Biomineralization-Tuned Nanounits Reprogram the Signal Transducer and Activator of Transcription 3 Signaling for Ferroptosis-Immunotherapy in Cancer Stem Cells

Cancer Stem Cells (CSCs) are promising targets for improving Anticancer treatment outcomes while eliminating recurrence, but their treatment remains a major challenge. Here, we report a nanointegrative strategy to realize CSC-targeted ferroptosis-immunotherapy through spatiotemporally controlled reprogramming of STAT3-regulated signaling circuits. Specifically, STAT3 Inhibitor niclosamide (Ni) and an experimental Ferroptosis drug (1S, 3R)-RSL3 (RSL3) are integrated into hyaluronic acid-modified amorphous calcium phosphate (ACP) nanounits through biomineralization (CaP-PEG-HA@Ni/RSL3), which could be recognized by CD44-overexpressing CSCs and released in a synchronized manner. Ni inhibits the CSC-intrinsic STAT3-PD-L1 axis to stimulate adaptive immunity and enhance interferon gamma (IFNγ) secretion by CD8⁺ T cells to downregulate SLC7A11 and SLC3A2 for blocking glutathione biosynthesis. Meanwhile, Ni-dependent STAT3 inhibition also upregulates ACSL4 through downstream signaling and IFNγ feedback. These effects cooperate with RSL3-mediated GPX4 deactivation to induce pronounced Ferroptosis. Furthermore, CaP-PEG-HA@Ni/RSL3 also impairs the immunosuppressive M2-like tumor-associated macrophages, while CA²⁺ ions released from degraded ACP could chelate with lipid peroxides in ferroptotic CSCs to avoid CD8⁺ T-cell inhibition, thus boosting the effector function of activated CD8⁺ T cells. This study offers a cooperative ferroptosis-immunotherapeutic approach for the treatment of refractory Cancer.

STAT3; biomineralized nanoassemblies; cancer stem cell treatment; ferroptosis; immunotherapy.