Kellie A. Charles

“Re-educating” tumor-associated macrophages by targeting NF-κB

The nuclear factor κB (NF-κB) signaling pathway is important in cancer-related inflammation and malignant progression. Here, we describe a new role for NF-κB in cancer in maintaining the immunosuppressive phenotype of tumor-associated macrophages (TAMs). We show that macrophages are polarized via interleukin (IL)-1R and MyD88 to an immunosuppressive “alternative” phenotype that requires IκB kinase β–mediated NF-κB activation. When NF-κB signaling is inhibited specifically in TAMs, they become cytotoxic to tumor cells and switch to a “classically” activated phenotype; IL-12high, major histocompatibility complex IIhigh, but IL-10low and arginase-1low. Targeting NF-κB signaling in TAMs also promotes regression of advanced tumors in vivo by induction of macrophage tumoricidal activity and activation of antitumor activity through IL-12–dependent NK cell recruitment. We provide a rationale for manipulating the phenotype of the abundant macrophage population already located within the tumor microenvironment; the potential to “re-educate” the tumor-promoting macrophage population may prove an effective and novel therapeutic approach for cancer that complements existing therapies.

The systemic inflammation-based neutrophil–lymphocyte ratio: Experience in patients with cancer

There is increasing and consistent evidence that cancer-associated inflammation is a key determinant of outcome in patients with cancer. Various markers of inflammation have been examined over the past decade in an attempt to refine stratification of patients to treatment and predict survival. One routinely available marker of the systemic inflammatory response is the neutrophil-lymphocyte ratio (NLR), which is derived from the absolute neutrophil and absolute lymphocyte counts of a full blood count. To date, over 60 studies (>37,000 patients) have examined the clinical utility of the NLR to predict patient outcomes in a variety of cancers. The present systematic review examines and comments on the clinical utility of the NLR. The NLR had independent prognostic value in (a) unselected cohorts (1 study of >12,000 patients), (b) operable disease (20 studies, >4000 patients), (c) patients receiving neoadjuvant treatment and resection (5 studies, >1000 patients), (d) patients receiving chemo/radiotherapy (12 studies, >2000 patients) and (e) patients with inoperable disease (6 studies, >1200 patients). These studies originated from ten different countries, in particular UK, Japan, and China. Further, correlative studies (15 studies, >8500 patients) have shown that NLR is elevated in patients with more advanced or aggressive disease evidenced by increased tumour stage, nodal stage, number of metastatic lesions and as such these patients may represent a particularly high-risk patient population. Further studies investigating the tumour and host-derived factors regulating the systemic inflammatory response, in particular the NLR, may identify novel treatment strategies for patients with cancer.

Macrophages Induce Invasiveness of Epithelial Cancer Cells Via NF-κB and JNK

Tumor-associated macrophages may influence tumor progression, angiogenesis and invasion. To investigate mechanisms by which macrophages interact with tumor cells, we developed an in vitro coculture model. Previously we reported that coculture enhanced invasiveness of the tumor cells in a TNF-α- and matrix metalloprotease-dependent manner. In this report, we studied intracellular signaling pathways and induction of inflammatory genes in malignant cells under the influence of macrophage coculture. We report that coculture of macrophages with ovarian or breast cancer cell lines led to TNF-α-dependent activation of JNK and NF-κB pathways in tumor cells, but not in benign immortalized epithelial cells. Tumor cells with increased JNK and NF-κB activity exhibited enhanced invasiveness. Inhibition of the NF-κB pathway by TNF-α neutralizing Abs, an NF-κB inhibitor, RNAi to RelA, or overexpression of IκB inhibited tumor cell invasiveness. Blockade of JNK also significantly reduced invasiveness, but blockade of p38 MAPK or p42 MAPK had no effect. Cocultured tumor cells were screened for the expression of 22 genes associated with inflammation and invasion that also contained an AP-1 and NF-κB binding site. EMMPRIN and MIF were up-regulated in cocultured tumor cells in a JNK- and NF-κB-dependent manner. Knocking down either MIF or EMMPRIN by RNAi in the tumor cells significantly reduced tumor cell invasiveness and matrix metalloprotease activity in the coculture supernatant. We conclude that TNF-α, via NF-κB, and JNK induces MIF and EMMPRIN in macrophage to tumor cell cocultures and this leads to increased invasive capacity of the tumor cells.

Ovarian cancer cells polarize macrophages toward a tumor-associated phenotype.

