CD274 and cancer: The understanding of PD-L1's role on cancer cells and their derived extracellular vesicles has been pivotal in prognosis and predicting outcomes of therapies targeting the PD-1/PD-L1 immune checkpoint.29,30,37 However, previous attempts to profile PD-L1+ EVs have been limited by technology that either analyzes bulk EV populations, such as plate ELISA, or technologies that can resolve individual EVs but that lack the throughput to sample enough EVs to reliably detect rare PD-L1+ EVs in blood.20–22