Immunogenic cell stress and death in the treatment of cancer

Cascade-recharged macrophage-biomimetic ruthenium-based nanobattery for enhanced photodynamic-induced immunotherapy

Photodynamic-induced immunotherapy (PDI) is often hampered by low reactive oxygen species (ROS) yield, intra-tumor hypoxia, high glutathione (GSH) concentration, and immunosuppressive microenvironment. In view of this, a ruthenium (Ru)-based nanobattery (termed as IRD) with cascade-charged oxygen (O2), ROS, and photodynamic-induced immunotherapy by coordination-driven self-assembly of transition-metal Ru, photosensitizer indocyanine green (ICG), and organic ligand dithiobispropionic acid (DTPA). Then, IRD is camouflaged with macrophage membranes to obtain a nanobattery (termed as IRD@M) with targeting and immune evasion capabilities. Upon intravenous administration, IRD@M with a core-shell structure, nano diameter, and good stability can specifically hoard in tumor location and internalize into tumor cells. Upon disassembly triggered by GSH, the released Ru³⁺ not only catalyzes the conversion of endogenous hydrogen peroxide (H₂O₂) into O₂ to alleviate tumor hypoxia and reduce the expression of hypoxia-inducible factor-1α (HIF-1α), but also generates hydroxyl radicals (·OH) to elevate intracellular ROS levels. This process significantly enhances the photodynamic therapy (PDT) efficacy of the released ICG. Meanwhile, the released DTPA can significantly downregulate overexpressed GSH to reduce the elimination of ROS deriving from PDT by the exchange reaction of thiol-disulfide bond. It is also found that alleviating the hypoxic tumor microenvironment synergistically enhances the PDT efficacy, which in turn cascades to recharge the subsequent immune response, significantly improving the immunosuppressive tumor microenvironment and activating systemic tumor-specific immunity. Notably, in vitro and in vivo experimental results jointly confirm that such cascade-recharged macrophage-biomimetic Ru-based nanobattery IRD@M can achieve an obvious tumor elimination while results in a minimized side effect. Taken together, this work highlights a promising strategy for simple, flexible, and effective Ru-based immunogenic cell death (ICD) agents within PDI.

Antitumor host immunity enhanced by near-infrared photoimmunotherapy

Near-infrared photoimmunotherapy (NIR-PIT) is a novel antitumor therapy that selectively kills cancer cells by NIR light-triggered photochemical reaction of IRDye700DX within Ab-photoabsorber conjugates (APCs). NIR-PIT induces immunogenic cell death, causing immune cell migration between the tumor and tumor-draining lymph nodes, and expanding multiclonal tumor-infiltrating CD8+ T cells. Crucially, the cytotoxic effects of NIR-PIT are limited to cancer cells, sparing immune cells such as antigen-presenting cells and T cells, which are key players in boosting antitumor host immunity. By modifying the Ab used in APC synthesis, NIR-PIT can be repurposed to target and deplete noncancerous immunosuppressive cells including regulatory T cells, myeloid-derived suppressor cells, and cancer-associated fibroblasts in the tumor microenvironment. Immunosuppressive cell targeted NIR-PIT strongly potentiates antitumor host immunity, including the induction of abscopal effects and the development of immune memory. Furthermore, antitumor immune responses and therapeutic efficacy are synergistically enhanced when NIR-PIT is combined with other immune-activating treatments, such as interleukin-15 and immune checkpoint inhibitors. These new findings make NIR-PIT a valuable tool in the evolving landscape of cancer immunotherapy. This review explains the role of NIR-PIT in activating antitumor host immunity.

Traditional Chinese medicine enhances the effectiveness of immune checkpoint inhibitors in tumor treatment: A mechanism discussion

ETHNOPHARMACOLOGICAL RELEVANCE

Immune checkpoint inhibitors (ICIs) have altered the landscape of tumor immunotherapy, offering novel therapeutic approaches alongside surgery, chemotherapy, and radiotherapy and significantly improving survival benefits. However, their clinical efficacy is limited in some patients, and their use may cause immune-related adverse events (irAEs). Integrating traditional Chinese medicine (TCM) with ICIs has demonstrated the potential to boost sensitization and reduce toxicity. Clinical trials and experimental explorations have confirmed that TCM and its active components synergistically enhance the effectiveness of ICIs.

