Cancer-associated fibroblasts (CAFs) are a key component of the tumour microenvironment with diverse functions, including matrix deposition and remodelling, extensive reciprocal signalling ...interactions with cancer cells and crosstalk with infiltrating leukocytes. As such, they are a potential target for optimizing therapeutic strategies against cancer. However, many challenges are present in ongoing attempts to modulate CAFs for therapeutic benefit. These include limitations in our understanding of the origin of CAFs and heterogeneity in CAF function, with it being desirable to retain some antitumorigenic functions. On the basis of a meeting of experts in the field of CAF biology, we summarize in this Consensus Statement our current knowledge and present a framework for advancing our understanding of this critical cell type within the tumour microenvironment.
An autochthonous model of pancreatic ductal adenocarcinoma (PDA) permitted the analysis of why immunotherapy is ineffective in this human disease. Despite finding that PDA-bearing mice had cancer ...cell-specific CD8 ⁺ T cells, the mice, like human patients with PDA, did not respond to two immunological checkpoint antagonists that promote the function of T cells: anti-cytotoxic T-lymphocyte-associated protein 4 (α-CTLA-4) and α-programmed cell death 1 ligand 1 (α-PD-L1). Immune control of PDA growth was achieved, however, by depleting carcinoma-associated fibroblasts (CAFs) that express fibroblast activation protein (FAP). The depletion of the FAP ⁺ stromal cell also uncovered the antitumor effects of α-CTLA-4 and α-PD-L1, indicating that its immune suppressive activity accounts for the failure of these T-cell checkpoint antagonists. Three findings suggested that chemokine (C-X-C motif) ligand 12 (CXCL12) explained the overriding immunosuppression by the FAP ⁺ cell: T cells were absent from regions of the tumor containing cancer cells, cancer cells were coated with the chemokine, CXCL12, and the FAP ⁺ CAF was the principal source of CXCL12 in the tumor. Administering AMD3100, a CXCL12 receptor chemokine (C-X-C motif) receptor 4 inhibitor, induced rapid T-cell accumulation among cancer cells and acted synergistically with α-PD-L1 to greatly diminish cancer cells, which were identified by their loss of heterozygosity of Trp53 gene. The residual tumor was composed only of premalignant epithelial cells and inflammatory cells. Thus, a single protein, CXCL12, from a single stromal cell type, the FAP ⁺ CAF, may direct tumor immune evasion in a model of human PDA.
Tumors consist of cancer cells and a network of non-cancerous stroma. Cancer-associated fibroblasts (CAF) are known to support tumorigenesis, and are emerging as immune modulators. Neutrophils ...release histone-bound nuclear DNA and cytotoxic granules as extracellular traps (NET). Here we show that CAFs induce NET formation within the tumor and systemically in the blood and bone marrow. These tumor-induced NETs (t-NETs) are driven by a ROS-mediated pathway dependent on CAF-derived Amyloid β, a peptide implicated in both neurodegenerative and inflammatory disorders. Inhibition of NETosis in murine tumors skews neutrophils to an anti-tumor phenotype, preventing tumor growth; reciprocally, t-NETs enhance CAF activation. Mirroring observations in mice, CAFs are detected juxtaposed to NETs in human melanoma and pancreatic adenocarcinoma, and show elevated amyloid and β-Secretase expression which correlates with poor prognosis. In summary, we report that CAFs drive NETosis to support cancer progression, identifying Amyloid β as the protagonist and potential therapeutic target.
Mechanically ventilated patients with COVID-19 have a mortality of 24-53%, in part due to distal mucopurulent secretions interfering with ventilation. DNA from neutrophil extracellular traps (NETs) ...contribute to the viscosity of mucopurulent secretions and NETs are found in the serum of COVID-19 patients. Dornase alfa is recombinant human DNase 1 and is used to digest DNA in mucoid sputum. Here, we report a single-center case series where dornase alfa was co-administered with albuterol through an in-line nebulizer system.
Demographic and clinical data were collected from the electronic medical records of five mechanically ventilated patients with COVID-19-including three requiring veno-venous extracorporeal membrane oxygenation-treated with nebulized in-line endotracheal dornase alfa and albuterol, between March 31 and April 24, 2020. Data on tolerability and response were analyzed.
The fraction of inspired oxygen requirements was reduced for all five patients after initiating dornase alfa administration. All patients were successfully extubated, discharged from hospital and remain alive. No drug-associated toxicities were identified.
Results suggest that dornase alfa will be well-tolerated by patients with severe COVID-19. Clinical trials are required to formally test the dosing, safety, and efficacy of dornase alfa in COVID-19, and several have been recently registered.
