Identification of circulating plasma ceramides as a potential sexually dimorphic biomarker of pancreatic cancer-induced cachexia.

Background: Cancer patients who exhibit cachexia lose weight and have low treatment tolerance and poor outcomes compared to cancer patients without weight loss. Despite the clear increased risk for patients, diagnosing cachexia still often relies on self-reported weight loss. A reliable biomarker to identify patients with cancer cachexia would be a valuable tool to improve clinical decision making and identification of patients at risk of adverse outcomes. Methods: Targeted metabolomics, that included panels of amino acids, tricarboxylic acids, fatty acids, acylcarnitines, and sphingolipids, were conducted on plasma samples from patients with confirmed pancreatic ductal adenocarcinoma (PDAC) with and without cachexia and control patients without cancer (n=10/group, equally divided by sex). Additional patient samples were analyzed (total n=95) and Receiver Operating Characteristic (ROC) analyses were performed to establish if any metabolite could effectively serve as a biomarker of cachexia. Results: Targeted profiling revealed that cachectic patients had decreased circulating levels of three sphingolipids compared to either non-cachectic PDAC patients or patients without cancer. The ratio of C18-ceramide to C24-ceramide (C18:C24) outperformed a number of other previously proposed biomarkers of cachexia (area under ROC = 0.810). It was notable that some biomarkers, including C18:C24, were only altered in cachectic males. Conclusions: Our findings identify C18:C24 as a potentially new biomarker of PDAC-induced cachexia that also highlight a previously unappreciated sexual dimorphism in cancer cachexia.

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.

Circulating monocyte chemoattractant protein-1 (MCP-1) is associated with cachexia in treatment-naïve pancreatic cancer patients.

BACKGROUND: Cancer-associated wasting, termed cancer cachexia, has a profound effect on the morbidity and mortality of cancer patients but remains difficult to recognize and diagnose. While increases in circulating levels of a number of inflammatory cytokines have been associated with cancer cachexia, these associations were generally made in patients with advanced disease and thus may be associated with disease progression rather than directly with the cachexia syndrome. Thus, we sought to assess potential biomarkers of cancer-induced cachexia in patients with earlier stages of disease. METHODS: A custom multiplex array was used to measure circulating levels of 25 soluble factors from 70 pancreatic cancer patients undergoing attempted tumour resections. A high-sensitivity multiplex was used for increased sensitivity for nine cytokines. RESULTS: Resectable pancreatic cancer patients with cachexia had low levels of canonical pro-inflammatory cytokines including interleukin-6 (IL-6), interleukin-1ß (IL-1ß), interferon-γ (IFN-γ), and tumour necrosis factor (TNF). Even in our more sensitive analysis, these cytokines were not associated with cancer cachexia. Of the 25 circulating factors tested, only monocyte chemoattractant protein-1 (MCP-1) was increased in treatment-naïve cachectic patients compared with weight stable patients and identified as a potential biomarker for cancer cachexia. Although circulating levels of leptin and granulocyte-macrophage colony-stimulating factor (GM-CSF) were found to be decreased in the same cohort of treatment-naïve cachectic patients, these factors were closely associated with body mass index, limiting their utility as cancer cachexia biomarkers. CONCLUSIONS: Unlike in advanced disease, it is possible that cachexia in patients with resectable pancreatic cancer is not associated with high levels of classical markers of systemic inflammation. However, cachectic, treatment-naïve patients have higher levels of MCP-1, suggesting that MCP-1 may be useful as a biomarker of cancer cachexia.

Perioperative cytokine levels portend early death after pancreatectomy for ductal adenocarcinoma.

