IL-6 and PD-L1 antibody blockade combination therapy reduces tumour progression in murine models of pancreatic cancer

Mechanisms of Resistance to Checkpoint Blockade Therapy

Immune checkpoint blockades (ICBs), as a major breakthrough in cancer immunotherapy, target CTLA-4 and the PD-1/PD-L1 axis and reinvigorate anti-tumor activities by disrupting co-inhibitory T-cell signaling. With unprecedented performance in clinical trials, ICBs have been approved by FDA for the treatment of malignancies such as melanoma, non-small-cell lung cancer, colorectal cancer, and hepatocellular carcinoma. However, while ICBs are revolutionizing therapeutic algorithms for cancers, the frequently observed innate, adaptive or acquired drug resistance remains an inevitable obstacle to a durable antitumor activity, thus leading to non-response or tumor relapse. Researches have shown that resistance could occur at each stage of the tumor's immune responses. From the current understanding, the molecular mechanisms for the resistance of ICB can be categorized into the following aspects: 1. Tumor-derived mechanism, 2. T cell-based mechanism, and 3. Tumor microenvironment-determined resistance. In order to overcome resistance, potential therapeutic strategies include enhancing antigen procession and presentation, reinforcing the activity and infiltration of T cells, and destroying immunosuppression microenvironment. In future, determining the driving factors behind ICB resistance by tools of precision medicine may maximize clinical benefits from ICBs. Moreover, efforts in individualized dosing, intermittent administration and/or combinatory regimens have opened new directions for overcoming ICB resistance.

Murine models for familial pancreatic cancer: Histopathology, latency and drug sensitivity among cancers of Palb2, Brca1 and Brca2 mutant mouse strains

Alterations of the PALB2 tumor suppressor gene have been identified in familial breast, ovarian and pancreatic cancer cases. PALB2 cooperates with BRCA1/2 proteins through physical interaction in initiation of homologous recombination, in maintenance of genome integrity following DNA double-strand breaks. To determine if the role of PALB2 as a linker between BRCA1 and BRCA2 is critical for BRCA1/2-mediated tumor suppression, we generated Palb2 mouse pancreatic cancer models and compared tumor latencies, phenotypes and drug responses with previously generated Brca1/2 pancreatic cancer models. For development of Palb2 pancreatic cancer, we crossed conditional Palb2 null mouse with mice carrying the Kras^G12D; p53^R270H; Pdx1-Cre (KPC) constructs, and these animals were observed for pancreatic tumor development. Individual deletion of Palb2, Brca1 or Brca2 genes in pancreas per se using Pdx1-Cre was insufficient to cause tumors, but it reduced pancreata size. Concurrent expression of mutant Kras^G12D and p53^R270H, with tumor suppressor inactivated strains in Palb2-KPC, Brca1-KPC or Brca2-KPC, accelerated pancreatic ductal adenocarcinoma (PDAC) development. Moreover, most Brca1-KPC and some Palb2-KPC animals developed mucinous cystic neoplasms with PDAC, while Brca2-KPC and KPC animals did not. 26% of Palb2-KPC mice developed MCNs in pancreata, which resemble closely the Brca1 deficient tumors. However, the remaining 74% of Palb2-KPC animals developed PDACs without any cysts like Brca2 deficient tumors. In addition, the number of ADM lesions and immune cells infiltrations (CD3⁺ and F/480⁺) were significantly increased in Brca1-KPC tumors, but not in Brca2-KPC tumors. Interestingly, the level of ADM lesions and infiltration of CD3⁺ or F/480⁺ cells in Palb2-KPC tumors were intermediate between Brca1-KPC and Brca2-KPC tumors. As expected, disruption of Palb2 and Brca1/2 sensitized tumor cells to DNA damaging agents in vitro and in vivo. Altogether, Palb2-KPC PDAC exhibited features observed in both Brca1-KPC and Brca2-KPC tumors, which could be due to its role, as a linker between Brca1 and Brca2.

Mesenchymal stromal cells in cancer: a review of their immunomodulatory functions and dual effects on tumor progression

Mesenchymal stem or stromal cells (MSCs) are pluripotent cells implicated in a broad range of physiological events, including organogenesis and maintenance of tissue homeostasis as well as tissue regeneration and repair. Because their current definition is somewhat loose – based primarily on their ability to differentiate into a variety of mesenchymal tissues, adhere to plastic, and express, or lack, a handful of cell surface markers – MSCs likely encompass several subpopulations, which may have diverse properties. Their diversity may explain, at least in part, the pleiotropic functions that they display in different physiological and pathological settings. In the context of tissue injury, MSCs can respectively promote and attenuate inflammation during the early and late phases of tissue repair. They may thereby act as sensors of the inflammatory response and secrete mediators that boost or temper the response as required by the stage of the reparatory and regenerative process. MSCs are also implicated in regulating tumor development, in which they are increasingly recognized to play a complex role. Thus, MSCs can both promote and constrain tumor progression by directly affecting tumor cells via secreted mediators and cell–cell interactions and by modulating the innate and adaptive immune response. This review summarizes our current understanding of MSC involvement in tumor development and highlights the mechanistic underpinnings of their implication in tumor growth and progression. © 2020 Authors. Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Targeting the Tumor Microenvironment: An Unexplored Strategy for Mutant KRAS Tumors

Current evidence strongly suggests that cancer cells depend on the microenvironment in order to thrive. In fact, signals from the surrounding tumor microenvironment are crucial for cancer cells´ aggressiveness, altering their expression profile and favoring their metastatic potential. As such, targeting the tumor microenvironment to impair cancer progression became an attractive therapeutic option. Interestingly, it has been shown that oncogenic KRAS signaling promotes a pro-tumorigenic microenvironment, and the associated crosstalk alters the expression profile of cancer cells. These findings award KRAS a key role in controlling the interactions between cancer cells and the microenvironment, granting cancer a poor prognosis. Given the lack of effective approaches to target KRAS itself or its downstream effectors in the clinic, exploring such interactions may open new perspectives on possible therapeutic strategies to hinder mutant KRAS tumors. This review highlights those communications and their implications for the development of effective therapies or to provide insights regarding response to existing regimens.

Fatal myositis and spontaneous haematoma induced by combined immune checkpoint inhibitor treatment in a patient with pancreatic adenocarcinoma

BACKGROUND

Immune checkpoint inhibitors (ICIs) have achieved unprecedented success in cancer treatment over the past decade. The application of ICIs hasled to the discovery of various types of immune-related adverse events (irAEs). Here, we report a case of fatal myositis and spontaneous haematoma following concurrent treatment of nivolumab and ipilimumab for pancreatic adenocarcinoma.

CASE PRESENTATION

A 71-year-old gentleman with pancreatic adenocarcinoma underwent the Whipple procedure in September 2014. The patient received 8 cycles of adjuvant chemotherapy with gemcitabineand achieved a complete responsein April 2015. Treatment with the PD-1 inhibitor nivolumab was started due to suspected tumour recurrence in November 2015. In August 2016, the CTLA-4 inhibitor ipilimumab was added to nivolumab for 2 cycles. Eight weeks after the last dose, the patient developed severe myositis complicated with spontaneous haematomain skeletalmuscle. Pathology of the skeletal muscle autopsy revealed lymphocytic infiltration. Intense immunosuppressive therapy, including high-dose corticosteroids and methotrexate, resulted in clinical success in the treatment of myositis. However, the patient died of cancer recurrence.

CONCLUSION

Myositis due to immunotherapy can be a fatal adverse event of ICIs, which requires close monitoring and cautious management.

