Dendritic Cells and Immunogenic Cancer Cell Death: A Combination for Improving Antitumor Immunity

Progress in application of nanomedicines for enhancing cancer sono-immunotherapy

Cancer immunotherapy has significant potential as a cancer treatment since it boosts the immune system and prevents immune escape to get rid of or fight cancers. However, its clinical applicability is still limited because of the low response rate and immune-related side effects. Recently ultrasound has been shown to alter the tumor immune microenvironment, enhance the effectiveness of other antitumor therapies, and cause tumors to become more sensitive to immunotherapy, thus providing new insights into cancer treatment. Nanomedicines are also anticipated to have a positive impact on improving the immunological effects and enhancing ultrasound effect for cancer therapy. Therefore, designing effective nanomedicines enhanced ultrasound effect for augmenting sono-immunotherapy has been a pivot on anticancer therapy. In this review, the immunological impacts of various ultrasound therapeutic modalities, ultrasound parameters, and their underlying mechanisms are discussed. Moreover, we highlight the recent progress of nanomedicines synergistically enhancing sono-immunotherapy. Finally, we put forward opportunities and challenges on sono-immunotherapy.

Immunometabolic characteristics of Dendritic Cells and its significant modulation by mitochondria-associated signaling in the tumor microenvironment influence cancer progression

Dendritic cells (DCs) mediated T-cell responses is critical to anti-tumor immunity. This study explores immunometabolic attributes of DC, emphasizing on mitochondrial association, in Tumor Microenvironment (TME) that regulate cancer progression. Conventional DC subtypes cross-present tumor-associated antigens to activate lymphocytes. However, plasmacytoid DCs participate in both pro- and anti-tumor signaling where mitochondrial reactive oxygen species (mtROS) play crucial role. CTLA-4, CD-47 and other surface-receptors of DC negatively regulates T-cell. Increased glycolysis-mediated mitochondrial citrate buildup and translocation to cytosol with augmented NADPH, enhances mitochondrial fatty acid synthesis fueling DCs. Different DC subtypes and stages, exhibit variable mitochondrial content, membrane potential, structural dynamics and bioenergetic metabolism regulated by various cytokine stimulation, e.g., GM-CSF, IL-4, etc. CD8α+ cDC1s augmented oxidative phosphorylation (OXPHOS) which diminishes at advance effector stages. Glutaminolysis in mitochondria supplement energy in DCs but production of kynurenine and other oncometabolites leads to immunosuppression. Mitochondria-associated DAMPs cause activation of cGAS-STING pathway and inflammasome oligomerization stimulating DC and T cells. In this study, through a comprehensive survey and critical analysis of the latest literature, the potential of DC metabolism for more effective tumor therapy is highlighted. This underscores the need for future research to explore specific therapeutic targets and potential drug candidates.

Efficacy of novel allogeneic cancer cells vaccine to treat colorectal cancer

Colorectal cancer (CRC) remains a significant global health burden, emphasizing the need for innovative treatment strategies. 95% of the CRC population are microsatellite stable (MSS), insensitive to classical immunotherapies such as anti-PD-1; on the other hand, responders can become resistant and relapse. Recently, the use of cancer vaccines enhanced the immune response against tumor cells. In this context, we developed a therapeutic vaccine based on Stimulated Tumor Cells (STC) platform technology. This vaccine is composed of selected tumor cell lines stressed and haptenated in vitro to generate a factory of immunogenic cancer-related antigens validated by a proteomic cross analysis with patient's biopsies. This technology allows a multi-specific education of the immune system to target tumor cells harboring resistant clones. Here, we report safety and antitumor efficacy of the murine version of the STC vaccine on CT26 BALB/c CRC syngeneic murine models. We showed that one cell line (1CL)-based STC vaccine suppressed tumor growth and extended survival. In addition, three cell lines (3CL)-based STC vaccine significantly improves these parameters by presenting additional tumor-related antigens inducing a multi-specific anti-tumor immune response. Furthermore, proteomic analyses validated that the 3CL-based STC vaccine represents a wider quality range of tumor-related proteins than the 1CL-based STC vaccine covering key categories of tumor antigens related to tumor plasticity and treatment resistance. We also evaluated the efficacy of STC vaccine in an MC38 anti-PD-1 resistant syngeneic murine model. Vaccination with the 3CL-based STC vaccine significantly improved survival and showed a confirmed complete response with an antitumor activity carried by the increase of CD8+ lymphocyte T cells and M1 macrophage infiltration. These results demonstrate the potential of this technology to produce human vaccines for the treatment of patients with CRC.

Impact of Genomic Mutation on Melanoma Immune Microenvironment and IFN-1 Pathway-Driven Therapeutic Responses

The BRAFV600E mutation, found in approximately 50% of melanoma cases, plays a crucial role in the activation of the MAPK/ERK signaling pathway, which promotes tumor cell proliferation. This study aimed to evaluate its impact on the melanoma immune microenvironment and therapeutic responses, particularly focusing on immunogenic cell death (ICD), a pivotal cytotoxic process triggering anti-tumor immune responses. Through comprehensive in silico analysis of the Cancer Genome Atlas data, we explored the association between the BRAFV600E mutation, immune subtype dynamics, and tumor mutation burden (TMB). Our findings revealed that the mutation correlated with a lower TMB, indicating a reduced generation of immunogenic neoantigens. Investigation into immune subtypes reveals an exacerbation of immunosuppression mechanisms in BRAFV600E-mutated tumors. To assess the response to ICD inducers, including doxorubicin and Me-ALA-based photodynamic therapy (PDT), compared to the non-ICD inducer cisplatin, we used distinct melanoma cell lines with wild-type BRAF (SK-MEL-2) and BRAFV600E mutation (SK-MEL-28, A375). We demonstrated a differential response to PDT between the WT and BRAFV600E cell lines. Further transcriptomic analysis revealed upregulation of IFNAR1, IFNAR2, and CXCL10 genes associated with the BRAFV600E mutation, suggesting their involvement in ICD. Using a gene reporter assay, we showed that PDT robustly activated the IFN-1 pathway through cGAS-STING signaling. Collectively, our results underscore the complex interplay between the BRAFV600E mutation and immune responses, suggesting a putative correlation between tumors carrying the mutation and their responsiveness to therapies inducing the IFN-1 pathway, such as the ICD inducer PDT, possibly mediated by the elevated expression of IFNAR1/2 receptors.

Exploring in vivo combinatorial chemo-immunotherapy: Addressing p97 suppression and immune reinvigoration in pancreatic cancer with tumor microenvironment-responsive nanoformulation

Pancreatic ductal adenocarcinoma (PDAC) has an extremely devastating nature with poor prognosis and increasing incidence, making it a formidable challenge in the global fight against cancer-related mortality. In this innovative preclinical investigation, the VCP/p97 inhibitor CB-5083 (CB), miR-142, a PD-L1 inhibitor, and immunoadjuvant resiquimod (R848; R) were synergistically encapsulated in solid lipid nanoparticles (SLNs). These SLNs demonstrated features of peptides targeting PD-L1, EGFR, and the endoplasmic reticulum, enclosed in a pH-responsive polyglutamic (PGA)-polyethylene glycol (PEG) shell. The homogeneous size and zeta potential of the nanoparticles were stable for 28 days at 4°C. The study substantiated the concurrent modulation of key pathways by the CB, miR, and R-loaded nanoformulation, prominently affecting VCP/Bip/ATF6, PD-L1/TGF-β/IL-4, -8, -10, and TNF-α/IFN-γ/IL-1, -12/GM-CSF/CCL4 pathways. This adaptable nanoformulation induced durable antitumor immune responses and inhibited Panc-02 tumor growth by enhancing T cell infiltration, dendritic cell maturation, and suppressing Tregs and TAMs in mice bearing Panc-02 tumors. Furthermore, tissue distribution studies, biochemical assays, and histological examinations highlighted enhanced safety with PGA and peptide-modified nanoformulations for CB, miR, and/or R in Panc-02-bearing mice. This versatile nanoformulation allows tailored adjustment of the tumor microenvironment, thereby optimizing the localized delivery of combined therapy. These compelling findings advocate the potential development of a pH-sensitive, three-in-one PGA-PEG nanoformulation that combines a VCP inhibitor, a PD-L1 inhibitor, and an immunoadjuvant for cancer treatment via combinatorial chemo-immunotherapy.

Dual molecule targeting HDAC6 leads to intratumoral CD4+ cytotoxic lymphocytes recruitment through MHC-II upregulation on lung cancer cells

BACKGROUND

Despite the current therapeutic treatments including surgery, chemotherapy, radiotherapy and more recently immunotherapy, the mortality rate of lung cancer stays high. Regarding lung cancer, epigenetic modifications altering cell cycle, angiogenesis and programmed cancer cell death are therapeutic targets to combine with immunotherapy to improve treatment success. In a recent study, we uncovered that a molecule called QAPHA ((E)-3-(5-((2-cyanoquinolin-4-yl)(methyl)amino)-2-methoxyphenyl)-N-hydroxyacrylamide) has a dual function as both a tubulin polymerization and HDAC inhibitors. Here, we investigate the impact of this novel dual inhibitor on the immune response to lung cancer.

