Restoration of the immunogenicity of cisplatin-induced cancer cell death by endoplasmic reticulum stress. Oncogene. 2011;30:1147-1158. [PMID: 21151176 DOI: 10.1038/onc.2010.500]

Targeting immunogenic cell death in cancer

Immunogenic cell death (ICD) is a type of cancer cell death triggered by certain chemotherapeutic drugs, oncolytic viruses, physicochemical therapies, photodynamic therapy, and radiotherapy. It involves the activation of the immune system against cancer in immunocompetent hosts. ICD comprises the release of damage-associated molecular patterns (DAMPs) from dying tumor cells that result in the activation of tumor-specific immune responses, thus eliciting long-term efficacy of anticancer drugs by combining direct cancer cell killing and antitumor immunity. Remarkably, subcutaneous injection of dying tumor cells undergoing ICD has been shown to provoke anticancer vaccine effects in vivo. DAMPs include the cell surface exposure of calreticulin (CRT) and heat-shock proteins (HSP70 and HSP90), extracellular release of adenosine triphosphate (ATP), high-mobility group box-1 (HMGB1), type I IFNs and members of the IL-1 cytokine family. In this review, we discuss the cell death modalities connected to ICD, the DAMPs exposed during ICD, and the mechanism by which they activate the immune system. Finally, we discuss the therapeutic potential and challenges of harnessing ICD in cancer immunotherapy.

Isobacachalcone induces autophagy and improves the outcome of immunogenic chemotherapy

A number of natural plant products have a long-standing history in both traditional and modern medical applications. Some secondary metabolites induce autophagy and mediate autophagy-dependent healthspan- and lifespan-extending effects in suitable mouse models. Here, we identified isobacachalcone (ISO) as a non-toxic inducer of autophagic flux that acts on human and mouse cells in vitro, as well as mouse organs in vivo. Mechanistically, ISO inhibits AKT as well as, downstream of AKT, the mechanistic target of rapamycin complex 1 (mTORC1), coupled to the activation of the pro-autophagic transcription factors EB (TFEB) and E3 (TFE3). Cells equipped with a constitutively active AKT mutant failed to activate autophagy. ISO also stimulated the AKT-repressible activation of all three arms of the unfolded stress response (UPR), including the PERK-dependent phosphorylation of eukaryotic initiation factor 2α (eIF2α). Knockout of TFEB and/or TFE3 blunted the UPR, while knockout of PERK or replacement of eIF2α by a non-phosphorylable mutant reduced TFEB/TFE3 activation and autophagy induced by ISO. This points to crosstalk between the UPR and autophagy. Of note, the administration of ISO to mice improved the efficacy of immunogenic anticancer chemotherapy. This effect relied on an improved T lymphocyte-dependent anticancer immune response and was lost upon constitutive AKT activation in, or deletion of the essential autophagy gene Atg5 from, the malignant cells. In conclusion, ISO is a bioavailable autophagy inducer that warrants further preclinical characterization.

Targeting stress granules: A novel therapeutic strategy for human diseases

Stress granules (SGs) are assemblies of mRNA and proteins that form from mRNAs stalled in translation initiation in response to stress. Chronic stress might even induce formation of cytotoxic pathological SGs. SGs participate in various biological functions including response to apoptosis, inflammation, immune modulation, and signalling pathways; moreover, SGs are involved in pathogenesis of neurodegenerative diseases, viral infection, aging, cancers and many other diseases. Emerging evidence has shown that small molecules can affect SG dynamics, including assembly, disassembly, maintenance and clearance. Thus, targeting SGs is a potential therapeutic strategy for the treatment of human diseases and the promotion of health. The established methods for detecting SGs provided ready tools for large-scale screening of agents that alter the dynamics of SGs. Here, we describe the effects of small molecules on SG assembly, disassembly, and their roles in the disease. Moreover, we provide perspective for the possible application of small molecules targeting SGs in the treatment of human diseases.

Role of Chikungunya nsP3 in Regulating G3BP1 Activity, Stress Granule Formation and Drug Efficacy

BACKGROUND

Ras-GTPase activating protein SH3-domain-binding proteins (G3BP) are a small family of RNA-binding proteins implicated in regulating gene expression. Changes in expression of G3BPs are correlated to several cancers including thyroid, colon, pancreatic and breast cancer. G3BPs are important regulators of stress granule (SG) formation and function. SG are ribonucleoprotein (RNP) particles that respond to cellular stresses to triage mRNA resulting in transcripts being selectively degraded, stored or translated resulting in a change of gene expression which confers a survival response to the cell. These changes in gene expression contribute to the development of drug resistance. Many RNA viruses, including Chikungunya (and potentially Coronavirus), dismantle SG so that the cell cannot respond to the viral infection. Non-structural protein 3 (nsP3), from the Chikungunya virus, has been shown to translocate G3BP away from SG. Interestingly in cancer cells, the formation of SG is correlated to drug-resistance and blocking SG formation has been shown to reestablish the efficacy of the anticancer drug bortezomib.

METHODS

Chikungunya nsP3 was transfected into breast cancer cell lines T47D and MCF7 to disrupt SG formation. Changes in the cytotoxicity of bortezomib were measured.

RESULTS

Bortezomib cytotoxicity in breast cancer cell lines changed with a 22 fold decrease in its IC₅₀ for T47D and a 7 fold decrease for MCF7 cells.

CONCLUSIONS

Chikungunya nsP3 disrupts SG formation. As a result, it increases the cytotoxicity of the FDA approved drug, bortezomib. In addition, the increased cytotoxicity appears to correlate to improved bortezomib selectivity when compared to control cell lines.

Intratumoral Cancer Chemotherapy with a Carrier-Based Immunogenic Cell-Death Eliciting Platinum (IV) Agent

A carrier-based, immunogenic cell death (ICD)-eliciting platinum(IV) chemotherapeutic agent was synthesized via complexation between an axially derivatized Pt(IV)-tocopherol and hyaluronan (HA)-tocopherol nanocarrier. The resultant HA-Pt(IV) complex demonstrated antiproliferative activity and induced calreticulin translocation, an indicator of ICD, in murine and human head and neck cancer (HNC) cells. The intratumorally administered HA-Pt(IV) treatments were tolerable and efficacious in both immunocompetent and immunodeficient mice with HNC, partially because of the direct cytotoxicity. Superior efficacy and survival were observed in the immunocompetent group, suggesting a possible Pt(IV)-induced immunological response, which would only manifest in animals with an intact immune system. Subsequent imaging of tumor tissues demonstrated increased macrophage infiltration in the HA-Pt(IV)-treated tumors compared to the nontreated controls and the cisplatin-treated tumors, suggesting favorable inflammatory activation. RNA sequencing of HA-Pt(IV)-treated tumors indicated that carbohydrate and vitamin metabolisms were the most important Kyoto Encyclopedia of Genes and Genomes pathways, and molecular function, biological process, and cellular component were highly enriched gene ontology categories.

Immunogenic Cell Death of Breast Cancer Stem Cells Induced by an Endoplasmic Reticulum-Targeting Copper(II) Complex

Immunogenic cell death (ICD) offers a method of stimulating the immune system to attack and remove cancer cells. We report a copper(II) complex containing a Schiff base ligand and a polypyridyl ligand, 4, capable of inducing ICD in breast cancer stem cells (CSCs). Complex 4 kills both bulk breast cancer cells and breast CSCs at sub‐micromolar concentrations. Notably, 4 exhibits greater potency (one order of magnitude) towards breast CSCs than salinomycin (an established breast CSC‐potent agent) and cisplatin (a clinically approved anticancer drug). Epithelial spheroid studies show that 4 is able to selectively inhibit breast CSC‐enriched HMLER‐shEcad spheroid formation and viability over non‐tumorigenic breast MCF10 A spheroids. Mechanistic studies show that 4 operates as a Type II ICD inducer. Specifically, 4 readily enters the endoplasmic reticulum (ER) of breast CSCs, elevates intracellular reactive oxygen species (ROS) levels, induces ER stress, evokes damage‐associated molecular patterns (DAMPs), and promotes breast CSC phagocytosis by macrophages. As far as we are aware, 4 is the first metal complex to induce ICD in breast CSCs and promote their engulfment by immune cells.

