Sieging tumor cells using an amorphous ferric coordination polymer.

Metastasis is one of the main reasons for cancer treatment failure. Unfortunately, most treatment approaches inevitably damage the extracellular matrix (ECM) during tumor cell elimination, thereby augmenting the risk of metastasis. Herein, we proposed a "sieging tumor cells" strategy based on ferric coordination polymers (FeCPs), which involved anchoring tumor cells through ECM consolidation and selectively eliminating them in the tumor regions. Due to the weak coordination interactions and amorphous structure of FeCPs, the acidic tumor microenvironment facilitated their disintegration, releasing salicylic acid (SA), 2,5-dihydroxyterephthalic acid (DHTA) and Fe³⁺ ions. The released SA inhibited heparinase activity to consolidate the ECM, while Fe-mediated chemodynamic therapy (CDT) was enhanced by DHTA due to its fast electron transport behavior, ultimately inhibiting tumor growth and metastasis. The results from the orthotopic 4T1 breast tumor model indicated that lung metastasis was reduced by about 90%, and the survival rate improved by 70% after FeCP treatment. Overall, this "sieging tumor cells" strategy provides an emerging approach for the treatment of malignant tumors by consolidating the ECM in combination with self-enhanced CDT.