Computational STAT3 activity inference reveals its roles in the pancreatic tumor microenvironment

Transcription factor (TF) STAT3 contributes to pancreatic cancer progression through its regulatory roles in both tumor cells and the tumor microenvironment (TME). In this study, we performed a systematic analysis of all TFs in patient-derived gene expression datasets and confirmed STAT3 as a critical regulator in the pancreatic TME. Importantly, we developed a novel framework that is based on TF target gene expression to distinguish between environmental- and tumor-specific STAT3 activities in gene expression studies. Using this framework, our results novelly showed that compartment-specific STAT3 activities, but not STAT3 mRNA, have prognostications towards clinical values within pancreatic cancer datasets. In addition, high TME-derived STAT3 activity correlates with an immunosuppressive TME in pancreatic cancer, characterized by CD4 T cell and monocyte infiltration and high copy number variation burden. Where environmental-STAT3 seemed to play a dominant role at primary pancreatic sites, tumor-specific STAT3 seemed dominant at metastatic sites where its high activity persisted. In conclusion, by combining compartment-specific inference with other tumor characteristics, including copy number variation and immune-related gene expression, we demonstrate our method’s utility as a tool to generate novel hypotheses about TFs in tumor biology.

NO• /RUNX3/kynurenine metabolic signaling enhances disease aggressiveness in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy and is refractory to available treatments. Delineating the regulatory mechanisms of metabolic reprogramming, a key event in pancreatic cancer progression, may identify candidate targets with potential therapeutic significance. We hypothesized that inflammatory signaling pathways regulate metabolic adaptations in pancreatic cancer. Metabolic profiling of tumors from PDAC patients with a high- (>median, n = 31) and low-NOS2 (inducible nitric oxide synthase; <median, n = 32) mRNA expression was performed. Differentially abundant metabolites were analyzed and linked with patient survival. The functional role of the prognostically significant metabolite and the mechanism of its regulation by NOS2/NO^• (nitric oxide)-mediated signaling pathway was elucidated. The level of kynurenine, a tryptophan metabolite, was associated with high NOS2 expression, and a higher level of kynurenine predicted poor survival in patients (n = 63, p = 0.01). Gene expression analysis in PDAC tumors (n = 63) showed a positive correlation between the expression of NOS2 and the tryptophan/kynurenine pathway genes, including indoleamine-2,3-dioxygenase 1 (IDO1) and several aryl hydrocarbon receptor (AHR)-target genes including NFE2L2 (NRF2), SERPINB2, IL1b, IL6 and IL8, which are implicated in pancreatic cancer. Consistently, treatment of pancreatic cancer cell lines with NO^• donor induced IDO1, kynurenine production and the expression of AHR-target genes. Furthermore, kynurenine treatment enhanced spheroid growth and invasive potential of pancreatic cancer cell lines. Mechanistically, NO^• -induced IDO1/Kynurenine/AHR signaling was mediated by RUNX3 transcription factor. Our findings identified a novel NO^• /RUNX3/Kynurenine metabolic axis, which enhances disease aggressiveness in pancreatic cancer and may have potential translational significance in improving disease outcome.

Cholest-4,6-Dien-3-One Promote Epithelial-To-Mesenchymal Transition (EMT) in Biliary Tree Stem/Progenitor Cell Cultures In Vitro

Human biliary tree stem/progenitor cells (hBTSCs), reside in peribiliary glands, are mainly stimulated by primary sclerosing cholangitis (PSC) and cholangiocarcinoma. In these pathologies, hBTSCs displayed epithelial-to-mesenchymal transition (EMT), senescence characteristics, and impaired differentiation. Here, we investigated the effects of cholest-4,6-dien-3-one, an oxysterol involved in cholangiopathies, on hBTSCs biology. hBTSCs were isolated from donor organs, cultured in self-renewal control conditions, differentiated in mature cholangiocytes by specifically tailored medium, or exposed for 10 days to concentration of cholest-4,6-dien-3-one (0.14 mM). Viability, proliferation, senescence, EMT genes expression, telomerase activity, interleukin 6 (IL6) secretion, differentiation capacity, and HDAC6 gene expression were analyzed. Although the effect of cholest-4,6-dien-3-one was not detected on hBTSCs viability, we found a significant increase in cell proliferation, senescence, and IL6 secretion. Interestingly, cholest-4.6-dien-3-one impaired differentiation in mature cholangiocytes and, simultaneously, induced the EMT markers, significantly reduced the telomerase activity, and induced HDAC6 gene expression. Moreover, cholest-4,6-dien-3-one enhanced bone morphogenic protein 4 (Bmp-4) and sonic hedgehog (Shh) pathways in hBTSCs. The same pathways activated by human recombinant proteins induced the expression of EMT markers in hBTSCs. In conclusion, we demonstrated that chronic exposition of cholest-4,6-dien-3-one induced cell proliferation, EMT markers, and senescence in hBTSC, and also impaired the differentiation in mature cholangiocytes.

Muscle alterations in the development and progression of cancer-induced muscle atrophy: a review

Cancer cachexia-cancer-associated body weight and muscle loss-is a significant predictor of mortality and morbidity in cancer patients across a variety of cancer types. However, despite the negative prognosis associated with cachexia onset, there are no clinical therapies approved to treat or prevent cachexia. This lack of treatment may be partially due to the relative dearth of literature on mechanisms occurring within the muscle before the onset of muscle wasting. Therefore, the purpose of this review is to compile the current scientific literature on mechanisms contributing to the development and progression of cancer cachexia, including protein turnover, inflammatory signaling, and mitochondrial dysfunction. We define "development" as changes in cell function occurring before the onset of cachexia and "progression" as alterations to cell function that coincide with the exacerbation of muscle wasting. Overall, the current literature suggests that multiple aspects of cellular function, such as protein turnover, inflammatory signaling, and mitochondrial quality, are altered before the onset of muscle loss during cancer cachexia and clearly highlights the need to study more thoroughly the developmental stages of cachexia. The studying of these early aberrations will allow for the development of effective therapeutics to prevent the onset of cachexia and improve health outcomes in cancer patients.

Cachexia Anorexia Syndrome and Associated Metabolic Dysfunction in Peritoneal Metastasis

Patients with peritoneal metastasis (PM) of gastrointestinal and gynecological origin present with a nutritional deficit characterized by increased resting energy expenditure (REE), loss of muscle mass, and protein catabolism. Progression of peritoneal metastasis, as with other advanced malignancies, is associated with cancer cachexia anorexia syndrome (CAS), involving poor appetite (anorexia), involuntary weight loss, and chronic inflammation. Eventual causes of mortality include dysfunctional metabolism and energy store exhaustion. Etiology of CAS in PM patients is multifactorial including tumor growth, host response, cytokine release, systemic inflammation, proteolysis, lipolysis, malignant small bowel obstruction, ascites, and gastrointestinal side effects of drug therapy (chemotherapy, opioids). Metabolic changes of CAS in PM relate more to a systemic inflammatory response than an adaptation to starvation. Metabolic reprogramming is required for cancer cells shed into the peritoneal cavity to resist anoikis (i.e., programmed cell death). Profound changes in hexokinase metabolism are needed to compensate ineffective oxidative phosphorylation in mitochondria. During the development of PM, hypoxia inducible factor-1α (HIF-1α) plays a key role in activating both aerobic and anaerobic glycolysis, increasing the uptake of glucose, lipid, and glutamine into cancer cells. HIF-1α upregulates hexokinase II, phosphoglycerate kinase 1 (PGK1), pyruvate dehydrogenase kinase (PDK), pyruvate kinase muscle isoenzyme 2 (PKM2), lactate dehydrogenase (LDH) and glucose transporters (GLUT) and promotes cytoplasmic glycolysis. HIF-1α also stimulates the utilization of glutamine and fatty acids as alternative energy substrates. Cancer cells in the peritoneal cavity interact with cancer-associated fibroblasts and adipocytes to meet metabolic demands and incorporate autophagy products for growth. Therapy of CAS in PM is challenging. Optimal nutritional intake alone including total parenteral nutrition is unable to reverse CAS. Pressurized intraperitoneal aerosol chemotherapy (PIPAC) stabilized nutritional status in a significant proportion of PM patients. Agents targeting the mechanisms of CAS are under development.

