Pancreatic ductal adenocarcinoma (PDAC) has a 5-year survival rate below 5%. Carbohydrate antigen 19-9 (CA19-9) is the most commonly used blood-based biomarker for PDAC in current clinical practice, despite having been shown repeatedly to be inaccurate and have poor diagnostic performance. This review aims to assess the reported diagnostic accuracy of all blood-based biomarkers investigated to date in PDAC, by directly comparing individual biomarkers and multi-biomarker panels, both containing CA19-9 and not (novel). A systematic review was conducted in accordance with PRISMA standards in July 2020. Individualized search strategies for three academic databases identified 5,885 studies between the years 1973 and 2020. After two rounds of screening, 250 studies were included. Data were extracted and assessed for bias. A multivariate three-level meta-analysis with subgroup moderators was run in R using AUC values as effect size. On the basis of this model, the pooled AUC value for all multi-biomarker panels (AUC = 0.898; 95% confidence interval (CI): 0.88–0.91) was significantly higher than all single biomarkers (AUC = 0.803; 95% CI: 0.78–0.83; P < 0.0001). The pooled AUC value for CA19-9 alone was significantly lower compared with the multi-biomarker panels containing CA19-9 (P < 0.0001). For the novel biomarkers, the pooled AUC for single biomarkers was also significantly lower compared with multi-biomarker panels (P < 0.0001). Novel biomarkers that have been repeatedly examined across the literature, such as TIMP-1, CEA, and CA125, are highlighted as promising. These results suggest that CA19-9 may be best used as an addition to a panel of biomarkers rather than alone, and that multi-biomarker panels generate the most robust results in blood-based PDAC diagnosis.Significance: In a systematic review and three-level multivariate meta-analysis, it is shown for the first time that blood-based multi-biomarker panels for the diagnosis of PDAC exhibit superior performance in comparison with single biomarkers. CA19-9 is demonstrated to have limited utility alone, and to perform poorly in patient control cohorts of both healthy and benign individuals. Multi-biomarker panels containing CA19-9 produce the best diagnostic performance overall.

The global obesity epidemic is contributing to increased prevalence of diseases fuelled by chronic inflammation, including cancer. Oesophageal adenocarcinoma (OAC) is an obesity-associated malignancy with increasing prevalence, dismal prognosis, and severely dysregulated immune processes. We previously reported that αβ T cells migrate to omentum and liver in OAC and contribute to inflammation in these tissues. Here, we assessed the tissue distribution and phenotype of gamma/delta (γδ) T cells in the blood, omentum, liver and tumour of OAC patients. Our data show that the Vδ1 and Vδ3 subsets of γδ T cells are most prevalent in omentum and liver of OAC patients. Furthermore, γδ T cells are predominantly pro-inflammatory in these tissues, and co-express IFN-γ and IL-17. Moreover, γδ T cells exhibit cytotoxic capabilities in OAC omentum and liver. This study provides the first indication that γδ T cells contribute to obesity-associated inflammation in OAC and might be exploited therapeutically.

Esophagogastric adenocarcinomas (EAC) are obesity-associated malignancies underpinned by severe immune dysregulation and inflammation. Our previous work indicates that NK cells migrate to EAC omentum, where they undergo phenotypic and functional alterations and apoptosis. In this study, we investigate whether such erroneous chemotaxis to omentum is paralleled by compromised NK cell infiltration of EAC patient tumor and examine the role of the inflammatory chemokine fractalkine in shaping the NK cell–mediated response. Our data show diminished NK cell frequencies in EAC tumor compared with those in the circulation and reveal that intratumoral NK cell frequencies decline as visceral obesity increases in EAC patients. Our in vitro findings demonstrate that antagonism of fractalkine receptor CX3CR1 significantly reduces NK cell migration to EAC patient–derived, omental adipose tissue–conditioned media, but not toward tumor-conditioned media. These data suggest fractalkine is a key driver of NK cell chemotaxis to omentum but has a lesser role in NK cell homing to tumor in EAC. We propose that this may offer a novel therapeutic strategy to limit NK cell depletion in the omentum of obese EAC patients, and our data suggest the optimal timing for CX3CR1 antagonism is after neoadjuvant chemoradiotherapy. Our functional studies demonstrate that fractalkine induces the conversion from CX3CR1⁺CD27⁻ to CX3CR1⁻CD27⁺ NK cells and increases their IFN-γ and TNF-α production, indicative of its role in shaping the dominant NK cell phenotype in EAC omentum. This study uncovers crucial and potentially druggable pathways underpinning NK cell dysfunction in obesity-associated cancer and provides compelling insights into fractalkine9s diverse biological functions. Key Points Intratumoral NK cell frequencies decline as visceral obesity increases in EAC. CX3CR1 antagonism has potential to spare NK cells from depletion in EAC omentum. Fractalkine promotes cytokine production and a CX3CR1⁻CD27⁺ phenotype in NK cells.

