Chemodynamic therapy (CDT) can effectively induce immunogenic cell death (ICD) in tumours and is thus a promising strategy for boosting the efficacy of immunotherapy. However, the mechanism by which CDT enhances ICD and lowers ICD efficiency is unknown and this restricts its clinical application. In this study, a second near-infrared (NIR-II) window irradiation-triggered hydrogen peroxide (H₂O₂) self-supplying nanocomposite ((Cu₂Se-CaO₂)@LA) was constructed. The modified lauric acid was melted by the heat energy of the NIR-II irradiation, to expose the CaO₂ nanoparticles, and they then reacted with water to produce H₂O₂ and Ca²⁺. H₂O₂ was then converted to hydroxyl radicals by the photothermal-enhanced CDT process of the Cu₂Se nanocubes. Notably, the CDT and Ca²⁺ overload was found to induce sequential damage to the mitochondria and endoplasmic reticulum (ER), which upregulated the PERK-mediated eIF2α phosphorylation pathway and caused subsequent ICD. NIR-II irradiation of the (Cu₂Se-CaO₂)@LA also increased reactive oxygen species (ROS) formation and this was sufficient to increase dendritic cell maturation, attracting cytotoxic T lymphocytes, and suppressing tumour growth in vivo. Overall, we demonstrated that an enhanced CDT strategy under NIR-II exposure and H₂O₂ self-supply can induce extensive ICD by inducing mitochondria-associated ER stress, which represents a highly effective and promising strategy for ICD amplification and tumour immunotherapy. STATEMENT OF SIGNIFICANCE: In this study, a second near-infrared window (NIR-II) irradiation-triggered and H₂O₂ self-supplying nanocomposite (named (Cu₂Se-CaO₂)@LA) was constructed and tested both in vitro and in vivo. These nanoparticles demonstrated promising antitumor activity as designed. Mechanistically, the nanoparticles could damage mitochondria and upregulate the PERK-mediated eIF2αphosphorylation pathway, further causing endoplasmic reticulum stress, and inducing immunogenic cell death through dendritic cell maturation and cytotoxic T lymphocyte recruitment augmented activity. This system represents a highly effective and promising strategy for enhancing tumor immunotherapy and provides new insights for future studies and design refinements.

This study aimed to explore the anti-tumor effect of icaritin loading poly (lactic-co-glycolic acid) nanoparticles (refer to PLGA@Icaritin NPs) on gastric cancer (GC) cells. Transmission Electron Microscope (TEM), size distribution, zeta potential, drug-loading capability, and other physicochemical characteristics of PLGA@Icaritin NPs were carried out. Furthermore, flow cytometry, confocal laser scanning microscope (CLSM), Cell Counting Kit-8 (CCK-8), Transwell, Elisa assay and Balb/c mice were applied to explore the cellular uptake, anti-proliferation, anti-metastasis, immune response activation effects, and related anti-tumor mechanism of PLGA@Icaritin NPs in vitro and in vivo. PLGA@Icaritin NPs showed spherical shape, with appropriate particle sizes and well drug loading and releasing capacities. Flow cytometry and CLSM results indicated that PLGA@Icaritin could efficiently enter into GC cells. CCK-8 proved that PLGA@Icaritin NPs dramatically suppressed cell growth, induced Lactic dehydrogenase (LDH) leakage, arrested more GC cells at G2 phase, and inhibited the invasion and metastasis of GC cells, compared to free icaritin. In addition, PLGA@Icaritin could help generate dozens of reactive oxygen species (ROS) within GC cells, following by significant mitochondrial membrane potentials (MMPs) loss and excessive production of oxidative-mitochondrial DNA (Ox-mitoDNA). Since that, Ox-mitoDNA further activated the releasing of damage associated molecular pattern molecules (DAMPs), and finally led to immunogenic cell death (ICD). Our in vivo data also elaborated that PLGA@Icaritin exerted a powerful inhibitory effect (∼80%), compared to free icaritin (∼60%). Most importantly, our results demonstrated that PLGA@Icaritin could activate the anti-tumor immunity via recruitment of infiltrating CD4+ cells, CD8+ T cells and increased secretion of cytokine immune factors, including interferon-γ (IFN-γ) tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1).⁺⁺ Our findings validate that the successful design of PLGA@Icaritin, which can effectively active ICD and facilitate tumor recruitment in GC through inducing mitoDNA oxidative damage.

In recent years, immunotherapy has emerged as a promising strategy for treating solid tumors, although its efficacy remains limited to a subset of patients. Transforming non-responsive “cold” tumor types into immuno-responsive “hot” ones is critical to enhance the efficacy of immune-based cancer treatments. Pyroptosis, a programmed cell death mechanism, not only effectively eliminates tumor cells but also triggers a potent inflammatory response to initiate anti-tumor immune activities. This sheds light on the potential of pyroptosis to sensitize tumors to immune therapy. Hence, it is urgent to explore and develop novel treatments (e.g., nanomedicines) which are capable of inducing pyroptosis. In this study, we constructed tumor-targeting nanoparticles (CS-HAP@ATO NPs) by loading atorvastatin (ATO) onto chondroitin sulfate (CS) modified hydroxyapatite (HAP) nanoparticles (CS-HAP). CS was strategically employed to target tumor cells, while HAP exhibited the capacity to release calcium ions (Ca²⁺) in response to the tumor microenvironment. Moreover, ATO disrupted the mitochondrial function, leading to intracellular energy depletion and consequential changes in mitochondrial membrane permeability, followed by the influx of Ca²⁺ into the cytoplasm and mitochondria. CS and HAP synergetically augmented mitochondrial calcium overload, inciting the production of substantial amount of reactive oxygen species (ROS) and the subsequent liberation of oxidized mitochondrial DNA (OX-mitoDNA). This intricate activation process promoted the assembly of inflammasomes, most notably the NLRP3 inflammasome, followed by triggering caspase-1 activation. The activated caspase-1 was able to induce gasderminD (GSDMD) protein cleavage and present the GSDM-N domain, which interacted with phospholipids in the cell membrane. Then, the cell membrane permeability was raised, cellular swelling was observed, and abundant cell contents and inflammatory mediators were released. Ultimately, this orchestrated sequence of events served to enhance the anti-tumor immunoresponse within the organism.