METHODS

To elucidate the mechanism of action of QAPHA, we conducted a chemical proteomics analysis. Using an in vivo mouse model of lung cancer (TC-1 tumor cells), we assessed the effects of QAPHA on tumor regression. Tumor infiltrating immune cells were characterized by flow cytometry.

RESULTS

In this study, we first showed that QAPHA effectively inhibited histone deacetylase 6, leading to upregulation of HSP90, cytochrome C and caspases, as revealed by proteomic analysis. We confirmed that QAPHA induces immunogenic cell death (ICD) by expressing calreticulin at cell surface in vitro and demonstrated its efficacy as a vaccine in vivo. Remarkably, even at a low concentration (0.5 mg/kg), QAPHA achieved complete tumor regression in approximately 60% of mice treated intratumorally, establishing a long-lasting anticancer immune response. Additionally, QAPHA treatment promoted the infiltration of M1-polarized macrophages in treated mice, indicating the induction of a pro-inflammatory environment within the tumor. Very interestingly, our findings also revealed that QAPHA upregulated major histocompatibility complex class II (MHC-II) expression on TC-1 tumor cells both in vitro and in vivo, facilitating the recruitment of cytotoxic CD4+T cells (CD4+CTL) expressing CD4+, NKG2D+, CRTAM+, and Perforin+. Finally, we showed that tumor regression strongly correlates to MHC-II expression level on tumor cell and CD4+ CTL infiltrate.

CONCLUSION

Collectively, our findings shed light on the discovery of a new multitarget inhibitor able to induce ICD and MHC-II upregulation in TC-1 tumor cell. These two processes participate in enhancing a specific CD4+ cytotoxic T cell-mediated antitumor response in vivo in our model of lung cancer. This breakthrough suggests the potential of QAPHA as a promising agent for cancer treatment.

Nanomedicines for reversing immunosuppressive microenvironment of hepatocellular carcinoma

Although immunotherapeutic strategies such as immune checkpoint inhibitors (ICIs) have gained promising advances, their limited efficacy and significant toxicity remain great challenges for hepatocellular carcinoma (HCC) immunotherapy. The tumor immunosuppressive microenvironment (TIME) with insufficient T-cell infiltration and low immunogenicity accounts for most HCC patients' poor response to ICIs. Worse still, the current immunotherapeutics without precise delivery may elicit enormous autoimmune side effects and systemic toxicity in the clinic. With a better understanding of the TIME in HCC, nanomedicines have emerged as an efficient strategy to achieve remodeling of the TIME and superadditive antitumor effects via targeted delivery of immunotherapeutics or multimodal synergistic therapy. Based on the typical characteristics of the TIME in HCC, this review summarizes the recent advancements in nanomedicine-based strategies for TIME-reversing HCC treatment. Additionally, perspectives on the awaiting challenges and opportunities of nanomedicines in modulating the TIME of HCC are presented. Acquisition of knowledge of nanomedicine-mediated TIME reversal will provide researchers with a better opportunity for clinical translation of HCC immunotherapy.

The role of dendritic cells in cancer immunity and therapeutic strategies

Dendritic cells (DCs) are asserted as the most potent antigen-presenting cells (APCs) that orchestrate both innate and adaptive immunity, being extremely effective in the induction of robust anti-cancer T cell responses. Hence, the modulation of DCs function represents an attractive target for improving cancer immunotherapy efficacy. A better understanding of the immunobiology of DCs, the interaction among DCs, immune effector cells and tumor cells in tumor microenvironment (TME) and the latest advances in biomedical engineering technology would be required for the design of optimal DC-based immunotherapy. In this review, we focus on elaborating the immunobiology of DCs in healthy and cancer environments, the recent advances in the development of enhancing endogenous DCs immunocompetence via immunomodulators as well as DC-based vaccines. The rapidly developing field of applying nanotechnology to improve DC-based immunotherapy is also highlighted.

Innate and adaptive immune-directed tumour microenvironment in pancreatic ductal adenocarcinoma

One of the most deadly and aggressive cancers in the world, pancreatic ductal adenocarcinoma (PDAC), typically manifests at an advanced stage. PDAC is becoming more common, and by the year 2030, it is expected to overtake lung cancer as the second greatest cause of cancer-related death. The poor prognosis can be attributed to a number of factors, including difficulties in early identification, a poor probability of curative radical resection, limited response to chemotherapy and radiotherapy, and its immunotherapy resistance. Furthermore, an extensive desmoplastic stroma that surrounds PDAC forms a mechanical barrier that prevents vascularization and promotes poor immune cell penetration. Phenotypic heterogeneity, drug resistance, and immunosuppressive tumor microenvironment are the main causes of PDAC aggressiveness. There is a complex and dynamic interaction between tumor cells in PDAC with stromal cells within the tumour immune microenvironment. The immune suppressive microenvironment that promotes PDAC aggressiveness is contributed by a range of cellular and humoral factors, which itself are modulated by the cancer. In this review, we describe the role of innate and adaptive immune cells, complex tumor microenvironment in PDAC, humoral factors, innate immune-mediated therapeutic advances, and recent clinical trials in PDAC.

Phospholipid scramblase 1 is involved in immunogenic cell death and contributes to dendritic cell-based vaccine efficiency to elicit antitumor immune response in vitro

BACKGROUND AIMS

Whole tumor cell lysates (TCLs) obtained from cancer cells previously killed by treatments able to promote immunogenic cell death (ICD) can be efficiently used as a source of tumor-associated antigens for the development of highly efficient dendritic cell (DC)-based vaccines. Herein, the potential role of the interferon (IFN)-inducible protein phospholipid scramblase 1 (PLSCR1) in influencing immunogenic features of dying cancer cells and in enhancing DC-based vaccine efficiency was investigated.

METHODS

PLSCR1 expression was evaluated in different mantle-cell lymphoma (MCL) cell lines following ICD induction by 9-cis-retinoic acid (RA)/IFN-α combination, and commercial kinase inhibitor was used to identify the signaling pathway involved in its upregulation. A Mino cell line ectopically expressing PLSCR1 was generated to investigate the potential involvement of this protein in modulating ICD features. Whole TCLs obtained from Mino overexpressing PLSCR1 were used for DC loading, and loaded DCs were employed for generation of tumor antigen-specific cytotoxic T lymphocytes.

RESULTS

The ICD inducer RA/IFN-α combination promoted PLSCR1 expression through STAT1 activation. PLSCR1 upregulation favored pro-apoptotic effects of RA/IFN-α treatment and enhanced the exposure of calreticulin on cell surface. Moreover, DCs loaded with TCLs obtained from Mino ectopically expressing PLSCR1 elicited in vitro greater T-cell-mediated antitumor responses compared with DCs loaded with TCLs derived from Mino infected with empty vector or the parental cell line. Conversely, PLSCR1 knock-down inhibited the stimulating activity of DCs loaded with RA/IFN-α-treated TCLs to elicit cyclin D1 peptide-specific cytotoxic T lymphocytes.

CONCLUSIONS

Our results indicate that PLSCR1 improved ICD-associated calreticulin exposure induced by RA/IFN-α and was clearly involved in DC-based vaccine efficiency as well, suggesting a potential contribution in the control of pathways associated to DC activation, possibly including those involved in antigen uptake and concomitant antitumor immune response activation.

Establishment of a prognosis prediction model for lung squamous cell carcinoma related to PET/CT: basing on immunogenic cell death-related lncRNA

BACKGROUND

Immunogenic cell death (ICD) stimulates adaptive immunity and holds significant promise in cancer therapy. Nevertheless, the influence of ICD-associated long non-coding RNAs (lncRNAs) on the prognosis of patients with lung squamous cell carcinoma (LUSC) remains unexplored.

METHODS

We employed data from the The Cancer Genome Atlas (TCGA)database to identify ICD-related lncRNAs associated with the prognosis of LUSC using univariate Cox regression analysis. Subsequently, we utilized the LOSS regression model to construct a predictive risk model for assessing the prognosis of LUSC patients based on ICD-related lncRNAs. Our study randomly allocated187 TCGA patients into a training group and 184 patients for testing the predictive model. Furthermore, we conducted quantitative polymerase chain reaction (qPCR) analysis on 43 tumor tissues from LUSC patients to evaluate lncRNA expression levelsPearson correlation analysis was utilized to analyze the correlation of risk scores with positron emission tomography/computed tomography (PET/CT) parameters among LUSC patients.

RESULTS

The findings from the univariate Cox regression revealed 16 ICD-associated lncRNAs linked to LUSC prognosis, with 12 of these lncRNAs integrated into our risk model utilizing the LOSS regression. Survival analysis indicated a markedly higher overall survival time among patients in the low-risk group compared to those in the high-risk group. The area under the Receiver operating characteristic (ROC) curve to differentiate high-risk and low-risk patients was 0.688. Additionally, the overall survival rate was superior in the low-risk group compared to the high-risk group. Correlation analysis demonstrated a positive association between the risk score calculated based on the ICD-lncRNA risk model and the maximum standard uptake value (SUVmax) (r = 0.427, P = 0.0043) as well as metabolic volume (MTV)of PET-CT (r = 0.360, P = 0.0177) in 43 LUSC patients.