Discovery of low-molecular weight anti-PD-L1 peptides for cancer immunotherapy

Background

Immunotherapy using checkpoint inhibitors, especially PD-1/PD-L1 inhibitors, has now evolved into the most promising therapy for cancer patients. However, most of these inhibitors are monoclonal antibodies, and their large size may limit their tumor penetration, leading to suboptimal efficacy. As a result, there has been a growing interest in developing low-molecular-weight checkpoint inhibitors.

Methods

We developed a novel biopanning strategy to discover small peptide-based anti-PD-L1 inhibitors. The affinity and specificity of the peptides to PD-L1 were examined using various assays. Three-dimensional (3D) spheroid penetration study was performed to determine the tumor penetration capability of the peptides. Anti-tumor activity of the peptides was evaluated in mice bearing CT26 tumor cells.

Results

We discover several anti-PD-L1 peptide inhibitors to block PD-1/PD-L1 interaction. The peptides exhibit high affinity and specificity to human PD-L1 protein as well as PD-L1-overexpressing human cancer cells MDA-MB-231 and DU-145. Molecular docking studies indicate that the peptide CLP002 specifically binds to PD-L1 at the residues where PD-L1 interacts with PD-1. The peptide also blocks the CD80/PD-L1 interaction, which may further enhance the immune response of tumor-infiltrating T cells. Compared to antibody, the peptide CLP002 exhibits better tumor penetration in a 3D tumor spheroid model. The peptide CLP002 restores proliferation and prevents apoptosis of T cells that are co-cultured with cancer cells. The peptide CLP002 also inhibits tumor growth and increases survival of CT26 tumor-bearing mice.

Conclusions

This study demonstrated the feasibility of using phage display to discover small peptide-based checkpoint inhibitors. Our results also suggested that the anti-PD-L1 peptide represents a promising low-molecular-weight checkpoint inhibitor for cancer immunotherapy.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0705-y) contains supplementary material, which is available to authorized users.

STAT3 Activity Promotes Programmed-Death Ligand 1 Expression and Suppresses Immune Responses in Breast Cancer

Signal transducer and activator of transcription 3 (STAT3) is an oncogene and multifaceted transcription factor involved in multiple cellular functions. Its role in modifying anti-tumor immunity has been recently recognized. In this study, the biologic effects of STAT3 on immune checkpoint expression and anti-tumor responses were investigated in breast cancer (BC). A transcriptional signature of phosphorylated STAT3 was positively correlated with PD-L1 expression in two independent cohorts of early BC. Pharmacologic inhibition and gene silencing of STAT3 led to decreased Programmed Death Ligand 1 (PD-L1) expression levels in vitro, and resulted as well in reduction of tumor growth and decreased metastatic dissemination in a mammary carcinoma mouse model. The hampering of tumor progression was correlated to an anti-tumoral macrophage phenotype and accumulation of natural-killer cells, but also in reduced accrual of cytotoxic lymphocytes. In human BC, pro-tumoral macrophages correlated to PD-L1 expression, proliferation status and higher grade of malignancy, indicating a subset of patients with immunosuppressive properties. In conclusion, this study provides evidence for STAT3-mediated regulation of PD-L1 and modulation of immune microenvironment in BC.

Current perspectives of cancer-associated fibroblast in therapeutic resistance: potential mechanism and future strategy

The goal of cancer eradication has been overshadowed despite the continuous improvement in research and generation of novel cancer therapeutic drugs. One of the undeniable existing problems is drug resistance due to which the paradigm of killing all cancer cells is ineffective. Tumor microenvironment plays a crucial role in inducing drug resistance besides cancer development and progression. Recently, many efforts have been devoted to understand the role of tumor microenvironment in cancer drug resistance as it provides the shelter, nutrition, and paracrine niche for cancer cells. Cancer-associated fibroblasts (CAFs), one major component of tumor microenvironment, reside in symbiotic relationship with cancer cells, supporting them to survive from cancer drugs. The present review summarizes the recent understandings in the role of CAFs in drug resistance in various tumors. Acknowledging the fact that drug resistance depends not only upon cancer cells but also upon the microenvironment niche could guide us to formulate novel cancer drugs and provide the optimal cancer treatment.

IL6 Modulates the Immune Status of the Tumor Microenvironment to Facilitate Metastatic Colonization of Colorectal Cancer Cells

It is unknown as to how liver metastases are correlated with host immune status in colorectal cancer. In this study, we found that IL6, a proinflammatory cytokine produced in tumor-bearing states, promoted the metastatic colonization of colon cancer cells in association with dysfunctional antitumor immunity. In IL6-deficient mice, metastatic colonization of CT26 cells in the liver was reduced, and the antitumor effector function of CD8⁺ T cells, as well as IL12 production by CD11c⁺ dendritic cells, were augmented in vivo IL6-deficient mice exhibited enhanced IFN-AR1-mediated type I interferon signaling, which upregulated PD-L1 and MHC class I expression on CT26 cells. In vivo injection of anti-PD-L1 effectively suppressed the metastatic colonization of CT26 cells in Il6 ^-/- but not in Il6 ^+/+ mice. Finally, we confirmed that colorectal cancer patients with low IL6 expression in their primary tumors showed prolonged disease-free survival. These findings suggest that IL6 may be a promising target for the treatment of metastasis in colorectal cancers by improving host immunity.

Hierarchical assembly of hyaluronan coated albumin nanoparticles for pancreatic cancer chemoimmunotherapy

Pancreatic cancer is a highly malignant carcinoma with limited effective treatment options, resulting in a poor patient survival rate of less than 5%. In this study, cationic albumin nanoparticles were assembled with negatively charged hyaluronic acid (HA) to achieve a hierarchical nanostructure and efficient delivery of small molecule drugs to the tumor site in the pancreas. A combination of chemotherapy with indoleamine-2,3-dioxygenase (IDO) inhibition was explored to enhance the chemotherapeutic efficacy in vivo. Hydrophobic celastrol (CLT) and hydrophilic 1-methyltryptophan (MT) were concurrently loaded in HA coated cationic albumin nanoparticles (HNPs) with an average size of ∼300 nm. The size of HNPs was reduced in the presence of hyaluronidase to facilitate penetration into deep tumor tissues. Also, the biodistribution study in the C57BL/6 mice xenograft model showed enhanced tumor accumulation and prolonged circulation of HNPs. Compared with CLT solution, the combination of CLT with MT showed significantly enhanced tumor inhibition in both xenograft and orthotopic pancreatic cancer mice models via downregulating the immunosuppressive tumor microenvironment. Taken together, the combination of CLT with MT administered via HNPs represents a highly promising strategy for targeted pancreatic cancer therapy.

Immunosuppression by monocytic myeloid-derived suppressor cells in patients with pancreatic ductal carcinoma is orchestrated by STAT3

Background

Pancreatic ductal adenocarcinoma (PDAC) is a highly devastating disease with an overall 5-year survival rate of less than 8%. New evidence indicates that PDAC cells release pro-inflammatory metabolites that induce a marked alteration of normal hematopoiesis, favoring the expansion and accumulation of myeloid-derived suppressor cells (MDSCs). We report here that PDAC patients show increased levels of both circulating and tumor-infiltrating MDSC-like cells.

Methods

The frequency of MDSC subsets in the peripheral blood was determined by flow cytometry in three independent cohorts of PDAC patients (total analyzed patients, n = 117). Frequency of circulating MDSCs was correlated with overall survival of PDAC patients. We also analyzed the frequency of tumor-infiltrating MDSC and the immune landscape in fresh biopsies. Purified myeloid cell subsets were tested in vitro for their T-cell suppressive capacity.

Results

Correlation with clinical data revealed that MDSC frequency was significantly associated with a shorter patients’ overall survival and metastatic disease. However, the immunosuppressive activity of purified MDSCs was detectable only in some patients and mainly limited to the monocytic subset. A transcriptome analysis of the immunosuppressive M-MDSCs highlighted a distinct gene signature in which STAT3 was crucial for monocyte re-programming. Suppressive M-MDSCs can be characterized as circulating STAT3/arginase1-expressing CD14⁺ cells.

