Exploration Of The Clinical Significance Of Tertiary Lymphoid Structure In Breast Cancer Using Single-cell Sequencing

Objective: Breast cancer(BC)is a highly heterogeneous disease.Although immunotherapy has improved survival rates of patients with various solid or hematologic malignancies in recent years,most subtypes of breast cancer exhibit negligible response to immune checkpoint blockade(ICB).B cells play a crucial role in antitumor immunity,particularly when they cluster in tertiary lymphoid structures(TLS).However,the clinical significance of B cell heterogeneity and TLS in breast cancer at the single-cell resolution remains to be further explored.Methods: The research materials used in this study were obtained from surgical resection specimens of breast cancer patients who received treatment at our hospital.A total of 14 breast cancer patients(2020-2021)who had never received any treatment were included in this study,of whom 10 had invasive ductal carcinoma and 4 had ductal carcinoma in situ.After diagnosis of breast cancer by pathological examination,the primary tumor lesions and adjacent normal tissues of the study subjects were collected for single-cell sequencing and bioinformatics analysis.Results: This study is based on the characterization of single-cell transcriptome data into multiple clusters using typical markers.The focus is on a comprehensive single-cell analysis of tumor infiltrating B cells(TIL-B),which were identified as five clusters,revealing rare cell types such as follicular B cells that are significantly associated with the efficacy of immunotherapy.Furthermore,the overall functional role of TIL-B in cancer development and treatment is elucidated.The presence of germinal center B cells and class-switched B cells indicates the possibility of tertiary lymphoid structures(TLS),which is confirmed by immunohistochemistry(IHC)staining of mature TLS using a convenient marker CD23.From both single-cell and clinical perspectives,it is demonstrated that mature TLS is significantly correlated with better survival in breast cancer patients.Conclusion: This study reveals the heterogeneity of B cells in breast cancer and analyzes the significant roles played by B cells and TLS in anti-tumor immunity at both the single-cell and clinical levels.Additionally,a simple and feasible marker CD23 is provided to identify TLS,and it is found that TLS and its marker are significantly associated with good prognosis in breast cancer.These findings provide valuable clues for personalized and precise treatment of tumors.