Immunogenic Cell Death and Elimination of Immunosuppressive Cells: A Double-Edged Sword of Chemotherapy

Chemotherapy is initially used to kill proliferative cells. In the current area of emerging immunotherapy, chemotherapies have shown their ability to modulate the tumor micro environment and immune response. We focus here on two main effects: first, immunogenic cell death, defined as a form of regulated cell death (RCD) that is sufficient to activate an adaptive immune response in immunocompetent hosts; and second, the depletion of suppressive cells, known to play a major role in immune escape and resistance to immunotherapy. In this review, we present a review of different classically used chemotherapies focusing on this double effect on immunity. These immunological effects of chemotherapy could be exploited to promote efficacy of immunotherapy. Broadening our understanding will make it possible to provide rationales for the combination of chemoimmunotherapy in early clinical trials.

A phase 2 study of combined chemo-immunotherapy with cisplatin-pembrolizumab and radiation for unresectable vulvar squamous cell carcinoma

Background

Unresectable or metastatic vulvar cancer has relatively poor outcomes despite chemotherapy-sensitized radiation therapy and combination cytotoxic therapy. Despite the virus-associated and immunogenic nature of this disease, novel immunotherapy options that exploit this advantage are currently lacking. Platinum agents such as cisplatin have been shown to prime dendritic cells for T-cell costimulation, promote downregulation of inhibitory checkpoint molecules, and sensitize tumor cells to cytotoxic T-cell killing. Radiation therapy has also been shown to promote immunogenetic cell death as monotherapy and in combination with cisplatin. In combination with pembrolizumab, cisplatin-sensitized radiation is hypothesized to increase overall response rates and recurrence-free survival in patients with vulvar cancer, via induction of an anti-tumor inflammatory response.

Methods

We propose a single-arm phase II clinical trial of pembrolizumab combined with cisplatin-sensitized radiation therapy for women with unresectable, locally advanced, or metastatic vulvar cancer. The first three patients with locally advanced or unresectable disease will receive cycle 1 of pembrolizumab followed by a break and resumption of pembrolizumab at cycle 4 and as part of a safety cohort. All other patients, including the fourth patient with locally advanced/unresectable disease, will receive weekly cisplatin and pembrolizumab every 3 weeks, concurrently with daily radiation therapy. Following the completion of Cis-RT, patients will continue pembrolizumab maintenance for a total of 12 cycles. Archived tissue will be used for HPV status, MSI status, PD-L1, and TIL stratification post hoc. Imaging will be performed at baseline and every 3 cycles (21-day cycles) as per standard-of-care. Laboratory analysis will occur on the first day of each cycle.

Discussion

The combination of cisplatin-sensitized radiation and immune checkpoint blockade has not been evaluated in the upfront setting for vulvar cancer. In this rare malignancy, there are limited interventional clinical trials. This trial is designed to be as accessible as possible by allowing patients to receive cisplatin and radiation locally according to accepted standard-of-care while receiving pembrolizumab and adverse event monitoring at a centralized site. A robust suite of translational correlative studies has also been built into the trial to evaluate tumor-directed immune activation.

Trial registration NCT04430699

Lack of myeloid cell infiltration as an acquired resistance strategy to immunotherapy

BACKGROUND

Immunotherapy of cancer is successful but tumor regression often is incomplete and followed by escape. Understanding the mechanisms underlying this acquired resistance will aid the development of more effective treatments.

METHODS

We exploited a mouse model where tumor-specific therapeutic vaccination results in tumor regression, followed by local recurrence and resistance. In depth studies on systemic, local and tumor intrinsic changes were performed with flow and mass cytometry, immunohistochemistry, transcriptomics and several perturbation studies with inhibitors or agonistic antibodies in mice. Main findings were recapitulated in vaccinated patients.

RESULTS

Full tumor regression and cure of tumor-bearing mice is dependent on the magnitude of the vaccine-induced T-cell response. Recurrence of tumors did not involve classical immune escape mechanisms, such as antigen-presentation alterations, immune checkpoint expression, resistance to killing or local immune suppression. However, the recurrent tumors displayed a changed transcriptome with alterations in p53, tumor necrosis factor-α and transforming growth factor-β signaling pathways and they became immunologically cold. Remarkably, ex vivo cell-sorted recurrent tumors, directly reinjected in naïve hosts retained their resistance to vaccination despite a strong infiltration with tumor-specific CD8⁺ T cells, similar to that of vaccine-responsive tumors. The influx of inflammatory mature myeloid effector cells in the resistant tumors, however, was impaired and this turned out to be the underlying mechanisms as restoration of inflammatory myeloid cell infiltration reinstated the sensitivity of these refractory tumors to vaccination. Notably, impaired myeloid cell infiltration after vaccination was also associated with vaccine resistance in patients.

CONCLUSION

An immunotherapy-induced disability of tumor cells to attract innate myeloid effector cells formed a major mechanism underlying immune escape and acquired resistance. These data not only stresses the importance of myeloid effector cells during immunotherapy but also demands for new studies to harness their tumoricidal activities.

A brief report on combination chemotherapy and anti-programmed death (ligand) 1 treatment in small-cell lung cancer: Did we choose the optimal chemotherapy backbone?

Extensive-stage small-cell lung cancer (ES-SCLC) is an aggressive cancer that remains very hard to treat. The life expectancy of a patient diagnosed with this disease has not changed over the past three decades. Recently, three large clinical studies showed a survival benefit by adding an anti-programmed death (ligand) 1 (PD-(L)1 antibody to the current chemotherapy regimen. Although significant and important, the benefit seems less than what has been achieved in patients with non-small-cell lung cancer treated with chemoimmunotherapy. A number of hypotheses have been explored to explain this discrepancy. Here, we hypothesise that the current chemotherapy backbone in ES-SCLC does not contain the optimal drugs to trigger immunogenic cell death and therefore does not induce a synergy between chemotherapy and immune checkpoint inhibitor therapy. Thereby, we advocate that doxorubicin treatment instead of etoposide should be reconsidered as standard-of-care (SoC) first-line treatment of SCLC.

Nanomicelle protects the immune activation effects of Paclitaxel and sensitizes tumors to anti-PD-1 Immunotherapy

Paclitaxel (PTX) has shown pleiotropic immunologic effects on the tumor microenvironment, and nanomicelle has emerged as a promising strategy for PTX delivery. However, the detailed mechanisms remain to be fully elucidated. Meanwhile, immunogenic cell death (ICD) is an effective approach to activate the immune system. This study investigated the ICD effect of PTX and how nanomicelle affected the immune-activation ability of PTX.

Methods: The ICD effects of PTX were identified via the expression of ICD markers and cell vaccine experiment. Tumor size and overall survival in multiple animal models with treatment were monitored to evaluate the antitumor effects. The mechanisms of PTX-induced ICD and antitumor immunity were determined by detecting gene expression related to ER stress and analyzing immune cell profile in tumor after treatment.