AIMS

This narrative review summarizes the TCM practices that enhance the clinical efficacy and reduce irAEs of ICIs. This paper also summarizes the mechanism of experimental studies on the synergies of Chinese herbal decoctions, Chinese herbal preparation, and Chinese herbal active ingredients. Most of the studies on TCM combined with ICIs are basic experiments. We discussed the mechanism of TCM enhanced ICIs to provide reference for the research and development of TCM adjuvant immunotherapy.

METHODS

We conducted a literature search using PubMed and Chinese National Knowledge Infrastructure databases, with a focus on herbal decoction, Chinese medicine preparations, and active ingredients that boost the effectiveness of ICIs and reduce irAEs. The search keywords were "ICIs and traditional Chinese medicine", "PD-1 and traditional Chinese medicine", "PD-L1 and traditional Chinese medicine", "CTLA-4 and traditional Chinese medicine", "IDO1 and traditional Chinese medicine", "Tim-3 and traditional Chinese medicine", "TIGIT and traditional Chinese medicine", "irAEs and traditional Chinese medicine". The search period was from May 2014 to May 2024. Articles involving the use of TCM or its components in combination with ICIs and investigating the underlying mechanisms were screened. Finally, 30 Chinese medicines used in combination with ICIs were obtained to explore the mechanism. In the part of immune checkpoint molecules other than PD-1, there were few studies on the combined application of TCM, so studies involving the regulation of immune checkpoint molecules by TCM were included.

RESULTS

TCM has been shown to boost the effectiveness of ICIs and reduce irAEs. Researchers indicate that TCM and its active components can work synergistically with ICIs by regulating immune checkpoints PD-1, PD-L1, CTLA-4, and IDO1, regulating intestinal flora, improving tumor microenvironment and more.

CONCLUSIONS

Combining TCM with ICIs can play a better anti-tumor role, but larger samples and high-quality clinical trials are necessary to confirm this. Many Chinese medicines and their ingredients have been shown to sensitize ICIs in experimental studies, which provides a rich choice for the subsequent development of ICI enhancers.

High circulating HMGB1 indicates good prognosis in patients with advanced leiomyosarcoma under chemoimmunotherapy

Few clinical studies investigated the putative link between the activation of immunogenic cell death (ICD) and the oncological outcome. Recent data, published in a Phase 1b trial, demonstrated that an ICD-associated surge in the plasma concentration of high-mobility group box 1 (HMGB1) indicates favorable prognosis in patients with advanced leiomyosarcomas treated with the combination of doxorubicin, dacarbazine and nivolumab.

Immunogenic cell death: A new strategy to enhancing cancer immunotherapy

Immunogenic cell death (ICD) is a distinct type of stress-induced regulated cell death that can lead to adaptive immune responses and the establishment of immunological memory. ICD exhibits both similarities and differences when compared to apoptosis and other non-apoptotic forms of regulated cell death (RCD). The interplay between ICD-mediated immunosurveillance against cancer and the ability of cancer cells to evade ICD influences the host-tumor immunological interaction. Consequently, the restoration of ICD and the development of effective strategies to induce ICD have emerged as crucial considerations in the treatment of cancer within the context of immunotherapy. To enhance comprehension of ICD in the setting of cancer, this paper examines the interconnected responsive pathways associated with ICD, the corresponding biomarkers indicative of ICD, and the mechanisms through which tumors subvert ICD. Additionally, this review explores strategies for reinstating ICD and the therapeutic potential of harnessing ICD in cancer immunotherapy.

