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Endoplasmic reticulum stress can stimulate calreticulin (CALR) presentation on the cell surface, promoting the phagocytic uptake of stressed cells by myeloid cells. Recent findings from Wattrus et al. demonstrate that zebrafish and mouse embryonic macrophages engulf CALR-exposing nascent hematopoietic stem cells to ensure the selective survival of stem cells apt for adult hematopoiesis. [ABSTRACT FROM AUTHOR]

Type I interferon (IFN) release by irradiated cancer cells is paramount for radiation therapy to elicit anticancer immunity. Our findings demonstrate that mitochondrial outer membrane permeabilization (MOMP) triggered by RT enables exposure of mitochondrial DNA to the cytosol, hence setting off CGAS-driven type I IFN synthesis. These data point to the existence of a therapeutically actionable mitochondrial checkpoint that restricts innate immune signaling in irradiated cancer cells. [ABSTRACT FROM AUTHOR]

The tremendous clinical success of checkpoint blockers illustrates the potential of reestablishing latent immunosurveillance for cancer therapy. Although largely neglected in the clinical practice, accumulating evidence indicates that the efficacy of conventional and targeted anticancer agents does not only involve direct cytostatic/cytotoxic effects, but also relies on the (re)activation of tumor-targeting immune responses. Chemotherapy can promote such responses by increasing the immunogenicity of malignant cells, or by inhibiting immunosuppressive circuitries that are established by developing neoplasms. These immunological “side” effects of chemotherapy are desirable, and their in-depth comprehension will facilitate the design of novel combinatorial regimens with improved clinical efficacy. [ABSTRACT FROM AUTHOR]

Demaria and colleagues have recently identified three prime repair exonuclease 1 (TREX1) as a key determinant for the limited immunogenicity of cancer cells responding to single high-dose radiation. TREX1 stands out as a promising target for the development of novel strategies to boost anticancer immune responses driven by radiation therapy (RT). [ABSTRACT FROM AUTHOR]

The success of anticancer chemotherapy relies at least in part on the induction of an immune response against tumor cells. Thus, tumors growing on mice that lack the pattern recognition receptor TLR4 or the purinergic receptor P2RX7 fail to respond to chemotherapy with anthracyclins or oxaliplatin in conditions in which the same neoplasms growing on immunocompetent mice would do so. Similarly, the therapeutic efficacy (measured as progression-free survival) of adjuvant chemotherapy with anthracyclins is reduced in breast cancer patients bearing loss-of-function alleles of TLR4 or P2RX7. TLR4 loss-of-function alleles also have a negative impact on the therapeutic outcome of oxaliplatin in colorectal cancer patients. Here, we report that loss-of-function TLR4 and P2RX7 alleles do not affect overall survival in non-small cell lung cancer (NSCLC) patients, irrespective of the administration and type of chemotherapy. The intrinsic characteristics of NSCLC (which near-to-always is chemoresistant and associated with poor prognosis) and/or the type of therapy that is employed to treat this malignancy (which near-to-always is based on cisplatin) may explain why two genes that affect the immune response to dying cells fail to influence the clinical progression of NSCLC patients. [ABSTRACT FROM AUTHOR]

The author presents information on immunogenic cell death in radiation therapy. He discusses the antineoplastic effects of radiation therapy, and mentions about the cancer cell-intrinsic and extrinsic mechanism. He also discusses the radiotherapy of autophagy-incompetent tumors along with pharmacological inhibition of extracellular nucleotidases.

Summary: Type I interferon (IFN) is a class of proinflammatory cytokines with a dual role on malignant transformation, tumor progression, and response to therapy. On the one hand, robust, acute, and resolving type I IFN responses have been shown to mediate prominent anticancer effects, reflecting not only their direct cytostatic/cytotoxic activity on (at least some) malignant cells, but also their pronounced immunostimulatory functions. In line with this notion, type I IFN signaling has been implicated in the antineoplastic effects of various immunogenic therapeutics, including (but not limited to) immunogenic cell death (ICD)‐inducing agents and immune checkpoint inhibitors (ICIs). On the other hand, weak, indolent, and non‐resolving type I IFN responses have been demonstrated to support tumor progression and resistance to therapy, reflecting the ability of suboptimal type I IFN signaling to mediate cytoprotective activity, promote stemness, favor tolerance to chromosomal instability, and facilitate the establishment of an immunologically exhausted tumor microenvironment. Here, we review fundamental aspects of type I IFN signaling and their context‐dependent impact on malignant transformation, tumor progression, and response to therapy. [ABSTRACT FROM AUTHOR]

