Editorial: Immunogenic Cell Death in Cancer: From Benchside Research to Bedside Reality

The "Immunoscore" in rectal cancer: could we search quality beyond quantity of life?

Because of the function and anatomical environment of the rectum, therapeutic strategies for local advanced rectal cancer (LARC) must deal with two challenging stressors that are a high-risk of local and distal recurrences and a high-risk of poor quality of life (QoL). Over the last three decades, advances in screening tests, therapies, and combined-modality treatment options and strategies have improved the prognosis of patients with LARC. However, owing to the heterogeneous nature of LARC and genetic status, the patient may not respond to a specific therapy and may be at increased risk of side-effects without the life-prolonging benefit. Indeed, each therapy can cause its own side-effects, which may worsen by a combination of treatments resulting in long-term poor QoL. In LARC, QoL has become even more essential with the increasing incidence of rectal cancer in young individuals. Herein, we analyzed the value of the Immunoscore-Biopsy (performed on tumor biopsy at diagnosis) in predicting outcomes, alone or in association with clinical and imaging data, for each therapy used in LARC.

Tumor-intrinsic determinants of immunogenic cell death modalities

The immune system can recognize tumor cells to mount antigen-specific T cell response. Central to the establishment of T cell-mediated adaptive immunity are the inflammatory events that facilitate antigen presentation by stimulating the expression of MHC and costimulatory molecules and the secretion of pro-inflammatory cytokines. Such inflammatory events can be triggered upon cytotoxic treatments that induce immunogenic cancer cell death modalities. However, cancers have acquired a plethora of mechanisms to subvert, or to hide from, host-encoded immunosurveillance. Here, we discuss how tumor intrinsic oncogenic factors subvert desirable intratumoral inflammation by suppressing immunogenic cell death.

Natural Compounds of Marine Origin as Inducers of Immunogenic Cell Death (ICD): Potential Role for Cancer Interception and Therapy

Regulated cell death (RCD) has always been considered a tolerogenic event. Immunogenic cell death (ICD) occurs as a consequence of tumour cell death accompanied by the release of damage-associated molecular patterns (DAMPs), triggering an immune response. ICD plays a major role in stimulating the function of the immune system in cancer during chemotherapy and radiotherapy. ICD can therefore represent one of the routes to boost anticancer immune responses. According to the recommendations of the Nomenclature Committee on Cell Death (2018), apoptosis (type I cell death) and necrosis (type II cell death) represent are not the only types of RCD, which also includes necroptosis, pyroptosis, ferroptosis and others. Specific downstream signalling molecules and death-inducing stimuli can regulate distinct forms of ICD, which develop and promote the immune cell response. Dying cells deliver different potential immunogenic signals, such as DAMPs, which are able to stimulate the immune system. The acute exposure of DAMPs can prime antitumour immunity by inducing activation of antigen-presenting cells (APC), such as dendritic cells (DC), leading to the downstream response by cytotoxic T cells and natural killer cells (NK). As ICD represents an important target to direct and develop new pharmacological interventions, the identification of bioactive natural products, which are endowed with low side effects, higher tolerability and preferentially inducing immunogenic programmed cell death, represents a priority in biomedical research. The ability of ICD to drive the immune response depends on two major factors, neither of which is intrinsic to cell death: ‘Antigenicity and adjuvanticity’. Indeed, the use of natural ICD-triggering molecules, alone or in combination with different (immuno)therapies, can result in higher efficacy and tolerability. Here, we focused on natural (marine) compounds, particularly on marine microalgae derived molecules such as exopolysaccharides, sulphated polysaccharides, glycopeptides, glycolipids, phospholipids, that are endowed with ICD-inducing properties and sulfavants. Here, we discuss novel and repurposed small-molecule ICD triggers, as well as their ability to target important molecular pathways including the IL-6, TNF-α and interferons (IFNs), leading to immune stimulation, which could be used alone or in combinatorial immunotherapeutic strategies in cancer prevention and therapies.

