Targeted APC Activation in Cancer Immunotherapy to Enhance the Abscopal Effect

Regulation of eukaryotic transcription initiation in response to cellular stress

Transcription initiation is a vital step in the regulation of eukaryotic gene expression. It can be dysregulated in response to various cellular stressors which is associated with numerous human diseases including cancer. Transcription initiation is facilitated via many gene-specific trans-regulatory elements such as transcription factors, activators, and coactivators through their interactions with transcription pre-initiation complex (PIC). These trans-regulatory elements can uniquely facilitate PIC formation (hence, transcription initiation) in response to cellular nutrient stress. Cellular nutrient stress also regulates the activity of other pathways such as target of rapamycin (TOR) pathway. TOR pathway exhibits distinct regulatory mechanisms of transcriptional activation in response to stress. Like TOR pathway, the cell cycle regulatory pathway is also found to be linked to transcriptional regulation in response to cellular stress. Several transcription factors such as p53, C/EBP Homologous Protein (CHOP), activating transcription factor 6 (ATF6α), E2F, transforming growth factor (TGF)-β, Adenomatous polyposis coli (APC), SMAD, and MYC have been implicated in regulation of transcription of target genes involved in cell cycle progression, apoptosis, and DNA damage repair pathways. Additionally, cellular metabolic and oxidative stressors have been found to regulate the activity of long non-coding RNAs (lncRNA). LncRNA regulates transcription by upregulating or downregulating the transcription regulatory proteins involved in metabolic and cell signaling pathways. Numerous human diseases, triggered by chronic cellular stressors, are associated with abnormal regulation of transcription. Hence, understanding these mechanisms would help unravel the molecular regulatory insights with potential therapeutic interventions. Therefore, here we emphasize the recent advances of regulation of eukaryotic transcription initiation in response to cellular stress.

Pulsed Photothermal Therapy of Solid Tumors as a Precondition for Immunotherapy

Photothermal therapy (PTT) refers to the use of plasmonic nanoparticles to convert electromagnetic radiation in the near infrared region to heat and kill tumor cells. Continuous wave lasers have been used clinically to induce PTT, but the treatment is associated with heat-induced tissue damage that limits usability. Here, the engineering and validation of a novel long-pulsed laser device able to induce selective and localized mild hyperthermia in tumors while reducing the heat affected zone and unwanted damage to surrounding tissue are reported. Long-pulsed PTT induces acute necrotic cell death in heat affected areas and the release of tumor associated antigens. This antigen release triggers maturation and stimulation of CD80/CD86 in dendritic cells in vivo that primes a cytotoxic T cell response. Accordingly, long-pulsed PTT enhances the therapeutic effects of immune checkpoint inhibition and increases survival of mice with bladder cancer. Combined, the data promote long-pulsed PTT as a safe and effective strategy for enhancing therapeutic responses to immune checkpoint inhibitors while minimizing unwanted tissue damage.

Plasmacytoid dendritic cells mediate CpG-ODN induced increase in survival in a mouse model of lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a devastating disease primarily found in women of reproductive age that leads to cystic destruction of the lungs. Recent work has shown that LAM causes immunosuppression and that checkpoint inhibitors can be used as LAM treatment. Toll-like receptor (TLR) agonists can also re-activate immunity and the TLR9 agonist, CpG-ODN, has been effective in treating lung cancer in animal models. Here we investigate the use of TLR9 agonist CpG-ODN as LAM immunotherapy in combination with checkpoint inhibitor, anti-PD1, standard of care rapamycin and determine the immune mechanisms underlying therapeutic efficacy. We used survival studies, flow cytometry, ELISA, and histology to assess immune response and survival after intranasal treatment with CpG-ODN in combination with rapamycin or anti-PD1 therapy in a mouse model of metastatic LAM. We found that local administration of CpG-ODN enhances survival in a mouse model of LAM. We found that a lower dose led to longer survival likely due to fewer local side effects but increased LAM nodule count and size compared to the higher dose. CpG-ODN treatment also reduced regulatory T cells and increased the number of Th17 helper T cells as well as cytotoxic T cells. These effects appear to be mediated in part by plasmacytoid dendritic cells (pDCs), as depletion of pDCs reduces survival and abrogates Th17 T cell response. Finally, we found that CpG-ODN treatment is effective in early stage and progressive disease and is additive with anti-PD1 therapy and rapamycin. In summary, we have found that TLR9 agonist CpG-ODN can be used as LAM immunotherapy and effectively synergizes with rapamycin and anti-PD1 therapy in LAM.

Immunogenicity of radiotherapy on bone metastases from prostate adenocarcinoma: What is the future for the combination with radiotherapy/immunotherapy?

Bone metastatic prostate cancers (PCa) are resistant to usual immunotherapies such as checkpoint inhibitors. The main hypothesis related to this immunoresistance is the lack of antigens to stimulate anti-tumor immunity. External radiation is a potential inducer antigens presentation and thus to immunotherapy proprieties. The aim of this review is to describe the tumor microenvironment specificities, especially in bone metastasis and the immune modifications after radiation therapy on a metastatic castration-resistant PCa population. PCa microenvironment is immunosuppressive because of many tumor factors. The complex interplay between PCa cells and bone microenvironment leads to a 'vicious circle' promoting bone metastasis. Furthermore, the immune and bone systems, are connected through an osteoclastogenic cytokine: the Receptor Activator Nuclear Factor Kappa B ligand. Adapted doses of ionizing radiation play a dual role on the tumor. Indeed, radiotherapy leads to immunogenicity by inducing damage associated with molecular patterns. However, it also induces an immunosuppressive effect by increasing the number of immunosuppressive cells. Interestingly, the abscopal effect could be used to optimize immunotherapy potential, especially on bone metastasis. Radiotherapy and immunotherapy combination is a promising strategy, however further studies are necessary to determine the more efficient types of radiation and to control the abscopal effect.

