The identification of noninvasive prognostic biomarkers for monitoring relapse in patients with locally advanced lung cancer remains a primary objective. Tumor-draining vein (TDV) plasma samples are known to be enriched in cancer biomarkers compared to peripheral vein (PV) samples and may therefore facilitate biomarker discovery. In this exploratory study, we investigated both proteomic profile from tumor and non-tumor tissues and from extracellular vesicles (EVs) purified from TDV and PV plasma samples of patients undergoing surgery for lung adenocarcinoma.

Twenty patients operated for a lung adenocarcinoma were enrolled. EVs purified from TDV and PV plasma samples were characterized for size distribution and concentration using nanoparticles tracking analysis. Proteomic profiling of both tissue and EVs was performed using mass spectrometry (nanoLC-MS/MS) analysis. Differential expression protein analysis in lung tissues from tumor compared to non-tumor counterpart and in EVs from TDV compared to EVs from PV were performed using DEP R package. Functional enrichment analysis and protein networking were conducted to gain biological insights into the set of deregulated proteins.

TDV-derived EVs were significantly smaller and more concentrated than PV-derived EVs. Proteomic analysis revealed that 466 proteins were deregulated in tumor as compared to normal lung tissue, while 369 proteins were differentially detected in TDV- versus PV-derived EVs. Nine of the 10 most upregulated proteins in TDV-derived EVs compared to PV-derived EVs were previously associated to lung cancer diagnosis and prognosis. Notably, SRPRB (Signal recognition particle receptor subunit beta) was the only protein upregulated in both tumor tissues and TDV-derived EVs.

This exploratory study showed that this subset of proteins carried by EVs from TDV plasma, may represent candidate circulating biomarkers for early-stage lung adenocarcinoma prognosis.

The ExOnSite-Pro (Molecular Profiling of Exosomes in Tumor-draining Vein of Early-staged Lung Cancer, Clinical Trial Register number: NCT04939324, https://clinicaltrials.gov/study/NCT04939324) is a prospective trial conducted from June 2021 to June 2024. Ethical approval was granted on May 21, 2021 by the independent protection committee SUD MEDITERRANEE III (approval number 2021.05.02 bis_21.03.15.45551, FRANCE). Written informed consent was obtained from all participants.