Results: We revealed the immune-regulation mechanism of PTX nanomicelle by inducing ICD, which can promote antigen presentation by dendritic cells (DCs) and activate antitumor immunity. Notably, nanomicelle encapsulation protected the ICD effects and immune activation, which were hampered by immune system impairment caused by chemotherapy. Compared with traditional formulations, a low dose of nanomicelle-encapsulated PTX (nano-PTX) treatment induced immune-dependent tumor control, which increased the infiltration and function of both T cells and DCs within tumors. However, this antitumor immunity was hampered by highly expressed PD-1 on tumor-infiltrating CD8⁺ T cells and upregulated PD-L1 on both immune cells and tumor cells after nano-PTX treatment. Combination therapy with a low dose of nano-PTX and PD-1 antibodies elicited CD8⁺ T cell-dependent antitumor immunity and remarkably improved the therapeutic efficacy.

Conclusions: Our results provide systemic insights into the immune-regulation ability of PTX to induce ICD, which acts as an inducer of endogenous vaccines through ICD effects, and also provides an experimental basis for clinical combination therapy with nano-PTX and PD-1 antibodies.

Combination treatments with hydroxychloroquine and azithromycin are compatible with the therapeutic induction of anticancer immune responses

Amid controversial reports that COVID-19 can be treated with a combination of the antimalarial drug hydroxychloroquine (HCQ) and the antibiotic azithromycin (AZI), a clinical trial (ONCOCOVID, NCT04341207) was launched at Gustave Roussy Cancer Campus to investigate the utility of this combination therapy in cancer patients. In this preclinical study, we investigated whether the combination of HCQ+AZI would be compatible with the therapeutic induction of anticancer immune responses. For this, we used doses of HCQ and AZI that affect whole-body physiology (as indicated by a partial blockade in cardiac and hepatic autophagic flux for HCQ and a reduction in body weight for AZI), showing that their combined administration did not interfere with tumor growth control induced by the immunogenic cell death inducer oxaliplatin. Moreover, the HCQ+AZI combination did not affect the capacity of a curative regimen (cisplatin + crizotinib + PD-1 blockade) to eradicate established orthotopic lung cancers in mice. In conclusion, it appears that HCQ+AZI does not interfere with the therapeutic induction of therapeutic anticancer immune responses.

Unraveling the regulatory role of endoplasmic-reticulum-associated degradation in tumor immunity

During malignant transformation and cancer progression, tumor cells face both intrinsic and extrinsic stress, endoplasmic reticulum (ER) stress in particular. To survive and proliferate, tumor cells use multiple stress response pathways to mitigate ER stress, promoting disease aggression and treatment resistance. Among the stress response pathways is ER-associated degradation (ERAD), which consists of multiple components and steps working together to ensure protein quality and quantity. In addition to its established role in stress responses and tumor cell survival, ERAD has recently been shown to regulate tumor immunity. Here we summarize current knowledge on how ERAD promotes protein degradation, regulates immune cell development and function, participates in antigen presentation, exerts paradoxical roles on tumorigenesis and immunity, and thus impacts current cancer therapy. Collectively, ERAD is a critical protein homeostasis pathway intertwined with cancer development and tumor immunity. Of particular importance is the need to further unveil ERAD's enigmatic roles in tumor immunity to develop effective targeted and combination therapy for successful treatment of cancer.

High levels of tumor-infiltrating lymphocytes showed better clinical outcomes in FOLFOX-treated gastric cancer patients

Background: Tumor-infiltrating lymphocytes (TILs) and postoperative chemotherapeutics interact in the tumor micro-environment. This interaction has not been well investigated in gastric cancer. Materials & methods: A total of 129 patients were divided into high or low TILs based on the median number of positive CD3⁺ and FoxP3⁺ T cells, which was assessed by immunocytochemistry. Results: Cox regression analysis showed that the stage III disease with shorter overall survival was significant. The analysis showed that high numbers of CD3⁺ or FoxP3⁺ T cells have better clinical outcomes in FOLFOX-treated patients. Conclusion: High CD3⁺ and FoxP3⁺ T-cell infiltration was associated with better clinical outcomes in patients with gastric cancer treated with FOLFOX, suggesting TILs incorporated into algorithms to improve the therapeutic efficacy of optimal chemotherapy.

Nanomedicine and Onco-Immunotherapy: From the Bench to Bedside to Biomarkers

The broad relationship between the immune system and cancer is opening a new hallmark to explore for nanomedicine. Here, all the common and synergy points between both areas are reviewed and described, and the recent approaches which show the progress from the bench to the beside to biomarkers developed in nanomedicine and onco-immunotherapy.

Clinically Relevant Chemotherapeutics Have the Ability to Induce Immunogenic Cell Death in Non-Small Cell Lung Cancer

The concept of immunogenic cell death (ICD) has emerged as a cornerstone of therapy-induced anti-tumor immunity. To this end, the following chemotherapies were evaluated for their ability to induce ICD in non-small cell lung cancer (NSCLC) cell lines: docetaxel, carboplatin, cisplatin, oxaliplatin and mafosfamide. The ICD hallmarks ATP, ecto-calreticulin, HMGB1, phagocytosis and maturation status of dendritic cells (DCs) were assessed in vitro. Furthermore, an in vivo vaccination assay on C57BL/6J mice was performed to validate our in vitro results. Docetaxel and the combination of docetaxel with carboplatin or cisplatin demonstrated the highest levels of ATP, ecto-calreticulin and HMGB1 in three out of four NSCLC cell lines. In addition, these regimens resulted in phagocytosis of treated NSCLC cells and maturation of DCs. Along similar lines, all mice vaccinated with NSCLC cells treated with docetaxel and cisplatin remained tumor-free after challenge. However, this was not the case for docetaxel, despite its induction of the ICD-related molecules in vitro, as it failed to reject tumor growth at the challenge site in 60% of the mice. Moreover, our in vitro and in vivo data show the inability of oxaliplatin to induce ICD in NSCLC cells. Overall with this study we demonstrate that clinically relevant chemotherapeutic regimens in NSCLC patients have the ability to induce ICD.

Unexpected therapeutic effects of cisplatin

Cisplatin is a widely used chemotherapeutic agent that is clinically approved to fight both carcinomas and sarcomas. It has relatively high efficiency in treating ovarian cancers and metastatic testicular cancers. It is generally accepted that the major mechanism of cisplatin anti-cancer action is DNA damage. However, cisplatin is also effective in metastatic cancers and should, therefore, affect slow-cycling cancer stem cells in some way. In this review, we focused on the alternative effects of cisplatin that can support a good therapeutic response. First, attention was paid to the effects of cisplatin at the cellular level such as changes in intracellular pH and cellular mechanical properties. Alternative cellular targets of cisplatin, and the effects of cisplatin on cancer cell metabolism and ER stress were also discussed. Furthermore, the impacts of cisplatin on the tumor microenvironment and in the whole organism context were reviewed. In this review, we try to reveal possible causes of the unexpected effectiveness of this anti-cancer drug.

Damage-associated molecular patterns (DAMPs) related to immunogenic cell death are differentially triggered by clinically relevant chemotherapeutics in lung adenocarcinoma cells

Background

Chemotherapeutics can stimulate immune antitumor response by inducing immunogenic cell death (ICD), which is activated by Damage-Associated Molecular Patterns (DAMPs) like the exposure of calreticulin (CRT) on the cell surface, the release of ATP and the secretion of High Mobility Group Box 1 (HMGB1).