Targeting cuproptosis with nano material: new way to enhancing the efficacy of immunotherapy in colorectal cancer

Colorectal cancer has emerged as one of the predominant malignant tumors globally. Immunotherapy, as a novel therapeutic methodology, has opened up new possibilities for colorectal cancer patients. However, its actual clinical efficacy requires further enhancement. Copper, as an exceptionally crucial trace element, can influence various signaling pathways, gene expression, and biological metabolic processes in cells, thus playing a critical role in the pathogenesis of colorectal cancer. Recent studies have revealed that cuproptosis, a novel mode of cell death, holds promise to become a potential target to overcome resistance to colorectal cancer immunotherapy. This shows substantial potential in the combination treatment of colorectal cancer. Conveying copper into tumor cells via a nano-drug delivery system to induce cuproptosis of colorectal cancer cells could offer a potential strategy for eliminating drug-resistant colorectal cancer cells and vastly improving the efficacy of immunotherapy while ultimately destroy colorectal tumors. Moreover, combining the cuproptosis induction strategy with other anti-tumor approaches such as photothermal therapy, photodynamic therapy, and chemodynamic therapy could further enhance its therapeutic effect. This review aims to illuminate the practical significance of cuproptosis and cuproptosis-inducing nano-drugs in colorectal cancer immunotherapy, and scrutinize the current challenges and limitations of this methodology, thereby providing innovative thoughts and references for the advancement of cuproptosis-based colorectal cancer immunotherapy strategies.

Emerging role of immunogenic cell death in cancer immunotherapy: Advancing next-generation CAR-T cell immunotherapy by combination

Immunogenic cell death (ICD) is a stress-driven form of regulated cell death (RCD) in which dying tumor cells' specific signaling pathways are activated to release damage-associated molecular patterns (DAMPs), leading to the robust anti-tumor immune response as well as a reversal of the tumor immune microenvironment from "cold" to "hot". Chimeric antigen receptor (CAR)-T cell therapy, as a landmark in anti-tumor immunotherapy, plays a formidable role in hematologic malignancies but falls short in solid tumors. The Gordian knot of CAR-T cells for solid tumors includes but is not limited to, tumor antigen heterogeneity or absence, physical and immune barriers of tumors. The combination of ICD induction therapy and CAR-T cell immunotherapy is expected to promote the intensive use of CAR-T cell in solid tumors. In this review, we summarize the characteristics of ICD, stress-responsive mechanism, and the synergistic effect of various ICD-based therapies with CAR-T cells to effectively improve anti-tumor capacity.

Inhibiting autophagy enhanced mitotic catastrophe-mediated anticancer immune responses by regulating the cGAS-STING pathway

Given the limitations of the response rate and efficacy of immune checkpoint inhibitors (ICIs) in clinical applications, exploring new therapeutic strategies for cancer immunotherapy is necessary. We found that 5-(3,4,5-trimethoxybenzoyl)-4-methyl-2-(p-tolyl)imidazole (BZML), a microtubule-targeting agent, exhibited potent anticancer activity by inducing mitotic catastrophe in A549/Taxol and L929 cells. Nuclear membrane disruption and nuclease reduction provided favorable conditions for cGAS-STING pathway activation in cells with mitotic catastrophe. Similar results were obtained in paclitaxel-, docetaxel- and doxorubicin-induced mitotic catastrophe in various cancer cells. Notably, the surface localization of CALR and MHC-I and the release of HMGB1 were also significantly increased in cells with mitotic catastrophe, but not in apoptotic cells, suggesting that mitotic catastrophe is an immunogenic cell death. Furthermore, activated CD8+T cells enhanced the anticancer effects originating from mitotic catastrophe induced by BZML. Inhibiting the cGAS-STING pathway failed to affect BZML-induced mitotic catastrophe but could inhibit mitotic catastrophe-mediated anticancer immune effects. Interestingly, the expression of p-TBK1 first increased and then declined; however, autophagy inhibition reversed the decrease in p-TBK1 expression and enhanced mitotic catastrophe-mediated anticancer immune effects. Collectively, the inhibition of autophagy can potentiate mitotic catastrophe-mediated anticancer immune effects by regulating the cGAS-STING pathway, which explains why the anticancer immune effects induced by chemotherapeutics have not fully exerted their therapeutic efficacy in some patients and opens a new area of research in cancer immunotherapy.