Nanotechnology-enhanced radiotherapy and the abscopal effect: Current status and challenges of nanomaterial-based radio-immunotherapy

Rare but consistent reports of abscopal remission in patients challenge the notion that radiotherapy (RT) is a local treatment; radiation-induced cancer cell death can trigger activation and recruitment of dendritic cells to the primary tumor site, which subsequently initiates systemic immune responses against metastatic lesions. Although this abscopal effect was initially considered an anomaly, combining RT with immune checkpoint inhibitor therapies has been shown to greatly improve the incidence of abscopal responses via modulation of the immunosuppressive tumor microenvironment. Preclinical studies have demonstrated that nanomaterials can further improve the reliability and potency of the abscopal effect for various different types of cancer by (1) altering the cell death process to be more immunogenic, (2) facilitating the capture and transfer of tumor antigens from the site of cancer cell death to antigen-presenting cells, and (3) co-delivering immune checkpoint inhibitors along with radio-enhancing agents. Several unanswered questions remain concerning the exact mechanisms of action for nanomaterial-enhanced RT and for its combination with immune checkpoint inhibition and other immunostimulatory treatments in clinically relevant settings. The purpose of this article is to summarize key recent developments in this field and also highlight knowledge gaps that exist in this field. An improved mechanistic understanding will be critical for clinical translation of nanomaterials for advanced radio-immunotherapy. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Cancer vaccine strategies for the treatment of diffusely infiltrating gliomas

Diffusely infiltrating gliomas - including glioblastoma (GBM), isocitrate dehydrogenase (IDH) mutant gliomas, and histone 3 (H3) altered gliomas - are primary brain tumors with an invariably fatal outcome. Despite advances in the understanding of their biology, standard, targeted and immune checkpoint inhibitor immunotherapies have proven ineffective in arresting their inexorable progression and associated morbidity and mortality. Recognizing the unique aspects of the immunogenicity of cancer cells, the last decade has seen the development and evaluation of vaccine-based therapies for the treatment of solid tumors, including gliomas. Here we review the current vaccine strategies for the treatment of GBM, IDH-mutant gliomas and diffuse midline glioma H3 K27M-altered. We discuss potential benefits and challenges of vaccine therapies in these specific patient populations.

Combination Therapy as a Promising Way to Fight Oral Cancer

Oral cancer is a highly aggressive tumor with invasive properties that can lead to metastasis and high mortality rates. Conventional treatment strategies, such as surgery, chemotherapy, and radiation therapy, alone or in combination, are associated with significant side effects. Currently, combination therapy has become the standard practice for the treatment of locally advanced oral cancer, emerging as an effective approach in improving outcomes. In this review, we present an in-depth analysis of the current advancements in combination therapies for oral cancer. The review explores the current therapeutic options and highlights the limitations of monotherapy approaches. It then focuses on combinatorial approaches that target microtubules, as well as various signaling pathway components implicated in oral cancer progression, namely, DNA repair players, the epidermal growth factor receptor, cyclin-dependent kinases, epigenetic readers, and immune checkpoint proteins. The review discusses the rationale behind combining different agents and examines the preclinical and clinical evidence supporting the effectiveness of these combinations, emphasizing their ability to enhance treatment response and overcome drug resistance. Challenges and limitations associated with combination therapy are discussed, including potential toxicity and the need for personalized treatment approaches. A future perspective is also provided to highlight the existing challenges and possible resolutions toward the clinical translation of current oral cancer therapies.

The abscopal effect in patients with cancer receiving immunotherapy

Interest in the abscopal effect has been rekindled over the past decade with the advent of immunotherapy. Although purportedly elusive, this phenomenon is being increasingly reported. Venturing further using a multimodality approach with an array of systemic agents and unconventional modalities is direly needed. In this perspective, we describe the fundamentals of abscopal responses (ARs), explore combinations with systemic therapies that hold promise in eliciting ARs, and reconnoiter unconventional modalities that may induce ARs. Finally, we scrutinize prospective agents and modalities that exhibit preclinical ability to elicit ARs and discuss prognostic biomarkers, their limitations, and pathways of abscopal resistance for reproducibility.

BSA-AIE Nanoparticles with Boosted ROS Generation for Immunogenic Cell Death Immunotherapy of Multiple Myeloma

The main obstacle of multiple myeloma (MM) therapy is the compromised immune microenvironment, which leads to MM relapses and extramedullary disease progression. In this study, a novel strategy is reported of enhanced immunogenic cell death (ICD) immunotherapy with aggregation-induced emission (AIE) photosensitizer-loaded bovine serum albumin (BSA) nanoparticles (referred as BSA/TPA-Erdn), which can activate T cells, convert the cold tumor to hot, and reverse T cell senescence to restore the immune microenvironment for MM treatment. Loading AIE photosensitizer into the hydrophobic domain of BSA proteins significantly immobilizes the molecular geometry, which massively increases reactive oxygen species (ROS) generation and elicits a promising ICD immune response. Employing a NOD-SCID IL-2receptor gamma null mice model with MM patients' monocytes, it is shown that BSA/TPA-Erdn can simulate human dentric cell maturation, activate functional T lymphocytes, and increase additional polarization and differentiation signals to deliver a promising immunotherapy performance. Intriguingly, for the first time, it is shown that BSA/TPA-Erdn can greatly reverse T cell senescence, a main challenge in treating MM. Additionally, BSA/TPA-Erdn can effectively recruit more functional T lymphocytes into MM tumor. As a consequence, BSA/TPA-Erdn restores MM immune microenvironment and shows the best MM tumor eradication performance, which shall pave new insights for MM treatment in clinical practices.