BACKGROUND: Soluble signaling molecules may play an important role in malignant pathogenesis. We hypothesize that perioperative cytokine levels are associated with outcomes in patients with pancreatic adenocarcinoma (PDAC) undergoing surgical resection. METHODS: One hundered and eighteen patients with benign or malignant pancreatic disease were enrolled in a prospective study through a protocol for banking biologic samples. Peripheral blood was drawn at time of operation, and a multiplex cytokine assay was performed. Statistical analysis was via χ2 and Kaplan Meier methods. RESULTS: Of 118 patients enrolled, 85 (72%) had a diagnosis of PDAC, and 60 (70%) ultimately underwent partial pancreatectomy. Cytokine levels were not associated with postoperative complications in this initial cohort. A plasma level of monocyte chemoattractant protein-1 (MCP-1) pg/mL ≤118 was associated with better overall survival (OS) (median survival 21 months vs 12.8 months, P = 0.023), as was non-detectable interleukin-8 (IL-8) (19 months) versus detectable IL-8 (12.8 months, P = 0.05). Patients with both MCP-1 >118 pg/mL and detectable IL-8 had a median survival of 10.6 months (P = 0.028). CONCLUSIONS: MCP-1 and IL-8 cytokine levels are associated with decreased survival following pancreatectomy for PDAC, and may be useful biomarkers. Measurement of these cytokine levels at different time points in future investigations will be important to validate these findings.

NF-κB regulates GDF-15 to suppress macrophage surveillance during early tumor development.

Macrophages are attracted to developing tumors and can participate in immune surveillance to eliminate neoplastic cells. In response, neoplastic cells utilize NF-κB to suppress this killing activity, but the mechanisms underlying their self-protection remain unclear. Here, we report that this dynamic interaction between tumor cells and macrophages is integrally linked by a soluble factor identified as growth and differentiation factor 15 (GDF-15). In vitro, tumor-derived GDF-15 signals in macrophages to suppress their proapoptotic activity by inhibiting TNF and nitric oxide (NO) production. In vivo, depletion of GDF-15 in Ras-driven tumor xenografts and in an orthotopic model of pancreatic cancer delayed tumor development. This delay correlated with increased infiltrating antitumor macrophages. Further, production of GDF-15 is directly regulated by NF-κB, and the colocalization of activated NF-κB and GDF-15 in epithelial ducts of human pancreatic adenocarcinoma supports the importance of this observation. Mechanistically, we found that GDF-15 suppresses macrophage activity by inhibiting TGF-ß-activated kinase (TAK1) signaling to NF-κB, thereby blocking synthesis of TNF and NO. Based on these results, we propose that the NF-κB/GDF-15 regulatory axis is important for tumor cells in evading macrophage immune surveillance during the early stages of tumorigenesis.

Dual Inhibition of MEK and PI3K/Akt Rescues Cancer Cachexia through both Tumor-Extrinsic and -Intrinsic Activities.

Involuntary weight loss, a part of the cachexia syndrome, is a debilitating comorbidity of cancer and currently has no treatment options. Results from a recent clinical trial at our institution showed that biliary tract cancer patients treated with a MEK inhibitor exhibited poor tumor responses but surprisingly gained weight and increased their skeletal muscle mass. This implied that MEK inhibition might be anticachectic. To test this potential effect of MEK inhibition, we utilized the established Colon-26 model of cancer cachexia and the MEK1/2 inhibitor MEK162. Results showed that MEK inhibition effectively prevented muscle wasting. Importantly, MEK162 retained its ability to spare muscle loss even in mice bearing a Colon-26 clone resistant to the MEK inhibitor, demonstrating that the effects of blocking MEK are at least in part independent of the tumor. Because single-agent MEK inhibitors have been limited as a first-line targeted therapy due to compensatory activation of other oncogenic signaling pathways, we combined MEK162 with the PI3K/Akt inhibitor buparlisib. Results showed that this combinatorial treatment significantly reduced tumor growth due to a direct activity on Colon-26 tumor cells in vitro and in vivo, while also preserving skeletal muscle mass. Together, our results suggest that as a monotherapy, MEK inhibition preserves muscle mass, but when combined with a PI3K/Akt inhibitor exhibits potent antitumor activity. Thus, combinatorial therapy might serve as a new approach for the treatment of cancer cachexia. Mol Cancer Ther; 16(2); 344-56. ©2016 AACRSee related article by Kobayashi et al., p. 357.

