A self-amplifying pyroptosis-STING nanotherapeutic for sensitizing triple-negative breast cancer to PD-1 blockade

HA@CZ enables acid-responsive local Ca 2+ /Zn 2+ ion therapy. • Zn 2+ impairs Ca 2+ extrusion and drives sustained Ca 2+ overload. • Dual-ion stress induces caspase-1/GSDMD and caspase-3/GSDME pyroptosis. • HA@CZ cascade-induces pyroptosis and activates the STING pathway. • Local HA@CZ treatment sensitizes 4 T1 tumors to PD-1 blockade. Triple-negative breast cancer responds poorly to immune checkpoint blockade, partly because of insufficient tumor-local immune priming. Controlled delivery of bioactive ions offers an opportunity to induce inflammatory tumor cell death while limiting nonspecific systemic exposure. Here, we developed hyaluronic acid-modified, zinc containing calcium carbonate nanoparticles (HA@CZ) for acid-responsive synchronized Ca 2+ /Zn 2+ delivery. HA@CZ remained colloidally stable under physiological conditions but released Ca 2+ and Zn 2+ more rapidly under tumor relevant acidic conditions. HA@CZ markedly promoted intracellular Ca 2+ /Zn 2+ accumulation, induced mitochondrial dysfunction, and triggered gasdermin dependent pyroptosis through the caspase-1/GSDMD and caspase-3/GSDME axes. Mechanistically, the key distinction of HA@CZ does not lie in Ca 2+ overload alone, but in converting Ca 2+ overload from a direct ion burden process into a Zn 2+ initiated Ca 2+ homeostasis collapse mechanism. Zn 2+ impaired mitochondrial energy metabolism and ATP dependent Ca 2+ extrusion, thereby lowering the threshold for sustained Ca 2+ overload after synchronized ion release. The resulting dual ion stress promoted mitochondrial deoxyribonucleic acid leakage and activated cyclic GMP–AMP synthase stimulator of interferon genes signaling, thereby coupling tumor cell pyroptosis with endogenous deoxyribonucleic acid sensing activation. In syngeneic 4 T1 tumor models, HA@CZ suppressed tumor growth after both systemic and local administration, promoted dendritic cell maturation and CD8 + T-cell infiltration, and remodeled the tumor immune microenvironment toward a pro-inflammatory phenotype. Intratumoral studies confirmed its intrinsic therapeutic superiority over free CaCO₃, Zn 2+ , and their physical mixture, while combination with anti-PD-1 therapy enhanced control of both primary and distant tumors. Furthermore, tumor re-challenge experiments demonstrated that HA@CZ induced durable antitumor immune memory. These findings establish HA@CZ as a controlled-release ion nanotherapeutic that couples synchronized Ca 2+ and Zn 2+ delivery to pyroptosis associated immune activation and checkpoint blockade sensitization. Download: Download high-res image (150KB) Download: Download full-size image