Tumor-associated macrophages (TAM) may have tumor-promoting activity, but it is not clear how their phenotype is achieved. In this study, we demonstrate that ovarian cancer cells switch cocultured macrophages to a phenotype similar to that found in ovarian tumors. Tumor cells caused dynamic changes in macrophage cytokine, chemokine, and matrix metalloprotease mRNA, and protein-inducing mediators that are found in human cancer. Macrophage mannose, mannose receptor, and scavenger receptors (SR-As) were also up-regulated by coculture, but not by conditioned medium. To further validate the model, we studied SR-A regulation on TAM in vitro and in vivo. Coculture of murine macrophages from mice deficient in TNF-α or its receptors revealed that TNF-α was key to SR-A induction via its p75 receptor. SR-A expression was also reduced in TAM from ovarian cancers treated with anti-TNF-α Abs or grown in TNF-α−/− mice. Chemical communication between tumor cells and macrophages may be important in regulating the cancer cytokine microenvironment.

Neutrophil/lymphocyte ratio predicts chemotherapy outcomes in patients with advanced colorectal cancer

Background:Advances in the treatment of metastatic colorectal cancer (mCRC) in the last decade have significantly improved survival; however, simple biomarkers to predict response or toxicity have not been identified, which are applicable to all community oncology settings worldwide. The use of inflammatory markers based on differential white-cell counts, such as the neutrophil/lymphocyte ratio (NLR), may be simple and readily available biomarkers.Methods:Clinical information and baseline laboratory parameters were available for 349 patients, from two independent cohorts, with unresectable mCRC receiving first-line palliative chemotherapy. Associations between baseline prognostic variables, including inflammatory markers such as the NLR and tumour response, progression and survival were investigated.Results:In the training cohort, combination-agent chemotherapy (P=0.001) and NLR⩽5 (P=0.003) were associated with improved clinical benefit. The ECOG performance status ⩾1 (P=0.002), NLR>5 (P=0.01), hypoalbuminaemia (P=0.03) and single-agent chemotherapy (P<0.0001) were associated with increased risk of progression. The ECOG performance status ⩾1 (P=0.004) and NLR>5 (P=0.002) predicted worse overall survival (OS). The NLR was confirmed to independently predict OS in the validation cohort (P<0.0001). Normalisation of the NLR after one cycle of chemotherapy in a subset of patients resulted in improved progression-free survival (P=0.012).Conclusion:These results have highlighted NLR as a potentially useful clinical biomarker of systemic inflammatory response in predicting clinically meaningful outcomes in two independent cohorts. Results of this study have also confirmed the importance of a chronic systemic inflammatory response influencing clinical outcomes in patients with mCRC.

Regulation of Drug-Metabolizing Enzymes and Transporters in Infection, Inflammation, and Cancer

This article is a report on a symposium sponsored by the American Society for Pharmacology and Experimental Therapeutics and held at the Experimental Biology 07 meeting in Washington, DC. The presentations discussed the phenomenology, clinical consequences, and underlying mechanisms of cytochrome P450 and drug transporter regulation by inflammatory and infectious stimuli. Although considerable insights into the links between inflammatory mediators and altered hepatic drug clearance pathways have been gained from previous studies with acute inflammatory stimuli, this symposium highlighted recent advances in understanding how these processes operate in other organs and chronic inflammatory states relevant to human diseases. The development of mouse models of live bacterial infection provides excellent opportunities to explore the impact of infection on drug metabolism beyond the well characterized effects of bacterial endotoxin. Altered levels of cytochromes P450 and especially drug transporters due to inflammation in brain, intestine, and placenta have significant implications for the use of many drugs in diverse clinical settings. The consequences of inflammatory cytokine production by tumors for drug safety and efficacy in cancer patients were outlined. Repression of drug clearance pathways by tumor-derived cytokines may result in extreme toxicity to chemotherapy, compromising treatment of many cancers. It is fitting that, in honoring the career contributions and achievements of Dr. Kenneth W. Renton, this symposium reinforced the clinical relevance of this field.

The tumor-promoting actions of TNF-α involve TNFR1 and IL-17 in ovarian cancer in mice and humans

