Spatial-Drug-Laden Protease-Activatable M1 Macrophage System Targets Lung Metastasis and Potentiates Antitumor Immunity

T cells to lung metastasis and, respectively, caused an 8.54-, 12.87- and 2.85-fold improvement of the granzyme-B-, interferon-γ-, and Ki67-positive subtypes versus negative control. Moreover, RDM treatment produced a 90.99% inhibition of lung metastasis in 4T1 models and significant prolongation of survival in three murine lung metastatic models. Therefore, the drug-laden FAP-sensitive M1 macrophage system represents a feasible strategy to target lung metastasis and boost antitumor immunity for antimetastasis therapy.