CONCLUSION

We have successfully developed a risk model founded on ICD-related lncRNAs that proves effective in predicting the overall survival of LUSC patients.

Methylglyoxal from gut microbes boosts radiosensitivity and radioimmunotherapy in rectal cancer by triggering endoplasmic reticulum stress and cGAS-STING activation

BACKGROUND

Preoperative radiation therapy (preRT) is a fundamental aspect of neoadjuvant treatment for rectal cancer (RC), but the response to this treatment remains unsatisfactory. The combination of radiation therapy (RT) and immunotherapy (iRT) presents a promising approach to cancer treatment, though the underlying mechanisms are not yet fully understood. The gut microbiota may influence the response to RT and immunotherapy. Therefore, we aimed to identify the metabolism of gut microbiota to reverse radioresistance and enhance the efficacy of iRT.

METHODS

Fecal and serum samples were prospectively collected from patients with locally advanced rectal cancer (LARC) who had undergone pre-RT treatment. Candidate gut microbiome-derived metabolites linked with radiosensitization were screened using 16s rRNA gene sequencing and ultrahigh-performance liquid chromatography-mass coupled with mass spectrometry. In vitro and in vivo studies were conducted to assess the radiosensitizing effects of the metabolites including the syngeneic CT26 tumor model and HCT116 xenograft tumor model, transcriptomics and immunofluorescence. The CT26 abscopal effect modeling was employed to evaluate the combined effects of metabolites on iRT.

RESULTS

We initially discovered the gut microbiota-associated metabolite, methylglyoxal (MG), which accurately predicts the response to preRT (Area Under Curve (AUC) value of 0.856) among patients with LARC. Subsequently, we observed that MG amplifies the RT response in RC by stimulating intracellular reactive oxygen species (ROS) and reducing hypoxia in the tumor in vitro and in vivo. Additionally, our study demonstrated that MG amplifies the RT-induced activation of the cyclic guanosine monophosphate AMP synthase-stimulator of interferon genes pathway by elevating DNA double-strand breaks. Moreover, it facilitates immunogenic cell death generated by ROS-mediated endoplasmic reticulum stress, consequently leading to an increase in CD8+ T and natural killer cells infiltrated in the tumor immune microenvironment. Lastly, we discovered that the combination of anti-programmed cell death protein 1 (anti-PD1) therapy produced long-lasting complete responses in all irradiated tumor sites and half of the non-irradiated ones.

CONCLUSIONS

Our research indicates that MG shows promise as a radiosensitizer and immunomodulator for RC. Furthermore, we propose that combining MG with iRT has great potential for clinical practice.

Immunotherapies inducing immunogenic cell death in cancer: insight of the innate immune system

Cancer immunotherapies include monoclonal antibodies, cytokines, oncolytic viruses, cellular therapies, and other biological and synthetic immunomodulators. These are traditionally studied for their effect on the immune system's role in eliminating cancer cells. However, some of these therapies have the unique ability to directly induce cytotoxicity in cancer cells by inducing immunogenic cell death (ICD). Unlike general immune stimulation, ICD triggers specific therapy-induced cell death pathways, based on the release of damage-associated molecular patterns (DAMPs) from dying tumour cells. These activate innate pattern recognition receptors (PRRs) and subsequent adaptive immune responses, offering the promise of sustained anticancer drug efficacy and durable antitumour immune memory. Exploring how onco-immunotherapies can trigger ICD, enhances our understanding of their mechanisms and potential for combination strategies. This review explores the complexities of these immunotherapeutic approaches that induce ICD, highlighting their implications for the innate immune system, addressing challenges in cancer treatment, and emphasising the pivotal role of ICD in contemporary cancer research.

Marine natural product lepadin A as a novel inducer of immunogenic cell death via CD91-dependent pathway

Immunogenic Cell Death (ICD) represents a mechanism of enhancing T cell-driven response against tumor cells. The process is enabled by release of damage-associated molecular patterns (DAMPs) and cytokines by dying cells. Based on molecular studies and clinical marker assessment, ICD can be a new target for cancer chemotherapy hitherto restricted to a few conventional anticancer drugs. In view of the development of small molecules in targeted cancer therapy, we reported the preliminary evidence on the role of the natural product lepadin A (1) as a novel ICD inducer. Here we describe the ICD mechanism of lepadin A (1) by proving the translocation of the protein calreticulin (CRT) to the plasma membrane of human A2058 melanoma cells. CRT exposure is an ICD marker in clinical studies and was associated with the activation of the intrinsic apoptotic pathway in A2058 cells with lepadin A (1). After the treatment, the tumour cells acquired the ability to activate dendritic cells (DCs) with cytokine release and costimulatory molecule expression that is consistent with a phenotypic profile committed to priming T lymphocytes via a CD91-dependent mechanism. The effect of lepadin A (1) was dose-dependent and comparable to the response of the chemotherapy drug doxorubicin (2), a well-established ICD inducer.

Poly-γ-glutamic acid nanoparticles as adjuvant and antigen carrier system for cancer vaccination

Vaccination is an innovative strategy for cancer treatment by leveraging various components of the patients' immunity to boost an anti-tumor immune response. Rationally designed nanoparticles are well suited to maximize cancer vaccination by the inclusion of immune stimulatory adjuvants. Also, nanoparticles might control the pharmacokinetics and destination of the immune potentiating compounds. Poly-γ-glutamic acid (γ-PGA) based nanoparticles (NPs), which have a natural origin, can be easily taken up by dendritic cells (DCs), which leads to the secretion of cytokines which ameliorates the stimulation capacity of T cells. The intrinsic adjuvant properties and antigen carrier properties of γ-PGA NPs have been the focus of recent investigations as they can modulate the tumor microenvironment, can contribute to systemic anti-tumor immunity and subsequently inhibit tumor growth. This review provides a comprehensive overview on the potential of γ-PGA NPs as antigen carriers and/or adjuvants for anti-cancer vaccination.

PDT-Induced Activation Enhanced by Hormone Response to Treatment

Photodynamic therapy (PDT) is a medical treatment with the use of a photosensitizing agent (PS), which, when activated by light, results in selective tissue damage with a cytotoxic effect on tumor cells. PDT leads to the induction of an acute-phase response, which results in the involvement of adrenal glucocorticoid (GC) hormones. PDT, by activating the hormonal response, affects the treatment of cancer. GC release is observed due to adrenal activity, which is driven by changes in the hypothalamic pituitary-adrenal axis triggered by stress signals emanating from the PDT treated tumor. The hormones released in this process in the context of the PDT-induced acute-phase response perform many important functions during anticancer therapy. They lead, among other things, to the systemic mobilization of neutrophils and the production of acute-phase reagents, and also control the production of immunoregulatory proteins and proteins that modulate inflammation. GCs can radically affect the activity of various inflammatory and immune cells, including the apoptosis of cancer cells. A better understanding of the modulation of GC activity could improve the outcomes of cancer patients treated with PDT.

Harnessing Oncolytic Extracellular Vesicles for Tumor Cell-Preferential Cytoplasmic Delivery of Misfolded Proteins for Cancer Immunotherapy

In this study, extracellular vesicles (EVs) are reimagined as more than just a cellular waste disposal system and are repurposed for cancer immunotherapy. Potent oncolytic EVs (bRSVF-EVs) loaded with misfolded proteins (MPs) are engineered, which are typically considered cellular debris. By impairing lysosomal function using bafilomycin A1 and expressing the respiratory syncytial virus F protein, a viral fusogen, MPs are successfully loaded into the EVs expressing RSVF. bRSVF-EVs preferentially transplant a xenogeneic antigen onto cancer cell membranes in a nucleolin-dependent manner, triggering an innate immune response. Furthermore, bRSVF-EV-mediated direct delivery of MPs into the cancer cell cytoplasm initiates endoplasmic reticulum stress and immunogenic cell death (ICD). This mechanism of action leads to substantial antitumor immune responses in murine tumor models. Importantly, when combined with PD-1 blockade, bRSVF-EV treatment elicits robust antitumor immunity, resulting in prolonged survival and complete remission in some cases. Overall, the findings demonstrate that utilizing tumor-targeting oncolytic EVs for direct cytoplasmic delivery of MPs to induce ICD in cancer cells represents a promising approach for enhancing durable antitumor immunity.

Reactive oxygen species-responsive dual-targeted nanosystem promoted immunogenic cell death against breast cancer

The development of an optimal treatment modality to improve the therapeutic outcome of breast cancer patients is still difficult. Poor antigen presentation to T cells is a major challenge in cancer immunotherapy. In this study, a synergistic immunotherapy strategy for breast cancer incorporating immune cell infiltration, immunogenic cell death (ICD), and dendritic cell (DC) maturation through a reactive oxygen species (ROS)-responsive dual-targeted smart nanosystem (anti-PD-L1-TKNP) for the simultaneous release of DOX, R848, and MIP-3α in the tumor microenvironment is reported. Following local injection, anti-PD-L1-DOX-R848-MIP-3α/thioketal nanoparticle (TKNP) converts tumor cells to a vaccine owing to the combinatorial effect of DOX-induced ICD, R848-mediated immunostimulatory properties, and MIP-3α-induced immune cell recruitment in the tumor microenvironment. Intratumoral injection of anti-PD-L1-DOX-R848-MIP-3α/TKNP caused significant regression of breast cancer. Mechanistic studies reveal that anti-PD-L1-DOX-R848-MIP-3α/TKNP specifically targets tumor tissue, resulting in maximum exposure of calreticulin (CRT) and HMGB1 in tumors, and significantly enhances intratumoral infiltration of CD4+ and CD8+ T cells in tumors. Therefore, a combined strategy using dual-targeted ROS-responsive TKNP highlights the significant application of nanoparticles in modulating the tumor microenvironment and could be a clinical treatment strategy for effective breast cancer management.