Calreticulin (CALR) exposed on the surface of cancer cells succumbing to therapy delivers robust phagocytic signals that support the activation of adaptive anticancer immune responses. Recent data from our group demonstrate that spontaneous CARL exposure on leukemic blasts also supports innate anticancer immunity by natural killer (NK) cells via an indirect mechanism relying on myeloid CD11c+CD14+ cells. [ABSTRACT FROM AUTHOR]

BCL2 robustly preserves mitochondrial integrity, hence inhibiting innate immune signaling and apoptotic cell death in several cell types. Here, we comment on our recent data demonstrating that BCL2 also limits the ability of dendritic cells to elicit adaptive immune responses, lending support to a universal immunosuppressive function for the mitochondrial immune checkpoint. [ABSTRACT FROM AUTHOR]

The anticancer immune response is shaped by immunogenic cell stress and death pathways. Thus, cancer cells can release danger-associated molecular patterns that act on pattern recognition receptors expressed by dendritic cells and their precursors to elicit an antitumor immune response. Here, we investigated the impact of single nucleotide polymorphisms (SNPs) in genes affecting this cancer-immunity dialogue in the context of head and neck squamous cell carcinoma (HNSCC). We observed that homozygosity for a loss-of-function SNP (rs2241880, leading to the substitution of a threonine residue in position 300 by an alanine) affecting autophagy related 16 like 1 (ATG16L1) is coupled to poor progression-free survival in platinum-treated HNSCC patients. This result was obtained on a cohort of patients enrolled at the Gustave Roussy Cancer Campus and was validated on an independent cohort of The Cancer Genome Atlas (TCGA). Homozygosity in rs2241880 is well known to predispose to Crohn's disease, and epidemiological associations between Crohn's disease and HNSCC have been reported at the levels of cancer incidence and prognosis. We speculate that rs2241880 might be partially responsible for this association. [ABSTRACT FROM AUTHOR]

While intracellular adenosine triphosphate (ATP) occupies a key position in the bioenergetic metabolism of all the cellular compartments that form the tumor microenvironment (TME), extracellular ATP operates as a potent signal transducer. The net effects of purinergic signaling on the biology of the TME depend not only on the specific receptors and cell types involved, but also on the activation status of cis‐ and trans‐regulatory circuitries. As an additional layer of complexity, extracellular ATP is rapidly catabolized by ectonucleotidases, culminating in the accumulation of metabolites that mediate distinct biological effects. Here, we discuss the molecular and cellular mechanisms through which ATP and its degradation products influence cancer immunosurveillance, with a focus on therapeutically targetable circuitries. [ABSTRACT FROM AUTHOR]

At odds with conventional chemotherapeutics, targeted anticancer agents are designed to inhibit precise molecular alterations that support oncogenesis or tumor progression. Despite such an elevated degree of molecular specificity, many clinically employed and experimental targeted anticancer agents also mediate immunostimulatory or immunosuppressive effects that (at least in some settings) influence therapeutic efficacy. Here, we discuss the main immunomodulatory effects of targeted anticancer agents and explore potential avenues to harness them in support of superior clinical efficacy. [ABSTRACT FROM AUTHOR]

Resiquimod (R848) and motolimod (VTX-2337) are second-generation experimental derivatives of imiquimod, an imidazoquinoline with immunostimulatory properties originally approved by the US Food and Drug Administration for the topical treatment of actinic keratosis and genital warts more than 20 years ago. Both resiquimod and motolimod operate as agonists of Toll-like receptor 7 (TLR7) and/or TLR8, in thus far delivering adjuvant-like signals to antigen-presenting cells (APCs). In line with such an activity, these compounds are currently investigated as immunostimulatory agents for the treatment of various malignancies, especially in combination with peptide-based, dendritic cell-based, cancer cell lysate-based, or DNA-based vaccines. Here, we summarize preclinical and clinical evidence recently collected to support the development of resiquimod and motolimod and other TLR7/TLR8 agonists as anticancer agents. [ABSTRACT FROM AUTHOR]