Macrophage activity at the site of tumor ablation can promote murine urothelial cancer via transforming growth factor-β1

Cell death and injury at the site of tumor ablation attracts macrophages. We sought to understand the status and activity of these cells while focusing on transforming growth factor-β1 (TGF-β1), a potent immunosuppressive and tumorigenic cytokine. Patients with urothelial cancer who underwent ablation using electrocautery or laser demonstrated increased infiltration and numbers of CD8+ T cells, along with FoxP3+ regulatory T cells, CD68+ macrophages and elevated levels of TGF-β1 in recurrent tumors. Similar findings were reproduced in a mouse model of urothelial cancer (MB49) by partial tumor ablation with irreversible electroporation (IRE). Stimulation of bone marrow derived macrophages with MB49 cell debris produced using IRE elicited strong M2 polarization, with exuberant secretion of TGF-β1. The motility, phenotypic markers and cytokine secretion by macrophages could be muted by treatment with Pirfenidone (PFD), a clinically approved drug targeting TGF-β1 signaling. MB49 cancer cells exposed to TGF-β1 exhibited increased migration, invasiveness and upregulation of epithelial-mesenchymal transition markers α-Smooth Muscle Actin and Vimentin. Such changes in MB49 cells were reduced by treatment with PFD even during stimulation with TGF-β1. IRE alone yielded better local tumor control when compared with control or PFD alone, while also reducing the overall number of lung metastases. Adjuvant PFD treatment did not provide additional benefit under in vivo conditions.

Oncolytic virus-based hepatocellular carcinoma treatment: Current status, intravenous delivery strategies, and emerging combination therapeutic solutions

Current treatments for advanced hepatocellular carcinoma (HCC) have limited success in improving patients' quality of life and prolonging life expectancy. The clinical need for more efficient and safe therapies has contributed to the exploration of emerging strategies. Recently, there has been increased interest in oncolytic viruses (OVs) as a therapeutic modality for HCC. OVs undergo selective replication in cancerous tissues and kill tumor cells. Strikingly, pexastimogene devacirepvec (Pexa-Vec) was granted an orphan drug status in HCC by the U.S. Food and Drug Administration (FDA) in 2013. Meanwhile, dozens of OVs are being tested in HCC-directed clinical and preclinical trials. In this review, the pathogenesis and current therapies of HCC are outlined. Next, we summarize multiple OVs as single therapeutic agents for the treatment of HCC, which have demonstrated certain efficacy and low toxicity. Emerging carrier cell-, bioengineered cell mimetic- or nonbiological vehicle-mediated OV intravenous delivery systems in HCC therapy are described. In addition, we highlight the combination treatments between oncolytic virotherapy and other modalities. Finally, the clinical challenges and prospects of OV-based biotherapy are discussed, with the aim of continuing to develop a fascinating approach in HCC patients.

Therapy-induced modulation of extracellular vesicles in hepatocellular carcinoma

Despite rapid development of anti-tumorigenic treatments, the clinical outcome for hepatocellular carcinoma (HCC) is still far from satisfactory. With a deeper understanding about tumor microenvironment (TME), the critical role of extracellular vesicles (EVs) as intercellular liaison has come into spotlight. The dynamic functionality of these nanoparticles revealed cancer cells can employ both tumor and non-tumorous components for their own benefit, so as to mediate cell-to-cell communication and interchange of oncogenic biomolecules. Increasing studies on HCC-derived EVs have identified various irregulated biomolecules, that may serve as biomarkers or therapeutic targets. In this review, we first introduce the current knowledge about EVs and how they operate to maintain a healthy liver microenvironment. We then summarize some of the aberrant observations reported on HCC-derived EVs and how they contribute to HCC pathogenesis. Finally, we describe how current treatments for HCC alter behavior of EVs, which may shed light for potential prognostic markers and therapeutic strategies.

Engineered nanomaterials trigger abscopal effect in immunotherapy of metastatic cancers

Despite advances in cancer treatment, metastatic cancer is still the main cause of death in cancer patients. At present, the treatment of metastatic cancer is limited to palliative care. The abscopal effect is a rare phenomenon in which shrinkage of metastatic tumors occurs simultaneously with the shrinkage of a tumor receiving localized treatment, such as local radiotherapy or immunotherapy. Immunotherapy shows promise for cancer treatment, but it also leads to consequences such as low responsiveness and immune-related adverse events. As a promising target-based approach, intravenous or intratumoral injection of nanomaterials provides new opportunities for improving cancer immunotherapy. Chemically modified nanomaterials may be able to trigger the abscopal effect by regulating immune cells. This review discusses the use of nanomaterials in killing metastatic tumor cells through the regulation of immune cells and the prospects of such nanomaterials for clinical use.

Tumor Cell-Surface Binding of Immune Stimulating Polymeric Glyco-Adjuvant via Cysteine-Reactive Pyridyl Disulfide Promotes Antitumor Immunity

Immune stimulating agents like Toll-like receptor 7 (TLR7) agonists induce potent antitumor immunity but are limited in their therapeutic window due to off-target immune activation. Here, we developed a polymeric delivery platform that binds excess unpaired cysteines on tumor cell surfaces and debris to adjuvant tumor neoantigens as an in situ vaccine. The metabolic and enzymatic dysregulation in the tumor microenvironment produces these exofacial free thiols, which can undergo efficient disulfide exchange with thiol-reactive pyridyl disulfide moieties upon intratumoral injection. These functional monomers are incorporated into a copolymer with pendant mannose groups and TLR7 agonists to target both antigen and adjuvant to antigen presenting cells. When tethered in the tumor, the polymeric glyco-adjuvant induces a robust antitumor response and prolongs survival of tumor-bearing mice, including in checkpoint-resistant B16F10 melanoma. The construct additionally reduces systemic toxicity associated with clinically relevant small molecule TLR7 agonists.