Methods

Here, we investigated the levels of ICD-associated DAMPs induced by chemotherapeutics commonly used in the clinical practice of non-small cell lung cancer (NSCLC) and the association of these DAMPs with apoptosis and autophagy. A549 human lung adenocarcinoma cells were treated with clinically relevant doses of cisplatin, carboplatin, etoposide, paclitaxel and gemcitabine. We assessed ICD-associated DAMPs, cell viability, apoptosis and autophagy in an integrated way.

Results

Cisplatin and its combination with etoposide induced the highest levels of apoptosis, while etoposide was the less pro-apoptotic treatment. Cisplatin also induced the highest levels of ICD-associated DAMPs, which was not incremented by co-treatments. Etoposide induced the lower levels of ICD and the highest levels of autophagy, suggesting that the cytoprotective role of autophagy is dominant in relation to its pro-ICD role. High levels of CRT were associated with better prognosis in TCGA databank. In an integrative analysis we found a strong positive correlation between DAMPs and apoptosis, and a negative correlation between cell number and ICD-associated DAMPs as well as between autophagy and apoptosis markers. We also purpose a mathematical integration of ICD-associated DAMPs in an index (IndImunnog) that may represent with greater biological relevance this process. Cisplatin-treated cells showed the highest IndImmunog, while etoposide was the less immunogenic and the more pro-autophagic treatment.

Conclusions

Cisplatin alone induced the highest levels of ICD-associated DAMPs, so that its combination with immunotherapy may be a promising therapeutic strategy in NSCLC.

Paclitaxel Induces Immunogenic Cell Death in Ovarian Cancer via TLR4/IKK2/SNARE-Dependent Exocytosis

Emerging evidence shows that the efficacy of chemotherapeutic drugs is reliant on their capability to induce immunogenic cell death (ICD), thus transforming dying tumor cells into antitumor vaccines. We wanted to uncover potential therapeutic strategies that target ovarian cancer by having a better understanding of the standard-of-care chemotherapy treatment. Here, we showed in ovarian cancer that paclitaxel induced ICD-associated damage-associated molecular patterns (DAMP, such as CALR exposure, ATP secretion, and HMGB1 release) in vitro and elicited significant antitumor responses in tumor vaccination assays in vivo Paclitaxel-induced TLR4 signaling was essential to the release of DAMPs, which led to the activation of NF-κB-mediated CCL2 transcription and IkappaB kinase 2-mediated SNARE-dependent vesicle exocytosis, thus exposing CALR on the cell surface. Paclitaxel induced endoplasmic reticulum stress, which triggered protein kinase R-like ER kinase activation and eukaryotic translation initiation factor 2α phosphorylation independent of TLR4. Paclitaxel chemotherapy induced T-cell infiltration in ovarian tumors of the responsive patients; CALR expression in primary ovarian tumors also correlated with patients' survival and patient response to chemotherapy. These findings suggest that the effectiveness of paclitaxel relied upon the activation of antitumor immunity through ICD via TLR4 and highlighted the importance of CALR expression in cancer cells as an indicator of response to paclitaxel chemotherapy in ovarian cancer.

Current Approaches for Combination Therapy of Cancer: The Role of Immunogenic Cell Death

Cell death resistance is a key feature of tumor cells. One of the main anticancer therapies is increasing the susceptibility of cells to death. Cancer cells have developed a capability of tumor immune escape. Hence, restoring the immunogenicity of cancer cells can be suggested as an effective approach against cancer. Accumulating evidence proposes that several anticancer agents provoke the release of danger-associated molecular patterns (DAMPs) that are determinants of immunogenicity and stimulate immunogenic cell death (ICD). It has been suggested that ICD inducers are two different types according to their various activities. Here, we review the well-characterized DAMPs and focus on the different types of ICD inducers and recent combination therapies that can augment the immunogenicity of cancer cells.

Inhibition of transcription by dactinomycin reveals a new characteristic of immunogenic cell stress

Chemotherapy still constitutes the standard of care for the treatment of most neoplastic diseases. Certain chemotherapeutics from the oncological armamentarium are able to trigger pre‐mortem stress signals that lead to immunogenic cell death (ICD), thus inducing an antitumor immune response and mediating long‐term tumor growth reduction. Here, we used an established model, built on artificial intelligence to identify, among a library of 50,000 compounds, anticancer agents that, based on their molecular descriptors, were predicted to induce ICD. This algorithm led us to the identification of dactinomycin (DACT, best known as actinomycin D), a highly potent cytotoxicant and ICD inducer that mediates immune‐dependent anticancer effects in vivo. Since DACT is commonly used as an inhibitor of DNA to RNA transcription, we investigated whether other experimentally established or algorithm‐selected, clinically employed ICD inducers would share this characteristic. As a common leitmotif, a panel of pharmacological ICD stimulators inhibited transcription and secondarily translation. These results establish the inhibition of RNA synthesis as an initial event for ICD induction.

FLT3LG - a biomarker reflecting clinical responses to the immunogenic cell death inducer oxaliplatin

The fms-related tyrosine kinase 3 (FLT3) ligand (FLT3LG) binds to FLT3 on dendritic cells to stimulate their differentiation and expansion, hence facilitating tumor antigen cross-presentation and anticancer immune responses. A recent study by Abrahamsson et al. demonstrates that, in patients receiving a hepatic arterial infusion of oxaliplatin for the treatment of colorectal cancer metastases, an increase in circulating FLT3LG predicts long-term survival of those individuals whose metastases have been rendered resectable. Thus, FLT3LG constitutes a potential biomarker of immune activation by immunogenic cell death-inducing chemotherapeutics such as oxaliplatin.

Abbreviations: DC, dendritic cell; FLT3, fms-related tyrosine kinase 3; FLT3LG, FLT3 ligand; ICI, immune checkpoint inhibitor; OXA, oxaliplatin

Sequential Interferon β-Cisplatin Treatment Enhances the Surface Exposure of Calreticulin in Cancer Cells via an Interferon Regulatory Factor 1-Dependent Manner

Immunogenic cell death (ICD) refers to a unique form of cell death that activates an adaptive immune response against dead-cell-associated antigens. Accumulating evidence indicates that the efficacy of conventional anticancer agents relies on not only their direct cytostatic/cytotoxic effects but also the activation of antitumor ICD. Common anticancer ICD inducers include certain chemotherapeutic agents (such as anthracyclines, oxaliplatin, and bortezomib), radiotherapy, photodynamic therapy (PDT), and oncolytic virotherapies. However, most chemotherapeutic reagents are inefficient or fail to trigger ICD. Therefore, better understanding on the molecular determinants of chemotherapy-induced ICD will help in the development of more efficient combinational anticancer strategies through converting non- or relatively weak ICD inducers into bona fide ICD inducers. In this study, we found that sequential, but not concurrent, treatment of cancer cells with interferon β (IFNβ), a type I IFN, and cisplatin (an inefficient ICD inducer) can enhance the expression of ICD biomarkers in cancer cells, including surface translocation of an endoplasmic reticulum (ER) chaperone, calreticulin (CRT), and phosphorylation of the eukaryotic translation initiation factor alpha (eIF2α). These results suggest that exogenous IFNβ may activate molecular determinants that convert cisplatin into an ICD inducer. Further bioinformatics and in vitro experimental analyses found that interferon regulatory factor 1 (IRF1) acted as an essential mediator of surface CRT exposure by sequential IFNβ-cisplatin combination. Our findings not only help to design more effective combinational anticancer therapy using IFNβ and cisplatin, but also provide a novel insight into the role of IRF1 in connecting the type I IFN responses and ICD.