Immune checkpoint inhibitors, are the fourth most common therapeutic tool after surgery, chemotherapy, and radiotherapy for colorectal cancer (CRC). However, only a small proportion (≈5%) of CRC patients, those with “hot” (immuno‐activated) tumors, benefit from the therapy. Pyroptosis, an innovative form of programmed cell death, is a potentially effective means to mediate a “cold” to “hot” transformation of the tumor microenvironment (TME). Calcium‐releasing hydroxyapatite (HAP) nanoparticles (NPs) trigger calcium overload and pyroptosis in tumor cells. However, current limitations of these nanomedicines, such as poor tumor‐targeting capabilities and insufficient calcium (Ca) ion release, limit their application. In this study, chondroitin sulfate (CS) is used to target tumors via binding to CD44 receptors and kaempferol (KAE) is used as a Ca homeostasis disruptor to construct CS‐HAP@KAE NPs that function as pyroptosis inducers in CRC cells. CS‐HAP@KAE NPs bind to the tumor cell membrane, HAP released Ca in response to the acidic environment of the TME, and kaempferol (KAE) enhances the influx of extracellular Ca, resulting in intracellular Ca overload and pyroptosis. This is associated with excessive endoplasmic reticulum stress triggered activation of the stimulator of interferon genes/interferon regulatory factor 3 pathway, ultimately transforming the TME from “cold” to “hot”.

Insufficient immune cell infiltration into the tumor microenvironment (TME) greatly compromises the clinical application of immune‐checkpoint inhibitors (ICIs)‐based immunotherapy. Recent findings have shown that activation of the cyclic GMP‐AMP synthase‐stimulator of interferon genes (cGAS‐STING) pathway can enhance natural immunity and increase lymphocyte infiltration into the TME, which presents a promising strategy for cancer immunotherapy. In this study, we constructed hydroxyapatite nanoparticles co‐loaded with curcumin and L‐oxaliplatin (Cur/L‐OHP@HAP NPs). We analyzed the particle‐size distribution, zeta potential, spectral characteristics (Fourier‐transform infrared spectroscopy, X‐ray photoelectron spectroscopy, ultraviolet–visible spectroscopy), and drug‐release properties of the Cur/L‐OHP@HAP NPs. The cellular uptake of the Cur/L‐OHP@HAP NPs detected by flow cytometry and confocal laser‐scanning microscopy. We comprehensively evaluated the anti‐tumor properties and immune‐activating effects of the NPs, both in vitro and in vivo. Physicochemical characterizations demonstrated that the Cur/L‐OHP@HAP NPs were successfully synthesized and were capable of pH‐dependent drug release. Notably, the Cur/L‐OHP@HAP NPs efficiently entered cancer cells, after which the released L‐OHP induced nuclear DNA (nDNA) damage to some extent. HAP promoted the release of intracellular Ca²⁺ stores in cancer cells, and curcumin inhibited Ca²⁺ efflux, resulting in intracellular Ca²⁺ overload and the release of mitochondrial DNA (mtDNA). Damage to both nDNA and mtDNA greatly stimulated the cGAS‐STING pathway, thereby activating natural immunity, accompanied by immune cell recruitment to the TME. In summary, the Cur/L‐OHP@HAP NPs show good prospects for improving cancer immunotherapy.

Colorectal cancer (CRC) remains therapeutically challenging due to high metastasis, recurrence, and immunotherapy resistance driven by tumor microenvironment‐mediated immune evasion. Immunogenic cell death (ICD) offers a promising strategy to reshape the immune microenvironment, yet existing ICD inducers suffer from poor targeting efficiency and insufficient death signal release. Here, we constructed a calcium overload‐based smart nanosystem, HA‐HAP@CUR, to achieve highly efficient ICD induction via a triple‐effect mechanism: hyaluronic acid (HA)‐mediated CD44 targeting enables tumor‐selective accumulation; pH‐responsive hydroxyapatite (HAP) degradation releases Ca ²⁺ in the acidic tumor microenvironment; and curcumin (CUR) amplifies intracellular calcium overload by promoting endoplasmic reticulum Ca ²⁺ release, collectively establishing a positive feedback loop disrupting calcium homeostasis. Mechanistically, calcium overload induces mitochondrial membrane potential dissipation and sustained mPTP opening, triggering mitochondrial oxidative stress and energy metabolic disorders. This mitochondrial crisis concurrently activates caspase‐3, GSDMD, and RIPK1, synergistically initiating apoptosis, pyroptosis, and necroptosis, ultimately converging into PANoptosis with potent immunostimulatory potential. This strategy, encompassing targeted accumulation, calcium storm activation, and multi‐modal cell death synergy, provides a biologically precise approach to overcoming immunotherapy resistance in CRC.