Conclusion

MDSC analysis aids in defining the immune landscape of PDAC patients for a more appropriate diagnosis, stratification and treatment.

Long non-coding RNA HOTTIP enhances IL-6 expression to potentiate immune escape of ovarian cancer cells by upregulating the expression of PD-L1 in neutrophils

Background

Long non-coding RNA (lncRNA) HOXA transcript at the distal tip (HOTTIP), has been demonstrated to be a vital biomarker when evaluating the prognosis of multiple cancers. Nevertheless, the potential function of HOTTIP in ovarian cancer (OC), a prevalent cancer among women worldwide, remains elusive. Hence, the current study aimed to elucidate the functional relevance of HOTTIP in the development of OC.

Methods

Positive expression of PD-L1 and IL-6 was determined using immunohistochemical staining in the collected OC and normal tissues. The correlation of IL-6 and PD-L1 was analyzed using flow cytometry, Western blot analysis as well as Pearson’s correlation coefficient. The interaction among HOTTIP, c-jun and IL-6 was investigated with the use of RIP, ChIP and dual luciferase reporter gene assays. Finally, the effects of HOTTIP on T cell proliferation and infiltration were identified through gain- and loss-of-function studies in vitro and in vivo.

Results

HOTTIP, IL-6 and PD-L1 were all highly expressed in OC tissues. A positive correlation was observed between IL-6 and PD-L1 and that between HOTTIP and IL-6 in OC tissues. HOTTIP was noted to promote the expression of IL-6 by binding to c-jun, which resulted in a promoted PD-L1 expression in neutrophils and immune escape while inhibiting T cell proliferation as well as tumor immunotherapy.

Conclusion

Taken together, our study unveiled that HOTTIP could promote the secretion of IL-6, and consequently up-regulate the expression of PD-L1 in neutrophils, thus inhibiting the activity of T cells and ultimately accelerating immune escape of OC cells. Our study provides a potential therapeutic strategy by targeting HOTTIP in OC.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1394-6) contains supplementary material, which is available to authorized users.

Evidence for interaction of the NLRP3 inflammasome and Bruton's tyrosine kinase in tumor-associated macrophages: implications for myeloid cell production of interleukin-1beta

An inflammatory microenvironment has been shown to play an important role in the growth and metastasis of tumors. The NLRP3 inflammasome is a multi-protein complex of the innate immune system that is responsible for the production of the potent inflammatory cytokine IL-1β. Tumor- associated macrophages (TAM) are an expanded population of immune cells found in the tumor microenvironment that can promote the initiation and metastasis of tumor cells. Their presence has been correlated with disease burden, highlighting the therapeutic potential of targeting this population. However, to date clinically relevant pharmacologic strategies to target TAM remain elusive. Here, we show that in vitro generated TAM harbor NLRP3 inflammasome components and produce IL-1β. Ibrutinib, an irreversible inhibitor of Bruton's tyrosine kinase (BTK), is in clinical use for the treatment of B- cell malignancies. We report that BTK is expressed by human in vitro generated TAM and murine macrophages and that it physically associates with the NLRP3 inflammasome. Furthermore, ibrutinib is able to inhibit BTK phosphorylation in TAM generated in vitro. Treatment of TAM with ibrutinib significantly impaired the ability of these cells to produce IL-1β. The present study provides evidence that BTK physically associates with the NLRP3 inflammasome and that inhibition of BTK with ibrutinib can impair the production of IL-1β by in vitro generated TAM. Thus, ibrutinib could potentially be of clinical use in abrogating inflammation-associated cancer progression and the immune-suppressive effects of myeloid cells within the tumor microenvironment.

The Dark Side of Fibroblasts: Cancer-Associated Fibroblasts as Mediators of Immunosuppression in the Tumor Microenvironment

Cancer-associated fibroblasts (CAFs) are prominent components of the microenvironment in most types of solid tumors, and were shown to facilitate cancer progression by supporting tumor cell growth, extracellular matrix remodeling, promoting angiogenesis, and by mediating tumor-promoting inflammation. In addition to an inflammatory microenvironment, tumors are characterized by immune evasion and an immunosuppressive milieu. In recent years, CAFs are emerging as central players in immune regulation that shapes the tumor microenvironment. CAFs contribute to immune escape of tumors via multiple mechanisms, including secretion of multiple cytokines and chemokines and reciprocal interactions that mediate the recruitment and functional differentiation of innate and adaptive immune cells. Moreover, CAFs directly abrogate the function of cytotoxic lymphocytes, thus inhibiting killing of tumor cells. In this review, we focus on recent advancements in our understanding of how CAFs drive the recruitment and functional fate of tumor-infiltrating immune cells toward an immunosuppressive microenvironment, and provide outlook on future therapeutic implications that may lead to integration of preclinical findings into the design of novel combination strategies, aimed at impairing the tumor-supportive function of CAFs.

IL-17C-mediated innate inflammation decreases the response to PD-1 blockade in a model of Kras-driven lung cancer

Chronic obstructive pulmonary disease (COPD) is associated with neutrophilic lung inflammation and CD8 T cell exhaustion and is an important risk factor for the development of non-small cell lung cancer (NSCLC). The clinical response to programmed cell death-1 (PD-1) blockade in NSCLC patients is variable and likely affected by a coexisting COPD. The pro-inflammatory cytokine interleukin-17C (IL-17C) promotes lung inflammation and is present in human lung tumors. Here, we used a Kras-driven lung cancer model to examine the function of IL-17C in inflammation-promoted tumor growth. Genetic ablation of Il-17c resulted in a decreased recruitment of inflammatory cells into the tumor microenvironment, a decreased expression of tumor-promoting cytokines (e.g. interleukin-6 (IL-6)), and a reduced tumor proliferation in the presence of Haemophilus influenzae- (NTHi) induced COPD-like lung inflammation. Chronic COPD-like inflammation was associated with the expression of PD-1 in CD8 lymphocytes and the membrane expression of the programmed death ligand (PD-L1) independent of IL-17C. Tumor growth was decreased in Il-17c deficient mice but not in wildtype mice after anti-PD-1 treatment. Our results suggest that strategies targeting innate immune mechanisms, such as blocking of IL-17C, may improve the response to anti-PD-1 treatment in lung cancer patients.

Pancreatic Cancer and Immunotherapy: Resistance Mechanisms and Proposed Solutions

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) continues to be one of the most aggressive and lethal diseases in the world. The success of immunotherapy in other types of malignancy has led to further trials to understand better the role of immunotherapy in PDAC. However, initial studies with immunotherapy, namely, the checkpoint inhibitors, in PDAC have not been met with the same outcomes. The purpose of this review is to identify and discuss the various resistance mechanisms of PDAC to immunotherapy (pancreatic stroma, genetic predisposition/epigenetics, and the immune inhibitory cells, cytokines, soluble factors, and enzymes that comprise the tumor microenvironment) and the solutions currently being studied to overcome them.

CONCLUSIONS

Various preclinical and early clinical studies have shown that immunotherapy, especially checkpoint inhibitors, in PDAC may be efficacious as part of a multi-modal treatment, in combination with other therapies that target these resistance mechanisms. Several clinical trials are ongoing to explore this concept further.