Synthetic Immunogenic Cell Death Mediated by Intracellular Delivery of STING Agonist Nanoshells Enhances Anticancer Chemo-immunotherapy

Many favorable anticancer treatments owe their success to the induction immunogenic cell death (ICD) in cancer cells, which results in the release of endogenous danger signals along with tumor antigens for effective priming of anticancer immunity. We describe a strategy to artificially induce ICD by delivering the agonist of stimulator of interferon genes (STING) into tumor cells using hollow polymeric nanoshells. Following intracellular delivery of exogenous adjuvant, subsequent cytotoxic treatment creates immunogenic cellular debris that spatiotemporally coordinate tumor antigens and STING agonist in a process herein termed synthetic immunogenic cell death (sICD). sICD is indiscriminate to the type of chemotherapeutics and enables colocalization of exogenously administered immunologic adjuvants and tumor antigens for enhanced antigen presentation and anticancer adaptive response. In three mouse tumor models, sICD enhances therapeutic efficacy and restrains tumor progression. The study highlights the benefit of delivering STING agonists to cancer cells, paving ways to new chemo-immunotherapeutic designs.

Evaluating the immunoproteasome as a potential therapeutic target in cisplatin-resistant small cell and non-small cell lung cancer

PURPOSE

We evaluated the expression of proteasome subunits to assess whether the proteasome could be a therapeutic target in cisplatin-resistant lung cancer cells.

METHODS

Cisplatin-resistant (CR) variants were established from three non-small cell lung cancer (NSCLC) cell lines (A549, H1299, and H1975) and two small cell lung cancer (SCLC) cell lines (SBC3 and SBC5). The expression of proteasome subunits, the sensitivity to immunoproteasome inhibitors, and 20S proteasomal proteolytic activity were examined in the CR variants of the lung cancer cell lines.

RESULTS

All five CR cell lines highly expressed one or both of the immunoproteasome subunit genes, PSMB8 and PSMB9, while no clear trend was observed in the expression of constitutive proteasome subunits. The CR cells expressed significantly higher levels of PSMB8 and PSMB9 proteins, as well. The CR variants of the H1299 and SBC3 cell lines were more sensitive to immunoproteasome inhibitors, and had significantly more proteasomal proteolytic activity than their parental counterparts.

CONCLUSIONS

The immunoproteasome may be an effective therapeutic target in a subset of CR lung cancers. Proteasomal proteolytic activity may be a predictive marker for the efficacy of immunoproteasome inhibitors in cisplatin-resistant SCLC and NSCLC.

Consensus guidelines for the definition, detection and interpretation of immunogenic cell death

Cells succumbing to stress via regulated cell death (RCD) can initiate an adaptive immune response associated with immunological memory, provided they display sufficient antigenicity and adjuvanticity. Moreover, multiple intracellular and microenvironmental features determine the propensity of RCD to drive adaptive immunity. Here, we provide an updated operational definition of immunogenic cell death (ICD), discuss the key factors that dictate the ability of dying cells to drive an adaptive immune response, summarize experimental assays that are currently available for the assessment of ICD in vitro and in vivo, and formulate guidelines for their interpretation.

PT-112 induces immunogenic cell death and synergizes with immune checkpoint blockers in mouse tumor models

PT-112 is a novel platinum-pyrophosphate conjugate under clinical development for cancer therapy. PT-112 mediates cytostatic and cytotoxic effects against a variety of human and mouse cancer cell lines in vitro. The cytotoxic response to PT-112 is associated with the emission of danger signals underpinning the initiation of anticancer immunity, including calreticulin exposure on the surface of dying cells, as well as ATP and HMGB1 secretion. Consistently, mouse cancer cells succumbing to PT-112 in vitro can be used to provide syngeneic, immunocompetent mice with immunological protection against a subsequent challenge with living tumor cells of the same type. Moreover, PT-112 administration synergizes with PD-1 or PD-L1 blockade in the control of mouse cancers in immunologically competent settings, as it simultaneously recruits immune effector cells and depletes immunosuppressive cells in the tumor microenvironment. Finally, PT-112 employed intratumorally in the context of immune checkpoint inhibition initiates a robust immune response that has systemic outreach and limits the growth of untreated, distant lesions. Thus, PT-112 induces the immunogenic demise of cancer cells, and hence stands out as a promising combinatorial partner of immune checkpoint blockers, especially for the treatment of otherwise immunologically cold tumors.

Trial watch: chemotherapy-induced immunogenic cell death in immuno-oncology

The term ‘immunogenic cell death’ (ICD) denotes an immunologically unique type of regulated cell death that enables, rather than suppresses, T cell-driven immune responses that are specific for antigens derived from the dying cells. The ability of ICD to elicit adaptive immunity heavily relies on the immunogenicity of dying cells, implying that such cells must encode and present antigens not covered by central tolerance (antigenicity), and deliver immunostimulatory molecules such as damage-associated molecular patterns and cytokines (adjuvanticity). Moreover, the host immune system must be equipped to detect the antigenicity and adjuvanticity of dying cells. As cancer (but not normal) cells express several antigens not covered by central tolerance, they can be driven into ICD by some therapeutic agents, including (but not limited to) chemotherapeutics of the anthracycline family, oxaliplatin and bortezomib, as well as radiation therapy. In this Trial Watch, we describe current trends in the preclinical and clinical development of ICD-eliciting chemotherapy as partner for immunotherapy, with a focus on trials assessing efficacy in the context of immunomonitoring.

Restoration and Enhancement of Immunogenic Cell Death of Cisplatin by Coadministration with Digoxin and Conjugation to HPMA Copolymer

Complete tumor eradication is the ultimate goal of cancer therapy. However, the majority of anticancer drugs cause nonimmunogenic cell death and only exert on-site anticancer activities. The intrinsic genomic instability of cancer allows for the persistence and later expansion of treatment-resistant clones after surviving a sort of Darwinian selection of chemotherapy. Additional incorporation of immunotherapy, which is robust and individualized could be game-changing. Herein, we report a combination strategy that delivers nonimmunogenic cell death inducer Cisplatin to treat primary tumors and converts the tumor cells into vaccines that spurs a long-lasting immune response against residual tumors to prevent tumor recurrence and metastasis. Cisplatin(IV) prodrug was linked to the N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer (P-Cis) and coadministered with digoxin (Dig), which eventually launched two attacks to cancer cells. First, P-Cis exhibited superior tumor retention and cytotoxicity over free Cisplatin (to inhibit the primary tumor growth). Then, Dig reversed the inability of Cisplatin to trigger calreticulin exposure, and HPMA copolymer-amplified Cisplatin-induced ATP release. These complementary mechanisms induced potent immunogenic cell death that promotes dendritic cell maturation and activates CD8⁺ T cell responses. In established tumor models, P-Cis + Dig combination completely eradicate tumors with no residual cancer cells remaining. Cancer cells succumbing to P-Cis + Dig could protect syngeneic mice against the subsequent challenge with living cells of the same type and stimulated robust abscopal and antimetastatic effects. Such a strategy might be promising to restore the immunogenicity of nonimmunogenic drugs and generate vaccine-like functions for improved immunochemotherapy.