Nanoenabled Tumor Oxygenation Strategies for Overcoming Hypoxia-Associated Immunosuppression

Cancer immunotherapy, which initiates or strengthens innate immune responses to attack cancer cells, has shown great promise in cancer treatment. However, low immune response impacted by immunosuppressive tumor microenvironment (TME) remains a key challenge, which has been found related to tumor hypoxia. Recently, nanomaterial systems are proving to be excellent platforms for tumor oxygenation, which can reverse hypoxia-associated immunosuppression, strengthen the systemic antitumor immune responses, and thus afford a striking abscopal effect to clear metastatic cancer cells. In this review, we would like to survey recent progress in utilizing nanomaterials for tumor oxygenation through approaches such as in situ O₂ generation, O₂ delivery, tumor vasculature normalization, and mitochondrial-respiration inhibition. Their effects on tumor hypoxia-associated immunosuppression are highlighted. We also discuss the ongoing challenges and how to further improve the clinical prospect of cancer immunotherapy.

ZnO-based multifunctional nanocomposites to inhibit progression and metastasis of melanoma by eliciting antitumor immunity via immunogenic cell death

Rationale: The development of a highly effective and tumor-specific therapeutic strategy, which can act against the primary tumor and also condition the host immune system to eliminate distant tumors, remains a clinical challenge.

Methods: Herein, we demonstrate a facile yet versatile ZnO-capping and Doxorubicin (DOX)-loaded multifunctional nanocomposite (AuNP@mSiO₂@DOX-ZnO) that integrates photothermal properties of gold nanoparticles (NPs), pH-responsive properties and preferential selectivity to tumor cells of ZnO QDs and chemotherapeutic agent into a single NP. The photothermal performance, pH-triggered release and preferential phagocytic ability were assessed. The induced anti-tumor immunity was determined by analyzing immune cell profile in tumor in vivo and molecular mechanism were identified by detecting expression of immunogenic cell death (ICD) markers in vitro. Moreover, mice models of unilateral and bilateral subcutaneous melanoma and lung metastasis were established to evaluate the antitumor effects.

Results: As an efficient drug carrier, ZnO-capped NPs guarantee a high DOX payload and an in vitro, efficient release of at pH 5.0. In murine melanoma models, the nanocomposite can significantly inhibit tumor growth for a short period upon low-power laser irradiation. Importantly, ZnO NPs not only demonstrate preferential selectivity for melanoma cells but can also induce ICD. Meanwhile, AuNP@mSiO₂-based photothermal therapy (PTT) and DOX are directly cytotoxic towards cancer cells and demonstrate an elevated ICD effect. The induced ICD promotes maturation of dendritic cells, further stimulating the infiltration of effector T cells into tumor sites, preventing tumor growth and distant lung metastases.

Conclusions: This study highlights the novel mechanism of ZnO-triggered anti-tumor immunity via inducing ICD. Additionally, we shed light on the multifunctionality of nanocomposites in delivering localized skin tumor therapy as well as inhibiting metastatic growth, which holds great promise in clinical applications.

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.

Integration of immunogenic activation and immunosuppressive reversion using mitochondrial-respiration-inhibited platelet-mimicking nanoparticles

Here, we developed platelet membranes (PM) as nano-carriers to co-encapsulate metformin (Met) and IR780 (PM-IR780-Met NPs). The resulting nano-carrier ensured a longer circulation lifetime and facilitated the greater accumulation of IR780 and Met in tumors owing to the active adhesion between PM and tumor cells. As a photodynamic therapy (PDT) agent, IR780 could effectively kill the tumor by producing toxic reactive singlet oxygen species (ROS), while the introduction of Met inhibited mitochondrial respiration and reduced tumor oxygen consumption, thereby evoking an oxygen-boosted PDT and propelling the immunogenic cell death (ICD)-based immunogenic pathway. Meanwhile, the reversed tumor hypoxia also impeded the myeloid derived suppressor cell (MDSC)-regulated immunosuppressive pathway. Finally, tremendous T cells were recruited and activated, providing a promising platform to eliminate the primary tumors and synchronously opening a new avenue for the effective ablation of tumor metastasis.

