Direct delivery of immune modulators to tumour‐infiltrating lymphocytes using engineered extracellular vesicles

Abstract Extracellular vesicles (EVs) are important mediators of cell–cell communication, including immune regulation. Despite the recent development of several EV‐based cancer immunotherapies, their clinical efficacy remains limited. Here, we created antigen‐presenting EVs to express peptide‐major histocompatibility complex (pMHC) class I, costimulatory molecule and IL‐2. This enabled the selective delivery of multiple immune modulators to antigen‐specific CD8 + T cells, promoting their expansion in vivo without severe adverse effects. Notably, antigen‐presenting EVs accumulated in the tumour microenvironment, increasing IFN‐γ + CD8 + T cell and decreasing exhausted CD8 + T cell numbers, suggesting that antigen‐presenting EVs transformed the ‘cold’ tumour microenvironment into a ‘hot’ one. Combination therapy with antigen‐presenting EVs and anti‐PD‐1 demonstrated enhanced anticancer immunity against established tumours. We successfully engineered humanized antigen‐presenting EVs, which selectively stimulated tumour antigen‐specific CD8 + T cells. In conclusion, engineering EVs to co‐express multiple immunomodulators represents a promising method for cancer immunotherapy.