Cell-intrinsic PD-1 promotes proliferation in pancreatic cancer by targeting CYR61/CTGF via the hippo pathway

Pancreatic ductal adenocarcinoma (PDAC) remains a refractory disease. Programmed cell death protein-1 (PD-1) monotherapy has shown strong performance in targeting several malignancies. However, the effect and mechanism of intrinsic PD-1 in pancreatic cancer cells is still unknown. In this study, associations between clinicopathological characteristics and stained tissue microarrays of PDAC specimens were analyzed along with profiling and functional analyses. The results showed that cell-intrinsic PD-1 was significantly correlated with overall survival (OS). Independently of adaptive immunity, intrinsic PD-1 promoted tumor growth in PDAC. Concomitantly, the overexpression of intrinsic PD-1 enhanced cancer proliferation and inhibited cell apoptosis in vitro and in vivo. Mechanistically, PD-1 binds to the downstream MOB1, thereby inhibiting its phosphorylation. Moreover, greater synergistic tumor suppression in vitro resulted from combining Hippo inhibitors with anti-PD-1 treatment compared with the suppression achieved by either single agent alone. Additionally, Hippo downstream targets, CYR61 (CCN1) and CTGF (CCN2), were directly affected by PD-1 mediated Hippo signaling activation in concert with survival outcomes. Finally, the formulated nomogram showed superior predictive accuracy for OS in comparison with the TNM stage alone. Therefore, PD-1 immunotherapy in combination with Hippo pathway inhibitors may optimize the anti-tumor efficacy in PDAC patients via targeting cell-intrinsic PD-1.

Glioblastoma-Derived IL6 Induces Immunosuppressive Peripheral Myeloid Cell PD-L1 and Promotes Tumor Growth

PURPOSE

Upregulation of programmed death-ligand 1 (PD-L1) on circulating and tumor-infiltrating myeloid cells is a critical component of GBM-mediated immunosuppression that has been associated with diminished response to vaccine immunotherapy and poor survival. Although GBM-derived soluble factors have been implicated in myeloid PD-L1 expression, the identity of such factors has remained unknown. This study aimed to identify factors responsible for myeloid PD-L1 upregulation as potential targets for immune modulation.

EXPERIMENTAL DESIGN

Conditioned media from patient-derived GBM explant cell cultures was assessed for cytokine expression and utilized to stimulate naïve myeloid cells. Myeloid PD-L1 induction was quantified by flow cytometry. Candidate cytokines correlated with PD-L1 induction were evaluated in tumor sections and plasma for relationships with survival and myeloid PD-L1 expression. The role of identified cytokines on immunosuppression and survival was investigated in vivo utilizing immunocompetent C57BL/6 mice bearing syngeneic GL261 and CT-2A tumors.

RESULTS

GBM-derived IL6 was identified as a cytokine that is necessary and sufficient for myeloid PD-L1 induction in GBM through a STAT3-dependent mechanism. Inhibition of IL6 signaling in orthotopic murine glioma models was associated with reduced myeloid PD-L1 expression, diminished tumor growth, and increased survival. The therapeutic benefit of anti-IL6 therapy proved to be CD8+ T-cell dependent, and the antitumor activity was additive with that provided by programmed death-1 (PD-1)-targeted immunotherapy.

CONCLUSIONS

Our findings suggest that disruption of IL6 signaling in GBM reduces local and systemic myeloid-driven immunosuppression and enhances immune-mediated antitumor responses against GBM.

Sequential Targeting TGF-β Signaling and KRAS Mutation Increases Therapeutic Efficacy in Pancreatic Cancer

Pancreatic cancer is a highly aggressive malignancy that strongly resists extant treatments. The failure of existing therapies is majorly attributed to the tough tumor microenvironment (TME) limiting drug access and the undruggable targets of tumor cells. The formation of suppressive TME is regulated by transforming growth factor beta (TGF-β) signaling, while the poor response and short survival of almost 90% of pancreatic cancer patients results from the oncogenic KRAS mutation. Hence, simultaneously targeting both the TGF-β and KRAS pathways might dismantle the obstacles of pancreatic cancer therapy. Here, a novel sequential-targeting strategy is developed, in which antifibrotic fraxinellone-loaded CGKRK-modified nanoparticles (Frax-NP-CGKRK) are constructed to regulate TGF-β signaling and siRNA-loaded lipid-coated calcium phosphate (LCP) biomimetic nanoparticles (siKras-LCP-ApoE3) are applied to interfere with the oncogenic KRAS. Frax-NP-CGKRK successfully targets the tumor sites through the recognition of overexpressed heparan sulfate proteoglycan, reverses the activated cancer-associated fibroblasts (CAFs), attenuates the dense stroma barrier, and enhances tumor blood perfusion. Afterward, siKras-LCP-ApoE3 is efficiently internalized by the tumor cells through macropinocytosis and specifically silencing KRAS mutation. Compared with gemcitabine, this sequential-targeting strategy significantly elongates the lifespans of pancreatic tumor-bearing animals, hence providing a promising approach for pancreatic cancer therapy.

Proteomics analysis of HSV-1-induced alterations in mouse brain microvascular endothelial cells

Herpes simplex virus 1 (HSV-1) is a predominant cause of herpes simplex encephalitis (HSE), leading to a high mortality rate and severe neurological sequelae worldwide. HSE is typically accompanied by the blood-brain barrier (BBB) disruption, but the underlying mechanisms are unclear. To explore the disruption mechanisms of the BBB, quantitative analysis of the cellular proteome was carried out to investigate the proteomic changes that occur after infection. In this study, bEnd.3 cells were infected with HSV-1, followed by liquid chromatography-tandem mass spectrometry. A total of 6761 proteins were identified in three independent mass spectrometry analyses. Compared to the uninfected cells, 386 and 293 differentially expressed proteins were markedly upregulated or downregulated, respectively. Bioinformatic analysis showed that the activator protein-1 factor, including Fos, Jun, and ATF family proteins and cell adhesion molecules were significantly changed. Further validation of the changes observed for these proteins was carried out by western blotting and quantitative real-time PCR. Transendothelial electrical resistance (TEER) studies were performed to explore the effects of ATF3, Fra1, or JunB overexpression on the function of bEnd.3 cells. Characterization of the differential expression of these proteins in bEnd.3 cells will facilitate further exploration of BBB disruption upon HSV-1 infection.

Prophylactic TNF blockade uncouples efficacy and toxicity in dual CTLA-4 and PD-1 immunotherapy

Combined PD-1 and CTLA-4-targeted immunotherapy with nivolumab and ipilimumab is effective against melanoma, renal cell carcinoma and non-small-cell lung cancer^1-3. However, this comes at the cost of frequent, serious immune-related adverse events, necessitating a reduction in the recommended dose of ipilimumab that is given to patients⁴. In mice, co-treatment with surrogate anti-PD-1 and anti-CTLA-4 monoclonal antibodies is effective in transplantable cancer models, but also exacerbates autoimmune colitis. Here we show that treating mice with clinically available TNF inhibitors concomitantly with combined CTLA-4 and PD-1 immunotherapy ameliorates colitis and, in addition, improves anti-tumour efficacy. Notably, TNF is upregulated in the intestine of patients suffering from colitis after dual ipilimumab and nivolumab treatment. We created a model in which Rag2^-/-Il2rg^-/- mice were adoptively transferred with human peripheral blood mononuclear cells, causing graft-versus-host disease that was further exacerbated by ipilimumab and nivolumab treatment. When human colon cancer cells were xenografted into these mice, prophylactic blockade of human TNF improved colitis and hepatitis in xenografted mice, and moreover, immunotherapeutic control of xenografted tumours was retained. Our results provide clinically feasible strategies to dissociate efficacy and toxicity in the use of combined immune checkpoint blockade for cancer immunotherapy.

Signaling Networks That Control Cellular Plasticity in Pancreatic Tumorigenesis, Progression, and Metastasis

Pancreatic ductal adenocarcinoma is one of the deadliest cancers, and its incidence on the rise. The major challenges in overcoming the poor prognosis with this disease include late detection and the aggressive biology of the disease. Intratumoral heterogeneity; presence of a robust, reactive, and desmoplastic stroma; and the crosstalk between the different tumor components require complete understanding of the pancreatic tumor biology to better understand the therapeutic challenges posed by this disease. In this review, we discuss the processes involved during tumorigenesis encompassing the inherent plasticity of the transformed cells, development of tumor stroma crosstalk, and enrichment of cancer stem cell population during tumorigenesis.