Inhibition of the chemokine receptor CXCR4 in combination with blockade of the PD-1/PD-L1 T cell checkpoint induces T cell infiltration and anticancer responses in murine and human pancreatic cancer. ...Here we elucidate the mechanism by which CXCR4 inhibition affects the tumor immune microenvironment. In human immune cell-based chemotaxis assays, we find that CXCL12-stimulated CXCR4 inhibits the directed migration mediated by CXCR1, CXCR3, CXCR5, CXCR6, and CCR2, respectively, chemokine receptors expressed by all of the immune cell types that participate in an integrated immune response. Inhibiting CXCR4 in an experimental cancer medicine study by 1-wk continuous infusion of the small-molecule inhibitor AMD3100 (plerixafor) induces an integrated immune response that is detected by transcriptional analysis of paired biopsies of metastases from patients with microsatellite stable colorectal and pancreatic cancer. This integrated immune response occurs in three other examples of immunemediated damage to noninfected tissues: Rejecting renal allografts, melanomas clinically responding to anti-PD1 antibody therapy, and microsatellite instable colorectal cancers. Thus, signaling by CXCR4 causes immune suppression in human pancreatic ductal adenocarcinoma and colorectal cancer by impairing the function of the chemokine receptors that mediate the intratumoral accumulation of immune cells.
In patients with cancer, the wasting syndrome, cachexia, is associated with caloric deficiency. Here, we describe tumor-induced alterations of the host metabolic response to caloric deficiency that ...cause intratumoral immune suppression. In pre-cachectic mice with transplanted colorectal cancer or autochthonous pancreatic ductal adenocarcinoma (PDA), we find that IL-6 reduces the hepatic ketogenic potential through suppression of PPARalpha, the transcriptional master regulator of ketogenesis. When these mice are challenged with caloric deficiency, the resulting relative hypoketonemia triggers a marked rise in glucocorticoid levels. Multiple intratumoral immune pathways are suppressed by this hormonal stress response. Moreover, administering corticosterone to elevate plasma corticosterone to a level that is lower than that occurring in cachectic mice abolishes the response of mouse PDA to an immunotherapy that has advanced to clinical trials. Therefore, tumor-induced IL-6 impairs the ketogenic response to reduced caloric intake, resulting in a systemic metabolic stress response that blocks anti-cancer immunotherapy.
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•IL-6 suppresses hepatic ketogenesis in pre-cachectic, tumor-bearing mice•During caloric deficiency, hypoketonemia triggers marked glucocorticoid secretion•Glucocorticoids, induced by metabolic stress, suppress intratumoral immunity•Stress-induced glucocorticoids cause failure of cancer immunotherapy
Flint and Janowitz et al. reveal the intricate links between cancer cachexia, hepatic metabolism, and tumor immunology. They find that tumor-induced IL-6 suppresses hepatic ketogenesis, and during caloric deficiency, this triggers marked glucocorticoid secretion. This hormonal stress response suppresses intratumoral immunity and causes failure of anti-cancer immunotherapy.
Separate research fields have advanced our understanding of, on the one hand, cancer immunology, and on the other, cachexia, the fatal tumor-induced wasting syndrome. A link between the host’s immune ...and metabolic responses to cancer has remained unexplored. Emerging work in preclinical models of colorectal and pancreatic cancer has unveiled tumor-induced reprogramming of liver metabolism in cachexia that leads to suppression of anti-tumor immunity and failure of immunotherapy. As research efforts in metabolism and immunology in cancer are rapidly expanding, it is timely to discuss the metabolic and immunological determinants of the cancer-host interaction. We also present the hypothesis that the convergence of host metabolism and anti-tumor immunity may offer a platform for biomarker-driven investigations of new combination therapies.
Summary Background Second-line chemotherapy for patients with oesophagogastric adenocarcinoma refractory to platinum and fluoropyrimidines has not shown benefits in health-related quality of life ...(HRQoL). We assessed whether the addition of docetaxel to active symptom control alone can improve survival and HRQoL for patients. Methods For this open-labelled, multicentre trial, we recruited patients aged 18 years or older from 30 UK centres. Patients were eligible if they had an advanced, histologically confirmed adenocarcinoma of the oesophagus, oesophagogastric junction, or stomach that had progressed on or within 6 months of treatment with a platinum-fluoropyrimidine combination. Patients could have an Eastern Cooperative Oncology Group performance status of 0–2. We randomly assigned patients using a central, computerised minimisation procedure to receive docetaxel plus active symptom control, or active symptom control alone (1:1; stratified by disease status, disease site, duration of response to previous chemotherapy, and performance status). Docetaxel was given at a dose of 75 mg/m2 by intravenous infusion every 3 weeks for up to six cycles. The primary endpoint was overall survival, analysed by intention to treat. This is the report of the planned final analysis. This study is an International Standardised Randomised Controlled Trial, number ISRCTN13366390. Findings Between April 21, 2008, and April 26, 2012, we recruited 168 patients, allocating 84 to each treatment group. After a median follow-up of 12 months IQR 10–21) and 161 (96%) deaths (80 in the docetaxel group, 81 in the active symptom control group), median overall survival in the docetaxel group was 5·2 months (95% CI 4·1–5·9) versus 3·6 months (3·3–4·4) in the active symptom control group (hazard ratio 0·67, 95% CI 0·49–0·92; p=0·01). Docetaxel was associated with higher incidence of grade 3–4 neutropenia (12 15% patients vs no patients), infection (15 19% patients vs two 3% patients), and febrile neutropenia (six 7% patients vs no patients). Patients receiving docetaxel reported less pain (p=0·0008) and less nausea and vomiting (p=0·02) and constipation (p=0·02). Global HRQoL was similar between the groups (p=0·53). Disease specific HRQoL measures also showed benefits for docetaxel in reducing dysphagia (p=0·02) and abdominal pain (p=0·01). Interpretation Our findings suggest that docetaxel can be recommended as an appropriate second-line treatment for patients with oesophagogastric adenocarcinoma that is refractory to treatment with platinum and fluoropyrimidine. Funding Cancer Research UK.