Methods to Detect Immunogenic Cell Death In Vivo

In response to selected stressors, cancer cells can undergo a form of regulated cell death that-in immunocompetent syngeneic hosts-is capable of eliciting an adaptive immune response specific for dead cell-associated antigens. Thus, such variant of regulated cell death manifests with robust antigenicity and adjuvanticity. As compared to their normal counterparts, malignant cells are highly antigenic per se, implying that they express a variety of antigens that are not covered by central tolerance. However, the precise modality through which cancer cells die in response to stress has a major influence on adjuvanticity. Moreover, the adjuvanticity threshold to productively drive anticancer immune responses is considerably lower in tumor-naïve hosts as compared to their tumor-bearing counterparts, largely reflecting the establishment of peripheral tolerance to malignant lesions in the latter (but not in the former). So far, no cellular biomarker or combination thereof has been found to reliably predict the ability of cancer cell death to initiate antitumor immunity. Thus, although some surrogate biomarkers of adjuvanticity can be used for screening purposes, the occurrence of bona fide immunogenic cell death (ICD) can only be ascertained in vivo. Here, we describe two methods that can be harnessed to straightforwardly determine the immunogenicity of mouse cancer cells succumbing to stress in both tumor-naïve and tumor-bearing hosts.

Regorafenib in Combination with First-Line Chemotherapy for Metastatic Esophagogastric Cancer

BACKGROUND

Angiogenesis is critical to gastroesophageal adenocarcinoma growth and metastasis. Regorafenib is a multikinase inhibitor targeting angiogenic and stromal receptor tyrosine kinases. We evaluated whether regorafenib augments the antitumor effect of first-line chemotherapy in metastatic esophagogastric cancer.

MATERIALS AND METHODS

Patients with previously untreated metastatic gastroesophageal adenocarcinoma received 5-fluorouracil, leucovorin, and oxaliplatin (mFOLFOX6) every 14 days and regorafenib 160 mg daily on days 4 to 10 of each 14-day cycle. The primary endpoint was 6-month progression-free survival (PFS). To identify predictive biomarkers of outcome, we examined correlations between genomic characteristics of sequenced pretreatment tumors and PFS.

RESULTS

Between August 2013 and November 2014, 36 patients with metastatic esophagogastric cancer were accrued to this single-center phase II study (NCT01913639). The most common grade 3-4 treatment-related adverse events were neutropenia (36%), leucopenia (11%) and hypertension (8%). The 6-month PFS was 53% (95% confidence interval [CI], 38%-71%), the objective response rate was 54% (95% CI, 37%-70%), and the disease control rate was 77% (95% CI, 67%-94%). Next-generation sequencing did not identify any genomic alterations significantly correlated with response, and there was no association between homologous recombination deficiency and PFS with platinum-based chemotherapy.

CONCLUSION

Regorafenib (one week on-one week off schedule) is well tolerated in combination with first-line FOLFOX but does not improve 6-month PFS relative to historical control.

IMPLICATIONS FOR PRACTICE

Prognosis for metastatic esophagogastric cancer remains poor despite modern systemic therapy regimens. This phase II trial indicates that the combination of regorafenib and FOLFOX is well tolerated but does not add to the efficacy of first-line chemotherapy in metastatic esophagogastric cancer. Notably, recently reported data suggest potential synergy between regorafenib and the PD-1 inhibitor nivolumab. As this study demonstrates that regorafenib plus FOLFOX is safe, and combined chemotherapy and immunotherapy show favorable toxicity profiles, future studies combining immunotherapy with regorafenib and chemotherapy may be feasible.

Platinum Derivatives Effects on Anticancer Immune Response

Along with surgery and radiotherapy, chemotherapeutic agents belong to the therapeutic arsenal in cancer treatment. In addition to their direct cytotoxic effects, these agents also impact the host immune system, which might enhance or counteract their antitumor activity. The platinum derivative compounds family, mainly composed of carboplatin, cisplatin and oxaliplatin, belongs to the chemotherapeutical arsenal used in numerous cancer types. Here, we will focus on the effects of these molecules on antitumor immune response. These compounds can induce or not immunogenic cell death (ICD), and some strategies have been found to induce or further enhance it. They also regulate immune cells’ fate. Platinum derivatives can lead to their activation. Additionally, they can also dampen immune cells by selective killing or inhibiting their activity, particularly by modulating immune checkpoints’ expression.

Hypotonic stress enhances colon cancer cell death induced by platinum derivatives and immunologically improves antitumor efficacy of intraperitoneal chemotherapy

Colorectal cancer is a highly metastatic disease that could invade various distal organs and also the peritoneal cavity leading to peritoneal carcinomatosis. This is a terminal condition with poor prognosis and only palliative treatments such as cytoreductive surgery and intraperitoneal chemotherapy are proposed to some patients. However, clinicians use different parameters of treatments without any consensus. Here we decided to evaluate the effect of osmolarity in the efficacy of this procedure to kill colon cancer cells. We first show that a short exposure of platinum derivatives in hypotonic conditions is more efficient to decrease cell viability of human and murine colon cancer cells in vitro as compared to isotonic conditions. This is related to more important incorporation of platinum and the capacity of hypotonic stress to induce the copper transporter CTR1 oligomerization. Oxaliplatin in hypotonic conditions induces caspase-dependent cell death of colon cancer cells. Moreover, hypotonic conditions also modulate the capacity of oxaliplatin and cisplatin (but not carboplatin) to induce immunogenic cell death (ICD). In vivo, oxaliplatin in hypotonic conditions increases CD8⁺ T cell tumor infiltration and activation. Finally, in a murine peritoneal carcinomatosis model, oxaliplatin in hypotonic conditions is the only tested protocol which is able to slow down the appearance of tumor nodules and increase mice survival, while showing no effect in CD8⁺ T cells depleted mice or in immunodeficient mice. Altogether, our study provides new information both in vitro and in a preclinical model of peritoneal carcinomatosis, which highlights the importance of hypoosmolarity in intraperitoneal chemotherapy.

Comedications influence immune infiltration and pathological response to neoadjuvant chemotherapy in breast cancer

Immunosurveillance plays an important role in breast cancer (BC) prognosis and progression, and can be geared by immunogenic chemotherapy. In a cohort of 1023 BC patients treated with neoadjuvant chemotherapy (NAC), 40% of the individuals took comedications mostly linked to aging and comorbidities. We systematically analyzed the off-target effects of 1178 concurrent comedications (classified according to the Anatomical Therapeutic Chemical (ATC) Classification System) on the density of tumor-infiltrating lymphocytes (TILs) and pathological complete responses (pCR). At level 1 of the ATC system, the main anatomical classes of drugs were those targeting the nervous system (class N, 39.1%), cardiovascular disorders (class C, 26.6%), alimentary and metabolism (class A, 16.9%), or hormonal preparations (class H, 6.5%). At level 2, the most frequent therapeutic classes were psycholeptics (N05), analgesics (N02), and psychoanaleptics (N06). Pre-NAC TIL density in triple-negative BC (TNBC) was influenced by medications from class H, N, and A, while TIL density in HER2⁺ BC was associated with the use of class C. Psycholeptics (N05) and agents acting on the renin-angiotensin system (C09) were independently associated with pCR in the whole population of BC or TNBC, and in HER2-positive BC, respectively. Importantly, level 3 hypnotics (N05C) alone were able to reduce tumor growth in BC bearing mice and increased the anti-cancer activity of cyclophosphamide in a T cell-dependent manner. These findings prompt for further exploration of drugs interactions in cancer, and for prospective drug-repositioning strategies to improve the efficacy of NAC in BC.