Ionizing irradiation has been extensively employed for the clinical management of solid tumors, with therapeutic or palliative intents, for decades. Until recently, radiation therapy ( RT) was believed to mediate antineoplastic activity mostly (if not only) as a consequence of cancer cell-intrinsic effects. Indeed, the macromolecular damage imposed to malignant cells by RT initiates one or multiple signal transduction cascades that drive a permanent proliferative arrest (cellular senescence) or regulated cell death. Both these phenomena show a rather linear dose-response correlation. However, RT also mediates consistent immunological activity, not only as an 'on-target effect' originating within irradiated cancer cells, but also as an 'off-target effect' depending on the interaction between RT and stromal, endothelial, and immune components of the tumor microenvironment. Interestingly, the immunological activity of RT does not exhibit linear dose-response correlation. Here, we discuss the mechanisms whereby RT alters the capacity of the immune system to recognize and eliminate irradiated cancer cells, either as an 'on-target' or as on 'off-target' effect. In particular, we discuss the antagonism between the immunostimulatory and immunosuppressive effects of RT as we delineate combinatorial strategies to boost the former at the expenses of the latter. [ABSTRACT FROM AUTHOR]

Depending on tumor type, stage and immunological contexture, the inhibition of chemokines or their receptors may yield positive or deleterious effects on disease progression. We have recently demonstrated in several murine models of anthracycline-based chemotherapy that the inhibition of chemokine (C-C motif) ligand 2 (CCL2) or chemokine (C-C motif) receptor 2 (CCR2) may impair the elicitation of anticancer immune responses that contribute to therapeutic success. [ABSTRACT FROM PUBLISHER]

Dendritic cells (DCs) occupy a privileged position at the interface between innate and adaptive immunity, orchestrating a large panel of responses to both physiological and pathological cues. In particular, whereas the presentation of antigens by immature DCs generally results in the development of immunological tolerance, mature DCs are capable of priming robust, and hence therapeutically relevant, adaptive immune responses. In line with this notion, functional defects in the DC compartment have been shown to etiologically contribute to pathological conditions including (but perhaps not limited to) infectious diseases, allergic and autoimmune disorders, graft rejection and cancer. Thus, the possibility of harnessing the elevated immunological potential of DCs for anticancer therapy has attracted considerable interest from both researchers and clinicians over the last decade. Alongside, several methods have been developed not only to isolate DCs from cancer patients, expand them, load them with tumorassociated antigens and hence generate highly immunogenic clinical grade infusion products, but also to directly target DCs in vivo. This intense experimental efort has culminated in 2010 with the approval by the US FDA of a DC-based preparation (sipuleucel-T, Provenge®) for the treatment of asymptomatic or minimally symptomatic metastatic castration-refractory prostate cancer. As an update to the latest Trial watch dealing with this exciting ield of research (October 2012), here we summarize recent advances in DC-based anticancer regimens, covering both high-impact studies that have been published during the last 13 mo and clinical trials that have been launched in the same period to assess the antineoplastic potential of this variant of cellular immunotherapy. [ABSTRACT FROM AUTHOR]

Radiotherapy has extensively been employed as a curative or palliative intervention against cancer throughout the last century, with a varying degree of success. For a long time, the antineoplastic activity of X- and γ-rays was entirely ascribed to their capacity of damaging macromolecules, in particular DNA, and hence triggering the (apoptotic) demise of malignant cells. However, accumulating evidence indicates that (at least part of) the clinical potential of radiotherapy stems from cancer cell-extrinsic mechanisms, including the normalization of tumor vasculature as well as short- and long-range bystander effects. Local bystander effects involve either the direct transmission of lethal signals between cells connected by gap junctions or the production of diffusible cytotoxic mediators, including reactive oxygen species, nitric oxide and cytokines. Conversely, long-range bystander effects, also known as out-of-field or abscopal effects, presumably reflect the elicitation of tumor-specific adaptive immune responses. Ionizing rays have indeed been shown to promote the immunogenic demise of malignant cells, a process that relies on the spatiotemporally defined emanation of specific damage-associated molecular patterns (DAMPs). Thus, irradiation reportedly improves the clinical efficacy of other treatment modalities such as surgery (both in neo-adjuvant and adjuvant settings) or chemotherapy. Moreover, at least under some circumstances, radiotherapy may potentiate anticancer immune responses as elicited by various immunotherapeutic agents, including (but presumably not limited to) immunomodulatory monoclonal antibodies, cancer-specific vaccines, dendritic cell-based interventions and Toll-like receptor agonists. Here, we review the rationale of using radiotherapy, alone or combined with immunomodulatory agents, as a means to elicit or boost anticancer immune responses, and present recent clinical trials investigating the therapeutic potential of this approach in cancer patients. [ABSTRACT FROM AUTHOR]

