Metal-coordinated oxidative stress amplifier to suppress tumor growth combined with M2 macrophage elimination

The anti-oxidative characteristic and immunosuppressive microenvironment contribute to a high resistance of tumor to many treatments. In this work, a glutathione (GSH)-responsive metal-coordinated oxidative stress amplifier (designated as CuPA) is fabricated to suppress tumor growth through elevating the cellular level of reactive oxygen species (ROS) and eliminating M2 macrophages. Among which, cooper ion (Cu2+) is capable of coordinating with thioredoxin (Trx) inhibitor of PX-12 and signal transducer and activator of transcription 6 (STAT6) inhibitor of AS1517499 with the assistance of distearoyl phosphoethanolamine-PEG2000 (DSPE-PEG2000), which can extensively increase the stability to enhance drug delivery in vitro and in vivo. Furthermore, CuPA can upregulate intracellular ROS to cause tumor cell death through restraining Trx and degrading GSH. Also, CuPA-mediated STAT6 inhibition results in the elimination of M2 macrophage to reverse the immunosuppressive tumor microenvironment. Finally, the elevated oxidative stress and increased immune activation amplify the synergistic antitumor effect without causing obvious side effect. This work provides a new sight for synergistic tumor suppression through chemo-immunotherapy in consideration of the complex resistant tumor microenvironment.