Combinational phototherapy and hypoxia-activated chemotherapy favoring antitumor immune responses

Background: Tumor metastasis is responsible for most cancer death worldwide, which lacks curative treatment.

Purpose: The objective of this study was to eliminate tumor and control the development of tumor metastasis.

Methods: Herein, we demonstrated a smart nano-enabled platform, in which 2-[2-[2-chloro-3-[(1,3-dihydro-3,3-dimethyl-1-propyl-2h-indol-2-ylidene)ethylidene]-1-cyclohexen-1-yl]ethenyl]-3,3-dimethyl-1-propylindolium iodide (IR780) and tirapazamine (TPZ) were co-loaded in poly(ε-caprolactone)-poly(ethylene glycol) (PEG-PCL) to form versatile nanoparticles (PEG-PCL-IR780-TPZ NPs).

Results: The intelligence of the system was reflected in the triggered and controlled engineering. Specially, PEG-PCL not only prolonged the circulation time of IR780 and TPZ but also promoted tumor accumulation of nanodrugs through enhanced permeability and retention (EPR) effect. Moreover, reactive oxygen species (ROS) generated by IR780 armed by an 808 nm laser irradiation evoked a cargo release. Meanwhile, IR780, as a mitochondria-targeting phototherapy agent exacerbated tumor hypoxic microenvironment and activated TPZ for accomplishing hypoxia-activated chemotherapy. Most significantly, IR780 was capable of triggering immunogenic cell death (ICD) during the synergic treatment. ICD biomarkers as a “danger signal” accelerated dendritic cells (DCs) maturation, and subsequently activated toxic T lymphocytes.

Conclusion: Eventually, antitumor immune responses stimulated by combinational phototherapy and hypoxia-activated chemotherapy revolutionized the current landscape of cancer treatment, strikingly inhibiting tumor metastasis and providing a promising prospect in the clinical application.

Plasma-activated medium triggers cell death and the presentation of immune activating danger signals in melanoma and pancreatic cancer cells

Over the past decade, cold atmospheric plasmas have shown promising application in cancer therapy. The therapeutic use of plasma-activated media is a topic addressed in an emerging field known as plasma pharmacy. In oncology, plasma-activated media are  used to harness the therapeutic effects of oxidant species when they come in contact with cancer cells. Among several factors that contribute to the anticancer effect of plasma-activated liquid media (PALM), H₂O₂ and NO derivatives likely play a key role in the apoptotic pathway. Despite the significant amount of literature produced in recent years, a full understanding of the mechanisms by which PALM exert their activity against cancer cells is limited. In this paper, a sealed dielectric-barrier discharge was used to disentangle the effect of reactive nitrogen species (RNS) from that of reactive oxygen species (ROS) on cancer cells. Two cancers characterized by poor prognosis have been investigated: metastatic melanoma and pancreatic cancer. Both tumour models exposed to PALM rich in H₂O₂ showed a reduction in proliferation and an increase in calreticulin exposure and ATP release, suggesting the potential use of activated media as an inducer of immunogenic cell death via activation of the innate immune system.

Nanoparticle-Mediated Trapping of Wnt Family Member 5A in Tumor Microenvironments Enhances Immunotherapy for B-Raf Proto-Oncogene Mutant Melanoma

