Low TWEAK expression indicates poor survival and is correlated with sparse TIICs in lung adenocarcinoma (LUAD)

e21017 Background: Lung adenocarcinoma (LUAD) occupies the most of non-small cell lung cancer (NSCLC) and shows promising response to PD-1 immunotherapy, but immune escape will cause treatment failure indicating poor prognosis. TWEAK (Tumor necrosis factor-related weak inducer of apoptosis, also known as TNFSF12) combining with its receptor FN14 (fibroblast growth factor–inducible 14) mediates crucial innate and adaptive immune pathways to promote the progression of multiple autoimmune diseases. So we assumed that TWEAK is a prognostic predictor and related with tumor-infiltrating immune cells (TIICs) in LUAD. Methods: TWEAK expression of LUAD was primarily investigated in The Cancer Immunome Atlas (TCIA) and then validated in Tumor Immune Estimation Resource (TIMER) databases. We assessed the effect of TWEAK on the survival via the Kaplan-Meier plotter, GEPIA2 (gene expression profiling interactive analysis) and PrognoScan databases. The relation between TWEAK and TIICs was explored in TIMER and TCIA, as well as the correlation of TWEAK and FN14 was analyzed in TIMER and GEPIA2. Results: Low TWEAK expression was significantly associated with poor relapse-free survival (RFS) (HR = 0.62, 95% CI = 0.4~0.97, logrank P = 0.035) and overall survival (OS) (HR = 0.61, 95% CI = 0.46~0.83, logrank P = 0.0012) in LUAD from Kaplan-Meier plotter. Similar impacts of TWEAK on the survival were validated in GEPIA2 and four independent cohorts from PrognoScan (jacob-00182-CANDF, GSE13213, jacob-00182-MSK and GSE31210). Moreover, reduced TWEAK expression was closely related with the paucity of TIICs which contributed to poor OS, including central memory CD8 T cells, plasmacytoid dendritic cells, activated CD8 T cells, monocytes, T follicular helper cells, immature B cells and eosinophils. In addition, TWEAK expression was positively related with the expression level of FN14 in both GEPIA2(R = 0.13, P= 0.0031) and TIMER (partial.cor = 0.212, P= 2.04e-06). Conclusions: Low TWEAK expression maybe indicate poor prognosis in LUAD, and correlated with the impaired infiltration of immune cells in the tumor region. The defective TWEAK/FN14 pathway possibly accounts for these observations, but the underlying mechanism needs to be further explored.