The antineoplastic effects of anthracyclines have been shown to rely, at least in part, on a local immune response that involves dendritic cells (DCs) and several distinct subsets of T lymphocytes. Here, we show that the administration of anthracyclines to mice bearing established neoplasms stimulates the intratumoral secretion of tumor necrosis factor α (TNFα). However, blocking the TNFα/TNF receptor (TNFR) system by three different strategies—namely, (1) neutralizing antibodies, (2) etanercept, a recombinant protein in which TNFR is fused to the constant domain of an IgG1 molecule, and (3) gene knockout—failed to negatively affect the therapeutic efficacy of anthracyclines in three distinct tumor models. In particular, TNFα-blocking strategies did not influence the antineoplastic effects of doxorubicin (a prototypic anthracycline) against MCA 205 fibrosarcomas growing in C57BL/6 mice, F244 sarcomas developing in 129/Sv hosts and H2N100 mammary carcinomas arising in BALB/c mice. These findings imply that, in contrast to other cytokines (such as interleukin-1β, interleukin-17 and interferon γ), TNFα is not required for anthracyclines to elicit therapeutic anticancer immune responses. [ABSTRACT FROM AUTHOR]

One of the driving forces of oncogenesis is tetraploidy, a duplication of the DNA content that, upon asymmetric cell division or progressive chromosome loss, can originate aneuploidy. Recent findings from our group indicate the existence of an immunosurveillance system that eliminates tetraploid cancer cells. We surmise that tetraploidy-inducing chemotherapeutic agents may elicit potent anticancer responses by re-activating this immunosurveillance system. [ABSTRACT FROM AUTHOR]

Tumor cells succumb to chemotherapy while releasing ATP. We have found that extracellular ATP attracts dendritic cell (DC) precursors into the tumor bed, facilitates their permanence in the proximity of dying cells and promotes their differentiation into mature DCs endowed with the capacity of presenting tumor-associated antigens. [ABSTRACT FROM AUTHOR]

Retrospective clinical data indicate that cardiac glycosides (CGs), notably digoxin, prolong the survival of carcinoma patients treated with conventional chemotherapy. CGs are known to influence the immune response at multiple levels. In addition, recent results suggest that CGs trigger the immunogenic demise of cancer cells, an effect that most likely contributes to their clinical anticancer activity. [ABSTRACT FROM AUTHOR]

Background: Adjuvanticity, which is the ability of neoplastic cells to deliver danger signals, is critical for the host immune system to mount spontaneous and therapy-driven anticancer immune responses. One of such signals, i.e., the exposure of calreticulin (CALR) on the membrane of malignant cells experiencing endoplasmic reticulum (ER) stress, is well known for its role in the activation of immune responses to dying cancer cells. However, the potential impact of CALR on the immune contexture of primary and metastatic high-grade serous carcinomas (HGSCs) and its prognostic value for patients with HGSC remains unclear. Method: We harnessed a retrospective cohort of primary (no = 152) and metastatic (no = 74) tumor samples from HGSC patients to investigate the CALR expression in relation with prognosis and function orientation of the tumor microenvironment. IHC data were complemented with transcriptomic and functional studies on second prospective cohort of freshly resected HGSC samples. In silico analysis of publicly available RNA expression data from 302 HGSC samples was used as a confirmatory approach. Results: We demonstrate that CALR exposure on the surface of primary and metastatic HGSC cells is driven by a chemotherapy-independent ER stress response and culminates with the establishment of a local immune contexture characterized by TH1 polarization and cytotoxic activity that enables superior clinical benefits. Conclusions: Our data indicate that CALR levels in primary and metastatic HGSC samples have robust prognostic value linked to the activation of clinically-relevant innate and adaptive anticancer immune responses. [ABSTRACT FROM AUTHOR]

Malignant cells succumbing to some forms of radiation therapy are particularly immunogenic and hence can initiate a therapeutically relevant adaptive immune response. This reflects the intrinsic antigenicity of malignant cells (which often synthesize a high number of potentially reactive neo-antigens) coupled with the ability of radiation therapy to boost the adjuvanticity of cell death as it stimulates the release of endogenous adjuvants from dying cells. Thus, radiation therapy has been intensively investigated for its capacity to improve the therapeutic profile of several anticancer immunotherapies, including (but not limited to) checkpoint blockers, anticancer vaccines, oncolytic viruses, Toll-like receptor (TLR) agonists, cytokines, and several small molecules with immunostimulatory effects. Here, we summarize recent preclinical and clinical advances in this field of investigation. [ABSTRACT FROM PUBLISHER]