Exosomes are extracellular vesicles released by various types of cells, including immune cells and cancer cells. The article by Emam et al evaluated in vivo secretion of exosomes following intravenous injection of free doxorubicin (DXR) or liposomal DXR (Doxil®) was evaluated using normal mice. Free DXR treatment markedly increased the serum exosome level, while Doxil® treatment did not change. Interestingly, splenectomy significantly suppressed the exosomal secretions induced by free DXR treatment. Their results suggest that conventional anticancer agents induce the secretion of exosomes via stimulating immune cells of the spleen, and might contribute to the antitumor effect of chemotherapeutic agents.