Large−scale profiling of extracellular vesicles identified miR−625−5p as a novel biomarker of immunotherapy response in advanced non−small−cell lung cancer patients

Immune checkpoint inhibitors (ICIs) are largely used in the treatment of patients with advanced non−small−cell lung cancer (NSCLC). Novel biomarkers that provide biological information that could be useful for clinical management are needed. In this respect, extracellular vesicles (EV)−associated microRNAs (miRNAs) that are the principal vehicle of intercellular communication may be important sources of biomarkers. We analyzed the levels of 799 EV−miRNAs in the pretreatment plasma of 88 advanced NSCLC patients who received anti−PD−1 therapy as single agent. After data normalization, we used a two−step approach to identify candidate biomarkers associated to both objective response (OR) by RECIST and longer overall survival (OS). Univariate and multivariate analyses including known clinicopathologic variables and new findings were performed. In our cohort, 24/88 (27.3%) patients showed OR by RECIST. Median OS in the whole cohort was 11.5 months. In total, 196 EV−miRNAs out 799 were selected as expressed above background. After multiplicity adjustment, abundance of EV−miR−625−5p was found to be correlated with PD−L1 expression and significantly associated to OR by RECIST (p = 0.0366) and OS (p = 0.0031). In multivariate analysis, PD−L1 staining and EV−miR−625−5p levels were constantly associated to OR and OS. Finally, we showed that EV−miR−625−5p levels could discriminate patients with longer survival, in particular in the class expressing PD−L1 ≥50%. EV−miRNAs represent a source of relevant biomarkers. EV−miR−625−5p is an independent biomarker of response and survival in ICI−treated NSCLC patients, in particular in patients with PD−L1 expression ≥50%.