Senescent cancer cell vaccines induce cytotoxic T cell responses targeting primary tumors and disseminated tumor cells

BACKGROUND

Immune tolerance contributes to resistance to conventional cancer therapies such as radiation. Radiotherapy induces immunogenic cell death, releasing a burst of tumor antigens, but this appears insufficient to stimulate an effective antitumor immune response. Radiation also increases infiltration of cytotoxic T lymphocytes (CTLs), but their effector function is short lived. Although CTL exhaustion may be at fault, combining immune checkpoint blockade with radiation is insufficient to restore CTL function in most patients. An alternative model is that antigen presentation is the limiting factor, suggesting a defect in dendritic cell (DC) function.

METHODS

Building on our prior work showing that cancer cells treated with radiation in the presence of the poly(ADP-ribose) polymerase-1 inhibitor veliparib undergo immunogenic senescence, we reexamined senescent cells (SnCs) as preventative or therapeutic cancer vaccines. SnCs formed in vitro were cocultured with splenocytes and evaluated by scRNA-seq to examine immunogenicity. Immature bone-marrow-derived DCs cocultured with SnCs were examined for maturation and activation by flow cytometry and T cell proliferation assays. Viable SnCs or SnC-activated DCs were injected subcutaneously, and vaccine effects were evaluated by analysis of immune response, prevention of tumor engraftment, regression of established tumors and/or potentiation of immunotherapy or radiotherapy.

RESULTS

Murine CT26 colon carcinoma or 4T1 mammary carcinoma cells treated with radiation and veliparib form SnCs that promote DC maturation and activation in vitro, leading to efficient, STING-dependent CTL priming. Injecting mice with SnCs induces antigen-specific CTLs and confers protection from tumor engraftment. Injecting immunogenic SnCs into tumor-bearing mice increases inflammation with activated CTLs, suppresses tumor growth, potentiates checkpoint blockade, enhances radiotherapy and blocks colonization by disseminated tumor cells. Addressing the concern that reinjecting tumor cells into patients may be impractical, DCs activated with SnCs in vitro were similarly effective to SnCs in suppressing established tumors and blocking metastases.

CONCLUSIONS

Therapeutic vaccines based on senescent tumor cells and/or SnC-activated DCs have the potential to improve genotoxic and immune therapies and limit recurrence or metastasis.

TiSe2-mediated sonodynamic and checkpoint blockade combined immunotherapy in hypoxic pancreatic cancer

Background

Pancreatic cancer remains among the most prevalent and aggressive forms of cancer. While immunotherapeutic treatment strategies have shown some promise in affected patients, the benefits of these interventions have been limited by insufficient tumor infiltration by activated T cells.

Results

Here, Titanium diselenide (TiSe₂) nanosheets were synthesized with good stability. When exposed to ultrasound (US), the TiSe₂ nanosheets served as a reliable nano-sensitizer capable of inducing large amounts of reactive oxygen species (ROS) mediating sonodynamic therapy (SDT) under hypoxic and normoxic conditions. The tumor-released TAAs induced by TiSe₂ nanosheet-mediated SDT promoted immunogenic cell death (ICD) conducive to the maturation of dendritic cells (DCs), and cytokine secretion and the subsequent activation and infiltration of T cells into the tumor. Combining TiSe₂-mediated SDT with anti-PD-1 immune checkpoint blockade treatment led to the efficient suppression of the growth of both primary tumor and distant tumor, while simultaneously preventing lung metastasis. These improved immunotherapeutic and anti-metastatic outcomes were associated with activated systematic antitumor immune responses, including the higher levels of DC maturation and cytokine secretion, the increased levels of CD8⁺ T cells and the decreased levels of T_reg cells infiltrated in tumors.

Conclusion

TiSe₂ can be used as a sonosensitizer with good efficacy and high safety to mediate efficient SDT. The combination treatment strategy comprised of TiSe₂-mediated SDT and PD-1 blockade activate anti-tumor immune responses effectively thorough inducing ICD, resulting in the inhibition the growth and metastasis of tumor. The combination therapy holds promise as a novel immunotherapy-based intervention strategy for pancreatic cancer patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01659-4.

Identification of circadian clock genes as regulators of immune infiltration in Hepatocellular Carcinoma

Background: Multiple studies have reported that the immune system is under the control of a circadian clock, especially in cancers, but how circadian clock genes shape tumor immune cell infiltration in hepatocellular carcinoma (HCC) remains unclear. Methods: The rhythmicity of circadian clock genes was investigated using the GETx database. The expression and methylation level of circadian clock genes in HCC and paracancerous was evaluated using the GETx and TCGA databases. The differential expression of circadian clock genes in HCC was analyzed using the "limma" package of the R 4.0.4 software. The prognosis of each circadian clock gene was accessed by Kaplan-Meier survival analysis and Cox proportional hazards regression analysis. Quantitative real-time PCR and immunohistochemistry (IHC) was carried out to confirm the results. The relationship between circadian rhythm and immune infiltration in HCC was evaluated using the TIMER database and the CIBERSORT algorithm. Results: In addition to RORA, RORB, and ARNTL2, there was a rhythmic expression of other circadian clock genes in liver tissue. The correlation between the expression of circadian clock genes differed when comparing HCC and liver tissue. HCC patients who express low levels of PER-1and CRY2 had a poor overall survival (OS). In contrast, patients with higher expression of NPAS2 had a poor prognosis. In HCC, the expression of the PER-1, CRY2, and NPAS2 genes was closely related to immune infiltration. Conclusion: Our study indicated the disruption of the expression of circadian clock-regulated genes in HCC and identified PER-1, CRY2, and NPAS2 as independent predictors of survival. These genes may be applied as candidate molecular targets for diagnosis and therapy of HCC.

Recombinant Viral Vectors for Therapeutic Programming of Tumour Microenvironment: Advantages and Limitations

Viral vectors have been widely investigated as tools for cancer immunotherapy. Although many preclinical studies demonstrate significant virus-mediated tumour inhibition in synergy with immune checkpoint molecules and other drugs, the clinical success of viral vector applications in cancer therapy currently is limited. A number of challenges have to be solved to translate promising vectors to clinics. One of the key elements of successful virus-based cancer immunotherapy is the understanding of the tumour immune state and the development of vectors to modify the immunosuppressive tumour microenvironment (TME). Tumour-associated immune cells, as the main component of TME, support tumour progression through multiple pathways inducing resistance to treatment and promoting cancer cell escape mechanisms. In this review, we consider DNA and RNA virus vectors delivering immunomodulatory genes (cytokines, chemokines, co-stimulatory molecules, antibodies, etc.) and discuss how these viruses break an immunosuppressive cell development and switch TME to an immune-responsive "hot" state. We highlight the advantages and limitations of virus vectors for targeted therapeutic programming of tumour immune cell populations and tumour stroma, and propose future steps to establish viral vectors as a standard, efficient, safe, and non-toxic cancer immunotherapy approach that can complement other promising treatment strategies, e.g., checkpoint inhibitors, CAR-T, and advanced chemotherapeutics.

Integration of miRNA:mRNA Co-Expression Revealed Crucial Mechanisms Modulated in Immunogenic Cancer Cell Death

Immunogenic cell death (ICD) in cancer represents a functionally unique therapeutic response that can induce tumor-targeting immune responses. ICD is characterized by the exposure and release of numerous damage-associated molecular patterns (DAMPs), which confer adjuvanticity to dying cancer cells. The spatiotemporally defined emission of DAMPs during ICD has been well described, whereas the epigenetic mechanisms that regulate ICD hallmarks have not yet been deeply elucidated. Here, we aimed to examine the involvement of miRNAs and their putative targets using well-established in vitro models of ICD. To this end, B cell lymphoma (Mino) and breast cancer (MDA-MB-231) cell lines were exposed to two different ICD inducers, the combination of retinoic acid (RA) and interferon-alpha (IFN-α) and doxorubicin, and to non ICD inducers such as gamma irradiation. Then, miRNA and mRNA profiles were studied by next generation sequencing. Co-expression analysis identified 16 miRNAs differentially modulated in cells undergoing ICD. Integrated miRNA-mRNA functional analysis revealed candidate miRNAs, mRNAs, and modulated pathways associated with Immune System Process (GO Term). Specifically, ICD induced a distinctive transcriptional signature hallmarked by regulation of antigen presentation, a crucial step for proper activation of immune system antitumor response. Interestingly, the major histocompatibility complex class I (MHC-I) pathway was upregulated whereas class II (MHC-II) was downregulated. Analysis of MHC-II associated transcripts and HLA-DR surface expression confirmed inhibition of this pathway by ICD on lymphoma cells. miR-4284 and miR-212-3p were the strongest miRNAs upregulated by ICD associated with this event and miR-212-3p overexpression was able to downregulate surface expression of HLA-DR. It is well known that MHC-II expression on tumor cells facilitates the recruitment of CD4+ T cells. However, the interaction between tumor MHC-II and inhibitory coreceptors on tumor-associated lymphocytes could provide an immunosuppressive signal that directly represses effector cytotoxic activity. In this context, MHC-II downregulation by ICD could enhance antitumor immunity. Overall, we found that the miRNA profile was significantly altered during ICD. Several miRNAs are predicted to be involved in the regulation of MHC-I and II pathways, whose implication in ICD is demonstrated herein for the first time, which could eventually modulate tumor recognition and attack by the immune system.

