Tertiary Lymphoid Structures in the Prognosis and Immunotherapy of Penile Squamous Cell Carcinoma

Background Tertiary lymphoid structures (TLSs) are key players in the tumor microenvironment, yet their role in penile squamous cell carcinoma (PSCC) is unexplored. This study investigates TLS presence, prognostic value, and correlation with anti-PD-1 efficacy in PSCC. Methods An immune atlas was constructed from transcriptomic data (56 PSCC, 7 normal tissues). TLSs were assessed via HE and multiplex immunohistochemistry in a SYSUCC cohort (n = 156) and an external validation set (n = 107). A four-tier TLS score-related (TSR) classification was established based on TLS density in tumor nest (TN) and tumor periphery (TS). Correlation with immunotherapy was tested in 30 anti-PD-1-treated patients. Pathway enrichment analysis was performed. Results Significant B-cell infiltration was noted in PSCC. TLSs were identified in TN (44.2%) and TS (54.5%). TSR classification revealed distinct prognostic patterns: high TLS scores in both TN and TS (class Ⅳ) correlated with longest progression-free and overall survival (P<.05). Multivariate analysis confirmed high tnTLS (P=.001), high tpTLS (P=.010), and lymph node metastasis (P<.001) as independent prognostic factors. Notably, class IV patients showed a favorable response rate (100% in this exploratory cohort). Androgen response pathway correlated with high TLS scores in both compartments. Conclusions TSR classification, reflecting TLS spatial distribution and abundance, may serve as a potential predictor for prognosis and immunotherapy response, pending further validation in PSCC. Androgen response pathway was identified as a potential correlated pathway in transcriptomic analysis, warranting further functional investigation.