A Self‐Amplifying ROS‐Responsive Nanoplatform for Simultaneous Cuproptosis and Cancer Immunotherapy

Abstract Cuproptosis is an emerging cell death pathway that depends on the intracellular Cu ions. Elesclomol (ES) as an efficient Cu ionophore can specifically transport Cu into mitochondria and trigger cuproptosis. However, ES can be rapidly removed and metabolized during intravenous administration, leading to a short half‐life and limited tumor accumulation, which hampers its clinical application. Here, the study develops a reactive oxygen species (ROS)‐responsive polymer (PCP) based on cinnamaldehyde (CA) and polyethylene glycol (PEG) to encapsulate ES‐Cu compound (EC), forming ECPCP. ECPCP significantly prolongs the systemic circulation of EC and enhances its tumor accumulation. After cellular internalization, the PCP coating stimulatingly dissociates exposing to the high‐level ROS, and releases ES and Cu, thereby triggering cell death via cuproptosis. Meanwhile, Cu2+‐stimulated Fenton‐like reaction together with CA‐stimulated ROS production simultaneously breaks the redox homeostasis, which compensates for the insufficient oxidative stress treated with ES alone, in turn inducing immunogenic cell death of tumor cells, achieving simultaneous cuproptosis and immunotherapy. Furthermore, the excessive ROS accelerates the stimuli‐dissociation of ECPCP, forming a positive feedback therapy loop against tumor self‐alleviation. Therefore, ECPCP as a nanoplatform for cuproptosis and immunotherapy improves the dual antitumor mechanism of ES and provides a potential optimization for ES clinical application.