Activation of Cellular Players in Adaptive Immunity via Exogenous Delivery of Tumor Cell Lysates

Tumor cell lysates (TCLs) are a good immunogenic source of tumor-associated antigens. Since whole necrotic TCLs can enhance the maturation and antigen-presenting ability of dendritic cells (DCs), multiple strategies for the exogenous delivery of TCLs have been investigated as novel cancer immunotherapeutic solutions. The TCL-mediated induction of DC maturation and the subsequent immunological response could be improved by utilizing various material-based carriers. Enhanced antitumor immunity and cancer vaccination efficacy could be eventually achieved through the in vivo administration of TCLs. Therefore, (1) important engineering methodologies to prepare antigen-containing TCLs, (2) current therapeutic approaches using TCL-mediated DC activation, and (3) the significant sequential mechanism of DC-based signaling and stimulation in adaptive immunity are summarized in this review. More importantly, the recently reported developments in biomaterial-based exogenous TCL delivery platforms and co-delivery strategies with adjuvants for effective cancer vaccination and antitumor effects are emphasized.

Experience with Photodynamic Therapy Using Indocyanine Green Liposomes for Refractory Cancer

We reported the development of an effective cancer treatment using a multidisciplinary treatment, including photodynamic therapy (PDT) with indocyanine green (ICG) liposomes and a combination of Lentinula edodes mycelia (LEM) and hydrogen gas inhalation therapy. ICG liposomes were prepared by adding 5 mg of ICG to 50 mL liposomes. Later, 25 mL of ICG liposomes were diluted with 250 mL of 5% glucose solution and administered intravenously to the patient. We selected the multi-laser delivery system (MLDS), a laser irradiator for performing PDT. Further, the patients received a combination of LEM and hydrogen gas inhalation therapy throughout the treatment. We reported two cases of PDT therapy, one with middle intrathoracic esophagus carcinoma and the other with hypopharyngeal cancer. In the first case, the MLDS laser was directly attached to the endoscope and directed to the cancer area with wavelengths of 810 nm. After the treatment, a biopsy demonstrated no tumor recurrence. In the second case, the patient was treated with endovascular PDT using ICG liposomes and MLDS fiber optics. Later, tumor shrinkage was demonstrated after the first round and disappeared after six months. In conclusion, the present findings suggest that the effect of PDT using ICG liposomes with LEM and hydrogen gas may eradicate cancer without burdening patients by enhancing tumor immunity.

Huaier Induces Immunogenic Cell Death Via CircCLASP1/PKR/eIF2α Signaling Pathway in Triple Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most lethal breast cancer subtype owing to the lack of targeted therapeutic strategies. Immunogenic cell death (ICD), a modality of regulated cancer cell death, offered a novel option for TNBC via augmenting tumor immunogenic microenvironment. However, few ICD-inducing agents are currently available. Here, we showed that Trametes robiniophila Murr (Huaier) triggered ICD in TNBC cells by promoting cell surface calreticulin (CRT) exposure, and increasing release of adenosine triphosphate (ATP) and high-mobility group protein B1 (HMGB1). Co-culturing with Huaier-treated TNBC cells efficiently enhanced the maturation of dendritic cells (DCs), which was further validated via cell-based vaccination assay. In the xenograft mouse model, oral administration of Huaier led to tumor-infiltrating lymphocytes (TILs) accumulation and significantly delayed tumor growth. Besides, depletion of endogenous T cells obviously abrogated the effect. Mechanically, Huaier could elicit endoplasmic reticulum (ER) stress-associated ICD through eIF2α signaling pathway. Further studies revealed that circCLASP1 was involved in the Huaier-induced immunogenicity by binding with PKR in the cytoplasm and thus blocking its degradation. Taken together, we highlighted an essential role of circCLASP1/PKR/eIF2α axis in Huaier-induced ICD. The findings of our study carried significant translational potential that Huaier might serve as a promising option to achieve long-term tumor remission in patients with TNBC.

Dual-functional alginate and collagen–based injectable hydrogel for the treatment of cancer and its metastasis

Background

Immunotherapies have been gaining attention for the prevention of cancer recurrence and metastasis. Cancer immunotherapy can induce memory cells to target cancer-specific antigens and, thus, selectively kill cancer cells. However, there are difficulties in inducing cancer antigen–specific immunity due to limited knowledge regarding cancer antigens. In this study, we synthesized a dual-functional hydrogel to induce antigen generation and immune activation.

Results

To elicit a cancer self-antigen–specific immune response, we synthesized an alginate-collagen–based injectable hydrogel, called thermally responsive hydrogel (pTRG), which was incorporated with indocyanine green and the immune stimulator polyinosinic:polycytidylic acid (poly I:C). pTRG was evaluated for its anticancer and anti-metastatic effects against CT-26 carcinoma and 4T1 breast tumor in mice by combining photothermal therapy (PTT) and immunotherapy. Near-infrared (NIR) irradiation promoted temperature elevation in pTRG, consequently exerting a therapeutic effect on mouse tumors. Lung metastasis was prevented in cured CT-26 tumor-injected mice following pTRG treatment via cancer antigen–specific T cell immunity. Moreover, pTRG successfully eliminated the original tumor in 4T1 tumor-bearing mice via PTT and protected them from lung metastasis. To further evaluate the carrier function of TRGs, different types of immunotherapeutic molecules were incorporated into TRGs, which led to the effective elimination of the first CT-26 tumor and the prevention of lung metastasis.

Conclusions

Our data demonstrate that TRG is a efficient material not only for treating primary tumors but also for preventing metastasis and recurrence.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01458-x.

Conventional amphotericin B elicits markers of immunogenic cell death on leukemic blasts, mediates immunostimulatory effects on phagocytic cells, and synergizes with PD-L1 blockade

Immunostimulatory regimens are a game changer in the fight against cancer, but still only a minority of patients achieve clinical benefit. Combination with immunomodulatory drugs and agents converting otherwise non-immunogenic forms of cell death into bona fide “immunogenic cell death” (ICD) could improve the efficacy of these novel therapies. The aim of our study was to investigate conventional Amphotericin B (AmB) as an enhancer of antitumor immune responses. In tumor cell line models, AmB induced ICD with its typical hallmarks of calreticulin (CALR) expression and release of high mobility group box 1 (HMGB1) as well as Adenosine 5’-triphosphate (ATP). Interestingly, in contrast to non-ICD inducing treatments, ICD induction led to up-regulation of PD-L1-expression by ICD experiencing cells, resulting in decreased maturation of dendritic cells (DCs). Blocking this PD-L1 expression on tumor cells could unleash full ICD effects on antigen presenting cells. Even at sub-toxic concentrations, AmB was able to enhance CALR on leukemic blasts, particularly on phagocytic monoblastic THP-1 cells, which also showed features of “M1-like” differentiation after AmB exposure. The ability of AmB to increase the immunogenicity of tumor cells was confirmed in vivo in a mouse vaccination experiment. In conclusion, we demonstrate that AmB can promote antitumor immune responses in a dose-dependent manner by ICD induction, surface translocation of CALR on leukemic blasts even at sub-toxic concentrations, and “M1-like” polarization of phagocytic cells, making it noteworthy as potential booster for cancer immunotherapy. We additionally report for the first time that PD-L1 expression may be a feature of ICD, possibly as a negative feedback mechanism regulating the maturation status of DCs and thus indirectly affecting T-cell priming.

Combination therapy for mCRPC with immune checkpoint inhibitors, ADT and vaccine: A mathematical model

Metastatic castration resistant prostate cancer (mCRPC) is commonly treated by androgen deprivation therapy (ADT) in combination with chemotherapy. Immune therapy by checkpoint inhibitors, has become a powerful new tool in the treatment of melanoma and lung cancer, and it is currently being used in clinical trials in other cancers, including mCRPC. However, so far, clinical trials with PD-1 and CTLA-4 inhibitors have been disappointing. In the present paper we develop a mathematical model to assess the efficacy of any combination of ADT with cancer vaccine, PD-1 inhibitor, and CTLA-4 inhibitor. The model is represented by a system of partial differential equations (PDEs) for cells, cytokines and drugs whose density/concentration evolves in time within the tumor. Efficacy of treatment is determined by the reduction in tumor volume at the endpoint of treatment. In mice experiments with ADT and various combinations of PD-1 and CTLA-4 inhibitors, tumor volume at day 30 was always larger than the initial tumor. Our model, however, shows that we can decrease tumor volume with large enough dose; for example, with 10 fold increase in the dose of anti-PD-1, initial tumor volume will decrease by 60%. Although the treatment with ADT in combination with PD-1 inhibitor or CTLA-4 inhibitor has been disappointing in clinical trials, our simulations suggest that, disregarding negative effects, combinations of ADT with checkpoint inhibitors can be effective in reducing tumor volume if larger doses are used. This points to the need for determining the optimal combination and amounts of dose for individual patients.