Coming in from the cold: overcoming the hostile immune microenvironment of medulloblastoma

Medulloblastoma is an aggressive brain tumor that occurs predominantly in children. Despite intensive therapy, many patients die of the disease, and novel therapies are desperately needed. Although immunotherapy has shown promise in many cancers, the low mutational burden, limited infiltration of immune effector cells, and immune-suppressive microenvironment of medulloblastoma have led to the assumption that it is unlikely to respond to immunotherapy. However, emerging evidence is challenging this view. Here we review recent preclinical and clinical studies that have identified mechanisms of immune evasion in medulloblastoma, and highlight possible therapeutic interventions that may give new hope to medulloblastoma patients and their families.

Targeting WEE1/AKT restores p53-dependent NK cell activation to induce immune checkpoint blockade responses in 'cold' melanoma

Immunotherapy has revolutionized cancer treatment. Unfortunately, most tumor types do not respond to immunotherapy due to a lack of immune infiltration or 'cold' tumor microenvironment (TME), a contributing factor in treatment failure. Activation of the p53 pathway can increase apoptosis of cancer cells, leading to enhanced antigen presentation, and can stimulate natural killer (NK) cells through expression of stress ligands. Therefore, modulation of the p53 pathway in cancer cells with wildtype TP53 has the potential to enhance tumor immunogenicity to NK cells, produce an inflammatory TME, and ultimately lead to tumor regression. In this study, we report simultaneous targeting of the AKT/WEE1 pathways is a novel and tolerable approach to synergistically induce p53 activation to inhibit tumor development. This approach reduced the growth of melanoma cells and induced plasma membrane surface localization of the ER-resident protein calreticulin, an indicator of immunogenic cell death (ICD). Increase in ICD led to enhanced expression of stress ligands recognized by the activating NK cell receptor NKG2D, promoting tumor lysis. WEE1/AKT inhibition resulted in recruitment and activation of immune cells, including NK cells, in the TME, triggering an inflammatory cascade that transformed the 'cold' TME of B16F10 melanoma into a 'hot' TME that responded to anti-PD-1, resulting in complete regression of established tumors. These results suggest that AKT/WEE1 pathway inhibition is a potential approach to broaden the utility of class-leading anti-PD-1 therapies by enhancing p53-mediated, NK cell-dependent tumor inflammation and supports the translation of this novel approach to further improve response rates for metastatic melanoma.

B cells imprint adoptively transferred CD8+ T cells with enhanced tumor immunity

BACKGROUND

Adoptive T cell transfer (ACT) therapy improves outcomes in patients with advanced malignancies, yet many individuals relapse due to the infusion of T cells with poor function or persistence. Toll-like receptor (TLR) agonists can invigorate antitumor T cell responses when administered directly to patients, but these responses often coincide with toxicities. We posited that TLR agonists could be repurposed ex vivo to condition T cells with remarkable potency in vivo, circumventing TLR-related toxicity.

METHODS

In this study we investigated how tumor-specific murine CD8+ T cells and human tumor infiltrating lymphocytes (TILs) are impacted when expanded ex vivo with the TLR9 agonist CpG.

RESULTS

Herein we reveal a new way to reverse the tolerant state of adoptively transferred CD8+ T cells against tumors using TLR-activated B cells. We repurposed the TLR9 agonist, CpG, commonly used in the clinic, to bolster T cell-B cell interactions during expansion for ACT. T cells expanded ex vivo from a CpG-treated culture demonstrated potent antitumor efficacy and prolonged persistence in vivo. This antitumor efficacy was accomplished without in vivo administration of TLR agonists or other adjuvants of high-dose interleukin (IL)-2 or vaccination, which are classically required for effective ACT therapy. CpG-conditioned CD8+ T cells acquired a unique proteomic signature hallmarked by an IL-2RαhighICOShighCD39low phenotype and an altered metabolic profile, all reliant on B cells transiently present in the culture. Likewise, human TILs benefitted from expansion with CpG ex vivo, as they also possessed the IL-2RαhighICOShighCD39low phenotype. CpG fostered the expansion of potent CD8+ T cells with the signature phenotype and antitumor ability via empowering a direct B-T cell interaction. Isolated B cells also imparted T cells with the CpG-associated phenotype and improved tumor immunity without the aid of additional antigen-presenting cells or other immune cells in the culture.

CONCLUSIONS

Our results demonstrate a novel way to use TLR agonists to improve immunotherapy and reveal a vital role for B cells in the generation of potent CD8+ T cell-based therapies. Our findings have immediate implications in the clinical treatment of advanced solid tumors.

Extracellular Vesicles in Lung Cancer Metastasis and Their Clinical Applications

Extracellular vesicles (EVs) are heterogenous membrane-encapsulated vesicles secreted by every cell into the extracellular environment. EVs carry bioactive molecules, including proteins, lipids, DNA, and different RNA forms, which can be internalized by recipient cells, thus altering their biological characteristics. Given that EVs are commonly found in most body fluids, they have been widely described as mediators of communication in several physiological and pathological processes, including cancer. Moreover, their easy detection in biofluids makes them potentially useful candidates as tumor biomarkers. In this manuscript, we review the current knowledge regarding EVs and non-coding RNAs and their role as drivers of the metastatic process in lung cancer. Furthermore, we present the most recent applications for EVs and non-coding RNAs as cancer therapeutics and their relevance as clinical biomarkers.

