Tertiary lymphoid structures correlate with reduced recurrence risk and enhanced antitumor immunity in esophageal squamous cell carcinoma with pathologic non-complete response to neoadjuvant chemoimmunotherapy.

BACKGROUND: The majority of patients with locally advanced esophageal squamous cell carcinoma (ESCC) undergoing neoadjuvant chemoimmunotherapy (nCIT) failed to achieve pathologic complete response (pCR), had high risk of postoperative recurrence and lacked prognostic biomarkers. Tertiary lymphoid structures (TLS) are organized aggregates of immune cells and have the potential to regulate antitumor immune response. This study aimed to investigate the prognostic value and immune profile of TLS in non-pCR ESCC. METHODS: We first analyzed clinicopathological features, recurrence events, and survival outcomes according to TLS status. Subsequently, based on the single-cell sequencing data, we analyzed the differences in the infiltration level, functional status and interaction mode of immune cells based on TLS status. The expression pattern of signature genes and the spatial localization of key immune cell subsets were verified through bulk RNA sequencing and multiplex immunohistochemistry. RESULTS: The TLS(+) group demonstrated a lower likelihood of postoperative recurrence and superior survival rates relative to the TLS(-) group. The key immune cell subsets responsive to immunotherapy were enriched in the TLS(+) group, and the immune cells in the TLS(+) group showed a functional state of high activation and low exhaustion. Multiplex immunohistochemistry and cell-cell communication analysis suggested that tumor reactive T cells were spatially colocalized with B cells and antigen presenting cells in TLS and exhibited high interaction potential. In the TLS(+) group, we also identified precursor exhausted T cells and long-lived plasma cells with tumor reactivity and matured affinity. The presence of TLS correlated with enhanced synergistic interaction, activation and maturation of immune cells, suggesting a potential role in shaping in situ antitumor immunity. CONCLUSIONS: TLS status was the independent predictor of postoperative recurrence in non-pCR ESCC. TLS status correlated with the composition, functional state, and interaction patterns of immune cells. Specialized immune niches existed in non-pCR ESCC with TLS, potentially contributing to antitumor immune responses.