FN1 and neoplasm: Nanovesicles with interleukin 15 (IL15) and IL15 receptor α complex (IL15c)‐presenting membrane and doxorubicin‐loaded ferritin (Dox‐Fn)‐based cores can disassemble in the tumor microenvironment to release Dox‐Fn and membrane‐bound IL15c, which targets cancer cells and effector cells, respectively, suppressing tumor growth in triple‐negative breast cancer mice models via facilitating infiltration and activity of effector cells of both innate and adaptive immunity.