Application of Immunotherapy in Hepatocellular Carcinoma

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

Effect of Cellular-Based Artificial Antigen Presenting Cells Expressing ICOSL, in T-cell Subtypes Differentiation and Activation

Purposes: Effective and selective T-cell activation and proliferation during the T-cell expansion phase of a cellular adoptive immunotherapy method, challenging because recent studies revealed the importance of each subtype of T-cells in different immunologic strategies against tumors, like CAR-T cell therapies. Artificial antigen presenting cells (aAPCs) regarded as a natural way to manipulate T-cell subtypes activation and specific proliferation. In the current study, we utilized K562 cells based aAPC method expressing the ICOSL molecule, to evaluate T-cell subtypes differentiation rate and functional status. Methods: CD3+T-cells isolated and, co-cultured with ICOSL expressing K562 cells. After 4, 6, and 10 days selective CD markers of T-cell subtypes and each subtype's activity-related genes levels evaluated by qPCR methods. Results: During the culture period, CD4+ Th related phenotype reduced continuously, and in day 10^th of culture CD4+ T-cell's population significantly reduced (P =0.029). In contrast, the CD8+ population ratio was ascending during the study period but was not statistically significant. FoxP3+CD25-, Treg population ratio was significantly increased during the time in comparison with the control group, as well as memory T-cell phenotypic marker, CD127+, expressing cells ratio. T-cell subpopulations activity-related genes expression levels evaluated too, and the Th1 related IL-2 and INF-γ reductions observed alongside regulatory T-cells gene (IL-10) and Cytotoxic T-cell's related gene (Geranzym-A) elevations. Conclusion: We concluded that the K562-ICOSL based aAPC system is working and effective in T-cell short to medium culture periods, and this approach preparing relatively selective milieu for CD8+ T-Cell differentiation and much less Treg differentiation.

A Combined TLR7/TLR9/GATA3 Score Can Predict Prognosis in Biliary Tract Cancer

Biliary tract cancer (BTC) refers to a heterogenous group of epithelial malignancies arising along the biliary tree. The highly aggressive nature combined with its silent presentation contribute to the dismal prognosis of this tumor. Tumor-infiltrating immune cells (TIICs) are frequently present in BTC and there is growing evidence regarding their role as therapeutic targets. In this study, we analyzed the immune cell infiltration in BTC and developed a promising immune signature score to predict prognosis in BTC. Immunohistochemistry (IHC) was carried out on tissue microarray sections from 45 patients with resectable cholangiocarcinoma for the detection of 6-sulfoLacNAc+ monocytes (slanMo), BDCA-2+ plasmacytoid dendritic cells (pDC), CD8+ or CD4+T-lymphocytes, CD103+ cells, GATA3+ cells, Toll-like receptor (TLR) 3, 7 and 9-expressing cells as well as programmed cell death protein 1 and programmed cell death ligand 1 positive cells. Data from the IHC staining were analyzed and correlated with clinicopathological and survival data. High expression of TLR7, TLR9, and GATA3 was associated with improved overall survival (OS, Log-rank p < 0.05). In addition, TLR9 was associated with better disease-free survival (Log-rank p < 0.05). In the multivariate Cox proportional-hazards model for OS, the TLR/TLR9/GATA3 score was found to be an independent prognostic factor for OS (“Score 2” vs. “Score 0”: HR 11.17 95% CI 2.27–54.95, p < 0.01).

Valproic acid triggers radiation-induced abscopal effect by modulating the unirradiated tumor immune microenvironment in a rat model of breast cancer

An abscopal effect occurs when localized radiotherapy causes the regression of tumors distant from the irradiated site. However, such a clinically detectable abscopal effect from radiotherapy alone is rare. This study investigated whether valproic acid ([VPA], a histone deacetylase inhibitor [HDACi]) treatment can stimulate radiation-induced abscopal effect. We used 7,12-dimethylbenz[a]anthracene, a typical environmental carcinogen, to establish a rat model with multiple breast tumors. Only one tumor received 8 Gy fractionated doses of X-rays (2 Gy daily fractions over four days) and 200 mg/kg VPA was administered intraperitoneally. We monitored the growth of both irradiated and unirradiated tumors after treatments. The unirradiated tumor was collected for hematoxylin and eosin (HE) staining, immunohistochemistry (IHC) (CD8, Granzyme B, Cleaved Caspase-3, BrdU, Ki67, F4/80 and CD68), double immunofluorescence (F4/80 and CD86), Western blot (Cleaved Caspase-3) and qRT-PCR (CD86, CD163, IL-1β, IL-6, IL-12, IL-23, IL-10, TGF-β) analysis. We found ionizing radiation (IR) + VPA treatment inhibited both irradiated and unirradiated tumor growth as compared to IR alone. Such observe abscopal effect was mediated by the recruitment of activated CD8+ T cells into the unirradiated tumor sites, which released Granzyme B to cause tumor cell apoptosis. Furthermore, IR + VPA treatment led to macrophages infiltration into the unirradiated tumor sites and polarization to M1 phenotype, resulted in increased levels of pro-inflammatory cytokines such as IL-1β and IL-12, and decreased levels of anti-inflammatory cytokines such as IL-10 and TGF-β. Our data supports the proposition that VPA may be a potential therapeutic candidate to trigger radiation-induced abscopal effect by modulating the unirradiated tumor immune microenvironment.

The Role of Tumor-Derived Exosomes in the Abscopal Effect and Immunotherapy

Exosomes are microvesicles that can be secreted by various cells and carry a variety of contents; thus, they play multiple biological functions. For instance, the tumor-derived exosomes (TEXs) have been proven to have the effect of immunostimulatory in addition to immunosuppression, making TEXs attractive in clinical immunotherapy and targeted therapy for cancer patients. In addition, TEXs as biomarkers have important clinical diagnostic and prognostic value. Recently, TEXs have been recognized to play important roles in the abscopal effect (AbE), a newly discovered mechanism by which the distant tumors are effectively targeted and repressed during immunotherapy and radiotherapy. Therefore, TEXs has demonstrated great clinical potential in the diagnosis, prognosis and treatment of cancer patients in the future. This review summarizes and discusses the role of TEXs in clinical therapy and their role in AbE in recent studies.