Cancer vaccines as a targeted immunotherapy approach for breast cancer: an update of clinical evidence

INTRODUCTION

Breast cancer (BC) is the first common neoplastic malignancy and the second leading cause of death in women worldwide. Conventional treatments for BC are often associated with severe side effects and may even lead to late recurrence. For this reason, in recent years, cancer immunotherapy (e.g., cancer vaccines), a novel approach based on the specificity and amplification of acquired immune responses, has been considered as a potential candidate in particular to treat metastatic BC.

AREAS COVERED

In this review, we summarize and discuss the recent development of therapeutic vaccines for BC, use of specific BC cellular antigens, antigen selection, and probable causes for their insufficient effectiveness.

EXPERT OPINION

Despite development of several different BC vaccines strategies including protein/peptide, dendritic cell, and genetic vaccines, until now, no BC vaccine has been approved for clinical use. Most of the current BC vaccines themselves fail to bring clinical benefit to BC patients and are applied in combination with radiotherapy, chemotherapy, or targeted therapy. It is hoped that with advances in our knowledge about tumor microenvironment and the development of novel combination strategies, the tumor immunosuppressive mechanisms can be overcome and prolonged immunologic and effective anti-tumor response can be developed in patients.

Modulation of the immune response by heterogeneous monocytes and dendritic cells in lung cancer

Different subpopulations of monocytes and dendritic cells (DCs) may have a key impact on the modulation of the immune response in malignancy. In this review, we summarize the monocyte and DCs heterogeneity and their function in the context of modulating the immune response in cancer. Subgroups of monocytes may play opposing roles in cancer, depending on the tumour growth and progression as well as the type of cancer. Monocytes can have pro-tumour and anti-tumour functions and can also differentiate into monocyte-derived DCs (moDCs). MoDCs have a similar antigen presentation ability as classical DCs, including cross-priming, a process by which DCs activate CD8 T-cells by cross-presenting exogenous antigens. DCs play a critical role in generating anti-tumour CD8 T-cell immunity. DCs have plastic characteristics and show distinct phenotypes depending on their mature state and depending on the influence of the tumour microenvironment. MoDCs and other DC subsets have been attracting increased interest owing to their possible beneficial effects in cancer immunotherapy. This review also highlights key strategies deploying specific DC subpopulations in combination with other therapies to enhance the anti-tumour response and summarizes the latest ongoing and completed clinical trials using DCs in lung cancer.

Enhancing Cancer Immunotherapeutic Efficacy with Sonotheranostic Strategies

Immunotherapy has revolutionized the modality for establishing a firm immune response and immunological memory. However, intrinsic limitations of conventional low responsive poor T cell infiltration and immune related adverse effects urge the coupling of cancer nanomedicines with immunotherapy for boosting antitumor response under ultrasound (US) sensitization to mimic dose-limiting toxicities for safe and effective therapy against advanced cancer. US is composed of high-frequency sound waves that mediate targeted spatiotemporal control over release and internalization of the drug. The unconventional US triggered immunogenic nanoengineered arena assists the limited immunogenic dose, limiting toxicities and efficacies. In this Review, we discuss current prospects of enhanced immunotherapy using nanomedicine under US. We highlight how nanotechnology designs and incorporates nanomedicines for the reprogramming of systematic immunity in the tumor microenvironment. We also emphasize the mechanical and biological potential of US, encompassing sonosensitizer activation for enhanced immunotherapeutic efficacies. Finally, the smartly converging combinational platform of US stimulated cancer nanomedicines for amending immunotherapy is summarized. This Review will widen scientists' ability to explore and understand the limiting factors for combating cancer in a precisely customized way.

Metallic Nanoparticle-Mediated Immune Cell Regulation and Advanced Cancer Immunotherapy

Cancer immunotherapy strategies leveraging the body's own immune system against cancer cells have gained significant attention due to their remarkable therapeutic efficacy. Several immune therapies have been approved for clinical use while expanding the modalities of cancer therapy. However, they are still not effective in a broad range of cancer patients because of the typical immunosuppressive microenvironment and limited antitumor immunity achieved with the current treatment. Novel approaches, such as nanoparticle-mediated cancer immunotherapies, are being developed to overcome these challenges. Various types of nanoparticles, including liposomal, polymeric, and metallic nanoparticles, are reported for the development of effective cancer therapeutics. Metallic nanoparticles (MNPs) are one of the promising candidates for anticancer therapy due to their unique theranostic properties and are thus explored as both imaging and therapeutic agents. In addition, MNPs offer a dense surface functionalization to target tumor tissue and deliver genetic, therapeutic, and immunomodulatory agents. Furthermore, MNPs interact with the tumor microenvironment (TME) and regulate the levels of tumor hypoxia, glutathione (GSH), and reactive oxygen species (ROS) for remodulation of TME for successful therapy. In this review, we discuss the role of nanoparticles in tumor microenvironment modulation and anticancer therapy. In particular, we evaluated the response of MNP-mediated immune cells, such as dendritic cells, macrophages, T cells and NK cells, against tumor cells and analyzed the role of MNP-based cancer therapies in regulating the immunosuppressive environment.

Chemotherapeutic drug-induced immunogenic cell death for nanomedicine-based cancer chemo-immunotherapy

Chemotherapy has been a conventional paradigm for cancer treatment, and multifarious chemotherapeutic drugs have been widely employed for decades with significant performances in suppressing tumors. Moreover, some of the antitumor chemotherapeutic agents, such as doxorubicin (DOX), oxaliplatin (OXA), cyclophosphamide (CPA) and paclitaxel (PTX), can also tackle tumors through the induction of immunogenic cell death (ICD) in tumor cells to trigger specific antitumor immune responses of the body and improve chemotherapy efficacy. In recent years, chemo-immunotherapy has attracted increasing attention as one of the most promising combination therapies to struggle with malignant tumors. Many effective antitumor therapies have benefited from the successful induction of ICD in tumors, which could incur the release of endogenous danger signals and tumor-associated antigens (TAAs), further stimulating antigen-presenting cells (APCs) and ultimately initiating efficient antitumor immunity. In this review, several well-characterized damage-associated molecular patterns (DAMPs) were introduced and the progress of ICD induced by representative chemotherapeutic drugs for nanomedicine-based chemo-immunotherapy was highlighted. In addition, the combination strategies involving ICD cooperated with other therapies were discussed. Finally, we shared some perspectives in chemotherapeutic drug-induced ICD for future chemo-immunotherapy. It was hoped that this review would provide worthwhile presentations and enlightenments for cancer chemo-immunotherapy.

Immunogenic Cell Death and Immunomodulatory Effects of Cabozantinib

Cabozantinib (XL-184) is a multitarget tyrosine kinase inhibitor (TKI) targeting receptor tyrosine kinases (RTKs) involved in oncogenesis and angiogenesis. It is currently the standard therapy for medullary thyroid cancer (MTC), metastatic renal cell carcinoma (mRCC), and hepatocellular carcinoma (HCC). Combination of Cabozantinib with immunotherapy is now a standard treatment in metastatic renal cancer, and its efficacy is being tested in ongoing clinical trial in prostate cancer patients. Here, we report that Cabozantinib may exert an immunostimulatory role by inducing immunogenic stress of prostate cancer cells and directly modulating dendritic cells (DCs). Cabozantinib treatment arrested the cell cycle and triggered immunogenic cell death (ICD) in prostate cancer cells in vitro. Cabozantinib had a direct effect on DCs by the down-modulation of β-catenin and change in migratory and costimulatory phenotype of the DCs. These results may suggest possible immunomodulatory effects induced by Cabozantinib that could be exploited to optimize patient-tailored immunotherapeutic treatments.

Abscopal Effect and Drug-Induced Xenogenization: A Strategic Alliance in Cancer Treatment?

