Constantin N. Baxevanis, Michael Sofopoulos, Ourania Tsitsilonis, Angelos D. Gritzapis
Tertiary lymphoid structures (TLS) arise from lymphoid neogenesis in non-lymphoid organs and are driven by persistent inflammation mediated by chemokines and cytokines. In cancer, TLS orchestrate immune mechanisms relevant to tumor growth and thereby influence clinical outcomes. Observations of a correlation between the presence of TLS and clinical benefits in cancer patients, which suggests that TLS may serve as prognostic and predictive biomarkers, have prompted increased investigation of TLS in tumors. Accumulating evidence indicates that the prognostic and predictive value of TLS is context-dependent and relevant to their cellular composition and functional state. Combining assessments of tumor-infiltrating lymphocytes (TILs) with TLS features yields a more refined prognostic tool by capturing both local immune activity and aspects of the broader tumor immune microenvironment. Improved understanding of TLS biology and of their interactions with TILs can enhance predictions of therapeutic response. Furthermore, therapeutic modulation of TLS composition or function to favor antitumor immunity represents a promising strategy to improve treatment outcomes.