Fig. 1

a Drug loaded NPs can inhibit tumor growth through multiple pathways: Drug loaded NPs can inhibit hypoxic tumor growth by targeting and reprogramming the abnormal tumor vasculature. Additionally, they can reprogram M₂ macrophages into M₁ phenotypes, which reactivate the immune response and inhibit tumor growth. Drug loaded NPs can also activate mature DCs, leading to the activation of B cells through T cells and the production of antibodies that can target and eradicate tumor cells. These NP-stimulated pathways can thus overcome the inhibitory effects exerted by MDSCs on mature DCs and the inhibitory effects of Tregs on INF-γ, thus killing tumor cells. b TAMs regulate the tumor vasculature: TAMs inhibit tumor vasculature through M₁ and IL12. Hypoxia induces TAM₁ to TAM₂ conversion, thus promoting tumor vasculature through IL-10. Drug-loaded NPs can inhibit the conversion of TAM₁ to TAM₂ and reduce tumor growth. SiRNA-loaded NPs can also suppress TAM₂ activity