The current state of cancer treatment is still far from being satisfactory considering the strong impairment of patients' quality of life and the high lethality of malignant diseases. Therefore, it is critical for innovative approaches to be tested in the near future. In view of the crucial role that is played by tumor immunity, the present review provides essential information on the immune-mediated effects potentially generated by the interplay between ionizing radiation and cytotoxic antitumor agents when interacting with target malignant cells. Therefore, the radiation-dependent abscopal effect (i.e., a biological effect of ionizing radiation that occurs outside the irradiated field), the influence of cancer chemotherapy on the antigenic pattern of target neoplastic cells, and the immunogenic cell death (ICD) caused by anticancer agents are the main topics of this presentation. It is widely accepted that tumor immunity plays a fundamental role in generating an abscopal effect and that anticancer drugs can profoundly influence not only the host immune responses, but also the immunogenic pattern of malignant cells. Remarkably, several anticancer drugs impact both the abscopal effect and ICD. In addition, certain classes of anticancer agents are able to amplify already expressed tumor-associated antigens (TAA). More importantly, other drugs, especially triazenes, induce the appearance of new tumor neoantigens (TNA), a phenomenon that we termed drug-induced xenogenization (DIX). The adoption of the abscopal effect is proposed as a potential therapeutic modality when properly applied concomitantly with drug-induced increase in tumor cell immunogenicity and ICD. Although little to no preclinical or clinical studies are presently available on this subject, we discuss this issue in terms of potential mechanisms and therapeutic benefits. Upcoming investigations are aimed at evaluating how chemical anticancer drugs, radiation, and immunotherapies are interacting and cooperate in evoking the abscopal effect, tumor xenogenization and ICD, paving the way for new and possibly successful approaches in cancer therapy.

Sequentially pH-Responsive Drug-Delivery Nanosystem for Tumor Immunogenic Cell Death and Cooperating with Immune Checkpoint Blockade for Efficient Cancer Chemoimmunotherapy

Chemoimmunotherapy has anchored a new blueprint for cancer management. As a burgeoning approach, immunotherapy has shifted the paradigm of traditional chemotherapy and opened up new prospects for cancer treatment. Here, a sequentially pH-responsive doxorubicin (DOX) delivery nanosystem is designed for simultaneous chemotherapy and tumor immunogenic cell death (ICD). DOX is modified into pH-sensitive cis-aconityl-doxorubicin (CAD) for being easily adsorbed by polycationic polyethylenimine (PEI), and the PEI/CAD complexes are in situ-shielded by aldehyde-modified polyethylene glycol (PEG). The PEG/PEI/CAD nanoparticles (NPs) can keep stable in neutral physiological pH during systemic circulation but will detach PEG shielding once in slightly acidic tumor extracellular pH. The exposed positive PEI/CAD complexes are endocytosed effortlessly, and CAD is then converted back to DOX by endosomal-acidity-triggered cis-aconityl cleavage. The released DOX further elicits ICD, and the moribund tumor cells will release antigens and damage-associated molecular patterns to recruit dendritic cells and activate antitumor immunity. An excellent therapeutic effect is achieved when the immune checkpoint PD-1 antibody (aPD-1) is utilized to cooperate with the PEG/PEI/CAD NPs for blocking tumor immune escape and maintaining antitumor activity of the ICD-instigated T cells. The sequentially pH-responsive DOX delivery nanosystem cooperating with immune checkpoint blockade will provide a potential strategy for cancer chemoimmunotherapy.

Application of Immunotherapy in Hepatocellular Carcinoma

Hepatocellular carcinoma is one of the most common malignancies globally. It not only has a hidden onset but also progresses rapidly. Most HCC patients are already in the advanced stage of cancer when they are diagnosed, and have even lost the opportunity for surgical treatment. As an inflammation-related tumor, the immunosuppressive microenvironment of HCC can promote immune tolerance through a variety of mechanisms. Immunotherapy can activate tumor-specific immune responses, which brings a new hope for the treatment of HCC. At the present time, main immunotherapy strategies of HCC include immune checkpoint inhibitors, tumor vaccines, adoptive cell therapy, and so on. This article reviews the application and research progress of immune checkpoint inhibitors, tumor vaccines, and adoptive cell therapy in the treatment of HCC.

Recent progress in stimuli-responsive nanosystems for inducing immunogenic cell death

Low immunogenicity and immunosuppressive tumor microenvironments are major hurdles in the application of cancer immunotherapy. To date, several immunogenic cell death (ICD) inducers have been reported to boost cancer immunotherapy by triggering ICD. ICD is characterized by the release of proinflammatory cytokines, danger-associated molecular patterns (DAMPs) and tumor associated antigens which will generate anticancer immunity by triggering adaptive immune cells. However, application of ICD inducers is limited due to severe toxicity issues and inefficient localization in the tumor microenvironment. To circumvent these challenges, stimuli-responsive nanoparticles have been exploited for improving cancer immunotherapy by limiting its toxicity. The combination of stimuli-responsive nanoparticles with an ICD inducer serves as a promising strategy for increasing the clinical applications of ICD induction in cancer immunotherapy. Here, we outline recent advances in ICD mediated by stimuli-responsive nanoparticles that may be near-infrared (NIR)-responsive, pH-responsive, redox responsive, pH and enzyme responsive, or pH and redox responsive, and evaluate their significant potential for successful clinical translation in cancer immunotherapy.

Impact of Tenascin-C on Radiotherapy in a Novel Syngeneic Oral Squamous Cell Carcinoma Model With Spontaneous Dissemination to the Lymph Nodes

Radiotherapy, the most frequent treatment of oral squamous cell carcinomas (OSCC) besides surgery is employed to kill tumor cells but, radiotherapy may also promote tumor relapse where the immune-suppressive tumor microenvironment (TME) could be instrumental. We established a novel syngeneic grafting model from a carcinogen-induced tongue tumor, OSCC13, to address the impact of radiotherapy on OSCC. This model revealed similarities with human OSCC, recapitulating carcinogen-induced mutations found in smoking associated human tongue tumors, abundant tumor infiltrating leukocytes (TIL) and, spontaneous tumor cell dissemination to the local lymph nodes. Cultured OSCC13 cells and OSCC13-derived tongue tumors were sensitive to irradiation. At the chosen dose of 2 Gy mimicking treatment of human OSCC patients not all tumor cells were killed allowing to investigate effects on the TME. By investigating expression of the extracellular matrix molecule tenascin-C (TNC), an indicator of an immune suppressive TME, we observed high local TNC expression and TIL infiltration in the irradiated tumors. In a TNC knockout host the TME appeared less immune suppressive with a tendency towards more tumor regression than in WT conditions. Altogether, our novel syngeneic tongue OSCC grafting model, sharing important features with the human OSCC disease could be relevant for future anti-cancer targeting of OSCC by radiotherapy and other therapeutic approaches.

Recent Advances and Future Perspective of DC-Based Therapy in NSCLC

Current treatment for patients with non-small-cell lung cancer (NSCLC) is suboptimal since therapy is only effective in a minority of patients and does not always induce a long-lasting response. This highlights the importance of exploring new treatment options. The clinical success of immunotherapy relies on the ability of the immune system to mount an adequate anti-tumor response. The activation of cytotoxic T cells, the effector immune cells responsible for tumor cell killing, is of paramount importance for the immunotherapy success. These cytotoxic T cells are primarily instructed by dendritic cells (DCs). DCs are the most potent antigen-presenting cells (APCs) and are capable of orchestrating a strong anti-cancer immune response. DC function is often suppressed in NSCLC. Therefore, resurrection of DC function is an interesting approach to enhance anti-cancer immune response. Recent data from DC-based treatment studies has given rise to the impression that DC-based treatment cannot induce clinical benefit in NSCLC by itself. However, these are all early-phase studies that were mainly designed to study safety and were not powered to study clinical benefit. The fact that these studies do show that DC-based therapies were well-tolerated and could induce the desired immune responses, indicates that DC-based therapy is still a promising option. Especially combination with other treatment modalities might enhance immunological response and clinical outcome. In this review, we will identify the possibilities from current DC-based treatment trials that could open up new venues to improve future treatment.

Significant difference in response of malignant tumor cells of individual patients to photodynamic treatment as revealed by digital holographic microscopy

The investigation of in-vitro response of cell cultures derived from tumor material of individual patients with similar tumor localizations to photodynamic treatment is presented. Tumor types included in the research were renal cell carcinoma, melanoma and alveolar, synovial, lypo- and osteo- sarcomas. Long-term observations of treatment-induced morphological changes in cells were performed by means of digital holographic microscopy. A substantial variance in response of cells of individual patients with similar tumor types and localizations to photodynamic treatment with the same dose has been observed. These peculiarities are indicative of the demand to personalized protocols of photodynamic treatment. The elevated resistance of cells of some patients to treatment at high doses highlights potential limitations of photodynamic therapy for some patients. Digital holographic microscopy is shown to be an informative label-free noninvasive tool allowing for long-term monitoring of cell samples in vitro and providing quantitative information on necrosis rate and loss of cellular dry mass. The developed methodology can be generalized for analysis of cellular response to various therapies.

Damage-Associated Molecular Patterns Modulation by microRNA: Relevance on Immunogenic Cell Death and Cancer Treatment Outcome

Simple Summary

Inside the cell, damage-associated molecular pattern molecules (DAMPs) play several physiological functions, but when they are released or translocated to the extracellular space, they gain additional immunogenic roles. Thus, DAMPs are considered key hallmarks of immunogenic cell death (ICD) in cancer, a functionally unique regulated form of stress-mediated cell death that activates the immune system response against tumor cells. Several epigenetic modulators of DAMPs have been reported. In this review, we aimed to provide an overview of the effects of microRNAs (miRNAs) on the expression of DAMPs and the putative link between miRNA, DAMPs, and cell death, focused on ICD. Overall, we propose that miRNAs, by targeting DAMPs, play critical roles in the regulation of both cell death and immune-associated mechanisms in cancer, while evidence of their potential involvement in ICD is limited. Finally, we discuss emerging data regarding the impact of miRNAs’ modulation on cancer treatment outcome.

