Tertiary Lymphoid Structures Are Associated with a Favorable Prognosis in High-Grade Serous Ovarian Cancer Patients

There was accumulating evidence indicating that tertiary lymphoid structures (TLSs) were strongly associated with improved survival and clinical outcome in several solid tumors. In this study, we intended to assess the presence of TLSs and their potential clinical significance in high-grade serous ovarian cancer (HGSOC). TCGA (The Cancer Genome Atlas) cohort included RNA-seq data of 376 HGSOC patients, of which 74 patients included available hematoxylin-eosin (H&E) sections; GEO (Gene Expression Omnibus) cohort, GSE140082, included microarray data of 212 HGSOC patients. TLSs were counted by pathological sections, and the relative abundance of TLSs was assessed by the unsupervised consensus clustering of 12-chemokine transcriptome signatures. The potential associations between TLSs and clinical prognosis, tumor microenvironment (TME), and immunotherapy response of HGSOC were further performed based on transcriptome data. In the H&E sections of HGSOC, TLSs were predominantly located in the stroma and invasive margin of the tumor. Pathological counting results suggested that the expression of 12 chemokines was significantly higher in samples abundant with TLSs than that in the lack of TLSs. Consensus clustering of both TCGA and GEO cohorts divided HGSOC patients into two clusters with different TLSs abundance: low- and high-TLSs. Based on transcriptome analysis, the high-TLS cluster was characterized by better clinical prognosis, a higher degree of immune infiltration, more biological pathways, higher tumor mutational burden score, and higher expression of immune checkpoints. In conclusion, TLSs strongly correlated with the immune-responsive microenvironment and remained a favorable prognostic factor independent of other clinical characteristics in HGSOC. The presence of TLSs was also associated with a potentially favorable response to immune checkpoint blockade (ICB) therapy in HGSOC.