The Interplay Between the Genetic and Immune Landscapes of AML: Mechanisms and Implications for Risk Stratification and Therapy

AML holds a unique place in the history of immunotherapy by virtue of being among the first malignancies in which durable remissions were achieved with "adoptive immunotherapy," now known as allogeneic stem cell transplantation. The successful deployment of unselected adoptive cell therapy established AML as a disease responsive to immunomodulation. Classification systems for AML have been refined and expanded over the years in an effort to capture the variability of this heterogeneous disease and risk-stratify patients. Current systems increasingly incorporate information about cytogenetic alterations and genetic mutations. The advent of next generation sequencing technology has enabled the comprehensive identification of recurrent genetic mutations, many with predictive power. Recurrent genetic mutations found in AML have been intensely studied from a cell intrinsic perspective leading to the genesis of multiple, recently approved targeted therapies including IDH1/2-mutant inhibitors and FLT3-ITD/-TKD inhibitors. However, there is a paucity of data on the effects of these targeted agents on the leukemia microenvironment, including the immune system. Recently, the phenomenal success of checkpoint inhibitors and CAR-T cells has re-ignited interest in understanding the mechanisms leading to immune dysregulation and suppression in leukemia, with the objective of harnessing the power of the immune system via novel immunotherapeutics. A paradigm has emerged that places crosstalk with the immune system at the crux of any effective therapy. Ongoing research will reveal how AML genetics inform the composition of the immune microenvironment paving the way for personalized immunotherapy.

Lurbinectedin synergizes with immune checkpoint blockade to generate anticancer immunity

Systemic treatment with the active transcription inhibitor lurbinectedin aims at inducing tumor cell death in hyperproliferative neoplasms. Here we show that cell death induced by lurbinectedin reinstates and enhances systemic anticancer immune responses. Lurbinectedin treatment showed traits of immunogenic cell death, including the exposure of calreticulin, the release of ATP, the exodus of high mobility group box 1 (HMGB1) and type 1 interferon responses in vitro. Lurbinectedin treated cells induced antitumor immunity when injected into immunocompetent animals and treatment of transplanted fibrosarcomas reduced tumor growth in immunocompetent yet not in immunodeficient hosts. Anticancer effects resulting from lurbinectedin treatment were boosted in combination with PD-1 and CTLA-4 double immune checkpoint blockade (ICB), and lurbinectedin combined with double ICB exhibited strong antineoplastic effects. Cured animals exhibited long term immune memory effects that rendered them resistant to rechallenge with syngeneic tumors underlining the potency of combination therapy with lurbinectedin.

cGAS/STING axis mediates a topoisomerase II inhibitor-induced tumor immunogenicity

Checkpoint blockade antibodies have been approved as immunotherapy for multiple types of cancer, but the response rate and efficacy are still limited. There are few immunogenic cell death (ICD)-inducing drugs available that can kill cancer cells, enhance tumor immunogenicity, increase the in vivo immune infiltration, and thereby boosting a tumor response to immunotherapy. So far, the ICD markers have been identified as the few immuno-stimulating characteristics of dead cells, but whether the presence of such ICD markers on tumor cells translates into enhanced antitumor immunity in vivo is still investigational. To identify anticancer drugs that could induce tumor cell death and boost T cell response, we performed drug screenings based on both an ICD reporter assay and T cell activation assay. We identified that teniposide, a DNA topoisomerase II inhibitor, could induce high mobility group box 1 (HMGB1) release and type I interferon signaling in tumor cells, and teniposide-treated tumor cells could activate antitumor T cell response both in vitro and in vivo. Mechanistically, teniposide induced tumor cell DNA damage and innate immune signaling including NF-κB activation and STING-dependent type I interferon signaling, both of which contribute to the activation of dendritic cells and subsequent T cells. Furthermore, teniposide potentiated the antitumor efficacy of anti-PD1 on multiple types of mouse tumor models. Our findings showed that teniposide could trigger tumor immunogenicity, and enabled a potential chemo-immunotherapeutic approach to potentiate the therapeutic efficacy of anti-PD1 immunotherapy.

Cell death in photodynamic therapy: From oxidative stress to anti-tumor immunity

Photodynamic therapy is a promising approach for cancer treatment that relies on the administration of a photosensitizer followed by tumor illumination. The generated oxidative stress may activate multiple mechanisms of cell death which are counteracted by cells through adaptive stress responses that target homeostasis rescue. The present renaissance of PDT was leveraged by the acknowledgment that this therapy has an immediate impact locally, in the illumination volume, but that subsequently it may also elicit immune responses with systemic impact. The investigation of the mechanisms of cell death under the oxidative stress of PDT is of paramount importance to understand how the immune system is activated and, ultimately, to make PDT a more appealing/relevant therapeutic option.

Extracorporeal photochemotherapy induces bona fide immunogenic cell death

Extracorporeal photochemotherapy (ECP) is employed for the management of cutaneous T cell lymphoma (CTCL). ECP involves the extracorporeal exposure of white blood cells (WBCs) to a photosensitizer, 8-methoxypsoralen (8-MOP), in the context of ultraviolet A (UVA) radiation, followed by WBC reinfusion. Historically, the therapeutic activity of ECP has been attributed to selective cytotoxicity on circulating CTCL cells. However, only a fraction of WBCs is exposed to ECP, and 8-MOP is inactive in the absence of UVA light, implying that other mechanisms underlie the anticancer effects of ECP. Recently, ECP has been shown to enable the physiological differentiation of monocytes into dendritic cells (DCs) that efficiently cross-present tumor-associated antigens (TAAs) to CD8⁺ T lymphocytes to initiate cognate immunity. However, the source of TAAs and immunostimulatory signals for such DCs remains to be elucidated. Here, we demonstrate that 8-MOP plus UVA light reduces melanoma cell viability along with the emission of ICD-associated danger signals including calreticulin (CALR) exposure on the cell surface and secretion of ATP, high mobility group box 1 (HMGB1) and type I interferon (IFN). Consistently, melanoma cells succumbing to 8-MOP plus UVA irradiation are efficiently engulfed by monocytes, ultimately leading to cross-priming of CD8⁺ T cells against cancer. Moreover, malignant cells killed by 8-MOP plus UVA irradiation in vitro vaccinate syngeneic immunocompetent mice against living cancer cells of the same type, and such a protection is lost when cancer cells are depleted of calreticulin or HMGB1, as well as in the presence of an ATP-degrading enzyme or antibodies blocking type I IFN receptors. ECP induces bona fide ICD, hence simultaneously providing monocytes with abundant amounts of TAAs and immunostimulatory signals that are sufficient to initiate cognate anticancer immunity.

Intratumorally delivered formulation, INT230-6, containing potent anticancer agents induces protective T cell immunity and memory

The benefits of anti-cancer agents extend beyond direct tumor killing. One aspect of cell death is the potential to release antigens that initiate adaptive immune responses. Here, a diffusion enhanced formulation, INT230-6, containing potent anti-cancer cytotoxic agents, was administered intratumorally into large (approx. 300mm³) subcutaneous murine Colon26 tumors. Treatment resulted in regression from baseline in 100% of the tumors and complete response in up to 90%. CD8⁺ or CD8⁺/CD4⁺ T cell double-depletion at treatment onset prevented complete responses, indicating a critical role of T cells in promoting complete tumor regression. Mice with complete response were protected from subcutaneous and intravenous re-challenge of Colon26 cells in a CD4⁺/CD8⁺ dependent manner. Thus, immunological T cell memory was induced by INT230-6. Colon26 tumors express the endogenous retroviral protein gp70 containing the CD8⁺ T-cell AH-1 epitope. AH-1-specific CD8⁺ T cells were detected in peripheral blood of tumor-bearing mice and their frequency increased 14 days after treatment onset. AH-1-specific CD8⁺ T cells were also significantly enriched in tumors of untreated mice. These cells had an activated phenotype and highly expressed Programmed cell-death protein-1 (PD-1) but did not lead to tumor regression. CD8⁺ T cell tumor infiltrate also increased 11 days after treatment. INT230-6 synergized with checkpoint blockade, inducing a complete remission of the primary tumors and shrinking of untreated contralateral tumors, which demonstrates not only a local but also systemic immunological effect of the combined therapy. Similar T-cell dependent inhibition of tumor growth was also found in an orthotopic 4T1 breast cancer model.

