On-treatment dynamics of circulating extracellular vesicles in the first-line setting of patients with advanced non-small cell lung cancer: the LEXOVE prospective study.

Extracellular vesicle (EV) monitoring can complement clinical assessment of cancer response. In this study, patients with advanced non-small cell lung cancer (NSCLC) undergoing osimertinib, alectinib, pembrolizumab or platinum-based chemotherapy ± pembrolizumab were enrolled. EVs were characterised using Bradford assay (BA) to quantify the circulating cell-free EV protein content (cfEV), and dynamic light scattering (DLS) to assess Rayleigh ratio excess at 90° (R90), z-averaged hydrodynamic diameter (Dz) and polydispersity index (PDI). A total of 135 plasma samples from 27 patients were collected at baseline (T0) and at the first radiological restaging (T1). A ∆cfEV <20% was associated with improved median progression-free survival (mPFS) in responders versus non-responders. Specifically, cfEV responders on pembrolizumab had a significantly better mPFS (25.2 months) compared to those on chemotherapy plus pembrolizumab (6.1 months). EGFR-positive cfEV responders also experienced longer mPFS compared to cfEV non-responders (35.1 months, 95% CI: 14.9–35.5 vs. 20.8 months, 95% CI: 11.2–30.4). This study suggested that monitoring circulating EV could provide valuable insights into treatment efficacy in NSCLC, particularly for patients receiving pembrolizumab or osimertinib.