Oesophagogastric adenocarcinomas (OAC) are obesity-associated malignancies, underpinned by severe immune dysregulation. We have previously shown that natural killer (NK) cells preferentially migrate to OAC omentum, where they undergo phenotypic and functional alterations and apoptosis. Furthermore, we have identified the CX3CR1:fractalkine (CX3CL1) pathway as pivotal in their recruitment to omentum. Here, we elucidate whether exposure to the soluble microenvironment of OAC omentum, and in particular fractalkine and IL-15 affects NK cell homing capacity towards oesophageal tumour. Our data uncover diminished NK cell migration towards OAC tumour tissue conditioned media (TCM) following exposure to omental adipose tissue conditioned media (ACM) and reveal that this migration can be rescued with CX3CR1 antagonist E6130. Furthermore, we show that fractalkine has opposing effects on NK cell migration towards TCM, when used alone or in combination with IL-15 and uncover its inhibitory effects on IL-15-mediated stimulation of death receptor ligand expression. Interestingly, treatment with fractalkine and/or IL-15 do not significantly affect NK cell adhesion to MAdCAM-1, despite changes they elicit to the expression of integrin α4β7. This study provides further evidence that CX3CR1 antagonism has therapeutic utility in rescuing NK cells from the deleterious effects of the omentum and fractalkine in OAC, thus limiting their dysfunction.

Oesophageal adenocarcinoma (OAC) is a poor prognosis cancer with limited response rates to current treatment modalities and has a strong link to obesity. To better elucidate the role of visceral adiposity in this disease state, a full metabolic profile combined with analysis of secreted pro-inflammatory cytokines, metabolites, and lipid profiles were assessed in human ex vivo adipose tissue explants from obese and non-obese OAC patients. These data were then related to extensive clinical data including obesity status, metabolic dysfunction, previous treatment exposure, and tumour regression grades. Real-time energy metabolism profiles were assessed using the seahorse technology. Adipose explant conditioned media was screened using multiplex ELISA to assess secreted levels of 54 pro-inflammatory mediators. Targeted secreted metabolite and lipid profiles were analysed using Ultra-High-Performance Liquid Chromatography coupled with Mass Spectrometry. Adipose tissue explants and matched clinical data were collected from OAC patients (n = 32). Compared to visceral fat from non-obese patients (n = 16), visceral fat explants from obese OAC patients (n = 16) had significantly elevated oxidative phosphorylation metabolism profiles and an increase in Eotaxin-3, IL-17A, IL-17D, IL-3, MCP-1, and MDC and altered secretions of glutamine associated metabolites. Adipose explants from patients with metabolic dysfunction correlated with increased oxidative phosphorylation metabolism, and increases in IL-5, IL-7, SAA, VEGF-C, triacylglycerides, and metabolites compared with metabolically healthy patients. Adipose explants generated from patients who had previously received neo-adjuvant chemotherapy (n = 14) showed elevated secretions of pro-inflammatory mediators, IL-12p40, IL-1$\mathsf{\alpha }$, IL-22, and TNF-$\mathsf{\beta }$ and a decreased expression of triacylglycerides. Furthermore, decreased secreted levels of triacylglycerides were also observed in the adipose secretome of patients who received the chemotherapy-only regimen FLOT compared with patients who received no neo-adjuvant treatment or chemo-radiotherapy regimen CROSS. For those patients who showed the poorest response to currently available treatments, their adipose tissue was associated with higher glycolytic metabolism compared to patients who had good treatment responses. This study demonstrates that the adipose secretome in OAC patients is enriched with mediators that could prime the tumour microenvironment to aid tumour progression and attenuate responses to conventional cancer treatments, an effect which appears to be augmented by obesity and metabolic dysfunction and exposure to different treatment regimes.

The presence of an immunosuppressive tumour microenvironment in oesophageal adenocarcinoma (OAC) is a major contributor to poor responses. Novel treatment strategies are required to supplement current regimens and improve patient survival. This study examined the immunomodulatory effects that radiation therapy and chemokine receptor antagonism impose on T cell phenotypes in OAC with a primary goal of identifying potential therapeutic targets to combine with radiation to improve anti-tumour responses. Compared with healthy controls, anti-tumour T cell function was impaired in OAC patients, demonstrated by lower IFN-γ production by CD4⁺ T helper cells and lower CD8⁺ T cell cytotoxic potential. Such diminished T cell effector functions were enhanced following treatment with clinically relevant doses of irradiation. Interestingly, CCR5⁺ T cells were significantly more abundant in OAC patient blood compared with healthy controls, and CCR5 surface expression by T cells was further enhanced by clinically relevant doses of irradiation. Moreover, irradiation enhanced T cell migration towards OAC patient-derived tumour-conditioned media (TCM). In vitro treatment with the CCR5 antagonist Maraviroc enhanced IFN-γ production by CD4⁺ T cells and increased the migration of irradiated CD8⁺ T cells towards irradiated TCM, suggesting its synergistic therapeutic potential in combination with irradiation. Overall, this study highlights the immunostimulatory properties of radiation in promoting anti-tumour T cell responses in OAC and increasing T cell migration towards chemotactic cues in the tumour. Importantly, the CCR5 antagonist Maraviroc holds promise to be repurposed in combination with radiotherapy to promote anti-tumour T cell responses in OAC.