Prognostic and immunological significance of tertiary lymphoid structures in nasopharyngeal carcinoma.

220 Background: Tertiary lymphoid structures (TLSs) are ectopic lymphoid tissues found in non-lymphoid organs, characterized by the presence of CD20 + B cell follicles adjacent to a T cell zone. Their presence has been associated with improved survival in various tumor types. However, the role of TLSs in nasopharyngeal carcinoma (NPC) remains unclear. In this study, we investigated the prognostic and immunological significance of TLSs in NPC patients. Methods: The investigation involved a discovery cohort (n = 145) comprising NPC patients diagnosed at Sun Yat-sen University Cancer Center between July 2010 and December 2016, with pretreatment primary tumor samples collected. An independent validation cohort included 150 NPC patients with gene expression profiles, among whom Hematoxylin & Eosin (H&E)-stained slides were available for 95 patients. The primary endpoint of this study is overall survival, defined as the duration of time from diagnosis until death from any cause. The presence of TLSs was assessed on H&E and CD20-stained slides. Analyses of tumor-infiltrating immune cell subsets, differentially expressed genes, and BCR/TCR clonotypes were performed to explore the association between TLSs and the anti-tumor immune response. A molecular definition of TLSs was proposed and assessed for its prognostic value across multiple cohorts. Results: The presence of TLSs was independently associated with a favorable overall survival (hazard ratio [HR], 0.26; 95% confidence interval [CI], 0.07-0.94; log-rank p = 0.04), surpassing the significance of B cell density in multivariate analysis (HR, 0.83; 95% CI, 0.38-1.79, log-rank p = 0.63). These findings were corroborated in the independent validation cohort. TLSs positively correlated with multiple immune-related pathways and a higher proportion of functionally mature immune cells. Notably, the counts of BCR and TCR clonotypes showed a significant positive correlation with the TLSs score. We proposed a TLSs gene signature and demonstrated its prognostic relevance across multiple cohorts, including patients treated with immune checkpoint blockade. Conclusions: TLSs exhibit heightened immune activity and indicate improved survival outcomes in NPC patients. A TLSs gene signature was proposed and demonstrated its prognostic relevance across multiple cohorts, indicating potential guidance for treatment decisions in cancer.