Pathogenetic Features and Current Management of Glioblastoma

Glioblastoma (GBM) is the most common form of primary malignant brain tumor with a devastatingly poor prognosis. The disease does not discriminate, affecting adults and children of both sexes, and has an average overall survival of 12-15 months, despite advances in diagnosis and rigorous treatment with chemotherapy, radiation therapy, and surgical resection. In addition, most survivors will eventually experience tumor recurrence that only imparts survival of a few months. GBM is highly heterogenous, invasive, vascularized, and almost always inaccessible for treatment. Based on all these outstanding obstacles, there have been tremendous efforts to develop alternative treatment options that allow for more efficient targeting of the tumor including small molecule drugs and immunotherapies. A number of other strategies in development include therapies based on nanoparticles, light, extracellular vesicles, and micro-RNA, and vessel co-option. Advances in these potential approaches shed a promising outlook on the future of GBM treatment. In this review, we briefly discuss the current understanding of adult GBM's pathogenetic features that promote treatment resistance. We also outline novel and promising targeted agents currently under development for GBM patients during the last few years with their current clinical status.

SQ3370 Activates Cytotoxic Drug via Click Chemistry at Tumor and Elicits Sustained Responses in Injected & Non-injected Lesions

While systemic immuno-oncology therapies have shown remarkable success, only a limited subset of patients benefit from them. Our Click Activated Protodrugs Against Cancer (CAPAC™) Platform is a click chemistry-based approach that activates cancer drugs at a specific tumor with minimal systemic toxicity. CAPAC Platform is agnostic to tumor characteristics that can vary across patients and hence applicable to several types of tumors. We describe the benefits of SQ3370 (lead candidate of CAPAC) to achieve systemic anti-tumor responses in mice bearing two tumors. SQ3370 consists of a biopolymer, injected in a single lesion, followed by systemic doses of an attenuated protodrug™ of doxorubicin (Dox). SQ3370 was well-tolerated at 5.9-times the maximum dose of conventional Dox, increased survival by 63% and induced a systemic anti-tumor response against injected and non-injected lesions. The sustained anti-tumor response also correlated with immune activation measured at both lesions. SQ3370 could potentially benefit patients with micro-metastatic lesions.

Immunotherapy and Immunotherapy Combinations in Metastatic Castration-Resistant Prostate Cancer

Although most prostate cancers are localized, and the majority are curable, recurrences occur in approximately 35% of men. Among patients with prostate-specific antigen (PSA) recurrence and PSA doubling time (PSADT) less than 15 months after radical prostatectomy, prostate cancer accounted for approximately 90% of the deaths by 15 years after recurrence. An immunosuppressive tumor microenvironment (TME) and impaired cellular immunity are likely largely responsible for the limited utility of checkpoint inhibitors (CPIs) in advanced prostate cancer compared with other tumor types. Thus, for immunologically "cold" malignancies such as prostate cancer, clinical trial development has pivoted towards novel approaches to enhance immune responses. Numerous clinical trials are currently evaluating combination immunomodulatory strategies incorporating vaccine-based therapies, checkpoint inhibitors, and chimeric antigen receptor (CAR) T cells. Other trials evaluate the efficacy and safety of these immunomodulatory agents' combinations with standard approaches such as androgen deprivation therapy (ADT), taxane-based chemotherapy, radiotherapy, and targeted therapies such as tyrosine kinase inhibitors (TKI) and poly ADP ribose polymerase (PARP) inhibitors. Here, we will review promising immunotherapies in development and ongoing trials for metastatic castration-resistant prostate cancer (mCRPC). These novel trials will build on past experiences and promise to usher a new era to treat patients with mCRPC.

Eftilagimod alpha, a soluble lymphocyte activation gene-3 (LAG-3) protein plus pembrolizumab in patients with metastatic melanoma

BACKGROUND

To evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of eftilagimod alpha (efti), a soluble lymphocyte activation gene-3 protein, in combination with the programmed cell death-1 (PD-1) antagonist pembrolizumab.

METHODS

The study was divided into two parts; parts A and B, where part A was the dose escalation part and part B was an extension part of the study. Patients with metastatic melanoma were treated with efti plus the standard dose of pembrolizumab. Blood samples were assayed to determine plasma pharmacokinetic parameters, detect efti antibody formation and determine long-lived CD8 T cell responses and associated pharmacodynamic parameters.

RESULTS

Twenty-four patients with melanoma received pembrolizumab and bi-weekly subcutaneous (s.c.) injections of efti at doses 1 mg, 6 mg or 30 mg/injection for up to 6 months (part A) or 30 mg/injection for up 12 months (part B). No dose-limiting toxicities were reported and the main adverse event for efti was injection site reactions. Sustained systemic exposure to the product was obtained in all patients following s.c. injections of 30 mg dose. Treatment induced an increase in activated CD8 and CD4 T cell counts, and in some of the soluble biomarkers, particularly interferon (IFN)-γ, a Th1 signature cytokine. An overall response rate (ORR) of 33% was observed in patients partly with pembrolizumab-refractory of part A and ORR of 50% was observed in patients with PD-1 naïve of part B.

CONCLUSIONS

Efti was well tolerated in combination with pembrolizumab with encouraging antitumor activity. This warrants further clinical studies of this new combination therapy combining an antigen-presenting cell activator with an immune checkpoint inhibitor.

