**1. Introduction**

Recent progress in the understanding of the role tumor microenvironment (TME) plays in cancer development has identified intercellular communication within and outside the TME as one of the major mechanisms driving tumor progression. A detailed characterization of the crosstalk of the tumor with various immune and tissue cells has become a major goal in cancer research. For years, many soluble factors, including cytokines and chemokines, have been postulated to play a major role in the regulation of cellular interactions in healthy and pathological tissues. The recognition of extracellular vesicles, EVs, as major players in the intercellular communication network occurred only a few years ago [1]. Since then, EVs produced by cancer cells and by immune as well as non-immune cells residing in the TME have become the topic of numerous studies evaluating their involvement in the regulation of tumor progression on the one hand and of the host anti-tumor immune responses on the other. This double role of EVs in cancer as well as other diseases emphasizes their potential as reporters or markers of changes that preface or accompany the emergence of disease or its outcome.