Broadening the Impact of Immunotherapy to Pancreatic Cancer: Challenges and Opportunities

Pancreatic ductal adenocarcinoma (PDAC) is projected to become the second deadliest cancer in the United States by 2025, with 5-year survival at less than 10%. In other recalcitrant cancers, immunotherapy has shown unprecedented response rates, including durable remissions after drug discontinuation. However, responses to immunotherapy in PDAC are rare. Accumulating evidence in mice and humans suggests that this remarkable resistance is linked to the complex, dueling role of the immune system in simultaneously promoting and restraining PDAC. In this review, we highlight the rationale that supports pursuing immunotherapy in PDAC, outline the key barriers that limit immunotherapy efficacy, and summarize the primary preclinical and clinical efforts to sensitize PDAC to immunotherapy.

Inflammation, Biomarkers and Immuno-Oncology Pathways in Pancreatic Cancer

It is estimated that pancreatic cancer will be the second leading cause of cancer-related deaths globally by 2030, highlighting the ongoing lack of effective treatment options for this devastating condition. There is a lack of reliable prognostic or predictive markers in pancreatic cancer to guide management decisions, whether for systemic chemotherapy, molecularly targeted therapies, or immunotherapies. To date, the results for targeted agents and immunotherapies in unselected populations of chemo-refractory pancreatic cancer have not met expectations. The reasons for this lack of efficacy of immunotherapy in pancreatic cancer are not completely understood. The challenges in pancreatic cancer include the physical barrier created by the dense desmoplastic stroma surrounding the tumor, chemokine-mediated exclusion of T cells, relatively poorer antigenicity compared to other solid tumors, paucity of infiltrating T cells within the tumor, ultimately leading to an immunosuppressive microenvironment. A better understanding of the role of inflammation in pancreatic cancer, its tumor microenvironment and individualized patient-related features, be they molecular, clinical or histopathological, would enable a more effective tailored approach to the management of pancreatic cancer. In this review, the role of inflammation, the immune tumor microenvironment and potential immune biomarkers in pancreatic cancer are explored.

Stress responses in stromal cells and tumor homeostasis

In most (if not all) solid tumors, malignant cells are outnumbered by their non-malignant counterparts, including immune, endothelial and stromal cells. However, while the mechanisms whereby cancer cells adapt to microenvironmental perturbations have been studied in great detail, relatively little is known on stress responses in non-malignant compartments of the tumor microenvironment. Here, we discuss the mechanisms whereby cancer-associated fibroblasts and other cellular components of the tumor stroma react to stress in the context of an intimate crosstalk with malignant, endothelial and immune cells, and how such crosstalk influences disease progression and response to treatment.

CSTP1 inhibits IL-6 expression through targeting Akt/FoxO3a signaling pathway in bladder cancer cells

CSTP1, a recently identified protein phosphotase, is frequently repressed in bladder cancers. Previous results showed that CSTP1 over-expression inhibited cell cycle progression and promoted apoptosis through dephosphorylating Akt kinase at Ser473 site in bladder cancer cells, but the mechanisms how CSTP1 exerted tumor suppressive activity remains unclear. In this study, we analyzed the gene expression profile changes that affected by CSTP1 overexpression by microarray, and reported that CSTP1 decreased IL-6 expression/secretion in bladder cancer cells and re-expression of IL-6 abrogated CSTP1's tumor suppressive activity. We also found that FoxO3a occupy IL-6 gene promoter and repressed IL mRNA transcription. Further results showed that decreased expression of IL-6 in CSTP1-overexpressing cells inactivated Stat3 transcriptional factor, which resulted in the down-regulation of cyclin D1, Bcl-xl expression. Spearman correlation analysis revealed that the mRNA level of CSTP1 correlated inversely with that of IL-6 in bladder cancer tissues. In conclusion, our studies revealed that protein phosphotase CSTP1 inhibited IL-6 expression through targeting Akt/FoxO3a signaling pathway and IL-6 inactivated Stat3 was necessary for CSTP1's tumor suppressive function.

BAG3 Suppresses Loading of Ago2 to IL6 mRNA in Pancreatic Ductal Adenocarcinoma

Pancreatic stellate cells (PSCs) are a subset of pancreatic cancer-associated fibroblasts, which play a critical role in pancreatic fibrosis, a characteristic feature of pancreatic cancer. The interplay between PSCs and pancreatic cancer cells is vital for promotion of tumor progression and metastasis. BAG3 is correlated with poor prognostics in patients with pancreatic ductal adenocarcinoma (PDAC), however, the exact mechanisms remain largely unknown. In this study, we demonstrated that BAG3 downregulation decreased IL6 release by PDACs, and IL6 reduction was, at least partially, responsible for suppression of PSCs activation by PDACs with BAG3 downmodulation. Importantly, BAG3 expression positively correlated with fibrosis in pancreatic cancer tissue. With regard to the underlying mechanism, we demonstrated that BAG3 knockdown facilitated recruitment of Agonaute 2 (Ago2) to IL6 mRNA, resulting in destabilization of IL6 mRNA. In addition, the current study demonstrated that phosphorylation at Serine (Ser) 387 site was required for recruitment of Ago2-containing miRISC to IL6 mRNA and BAG3 knockdown facilitated Ago2 loading to IL6 mRNA via increasing its phosphorylation at Ser 387. This study shed new light on the tumor-promoting role of BAG3 in PDAC tumors, suggesting BAG3 might represent an interesting therapeutic opportunity to PDAC patients.

Determinant roles of dendritic cell-expressed Notch Delta-like and Jagged ligands on anti-tumor T cell immunity

Background

Notch intercellular communication instructs tissue-specific T-cell development and function. In this study, we explored the roles of dendritic cell (DC)-expressed Notch ligands in the regulation of T-cell effector function.

Methods

We generated mice with CD11c lineage-specific deletion of Notch Delta-like ligand (Dll)1 and Jagged (Jag)2. Using these genetically-ablated mice and engineered pharmacological Notch ligand constructs, the roles of various Delta-like and Jagged ligands in the regulation of T-cell-mediated immunity were investigated. We assessed tumor growth, mouse survival, cytokine production, immunophenotyping of myeloid and lymphoid populations infiltrating the tumors, expression of checkpoint molecules and T-cell function in the experimental settings of murine lung and pancreatic tumors and cardiac allograft rejection. Correlative studies were also performed for the expression of NOTCH ligands, NOTCH receptors and PD-1 on various subsets of myeloid and lymphoid cells in tumor-infiltrating immune cells analyzed from primary human lung cancers.

Results

Mice with CD11c lineage-specific deletion of Notch ligand gene Dll1, but not Jag2, exhibited accelerated growth of lung and pancreatic tumors concomitant with decreased antigen-specific CD8⁺T-cell functions and effector-memory (Tem) differentiation. Increased IL-4 but decreased IFN-γ production and elevated populations of T-regulatory and myeloid-derived suppressor cells were observed in Dll1-ablated mice. Multivalent clustered DLL1-triggered Notch signaling overcame DC Dll1 deficiency and improved anti-tumor T-cell responses, whereas the pharmacological interference by monomeric soluble DLL1 construct suppressed the rejection of mouse tumors and cardiac allograft. Moreover, monomeric soluble JAG1 treatment reduced T-regulatory cells and improved anti-tumor immune responses by decreasing the expression of PD-1 on CD8⁺Tem cells. A significant correlation was observed between DC-expressed Jagged and Delta-like ligands with Tem-expressed PD-1 and Notch receptors, respectively, in human lung tumor-infiltrates.

Conclusion

Our data show the importance of specific expression of Notch ligands on DCs in the regulation of T-cell effector function. Thus, strategies incorporating selectively engineered Notch ligands could provide a novel approach of therapeutics for modulating immunity in various immunosuppressive conditions including cancer.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0566-4) contains supplementary material, which is available to authorized users.