Cytokines orchestrate the tumor-promoting interplay between malignant cells and the immune system. In many experimental and human cancers, the cytokine TNF-alpha is an important component of this interplay, but its effects are pleiotropic and therefore remain to be completely defined. Using a mouse model of ovarian cancer in which either TNF receptor 1 (TNFR1) signaling was manipulated in different leukocyte populations or TNF-alpha was neutralized by antibody treatment, we found that this inflammatory cytokine maintained TNFR1-dependent IL-17 production by CD4+ cells and that this led to myeloid cell recruitment into the tumor microenvironment and enhanced tumor growth. Consistent with this, in patients with advanced cancer, treatment with the TNF-alpha-specific antibody infliximab substantially reduced plasma IL-17 levels. Furthermore, expression of IL-1R and IL-23R was downregulated in CD4+CD25- cells isolated from ascites of ovarian cancer patients treated with infliximab. We have also shown that genes ascribed to the Th17 pathway map closely with the TNF-alpha signaling pathway in ovarian cancer biopsy samples, showing particularly high levels of expression of genes encoding IL-23, components of the NF-kappaB system, TGF-beta1, and proteins involved in neutrophil activation. We conclude that chronic production of TNF-alpha in the tumor microenvironment increases myeloid cell recruitment in an IL-17-dependent manner that contributes to the tumor-promoting action of this proinflammatory cytokine.

Cancer-related inflammation and treatment effectiveness

Inflammation is a recognised hallmark of cancer that substantially contributes to the development and progression of malignancies. In established cancers, there is increasing evidence for the roles that local immune response and systemic inflammation have in progression of tumours and survival of patients with cancer. This knowledge provides an opportunity to target these inflammatory responses to improve patient outcomes. In this Review, we examine the complex interplay between local immune responses and systemic inflammation, and their influence on clinical outcomes, and propose potential anti-inflammatory interventions for patients with cancer.

Tumor Necrosis Factor α As a New Target for Renal Cell Carcinoma: Two Sequential Phase II Trials of Infliximab at Standard and High Dose

PURPOSE Tumor necrosis factor alpha (TNF-alpha) may play a role in renal cell carcinoma (RCC). We performed two sequential phase II studies of infliximab, an anti-TNF-alpha monoclonal antibody, in patients with immunotherapy-resistant or refractory RCC. PATIENTS AND METHODS Patients progressing after cytokine therapy were treated with intravenous infliximab as follows: study 1 (19 patients), 5 mg/kg at weeks 0, 2, and 6, and then every 8 weeks; study 2 (18 patients), 10 mg/kg at weeks 0, 2, and 6, and then every 4 weeks. Treatment continued until disease progression (PD). Response was assessed according to Response Evaluation Criteria in Solid Tumors. Plasma levels of TNF-alpha, CCL2, and interleukin-6 (IL-6) were measured before and during treatment. RESULTS TNF-alpha and its receptors were detected in malignant cells in RCC biopsies. In study 1, three patients (16%) achieved partial response (PR) and three patients (16%) achieved stable disease (SD). Median duration of response (PR + SD) was 7.7 months (range, 5.0 to 40.5+ months). In study 2, 11 patients (61%) achieved SD. Median duration of response was 6.2 months (range, 3.5 to 24+ months). One patient developed grade 3 hypersensitivity and another died as a result of pulmonary infection/sepsis. Enzyme-linked immunosorbent assay analysis of plasma revealed that higher levels of TNF-alpha at baseline and higher levels of CCL2 during treatment were associated with PD. There were also correlations between higher levels of TNF-alpha, IL-6, and CCL2 and poor survival (< 12 months). CONCLUSION This is the first direct clinical evidence suggesting that TNF-alpha may be a therapeutic target in RCC. Plasma levels of TNF-alpha, IL-6, and CCL2 may have predictive and prognostic significance.

A clinical study assessing the tolerability and biological effects of infliximab, a TNF-α inhibitor, in patients with advanced cancer

BACKGROUND Tumour necrosis factor-alpha (TNF-alpha) is an important regulator of the chronic inflammation contributing to tumour progression. Infliximab, an anti-TNF-alpha monoclonal antibody was investigated in this trial of patients with advanced cancer. The primary objectives were to determine the safety profile and biological response of infliximab in a cancer population. Clinical response was a secondary objective. PATIENTS AND METHODS Forty-one patients received infliximab at 5 mg/kg (n = 21) or 10 mg/kg (n = 20) i.v. at 0 and 2 weeks and then every 4 weeks. Post-treatment samples were measured for changes in plasma and serum TNF-alpha, CCL2, IL-6 and C-reactive protein (CRP). RESULTS Infliximab was well tolerated with no dose-limiting toxic effects. At both doses of infliximab, neutralisation of serum TNF-alpha was observed after 1 h while plasma CCL2, IL-6 and serum CRP were decreased 24 and 48 h following infliximab administration. Seven patients experienced disease stablisation (range 10-50+ weeks). There was no evidence of disease acceleration in any patient. CONCLUSIONS Infliximab treatment was safe and well tolerated in patients with advanced cancer. There was evidence of biological activity with baseline TNF-alpha and CCL2 being correlated with infliximab response.