Stimulation of In Vivo Antitumor Immunity with Hollow Mesoporous Silica Nanospheres

The use of appropriate adjuvants that support the generation of robust and long-lasting antitumor immune responses is crucial for tumor immunotherapy owing to the immunosuppressive environment of the growing tumor. However, the most commonly used adjuvant, aluminum hydroxide, is ineffective for generating such immune responses and therefore not suitable for cancer immunotherapy. It is now shown that plain hollow mesoporous silica nanospheres markedly improve the antitumor immunity, the Th1 and Th2 immunity, and the CD4(+) and CD8(+) effector memory T cell population in bone marrow in vivo and may thus be used as immunoadjuvants to treat cancer in humans.