Cience University plus the VA Portland Overall health Care Technique. We utilised single Vesicle Flow Cytometry to straight measure plasma EV concentration and size. We utilised size-exclusion chromatography (iZON Science) to isolate plasma EVs. EV total RNA isolated by mirVanaTM PARISTM RNA Kit (ThermoFisher) was analysed onJOURNAL OF EXTRACELLULAR VESICLES Institute Oncology Center, Department of Soft Tissue/Bone Sarcoma and Melanoma, Warsaw, Poland, CD176 Proteins Source Varsaw, USAIntroduction: Liquid biopsies in melanoma individuals have the prospective to enhance prognosis. Exudative seroma obtained inside the drainage implanted post-lymphadenectomy has never ever been explored as a source of biomarkers. The usage of circulating extracellular vesicles (EVs) as surrogate markers of residual disease could be a novel and strong non-invasive tool. Procedures: Exosomes were purified by ultracentrifugation from exudative seroma obtained immediately after lymphadenectomy from stage III melanoma sufferers, were analysed by nanosight analysis and electron microscopy, and in comparison with plasma within a total of 92 samples. We profiled the proteomic profiles of exudative seroma- and plasma-derived exosomes by mass spectrometry. Extracellular vesicle-associated nucleic acids (EV-NAs) and analysed BRAFV600E by an allele-specific PCR in exudative seroma samples as a novel parameter to detect residual illness Outcomes: We located that exudative seroma is actually a novel biofluid extremely enriched in EVs, larger size and improved DNA cargo in comparison to plasma. Proteomic evaluation of seroma-derived exosomesdemonstrated that they’re enriched in melanoma oncogenic pathways with each other with immune-related pathways; however, proteomic evaluation didn’t let identify biomarkers of relapse or progression. Importantly, detection of BRAFV600E mutation in seroma-derived EVs obtained 248 hours post-lymphadenectomy identified patients at danger of relapse drastically (Log rank p = .0067) inside a cohort of 17 stage III melanoma patients followed up for 700 days. Summary/conclusion: Our data show for the very first time that exudative seroma obtained post-lymphadenectomy is often a novel biofluid enriched on EVs and DNA that can be interrogated for melanoma markers and BRAF mutation. Analysis of BRAFV600 mutation identified patients at danger of relapse with higher significance. These information support that our approach may very well be a novel aspect to detect residual disease appropriate right after surgery in stage III melanoma sufferers. Our analysis could be a novel approach to aid oncologists to recognize high-risk groups of sufferers post-lymphadenectomy and strengthen patient outcome. Funding: MINECO, NIH, Starr Foundation, Ramon y Cajal Programme, AECC, FERO foundation, and MINECO-REDiEX.ISEV2019 ABSTRACT BOOKSymposium Session three: EVs in Cancer Metastasis and Angiogenesis Protease-Activated Receptor Proteins web Chairs: Kyoko Hida; Alissa Weaver Place: Level three, Hall B 11:002:OT03.Stem cell-derived extracellular vesicles increase cancer stem cell sensitivity to tyrosine kinase inhibitors through Akt/mTOR/PTENcombined modulation Benedetta Bussolatia, Valentina Fonsatob, Michela De Lenac, Stefania Trittad, Alessia Brossab, Ruggero Calvettie, Ciro Tettaf and Giovanni CamussigaDepartment of Molecular Biotechnology and Health Sciences, University of Turin, Turin, Italy; bMolecular Biotechnology Center, University of Torino, Torino, Italy; cMolecular Biotechnology Center, University of Torino, Torino, Italy; dUniversitdi Torino, Nichelino, Italy; eDepartment of Molecular Biotechnology and Health Sciences, Torino, Italy; fUnicyte srl.