A review of radiation induced abscopal effect: combining radiotherapy and immunotherapy to treat the untreated distant metastatic tumours

Background:

Radiotherapy is an effective and significant mode of definitive cancer treatment with well-established local tumour control success, especially in the treatment of localised tumours. Although, for metastatic disease, the role of radiotherapy has generally been limited to palliation of symptoms. In the treatment of metastatic diseases settings, the radiation therapy technique has always been confronted with the challenge of the simultaneous treatment of all of the various distant metastatic tumour sites, however, some recent evidence suggests that radiotherapy can potentially induce anticancer immune responses whose effectors potentially migrate to distant metastatic tumours to provoke their regression in cancer patients. Thus, unirradiated distant metastatic tumour sites can exhibit a delayed therapeutic response termed the abscopal effect.

Materials and methods:

This paper reports on a review of the abscopal effect, including its biological mechanism, the effect of radiation dose and fractionation regime and the timing of immunotherapy administration on radiotherapy-induced abscopal effect, the enhancement of radiotherapy-induced abscopal effects with immunotherapy, the effect of the location of the irradiated tumour and the radiotherapy of multiple tumour sites on the likelihood and effectiveness of inducing abscopal responses in the preclinical and clinical settings and also reports on some evidence of clinical observations in patients.

Conclusions:

Although abscopal effects of radiotherapy are still relatively rare in patients, it has gained a lot of interest due to recent development and use of immunotherapy strategies incorporating combinations of targeted immunomodulators and immune checkpoint blockade with radiation therapy. The enhancement of cancer immunotherapy could potentially enable the translation of the concept of abscopal effect into the clinics as a new strategy to induce therapeutically effective anti-tumour immune responses in cancer patients. The combination of radiotherapy and immunotherapy has the potential to expand the role of radiotherapy from a purely local tumour control treatment to play a significant role in advanced and metastatic tumour control and this could likely lead to a paradigm shift in the treatment of patients with metastatic cancer.

Cationic Liposome/DNA Complexes Mediate Antitumor Immunotherapy by Promoting Immunogenic Tumor Cell Death and Dendritic Cell Activation

Immunotherapy has been successfully used in the treatment of multiple malignancies, but clinical studies revealed low response rates. Thus, the development of new effective immunotherapeutic modalities is urgently needed. Successfully inducing tumor cell death with enhanced antigenicity is important for the expansion and differentiation of tumor-specific CD8⁺ cytotoxic T lymphocytes. Cationic liposome/DNA complexes (CLN/DNA), which usually have obvious cytotoxic effects, may improve the antitumor immunity through enhancing the immunogenicity of dying tumor cells. Herein, we report that a plasmid DNA-encapsulated cationic lipid nanoparticle formulated with cholesterol, DOTAP, and DSPE-mPEG₂₀₀₀ significantly increases the tumor cell death with high antigenicity in vitro. Furthermore, the cationic liposome/DNA complex (CLN/DNA) treatment promotes the activation of dendritic cells (DCs). We also find that the intratumorally injected CLN/DNA successfully promoted the activation of DCs in the tumor-draining lymph node. Importantly, both local tumor growth and distant tumor formation were significantly inhibited by T cell-dependent antitumor immune responses after intratumoral injection of CLN/DNA. This study presents a simple and effective strategy for improving the cancer immunotherapy.

Adjuvant Effect of Toll-Like Receptor 9 Activation on Cancer Immunotherapy Using Checkpoint Blockade

Immunotherapy using checkpoint blockade has revolutionized cancer treatment, improving patient survival and quality of life. Nevertheless, the clinical outcomes of such immunotherapy are highly heterogeneous between patients. Depending on the cancer type, the patient response rates to this immunotherapy are limited to 20–30%. Based on the mechanism underlying the antitumor immune response, new therapeutic strategies have been designed with the aim of increasing the effectiveness and specificity of the antitumor immune response elicited by checkpoint blockade agents. The activation of toll-like receptor 9 (TLR9) by its synthetic agonists induces the antitumor response within the innate immunity arm, generating adjuvant effects and priming the adaptive immune response elicited by checkpoint blockade during the effector phase of tumor-cell killing. This review first describes the underlying mechanisms of action and current status of monotherapy using TLR9 agonists and immune checkpoint inhibitors for cancer immunotherapy. The rationale for combining these two agents is discussed, and evidence indicating the current status of such combination therapy as a novel cancer treatment strategy is presented.

Radiation-induced augmentation in dendritic cell function is mediated by apoptotic bodies/STAT5/Zbtb46 signaling

Purpose: To evaluate the effect of ionizing radiation (IR) exposure on differentiation and maturation of dendritic cells (DC).Materials and methods: Bone marrow progenitor cells irradiated in vitro or isolated from mice exposed to whole body or localized tumor irradiation were differentiated into DC. Phenotypic maturation of DC was characterized by labeling with specific antibodies and flow cytometry analysis. Cytokines were estimated by ELISA.Results: Splenic and bone marrow-derived DC (BMDC) from tumor-bearing mice exposed to localized irradiation showed abrogation of tumor-induced immunosuppression. This was not due to the effect of radiation on tumor cells as DC derived from normal mice exposed to whole-body irradiation (WBI) also showed increase in immune-activating potential of DC. This was observed in terms of increased phenotypic and functional activation of DCs. This phenomenon was also recapitulated if DC were differentiated from in vitro irradiated progenitor cells and was found to be due to STAT5/Zbtb46 signaling mediated by the irradiation-induced apoptotic bodies (ABs). When these ABs were depleted using annexin-beads, these effects were reversed confirming the involvement of this pathway. The role of ABs was further validated in DC derived from mice exposed to WBI in adaptive response experiments with 0.1 Gy priming dose prior to 2 Gy challenge dose. A corresponding reduction in DC maturation markers was observed with decrease in apoptosis in vivo. Further, these DCs derived from irradiated progenitors (IP) could resist the suppressive effects of tumor conditioned medium (TCM) and had increased immune-activating potential as seen in the tumor-bearing mice.Conclusions: Though radiation is the most commonly used therapeutic modality for cancer, its effects on dendritic cell differentiation is not completely understood. We demonstrate here for the first time that exposure to select doses of IR can increase immune-activating potential of DC through ABs. This can have implications in selection of appropriate doses of IR during radiotherapy of cancer patients.

