A Biodegradable Nanosuspension Locally Used for Inhibiting Postoperative Recurrence and Brain Metastasis of Breast Cancer.

Addressing the urgent need to prevent breast cancer postoperative recurrence and brain metastasis, Fe-metal organic framework (MOF)-coated hollow mesoporous organosilica nanoparticles (HMON) with tumor microenvironment dual-responsive degradability were prepared to encapsulate doxorubicin (DOX), formulating a tissue-adhesive nanosuspension for perioperative topical medication. This nanosuspension can not only retain the sustainably released drug in the postoperative residual tumor sites but also enhance the intracellular oxidative stress of tumors for remarkable tumor ferroptosis. Interestingly, the nanosuspension can act as an immune amplifier, which could not only stimulate DC cells to secrete chemokines for T cell recruitment but also elevate antigen exposure to facilitate the antigen presentation in lymph nodes. Thus, this nanosuspension could significantly activate antitumor immune responses in both in situ tumors and metastatic encephaloma for enhanced immunotherapy. In conjunction with the clinical PD-1 antibody, the locally administered nanosuspension could achieve an advanced therapeutic outcome for inhibiting postoperative recurrence and metastasis.