Theoretically, our immune system could detect and kill cancer cells. Unfortunately, tumors are well armed to fight these attacks. Despite modern cancer treatments, metastases and relapses remain a major problem. Increasing anti-tumor immunity might now be made possible, thanks to copper telluride nanoparticles that mimic enzymes, especially under NIR-II light irradiation. This induces oxidative stress in tumor cells, quashing their immunosuppressive status and triggering inflammatory processes, as scientists have recently reported.