Hypoxia as a barrier to immunotherapy in pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDA) is a lethal disease with limited response to cytotoxic chemoradiotherapy, as well as newer immunotherapies. The PDA tumor microenvironment contains infiltrating immune cells including cytotoxic T cells; however, there is an overall immunosuppressive milieu. Hypoxia is a known element of the solid tumor microenvironment and may promote tumor survival. Through various mechanisms including, but not limited to, those mediated by HIF-1α, hypoxia also leads to increased tumor proliferation and metabolic changes. Furthermore, epithelial to mesenchymal transition is promoted through several pathways, including NOTCH and c-MET, regulated by hypoxia. Hypoxia-promoted changes also contribute to the immunosuppressive phenotype seen in many different cell types within the microenvironment and thereby may inhibit an effective immune system response to PDA. Pancreatic stellate cells (PSCs) and myofibroblasts appear to contribute to the recruitment of myeloid derived suppressor cells (MDSCs) and B cells in PDA via cytokines increased due to hypoxia. PSCs also increase collagen secretion in response to HIF-1α, which promotes a fibrotic stroma that alters T cell homing and migration. In hypoxic environments, B cells contribute to cytotoxic T cell exhaustion and produce chemokines to attract more immunosuppressive regulatory T cells. MDSCs inhibit T cell metabolism by hoarding key amino acids, modulate T cell homing by cleaving L-selectin, and prevent T cell activation by increasing PD-L1 expression. Immunosuppressive M2 phenotype macrophages promote T cell anergy via increased nitric oxide (NO) and decreased arginine in hypoxia. Increased numbers of regulatory T cells are seen in hypoxia which prevent effector T cell activation through cytokine production and increased CTLA-4. Effective immunotherapy for pancreatic adenocarcinoma and other solid tumors will need to help counteract the immunosuppressive nature of hypoxia-induced changes in the tumor microenvironment. Promising studies will look at combination therapies involving checkpoint inhibitors, chemokine inhibitors, and possible targeting of hypoxia. While no model is perfect, assuring that models incorporate the effects of hypoxia on cancer cells, stromal cells, and effector immune cells will be crucial in developing successful therapies.

Cationic liposome codelivering PI3K pathway regulator improves the response of BRCA1-deficient breast cancer cells to PARP1 inhibition

Although some progresses have been made in breast cancer therapy, effective treatment for BRCA1-deficient breast cancer remains to be a great challenge. It has been demonstrated that the PI3K pathway is inappropriately activated in BRCA1-deficient breast cancers which can be downregulated by microRNA 451 (miR-451). In addition, although PARP1 inhibitors showed relatively positive results in both preclinical and clinical studies, additional efforts to decrease drug resistance as well as reduce systematic toxicity need to be addressed. To this end, by encapsulating the miR-451 mimic and PARP1 inhibitor in the same cationic liposome, we examined the potential of enhancing the response of PARP1 inhibition on BRCA1-deficient breast cancer by regulating the PI3K pathway. Our results revealed that in BRCA1-deficient human breast cancer cell line, PARP1 inhibition resulted in DNA damage with viability decrease, G2/M arrest as well as apoptosis. In contrast, single PI3K inhibition induced G1 arrest along with retarded cell proliferation. However, it was noted that combination of PARP inhibitor and PI3K regulator could exert synergetic function to evidently decrease cell proliferation compared with PARP inhibition alone, which was also confirmed by in vivo antitumor assay using xenograft tumor models. Collectively, our results offer an alternative but superior strategy for the therapy of BRCA1-deficient human breast cancers which may benefit the clinical applications.

Impact of early inflammatory cytokine elevation after commencement of PD-1 inhibitors to predict efficacy in patients with non-small cell lung cancer

Early elevation of inflammatory cytokines, such as IL-6 or TNF-α, or CRP, which is a surrogate marker for IL-6, following commencement of PD-1/L1 inhibitors (PD1-I) may represent early activation of immune-cells. Serum IL-6 and TNF-α were measured in 10 non-small cell lung cancer patients who were evaluable within the 7 days before and after commencement of PD1-I. For CRP, medical records were reviewed and 34 patients with measured CRP within the 7 days before and after the treatment were evaluated. In the 10 patients analyzed for IL-6/TNF-α, the serum levels of IL-6/TNF-α were not significantly different between pre- and post-initial PD1-I [IL-6 20.3 (2.6-49.9) and 22.9 (3.6-96.1) pg/mL, p = 0.453; TNF-α 1.6 (0.7-6.3) and 3.3 (0.7-9.6) pg/mL, p = 0.329]; however, all four responses were observed among the 7 IL-6-elevated cases, resulting in a response rate of 57%. In the 34 patients analyzed for CRP, CRP was significantly increased after initial PD1-I [1.8 (0.1-17.8) mg/dL, 2.4 (0.0-27.8), p = 0.001]. Notably, in the 31 evaluable cases, all responses were again observed in either the IL-6 or CRP elevated groups and the response rate was 46% (11 of 24). The median overall survival time was not reached in the elevated group and was 112 days in the non-elevated group (p = 0.069). The early increase in inflammatory cytokines with PD1-I was indicated to be predictive for the efficacy in patients with non-small cell lung cancer.

DNA Mismatch Repair Deficiency and Immune Checkpoint Inhibitors in Gastrointestinal Cancers

In the recent few years, significant efforts have been undertaken for the development of different immunotherapeutic approaches against cancer. In this context, immune checkpoint inhibitors (ICIs), a novel class of immunotherapeutic drugs with the potential to unleash the immune system, have emerged as authentic game-changers for managing patients with various cancers, including gastrointestinal malignancies. Although the majority of gastrointestinal cancers are generally considered poorly immunogenic, basic research findings and data from clinical trials have proven that subset(s) of patients with various digestive tract cancers are highly responsive to ICI-based therapy. In this context, a better understanding on the role of various DNA repair pathway alterations, especially the evidence supporting the significant importance of DNA mismatch repair deficiencies and the efficacy of the anti-programmed cell death 1 drugs, have led to US Food and Drug Administration approval of 2 anti-programmed cell death 1 antibodies (pembrolizumab and nivolumab) for the treatment of patients with microsatellite instability. This review aims to provide a comprehensive and up-to-date summary for the role of DNA mismatch repair deficiency in cancer, and its importance in the development of ICI therapy. In addition, we provide insights into the spectrum of various genetic alterations underlying ICI resistance, together with the important influence that the tumor microenvironment plays in mediating the therapeutic response to this new class of drugs. Finally, we provide a comprehensive yet succinct glimpse into the most exciting preclinical discoveries and ongoing clinical trials in the field, highlighting bench-to-beside translational impact of this exciting area of research.

HDAC3 modulates cancer immunity via increasing PD-L1 expression in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is the second leading cause of cancer-related deaths worldwide. Despite immune checkpoints based immunotherapy highlights a new therapeutic strategy and achieves a remarkable therapeutic effect in various types of malignant tumors. Pancreatic cancer is one of the non-immunogenic cancers and is resistant to immunotherapy. Programmed death ligand 1 (PD-L1) is expressed on the surface of tumor cells and its level is a key determinant of the checkpoint immunotherapy efficacy. Here, we reported that the specific inhibitor of histone deacetylase 3 (HDAC3) decreased the protein and mRNA level of PD-L1 in pancreatic cancer cells. Furthermore, we showed that HDAC3 was critical for PD-L1 regulation and positively correlated with PD-L1 in PDAC patient specimens. Finally, we demonstrated that HDAC3/signal transducer and activator of transcription 3 (STAT3) pathway transcriptionally regulated PD-L1 expression. Collectively, our data contributes to a better understanding of the function of HDAC3 in cancer immunity and the regulatory mechanism of PD-L1. More importantly, these data suggest that the HDAC3 inhibitors might be used to improve immunotherapy in pancreatic cancer.

