TLS-related immune organization and regional IRF4 expression in pretreatment biopsies of advanced lung adenocarcinoma

Tertiary lymphoid structure (TLS) assessment is challenging in advanced lung adenocarcinoma because pretreatment diagnosis often relies on limited biopsy tissue that may incompletely represent lymphoid architecture. We investigated whether biopsy-captured B-cell organization and regional interferon regulatory factor 4 (IRF4) expression could provide complementary information on TLS-related immunity in this setting.

A TLS-related transcriptional program was analyzed in TCGA-LUAD to prioritize candidate genes, followed by tissue-level and functional evaluation of IRF4 in a murine tumor model and A20 B cells. Pretreatment small-biopsy specimens from 34 patients with stage IV lung adenocarcinoma receiving first-line immunotherapy plus chemotherapy were evaluated for CD20⁺ B-cell aggregation patterns, regional IRF4 expression, and clinical outcomes.

Within pretreatment small biopsies, CD20⁺ B cells showed distinct patterns of local organization. Regional IRF4 expression differed among aggregation grades (p = 0.0216), with higher expression in Grade 3 than Grade 2 (adjusted p = 0.0260), but did not increase monotonically with morphological organization. Grade 3 aggregation was associated with longer overall survival (HR, 0.372; 95% CI, 0.172-0.807; p = 0.0177) and post-progression survival (HR, 0.307; 95% CI, 0.142-0.663; p = 0.0042), but not progression-free survival. Transcriptomic analysis placed IRF4 within a TLS-related immune context, while IRF4 manipulation in A20 cells altered Cxcr5, Ccr7, Lta, and Ltb expression and Tfh-like/IL-21 responses.

Biopsy-captured B-cell organization and regional IRF4 expression may provide complementary information on TLS-related immunity when comprehensive TLS characterization is limited by small-biopsy sampling.