Review: Cancer Immunotherapy by Exosome-Based Vaccines

Exosomes (EXOs) are nanometer-sized membrane vesicles secreted from epithelial and hematopoietic cells. They display a spectrum of molecules involved in immune responses and signal transductions. Previous studies showed that tumor antigen–loaded dendritic cell (DC)- and tumor cell-derived EXOs (Dexo and Texo) induce tumor antigen–specific CD8+ cytotoxic T-lymphocyte responses and antitumor immunity in experimental animal models and human clinical trials. This review will present the main biologic features of Dexo and Texo as cell-free cancer vaccines with emphasis on their immunostimulatory properties and their potential efficacy in cancer immunotherapy.