Reflections on depletion of tumor stroma in pancreatic cancer

Pancreatic cancer characteristically has an extremely dense stroma, which facilitates chemoresistance by creating physical and biological barriers to therapeutic agents. Thus, stroma-depleting agents may enhance the delivery and efficacy of chemotherapy drugs. However, stroma-targeting therapy for pancreatic cancer is a double-edged sword, as the stroma can also inhibit tumor metastasis and malignancy. In-depth understanding of the critical role of the stroma in cancer metastasis may improve therapeutic approaches by allowing them to harness specific features of the stroma to treat pancreatic cancer.

Vitamin C in Cancer Therapeutics and Metastasis

There have been significant increased publications of preclinical studies and clinical trials of vitamin C (ascorbate) on cancer therapeutics in the past a few years. In this communication reflecting my personal opinions, I will highlight the main points of current research status; discuss impacts of vitamin C on immune cell function and inflammation at tumor microenvironment, and tumor metastasis; and propose stimulating questions and direction for future research in this area.

Circulating interleukin-6 is associated with disease progression, but not cachexia in pancreatic cancer

BACKGROUND

Cachexia is a wasting syndrome characterized by involuntary loss of >5% body weight due to depletion of adipose and skeletal muscle mass. In cancer, the pro-inflammatory cytokine interleukin-6 (IL-6) is considered a mediator of cachexia and a potential biomarker, but the relationship between IL-6, weight loss, and cancer stage is unknown. In this study we sought to evaluate IL-6 as a biomarker of cancer cachexia while accounting for disease progression.

METHODS

We retrospectively studied 136 subjects with biopsy-proven pancreatic ductal adenocarcinoma (PDAC), considering the high prevalence of cachexia is this population. Clinical data were abstracted from subjects in all cancer stages, and plasma IL-6 levels were measured using a multiplex array and a more sensitive ELISA. Data were evaluated with univariate comparisons, including Kaplan-Meier survival curves, and multivariate Cox survival models.

RESULTS

On multiplex, a total of 43 (31.4%) subjects had detectable levels of plasma IL-6, while by ELISA all subjects had detectable IL-6 levels. We found that increased plasma IL-6 levels, defined as detectable for multiplex and greater than median for ELISA, were not associated with weight loss at diagnosis, but rather with the presence of metastasis (p < 0.001 for multiplex and p = 0.007 for ELISA). Further, while >5% weight loss was not associated with worse survival, increased plasma IL-6 by either methodology was.

CONCLUSION

Circulating IL-6 levels do not correlate with cachexia (when defined by weight loss), but rather with advanced cancer stage. This suggests that IL-6 may mediate wasting, but should not be considered a diagnostic biomarker for PDAC-induced cachexia.

Stromal biology and therapy in pancreatic cancer: ready for clinical translation?

Pancreatic ductal adenocarcinoma (PDA) is notoriously aggressive and hard to treat. The tumour microenvironment (TME) in PDA is highly dynamic and has been found to promote tumour progression, metastasis niche formation and therapeutic resistance. Intensive research of recent years has revealed an incredible heterogeneity and complexity of the different components of the TME, including cancer-associated fibroblasts, immune cells, extracellular matrix components, tumour vessels and nerves. It has been hypothesised that paracrine interactions between neoplastic epithelial cells and TME compartments may result in either tumour-promoting or tumour-restraining consequences. A better preclinical understanding of such complex and dynamic network systems is required to develop more powerful treatment strategies for patients. Scientific activity and the number of compelling findings has virtually exploded during recent years. Here, we provide an update of the most recent findings in this area and discuss their translational and clinical implications for basic scientists and clinicians alike.

A severe case of refractory esophageal stenosis induced by nivolumab and responding to tocilizumab therapy

BACKGROUND

The prevalence of esophageal stenosis caused by immune checkpoint inhibitors in the context of induced immune mucositis and esophagitis is extremely rare.

CASE PRESENTATION

We report the case of a patient with stage IV pulmonary adenocarcinoma treated for 6 months with nivolumab who developed bilateral sterile conjunctivitis followed by oropharyngeal mucositis and esophagitis complicated by a severe esophageal stenosis. The laryngeal margin and hypopharyngeal mucosa appeared highly inflammatory with fibrinous deposits. Esophagogastroduodenoscopy revealed mucositis with a scar-like structure immediately below the upper esophageal sphincter with nonulcerative mucosa and an inflammatory aspect of the entire esophagus. No involvement of the stomach was observed. Oropharynx biopsies displayed marked lymphocytic T cell-infiltration with several foci of monocellular necrosis in the squamous epithelium. No morphologic evidence of adenocarcinoma and no signs of mycotic, bacterial or viral infection were noted. A blood sample revealed a discrete increase in the erythrocyte sedimentation rate (ESR) with no eosinophilia or leukocytosis. Liver and kidney function panel tests were normal. A thoracoabdominal CT scan reported no evidence of disease recurrence. Despite multiple boluses of methylprednisolone and high doses of prednisone continued for several months, the patient experienced very rapid symptomatological reappearance during three steroid tapering attempts and aggravation of his esophageal stenosis to an aphagic stage, requiring a nasogastric tube. This long course of high-dose corticosteroid treatment was complicated with osteoporosis-induced fractures with several spontaneous compressions of thoracolumbar vertebrae requiring an enlarged T10 to L5 cementoplasty. Anti-IL-6 blockade therapy with tocilizumab resulted in excellent clinical response, allowing the total resolution of the immune-related adverse events (irAEs) and leading to successful steroid tapering.

CONCLUSIONS

Herein, we describe the first case of a patient who developed autoimmune mucositis and esophagitis complicated by a severe refractory esophageal stenosis induced during treatment by nivolumab, which completely resolved after personalized treatment with tocilizumab, suggesting a role of IL-6 blockade in the management of severe steroid refractory esophageal stenosis and more broadly in refractory immune-related adverse events.

The role of the interleukin (IL)-6/IL-6 receptor axis in cancer

Interleukin-6 (IL-6) is a pleiotropic cytokine that activates a classic signalling pathway upon binding to its membrane-bound receptor (IL-6R). Alternatively, IL-6 may 'trans-signal' in a manner that is facilitated by its binding to a soluble derivative of the IL-6 receptor (sIL-6R). Resultant signal transduction is, respectively, driven by the association of IL-6/IL-6R or IL-6/sIL-6R complex with the membrane-associated signal transducer, gp130 (Glycoprotein 130). Distinct JAK (Janus tyrosine kinase)/STAT (signal transducers and activators of transcription) and other signalling pathways are activated as a consequence. Of translational relevance, overexpression of IL-6 has been documented in several neoplastic disorders, including but not limited to colorectal, ovarian and breast cancer and several haematological malignancies. This review attempts to summarise our current understanding of the role of IL-6 in cancer development. In short, these studies have shown important roles for IL-6 signalling in tumour cell growth and survival, angiogenesis, immunomodulation of the tumour microenvironment, stromal cell activation, and ultimate disease progression. Given this background, we also consider the potential for therapeutic targeting of this system in cancer.

The 150 most important questions in cancer research and clinical oncology series: questions 94-101 : Edited by Cancer Communications

Since the beginning of 2017, Cancer Communications (former title: Chinese Journal of Cancer) has published a series of important questions regarding cancer research and clinical oncology, to provide an enhanced stimulus for cancer research, and to accelerate collaborations between institutions and investigators. In this edition, the following 8 valuable questions are presented. Question 94. The origin of tumors: time for a new paradigm? Question 95. How can we accelerate the identification of biomarkers for the early detection of pancreatic ductal adenocarcinoma? Question 96. Can we improve the treatment outcomes of metastatic pancreatic ductal adenocarcinoma through precision medicine guided by a combination of the genetic and proteomic information of the tumor? Question 97. What are the parameters that determine a competent immune system that gives a complete response to cancers after immune induction? Question 98. Is high local concentration of metformin essential for its anti-cancer activity? Question 99. How can we monitor the emergence of cancer cells anywhere in the body through plasma testing? Question 100. Can phytochemicals be more specific and efficient at targeting P-glycoproteins to overcome multi-drug resistance in cancer cells? Question 101. Is cell migration a selectable trait in the natural evolution of carcinoma?