Cisplatin and oxaliplatin induce similar immunogenic changes in preclinical models of head and neck cancer

OBJECTIVES

Prior studies suggest that oxaliplatin is unique among platinum chemotherapy drugs in its ability to enhance anti-tumor immunity, but the immune mechanisms of different platinum chemotherapy drugs have not been previously compared in preclinical models of head and neck squamous cell carcinoma (HNSCC).

MATERIALS AND METHODS

Human HNSCC cell lines were treated with cisplatin or oxaliplatin, then assessed for markers associated with immunogenic cell death (ICD) and antigen processing. A syngeneic mouse model of oral cancer was then used to compare the effects of cisplatin vs. oxaliplatin, alone or in combination with anti-PD-1 immunotherapy, on tumor growth and survival. A subset of spleens and tumors were analyzed for ICD markers and immune cell infiltrates by flow cytometry.

RESULTS

Cisplatin and oxaliplatin both increased cell surface levels of calreticulin, HSP70, MHC class I and PD-L1 in multiple cell lines. Inoculation of immunocompetent mice with cells killed in vitro by either drug resulted in failure of subsequently-injected live tumor cells to establish and grow in a small proportion of animals. Systemic cisplatin and oxaliplatin induced similar tumor growth delay when combined with anti-PD-1 therapy.

CONCLUSIONS

Treatment of HNSCC cells with platinum chemotherapy appears to induce some features of anti-tumor immunity, which may be enhanced by anti-PD-1 therapy. Cisplatin, the standard drug for HNSCC, appears to affect anti-tumor immunity in a similar fashion to oxaliplatin in these preclinical models.

Surrogates of immunologic cell death (ICD) and chemoradiotherapy outcomes in head and neck squamous cell carcinoma (HNSCC)

OBJECTIVES

Chemoradiation can induce immunogenic (ICD) or tolerogenic cell death. ICD relies on the generation of damage-associated molecular patterns which can stimulate toll-like receptors (TLRs). We sought to determine whether we can predict responses to chemoradiation by measuring surrogate biomarkers of ICD in a cohort of patients with locally advanced (LA) head and neck squamous cell carcinoma (HNSCC).

MATERIALS AND METHODS

In a cohort of 113 LA HNSCC pts we evaluated expression of TLR4, TLR7 and TLR9 in the EpCAM + circulating tumor cell (CTC) fraction at baseline and after cisplatin chemoradiation. We also quantified changes in chemokines CXCL10, CXCL16 and IL-2R in the serum.

RESULTS

Seventy three patients had evaluable specimens. Among cases with biomarker assessment at baseline and post treatment, 36.8% had an increase in CXCL10 levels (p = 0.022), 73.7% had an increase in CXCL16 levels (p = 0.002) and 63.8% had an increase in IL2Ra levels (p = 0.032) with treatment. 52.0% of evaluable cases at baseline and post-treatment had an increase in TLR4 levels (p = 0.996), 42.9% had an increase in TLR7 levels (p = 0.042) and 27.7% had increase in TLR9 levels (p = 0.011) with treatment. CXCL10 levels at baseline were significantly associated with PFS and OS (p = 0.010 and p = 0.032, respectively).

CONCLUSIONS

Our results suggest that chemoradiation leads to quantifiable effects in surrogate markers of ICD. These effects may inform trials combining chemoradiation with immune checkpoint inhibitors. In addition, CXCL10 has prognostic effect in pts treated with chemoradiation.

Platinum(IV)-Ferrocene Conjugates and Their Cyclodextrin Host-Guest Complexes

Reported here are new platinum(IV) (Pt(IV)) complexes bearing ferrocene (Fc) moieties. These systems differ from one another only by the nature of the functional group (ester vs amide) connecting the linker to the Fc subunits. This minor structural variation (one atom difference) leads to major differences in solubility, stability, and antiproliferative activity against lung (A549) cancer cells. The host-guest chemistry of these complexes was investigated in an aqueous medium in the presence of β-cyclodextrins (β-CD), either free or in the form of a covalently linked Fc-Pt-β-CD hybrid. An inclusion complex between Fc and β-CD is formed in aqueous media, presumably as a result of hydrophobic interactions involving the Fc and the inner β-CD cavity. Consequently, it proved possible to use a β-CD-based strategy to purify the Pt-Fc conjugates in this study under aqueous conditions (by means of C18 silica gel columns). The use of a β-CD adjuvant also allowed dimethyl sulfoxide (DMSO) to be avoided as an organic cosolvent in cell studies. The amide version reported here (2) proved to be more soluble, more stable, and more active than the ester analogue (11) in A549 cells. The use of a β-CD functionalized with a fluorescent probe allowed intracellular Pt-Fc localization to be visualized by confocal fluorescence microscopy.

Decoding cancer cell death-driven immune cell recruitment: An in vivo method for site-of-vaccination analyses

Anticancer vaccines have recently received renewed attention for immunotherapy of at least a subset of cancer-types. Such vaccines mostly involve either killed cancer or tumor cells alone, or combinations thereof with specific (co-incubated) innate immune cells. In recent years, the immunogenic characteristics of the dead or dying cancer cells have emerged as decisive factors behind the success of anticancer vaccines. This has amplified the importance of accounting for immunology of cell death while preparing anticancer vaccines. This, in turn, has increased the emphasis on the immune reactions at the site-of-vaccination since the therapeutic efficacy of the killed cancer/tumor cell vaccines is contingent upon the nature and characteristics of these reactions at the site-of-injection. In this article, we present a systematic methodology that exploits the murine ear pinna model to study differential immune cell recruitment by dead/dying cancer cells injected in vivo, thereby modeling the site-of-injection relevant for anticancer vaccines.

Immunogenic Cell Death and Immunotherapy of Multiple Myeloma

Over the past decades, immunotherapy has demonstrated a prominent clinical efficacy in a wide variety of human tumors. For many years, apoptosis has been considered a non-immunogenic or tolerogenic process whereas necrosis or necroptosis has long been acknowledged to play a key role in inflammation and immune-related processes. However, the new concept of “immunogenic cell death” (ICD) has challenged this traditional view and has granted apoptosis with immunogenic abilities. This paradigm shift offers clear implications in designing novel anti-cancer therapeutic approaches. To date, several screening studies have been carried out to discover bona fide ICD inducers and reveal the inherent capacity of a wide variety of drugs to induce cell death-associated exposure of danger signals and to bring about in vivo anti-cancer immune responses. Recent shreds of evidence place ER stress at the core of all the scenarios where ICD occur. Furthermore, ER stress and the unfolded protein response (UPR) have emerged as important targets in different human cancers. Notably, in multiple myeloma (MM), a lethal plasma cell disorder, the elevated production of immunoglobulins leaves these cells heavily reliant on the survival arm of the UPR. For that reason, drugs that disrupt ER homeostasis and engage ER stress-associated cell death, such as proteasome inhibitors, which are currently used for the treatment of MM, as well as novel ER stressors are intended to be promising therapeutic agents in MM. This not only holds true for their capacity to induce cell death, but also to their potential ability to activate the immunogenic arm of the ER stress response, with the ensuing exposure of danger signals. We provide here an overview of the up-to-date knowledge regarding the cell death mechanisms involved in situations of ER stress with a special focus on the connections with the drug-induced ER stress pathways that evoke ICD. We will also discuss how this could assist in optimizing and developing better immunotherapeutic approaches, especially in MM treatment.