Tracking the EMT-like phenotype switching during targeted therapy in melanoma by analyzing extracellular vesicle phenotypes.

Melanoma continues to be a leading cause of mortality among skin cancers. Despite advancements in targeted therapy, patients frequently develop resistance, leading to disease progression within a year. This resistance may result from the epithelial-to-mesenchymal transition (EMT)-like phenotype switching of melanoma cells. Tracking EMT-related phenotypic changes on extracellular vesicles (EVs) has potential to inform early about response to targeted therapy and melanoma progression. However, the knowledge on protein biomarkers carried by melanoma EVs involved in the EMT-like process remains unexplored. Herein, we present a biosensor integrating surface-enhanced Raman scattering and alternating current electrohydrodynamics-induced nanomixing enhancement, for sensitive detection of EMT-associated biomarkers on EV surfaces during targeted therapy. This biosensor successfully tracks the EMT-like phenotype switching in melanoma cell lines treated with mitogen-activated protein kinase inhibitor (MAPKi). Longitudinal monitoring of patients who receive MAPKi therapy and develop resistance, our biosensor shows its ability to identify the EMT-like phenotype switching on circulating EVs. This ability potentially can be leveraged to predict the development of resistance to targeted therapy, allowing for timely intervention and personalized treatment strategies.