNA-seq结果表明，在NACI治疗的HNSCC患者中，CD103+ CD8+ TILs的中性增加在反应者中明显增加，而mIHC分析证实了肿瘤内CD103+ CD8+ TILs密度与NACI疗效在HNSCC患者中的相关性。进一步的受试者工作特征曲线分析将这种TIL亚群定义为预测患者对NACI反应的强大标记物。功能实验表明，CD103+ CD8+ TILs是肿瘤反应性T细胞，而程序性细胞死亡蛋白-1（PD-1）阻断增强了CD103+ CD8+ TILs对体内肿瘤生长的细胞毒性。在机制上，靶向髓样细胞表达的激发受体2阳性（TREM2+）巨噬细胞可能增加CD103+ CD8+ TILs的群体并促进NACI治疗期间的抗肿瘤免疫。我们的研究强调了肿瘤内CD103+ CD8+ TILs密度对不同癌症中NACI疗效的影响，而提高其群体的努力需要进一步进行临床调查。 © 2023 The Authors. Cancer Communications published by John Wiley & Sons Australia, Ltd. on behalf of Sun Yat-sen University Cancer Center.

Immune cell heterogenicity is known to determine the therapeutic response to cancer progression. Neoadjuvant chemoimmunotherapy (NACI) has shown clinical benefits in some patients with advanced head and neck squamous cell carcinoma (HNSCC), but the underlying mechanism behind this clinical response is unknown. The efficacy of NACI needs to be potentiated by identifying accurate biomarkers to predict clinical responses. Here, we attempted to identify molecules predicting NACI response in advanced HNSCC.We performed combined single-cell RNA sequencing (scRNA-seq) and multiplex immunofluorescence (mIHC) staining with tumor samples derived from NACI-treated HNSCC patients to identify a new tumor-infiltrating cell (TIL) subtype, CD103+ CD8+ TILs, associated with clinical response, while both in vitro and in vivo assays were carried out to determine its antitumor efficiency. The regulatory mechanism of the CD103+ CD8+ TILs population was examined by performing cell-cell interaction analysis of the scRNA-seq data and spatial analysis of the mIHC images.We established intratumoral CD103+ CD8+ TILs density as a determinant of NACI efficacy in cancers. Our scRNA-seq results indicated that the population of CD103+ CD8+ TILs was dramatically increased in the responders of NACI-treated HNSCC patients, while mIHC analysis confirmed the correlation between intratumoral CD103+ CD8+ TILs density and NACI efficacy in HNSCC patients. Further receiver operating characteristic curve analysis defined this TIL subset as a potent marker to predict patient response to NACI. Functional assays showed that CD103+ CD8+ TILs were tumor-reactive T cells, while programmed cell death protein-1 (PD-1) blockade enhanced CD103+ CD8+ TILs cytotoxicity against tumor growth in vivo. Mechanistically, targeting the triggering receptor expressed on myeloid cells 2-positive (TREM2+ ) macrophages might enhance the population of CD103+ CD8+ TILs and facilitate antitumor immunity during NACI treatment.Our study highlights the impact of intratumoral CD103+ CD8+ TILs density on NACI efficacy in different cancers, while the efforts to elevate its population warrant further clinical investigation.© 2023 The Authors. Cancer Communications published by John Wiley & Sons Australia, Ltd. on behalf of Sun Yat-sen University Cancer Center.