Development of an effective treatment against advanced tumors remains a major challenge for cancer immunotherapy. Approximately 50% of human melanoma is driven by B-Raf proto-oncogene mutation (BRAF mutant). Tumors with such mutation are desmoplastic, highly immunosuppressive, and often resistant to immune checkpoint therapies. We have shown that immunotherapy mediated by low-dose doxorubicin-induced immunogenic cell death was only partially effective for this type of tumor and not effective in long-term inhibition of tumor progression. Wnt family member 5A (Wnt5a), a signaling protein highly produced by BRAF mutant melanoma cells, has been implicated in inducing dendritic cell tolerance and tumor fibrosis, thus hindering effective antigen presentation and T-cell infiltration. We hypothesized that Wnt5a is a key molecule controlling the immunosuppressive tumor microenvironment in metastatic melanoma. Accordingly, we have designed and generated a trimeric trap protein, containing the extracellular domain of Fizzled 7 receptor that binds Wnt5a with a K_d ∼ 278 nM. Plasmid DNA encoding for the Wnt5a trap was delivered to the tumor by using cationic lipid-protamine-DNA nanoparticles. Expression of Wnt5a trap in the tumor, although transient, was greater than that of any other major organs including liver, resulting in a significant reduction of the Wnt5a level in the tumor microenvironment without systematic toxicity. Significantly, combination of Wnt5a trapping and low-dose doxorubicin showed great tumor growth inhibition and host survival prolongation. Our findings indicated that efficient local Wnt5a trapping significantly remodeled the immunosuppressive tumor microenvironment to facilitate immunogenic cell-death-mediated immunotherapy.

Generation of potent cytotoxic T lymphocytes against in male patients with non-muscle invasive bladder cancer by dendritic cells loaded with dying T24 bladder cancer cells

Background

In order to induce a potent cytotoxic T lymphocyte (CTL) response in dendritic cell (DC)-based immunotherapy for bladder cancer, various tumor antigens can be loaded onto DCs.

Objective

The aim of this study was to establish a method of immunotherapy for male patients with non-muscle invasive bladder cancer (NMIBC), using bladder cancer-specific CTLs generated in vitro by DCs.

Materials and Methods

Monocyte-derived DCs from bladder cancer patients were induced to mature in a standard cytokine cocktail (IL-1β, TNF-α, IL-6, and PGE₂: standard DCs, sDCs) or anα-type 1-polarized DC (αDC1) cocktail (IL-1β, TNF-α, IFN-α, IFN-γ, and polyinosinic:polycytidylic acid) and loaded with the UVB-irradiated bladder cancer cell line, T24. Antigen-loaded αDC1s were evaluated by morphological and functional assays, and the bladder cancer-specific CTL response was analyzed by cytotoxic assay.

Results

The αDC1s significantly increased the expression of several molecules pertaining to DC maturation, regardless of whether or not the αDC1s were loaded with tumor antigens, relative to sDCs. The αDC1s demonstrated increased production of interleukin-12 both during maturation and after subsequent stimulation with CD40L that was not significantly affected by loading with tumor antigens as compared to that of sDCs. Bladder cancer-specific CTLs targeting autologous bladder cancer cells were successfully induced by αDC1s loaded with dying T24 cells.

Conclusion

Autologous αDC1s loaded with an allogeneic bladder cancer cell line resulted in increased bladder cancer-specific CTL responses as compared to that with sDCs, and therefore, may provide a novel source of DC-based vaccines that canbe used in immunotherapy for male patients with NMIBC.

Trial watch: Immunogenic cell death induction by anticancer chemotherapeutics

The expression "immunogenic cell death" (ICD) refers to a functionally unique form of cell death that facilitates (instead of suppressing) a T cell-dependent immune response specific for dead cell-derived antigens. ICD critically relies on the activation of adaptive responses in dying cells, culminating with the exposure or secretion of immunostimulatory molecules commonly referred to as "damage-associated molecular patterns". Only a few agents can elicit bona fide ICD, including some clinically established chemotherapeutics such as doxorubicin, epirubicin, idarubicin, mitoxantrone, bleomycin, bortezomib, cyclophosphamide and oxaliplatin. In this Trial Watch, we discuss recent progress on the development of ICD-inducing chemotherapeutic regimens, focusing on studies that evaluate clinical efficacy in conjunction with immunological biomarkers.