Diphtheria toxin-based recombinant murine IL-2 fusion toxin for depleting murine regulatory T cells in vivo.

Regulatory T cells (Tregs) are a subpopulation of CD4(+) T cells which suppress immune responses of effector cells and are known to play a very important role in protection against autoimmune disease development, induction of transplantation tolerance and suppression of effective immune response against tumor cells. An effective in vivo Treg depletion agent would facilitate Treg-associated studies across many research areas. In this study, we have developed diphtheria toxin-based monovalent and bivalent murine IL-2 fusion toxins for depleting murine IL-2 receptor positive cells including CD25(+) Treg in vivo. Their potencies were assessed by in vitro protein synthesis inhibition and cell proliferation inhibition assays using a murine CD25(+) CTLL-2 cell line. Surprisingly, in contrast to our previously developed recombinant fusion toxins, the monovalent isoform (DT390-mIL-2) was approximately 4-fold more potent than its bivalent counterpart (DT390-bi-mIL-2). Binding analysis by flow cytometry demonstrated that the monovalent isoform bound stronger than the bivalent version. In vivo Treg depletion with the monovalent murine IL-2 fusion toxin was performed using C57BL/6J (B6) mice. Spleen Treg were significantly depleted with a maximum reduction of ∼70% and detectable as early as 12 h after the last injection. The spleen Treg numbers were reduced until Day 3 and returned to control levels by Day 7. We believe that this monovalent murine IL-2 fusion toxin will be an effective in vivo murine Treg depleter.

Diphtheria toxin-based bivalent human IL-2 fusion toxin with improved efficacy for targeting human CD25(+) cells.

Regulatory T cells (Treg) constitute a major inhibitory cell population which suppresses immune responses. Thus, Treg have proven to be key players in the induction of transplantation tolerance, protection from autoimmune disease and prevention of the development of effective anti-tumor immune reactions. Treg express high levels of the high affinity interleukin-2 receptor (IL-2R) consisting of IL-2Rα (CD25) together with IL-2Rß (CD122) and the common γ-chain (CD132). An effective reagent capable of depleting Treg in vivo would facilitate better cancer treatment and allow mechanistic studies of the role of Treg in transplantation tolerance and the development of autoimmune disease. In this study, we have developed a novel bivalent human IL-2 fusion toxin along with an Ontak®-like monovalent human IL-2 fusion toxin and compared the functional ability of these reagents in vitro. Here we show that genetically linking two human IL-2 domains in tandem, thereby generating a bivalent fusion toxin, results in significantly improved capacity in targeting human CD25(+) cells in vitro. Binding analysis by flow cytometry showed that the bivalent human IL-2 fusion toxin has notably increased affinity for human CD25(+) cells. In vitro functional analysis demonstrated that the bivalent isoform has an increased potency of approximately 2 logs in inhibiting cellular proliferation and protein synthesis in human CD25(+) cells compared to the monovalent human IL-2 fusion toxin. Additionally, we performed two inhibition assays in order to verify that the fusion toxins target the cells specifically through binding of the human IL-2 domain of the fusion toxin to the human IL-2 receptor on the cell surface. These results demonstrated that 1) both monovalent and bivalent human IL-2 fusion toxins are capable of blocking the binding of biotinylated human IL-2 to human CD25 by flow cytometry; and 2) human IL-2 blocked the fusion toxins from inhibiting protein synthesis and cellular proliferation in vitro, thus confirming that the human IL-2 fusion toxins target the cells specifically through binding to the human IL-2 receptor. We believe that the bivalent human IL-2 fusion toxin will be a more potent, and therefore, more optimal agent than the current clinically-used monovalent fusion toxin (denileukin diftitox, Ontak®) for in vivo depletion of Treg.