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

The safety and feasibility of dendritic cell (DC)-based immunotherapies in cancer management have been well documented after more than twenty-five years of experimentation, and, by now, undeniably accepted. On the other hand, it is equally evident that DC-based vaccination as monotherapy did not achieve the clinical benefits that were predicted in a number of promising preclinical studies. The current availability of several immune modulatory and targeting approaches opens the way to many potential therapeutic combinations. In particular, the evidence that the immune-related effects that are elicited by immunogenic cell death (ICD)-inducing therapies are strictly associated with DC engagement and activation strongly support the combination of ICD-inducing and DC-based immunotherapies. In this review, we examine the data in recent studies employing tumor cells, killed through ICD induction, in the formulation of anticancer DC-based vaccines. In addition, we discuss the opportunity to combine pharmacologic or physical therapeutic approaches that can promote ICD in vivo with in situ DC vaccination.

The miRNAs Role in Melanoma and in Its Resistance to Therapy

Melanoma is the less common but the most malignant skin cancer. Since the survival rate of melanoma metastasis is about 10–15%, many different studies have been carried out in order to find a more effective treatment. Although the development of target-based therapies and immunotherapeutic strategies has improved chances for patient survival, melanoma treatment still remains a big challenge for oncologists. Here, we collect recent data about the emerging role of melanoma-associated microRNAs (miRNAs) currently available treatments, and their involvement in drug resistance. We also reviewed miRNAs as prognostic factors, because of their chemical stability and resistance to RNase activity, in melanoma progression. Moreover, despite miRNAs being considered small conserved regulators with the limitation of target specificity, we outline the dual role of melanoma-associated miRNAs, as oncogenic and/or tumor suppressive factors, compared to other 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.

Bioactive Polysaccharide Nanoparticles Improve Radiation-Induced Abscopal Effect through Manipulation of Dendritic Cells

Radiotherapy was considered to induce an abscopal effect initiated through antigen release and presented by dendritic cells (DC), while the immunosuppressive tumor microenvironment (TEM) attenuated the effects. Herein, we utilized bioactive polysaccharides extracted from the natural herb Astragalus membranaceus and developed polysaccharide nanoparticles (ANPs) that can reverse TEM and, accordingly, enhance the radiation-induced abscopal effect. ANP showed ability to prolong the survival rate of tumor-bearing mice. In addition, ANP dramatically inhibited the growth of the primary tumor subjected to radiation as well as the secondary tumor distant from the primary lesion. Mechanistic study demonstrated that an ANP-induced immune response was mainly reflected by DC activation, represented by phenotypic maturation and enhanced antigen presentation through the TLR4 signaling pathway. Mature DC induced by ANP migrated to the tumor-draining lymph node and initiated T-cell expansion. Specifically, DC activation was successfully translated into an increase in CD4⁺ T/T_reg and CD8⁺ T/T_reg ratios within both primary (irradiated) and secondary (unirradiated) tumors. Our results also indicated that the systemic antitumor immune response and immune memory were enhanced with the increase in IFN-γ production and effector memory T-cell population. Our work provided a novel strategy to facilitate the incorporation of immunoactive macromolecules purified from natural herbs into modern nanotechnology in the era of immunotherapy.

In situ Vaccination by Direct Dendritic Cell Inoculation: The Coming of Age of an Old Idea?

For more than 25 years, dendritic cell (DC) based vaccination has flashily held promises to represent a therapeutic approach for cancer treatment. While the vast majority of studies has focused on the use of antigen loaded DC, the intratumoral delivery of unloaded DC aiming at in situ vaccination has gained much less attention. Such approach grounds on the ability of inoculated DC to internalize and process antigens directly released by tumor (usually in combination with cell-death-inducing agents) to activate broad patient-specific antitumor T cell response. In this review, we highlight the recent studies in both solid and hematological tumors showing promising clinical results and discuss the main pitfalls and advantages of this approach for endogenous cancer vaccination. Lastly, we discuss how in situ vaccination by DC inoculation may fit with current immunotherapy approaches to expand and prolong patient response.

Concepts for agonistic targeting of CD40 in immuno-oncology

TNF Receptor Superfamily (TNF-R-SF) signaling is a structurally well-defined event that requires proper receptor clustering and trimerization. While the TNF-SF ligands naturally exist as trivalent functional units, the receptors are usually separated on the cell surface. Critically, receptor assembly into functional trimeric signaling complexes occurs through binding of the natural ligand unit. TNF-R-SF members, including CD40, have been key immunotherapeutic targets for over 20 years. CD40, expressed by antigen-presenting cells, endothelial cells, and many tumors, plays a fundamental role in connecting innate and adaptive immunity. The multiple investigated strategies to induce CD40 signaling can be broadly grouped into antibody-based or CD40L-based approaches. Currently, seven different antibodies and one CD40L-based hexavalent fusion protein are in active clinical trials. In this review, we describe the biology and structural properties of CD40, requirements for agonistic signal transduction through CD40 and summarize current attempts to exploit the CD40 signaling pathway for the treatment of cancer.