Dear Editor,Increasing numbers of studies have revealed the immunomodulating effects of radiotherapy when combined with immune checkpoint inhibitors, as radioimmunotherapy has proven to be a promising treatment [1]. Radioimmunotherapy has shown significantly improved tumor responses than radiotherapy or immunotherapy alone in various malignant tumors [2][3][4]. It has also been applied to cervical cancer in multiple ongoing clinical trials (NCT03612791 [5] and NCT02635360 [6]). However, tumor recurrence and metastasis are often unavoidable. As such, investigations into radioimmunotherapy-induced tumor ecosystem evolution are essential for guiding improvements in treatment strategies that achieve better long-term disease control. To date, several studies have investigated radiochemotherapy-induced tumor ecosystem evolution using bulk RNA-sequencing and immune staining [7,8]. However, these findings were limited owing to the cellular heterogeneity in cancers. Single-cell RNA-sequencing (scRNA-seq) enables the characterization of cell compositions and transcriptomic states in the tumor at single-cell resolution.To investigate radioimmunotherapy-induced intratumoral changes, we performed scRNA-seq on a pair of cervical squamous cell carcinoma (CESC) samples before and during radioimmunotherapy. The study protocols are found in the Supplementary Materials. A total of 17,769 cells were obtained, with an average gene number of 1,875 after quality control. Using uniform manifold approximation and projection (UMAP) analysis, we identified nine main cell types: T cells (CD3D + , CD3E + ), plasma cells (IGHG1 + , IGHG3 + ), macrophages (CD14 + , CD68 + ), monocytic myeloid-derived suppressor cells (M-MDSCs