Circulating EV-MicroRNAs in Metastatic Melanoma as non-invasive biomarkers for diagnosis and treatment response

Background Melanoma is the most aggressive skin cancer, with 50% of patients having metastatic melanoma facing high 5-year mortality. Identifying non-invasive biomarkers for diagnosing and stratifying metastatic melanoma could prove essential to guide treatment decisions. MicroRNAs (miRNAs), small non-coding RNA molecules abundant in extracellular vesicles (EVs), have been studied as biomarkers in various cancers. Aim This study aims to identify EV-miRNAs as circulating biomarkers in metastatic melanoma and assess their role in treatment response. Methods We explored EV-miRNAs in unresectable stage III and IV melanoma patients treated with immune checkpoint inhibitors (ICI) and Guadecitabine (NIBIT-M4 clinical trial). Plasma was ABSTRACT FORM collected before treatment (W0) and 12 weeks (W12) after treatment, and EVs were isolated for miRNA profiling. EV-miRNA profiling was first conducted on W0 samples and on a matched cohort of healthy donors. Enrichment analysis and logistic regression analysis were used to characterize differentially expressed (DE) EV-miRNAs at W0 and identify a specific signature distinguishing metastatic melanoma patients from healthy individuals. This signature was validated in an external dataset and in an independent internal cohort using droplet digital PCR, confirming its diagnostic relevance. Clinicians classified patients as responders (R) or non-responders (NR), and EV-miRNA profiles at W12 were associated with treatment response. Results At W0, EV-miRNAs profiling found 65 DE EV-miRNAs distinguishing melanoma patients from healthy controls. The enrichment analysis performed on these DE EV-miRNAs showed their involvement in migration, angiogenesis, and immune regulation. Logistic regression analysis identified as a signature 4 EV-miRNAs distinguishing patients from healthy controls. At W12, 58 EV-miRNAs were modulated compared to W0, and two EV-miRNAs, including one from the diagnostic signature, were associated with treatment response. Conclusions These findings suggest that the two discovered EV-miRNAs could be useful as biomarkers for monitoring response to ICI and Guadecitabine treatment, highlighting EV-miRNAs as a tool for precision medicine.