Interleukin-6 (IL-6) has been long considered a key player in cancer cachexia. It is believed that sustained elevation of IL-6 production during cancer progression causes brain dysfunctions, which ...ultimately result in cachexia. However, how peripheral IL-6 influences the brain remains poorly understood. Here we show that neurons in the area postrema (AP), a circumventricular structure in the hindbrain, is a critical mediator of IL-6 function in cancer cachexia in male mice. We find that circulating IL-6 can rapidly enter the AP and activate neurons in the AP and its associated network. Peripheral tumor, known to increase circulating IL-6, leads to elevated IL-6 in the AP, and causes potentiated excitatory synaptic transmission onto AP neurons and AP network hyperactivity. Remarkably, neutralization of IL-6 in the brain of tumor-bearing mice with an anti-IL-6 antibody attenuates cachexia and the hyperactivity in the AP network, and markedly prolongs lifespan. Furthermore, suppression of Il6ra, the gene encoding IL-6 receptor, specifically in AP neurons with CRISPR/dCas9 interference achieves similar effects. Silencing Gfral-expressing AP neurons also attenuates cancer cachectic phenotypes and AP network hyperactivity. Our study identifies a central mechanism underlying the function of peripheral IL-6, which may serve as a target for treating cancer cachexia.
Obesity is a risk factor for pancreatic cancer. In mice, a high-fat diet (HFD) and expression of oncogenic KRAS lead to development of invasive pancreatic ductal adenocarcinoma (PDAC) by unknown ...mechanisms. We investigated how oncogenic KRAS regulates the expression of fibroblast growth factor 21, FGF21, a metabolic regulator that prevents obesity, and the effects of recombinant human FGF21 (rhFGF21) on pancreatic tumorigenesis.
We performed immunohistochemical analyses of FGF21 levels in human pancreatic tissue arrays, comprising 59 PDAC specimens and 45 nontumor tissues. We also studied mice with tamoxifen-inducible expression of oncogenic KRAS in acinar cells (KrasG12D/+ mice) and fElasCreERT mice (controls). KrasG12D/+ mice were placed on an HFD or regular chow diet (control) and given injections of rhFGF21 or vehicle; pancreata were collected and analyzed by histology, immunoblots, quantitative polymerase chain reaction, and immunohistochemistry. We measured markers of inflammation in the pancreas, liver, and adipose tissue. Activity of RAS was measured based on the amount of bound guanosine triphosphate.
Pancreatic tissues of mice expressed high levels of FGF21 compared with liver tissues. FGF21 and its receptor proteins were expressed by acinar cells. Acinar cells that expressed KrasG12D/+ had significantly lower expression of Fgf21 messenger RNA compared with acinar cells from control mice, partly due to down-regulation of PPARG expression—a transcription factor that activates Fgf21 transcription. Pancreata from KrasG12D/+ mice on a control diet and given injections of rhFGF21 had reduced pancreatic inflammation, infiltration by immune cells, and acinar-to-ductal metaplasia compared with mice given injections of vehicle. HFD-fed KrasG12D/+ mice given injections of vehicle accumulated abdominal fat, developed extensive inflammation, pancreatic cysts, and high-grade pancreatic intraepithelial neoplasias (PanINs); half the mice developed PDAC with liver metastases. HFD-fed KrasG12D/+ mice given injections of rhFGF21 had reduced accumulation of abdominal fat and pancreatic triglycerides, fewer pancreatic cysts, reduced systemic and pancreatic markers of inflammation, fewer PanINs, and longer survival—only approximately 12% of the mice developed PDACs, and none of the mice had metastases. Pancreata from HFD-fed KrasG12D/+ mice given injections of rhFGF21 had lower levels of active RAS than from mice given vehicle.
Normal acinar cells from mice and humans express high levels of FGF21. In mice, acinar expression of oncogenic KRAS significantly reduces FGF21 expression. When these mice are placed on an HFD, they develop extensive inflammation, pancreatic cysts, PanINs, and PDACs, which are reduced by injection of FGF21. FGF21 also reduces the guanosine triphosphate binding capacity of RAS. FGF21 might be used in the prevention or treatment of pancreatic cancer.
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