Abstract

Immunogenic cell death (ICD) in cancer is a functionally unique regulated form of stress-mediated cell death that activates both the innate and adaptive immune response against tumor cells. ICD makes dying cancer cells immunogenic by improving both antigenicity and adjuvanticity. The latter relies on the spatiotemporally coordinated release or exposure of danger signals (DAMPs) that drive robust antigen-presenting cell activation. The expression of DAMPs is often constitutive in tumor cells, but it is the initiating stressor, called ICD-inducer, which finally triggers the intracellular response that determines the kinetics and intensity of their release. However, the contribution of cell-autonomous features, such as the epigenetic background, to the development of ICD has not been addressed in sufficient depth. In this context, it has been revealed that several microRNAs (miRNAs), besides acting as tumor promoters or suppressors, can control the ICD-associated exposure of some DAMPs and their basal expression in cancer. Here, we provide a general overview of the dysregulation of cancer-associated miRNAs whose targets are DAMPs, through which new molecular mediators that underlie the immunogenicity of ICD were identified. The current status of miRNA-targeted therapeutics combined with ICD inducers is discussed. A solid comprehension of these processes will provide a framework to evaluate miRNA targets for cancer immunotherapy.

NLRP3 inflammasomes that induce antitumor immunity

Inflammasomes have emerged as context-dependent regulators of inflammation and protective immunity in vertebrates. Depending on the cell type and stimulus, inflammasome activities lead to interleukin (IL)-1 release from living (hyperactive) or dead (pyroptotic) cells. Herein, we review the mechanisms by which inflammasomes can impact CD8⁺ T cell-mediated antitumor immunity. We describe recent work demonstrating the differential impact of pyroptosis in cancer cells and dendritic cells (DCs) on antitumor immunity. We further highlight the surprising ability of inflammasomes within hyperactive DCs to facilitate the use of tumor lysates as immunogens, promoting CD8⁺ T cell-mediated antitumor responses. These context-dependent roles of inflammasomes in living and dead cells offer much opportunity for future research and should inform discussions of next-generation immunotherapy development.

ROS Cocktails as an Adjuvant for Personalized Antitumor Vaccination?

Cancer is the second leading cause of death worldwide. Today, the critical role of the immune system in tumor control is undisputed. Checkpoint antibody immunotherapy augments existing antitumor T cell activity with durable clinical responses in many tumor entities. Despite the presence of tumor-associated antigens and neoantigens, many patients have an insufficient repertoires of antitumor T cells. Autologous tumor vaccinations aim at alleviating this defect, but clinical success is modest. Loading tumor material into autologous dendritic cells followed by their laboratory expansion and therapeutic vaccination is promising, both conceptually and clinically. However, this process is laborious, time-consuming, costly, and hence less likely to solve the global cancer crisis. Therefore, it is proposed to re-focus on personalized anticancer vaccinations to enhance the immunogenicity of autologous therapeutic tumor vaccines. Recent work re-established the idea of using the alarming agents of the immune system, oxidative modifications, as an intrinsic adjuvant to broaden the antitumor T cell receptor repertoire in cancer patients. The key novelty is the use of gas plasma, a multi-reactive oxygen and nitrogen species-generating technology, for diversifying oxidative protein modifications in a, so far, unparalleled manner. This significant innovation has been successfully used in proof-of-concept studies and awaits broader recognition and implementation to explore its chances and limitations of providing affordable personalized anticancer vaccines in the future. Such multidisciplinary advance is timely, as the current COVID-19 crisis is inexorably reflecting the utmost importance of innovative and effective vaccinations in modern times.

Current Prospects for Treatment of Solid Tumors via Photodynamic, Photothermal, or Ionizing Radiation Therapies Combined with Immune Checkpoint Inhibition (A Review)

Photodynamic therapy (PDT) causes selective damage to tumor cells and vasculature and also triggers an anti-tumor immune response. The latter fact has prompted the exploration of PDT as an immune-stimulatory adjuvant. PDT is not the only cancer treatment that relies on electromagnetic energy to destroy cancer tissue. Ionizing radiation therapy (RT) and photothermal therapy (PTT) are two other treatment modalities that employ photons (with wavelengths either shorter or longer than PDT, respectively) and also cause tissue damage and immunomodulation. Research on the three modalities has occurred in different “silos”, with minimal interaction between the three topics. This is happening at a time when immune checkpoint inhibition (ICI), another focus of intense research and clinical development, has opened exciting possibilities for combining PDT, PTT, or RT with ICI to achieve improved therapeutic benefits. In this review, we surveyed the literature for studies that describe changes in anti-tumor immunity following the administration of PDT, PTT, and RT, including efforts to combine each modality with ICI. This information, collected all in one place, may make it easier to recognize similarities and differences and help to identify new mechanistic hypotheses toward the goal of achieving optimized combinations and tumor cures.

Circadian clock: a regulator of the immunity in cancer

The circadian clock is an endogenous timekeeper system that controls and optimizes biological processes, which are consistent with a master circadian clock and peripheral clocks and are controlled by various genes. Notably, the disruption of circadian clock genes has been identified to affect a wide range of ailments, including cancers. The cancer-immunity cycle is composed of seven major steps, namely cancer cell antigen release and presentation, priming and activation of effector immunity cells, trafficking, and infiltration of immunity to tumors, and elimination of cancer cells. Existing evidence indicates that the circadian clock functions as a gate that govern many aspects of the cancer-immunity cycle. In this review, we highlight the importance of the circadian clock during tumorigenesis, and discuss the potential role of the circadian clock in the cancer-immunity cycle. A comprehensive understanding of the regulatory function of the circadian clock in the cancer-immunity cycle holds promise in developing new strategies for the treatment of cancer.

Solutions to the Drawbacks of Photothermal and Photodynamic Cancer Therapy

Phototherapy such as photothermal therapy and photodynamic therapy in cancer treatment has been developed quickly over the past few years for its noninvasive nature and high efficiency. However, there are still many drawbacks in phototherapy that prevent it from clinical applications. Thus, scientists have designed different systems to overcome the issues associated with phototherapy, including enhancing the targeting ability of phototherapy, low-temperature photothermal therapy, replacing near-infrared light with other excitation sources, and so on. This article discusses the problems and shortcomings encountered in the development of phototherapy and highlights possible solutions to address them so that phototherapy may become a useful cancer treatment approach in clinical practice. This article aims to give a brief summary about current research advancements in phototherapy research and provides a quick guideline toward future developments in the field.

Pingyangmycin enhances the antitumor efficacy of anti-PD-1 therapy associated with tumor-infiltrating CD8+ T cell augmentation

PURPOSE

To investigate the antitumor efficacy of pingyangmycin (PYM) in combination with anti-PD-1 antibody and determine the capability of PYM to induce immunogenic cell death (ICD) in cancer cells.

METHODS

The murine 4T1 breast cancer and B16 melanoma models were used for evaluation of therapeutic efficacy of the combination of PYM with anti-PD-1 antibody. The ELISA kits were used to quantify the ICD related ATP and HMGB1 levels. The Transwell assay was conducted to determine the chemotaxis ability of THP-1 cell in vitro. The flow cytometry was used to measure reactive oxygen species level and analyze the ratio of immune cell subsets.

RESULTS

PYM induced ICD in murine 4T1 breast cancer and B16 melanoma cells and increased the release of nucleic acid fragments that may further promote the monocytic chemotaxis. In the 4T1 murine breast cancer model, PYM alone, anti-PD-1 antibody alone, and their combination suppressed tumor growth by 66.3%, 16.1% and 77.6%, respectively. PYM markedly enhanced the therapeutic efficacy of anti-PD-1 antibody against 4T1 breast cancer. The calculated CDI (coefficient of drug interaction) indicated synergistic effect. Evaluated by graphic analysis, the nucleated cells intensity in the femur bone marrow remained unchanged. Histopathological observations revealed no noticeable toxico-pathological changes in the lung and various organs, indicating that the PYM and anti-PD-1 antibody combination exerted enhanced efficacy at well-tolerated dosage level. By the combination treatment, a panel of immunological changes emerged. The ratio of CD3⁺ cells, NK cells and NKT cells increased and Tregs decreased in peripheral blood. The DCs increased in the spleen. Prominent changes occurred in tumor infiltrating lymphocytes. The ratio of CD8⁺ cells increased, while that of CD4⁺ cells decreased; however, the ratio of CD3⁺ cells remained unchanged, implying that certain immunological responses emerged in the tumor microenvironment. PYM alone could also increase CD8⁺ cells and reduce CD4⁺ cells in tumor infiltrating lymphocytes.

CONCLUSIONS

The studies indicate that PYM, as an ICD inducer with mild myelosuppression effect, may enhance the therapeutic efficacy of anti-PD-1 antibody in association with tumor infiltrating CD8⁺ T cell augmentation.