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Tumour acidosis contributes to cancer progression by inhibiting anti-tumour immunity. However, the effect of acidosis on anti-tumour T cell phenotypes in oesophageal adenocarcinoma (OAC) is unknown. Therefore, this study investigated the effect of acidosis on anti-tumour T cell profiles and if immune checkpoint blockade (ICB) could enhance anti-tumour T cell immunity under acidosis. Acidic conditions substantially altered immune checkpoint expression profiles of OAC patient-derived T cells, upregulating TIM-3, LAG-3 and CTLA-4. Severe acidosis (pH 5.5) significantly decreased the percentage of central memory CD4+ T cells, an effect that was attenuated by ICB treatment. ICB increased T cell production of IFN-γ under moderate acidosis (pH 6.6) but not severe acidosis (pH 5.5) and decreased IL-10 production by T cells under severe acidic conditions only. A link between lactate and metastasis was also depicted; patients with nodal metastasis had higher serum lactate levels (p = 0.07) which also positively correlated with circulating levels of pro-angiogenic factor Tie-2. Our findings establish that acidosis-induced upregulation of immune checkpoints on T cells may potentially contribute to immune evasion and disease progression in OAC. However, acidic conditions curtailed ICB efficacy, supporting a rationale for utilizing systemic oral buffers to neutralize tumour acidity to improve ICB efficacy. Graphical abstract Study schematic—PBMCs were isolated from OAC patients (A) and expanded ex vivo for 7 days using anti-CD3/28 +IL-2 T cell activation protocol (B) and further cultured for 48 h under increasing acidic conditions in the absence or presence of immune checkpoint blockade (nivolumab, ipilimumab or dual nivolumab + ipilimumab) (C). Immunophenotyping was then carried out to assess immune checkpoint expression profiles and anti-tumour T cell phenotypes (D). Serum lactate was assessed in OAC patients (E–F) and levels were correlated with patient demographics (G) and the levels of circulating immune/pro-angiogenic cytokines that were determined by multiplex ELISA (H). Key Findings—severe acidic conditions upregulated multiple immune checkpoints on T cells (I). Efficacy of ICB was curtailed under severe acidic conditions (J). Circulating lactate levels positively correlated with circulating levels of pro-angiogenic factor tie-2 and higher serum lactate levels were found in patients who had nodal metastasis (K).

In the contemporary era of cancer immunotherapy, an abundance of clinical and translational studies have reported radiotherapy (RT) and immunotherapies as a viable option for immunomodulation of many cancer subtypes, with many related clinical trials ongoing. In locally advanced disease, chemotherapy or chemoradiotherapy followed by surgical excision of the tumour remain the principal treatment strategy in oesophageal adenocarcinoma (OAC), however, the use of the host immune system to improve anti-tumour immunity is rapidly garnering increased support in the curative setting.To immunophenotype OAC patients' immune checkpoint (IC) expression with and without radiation and evaluate the effects of checkpoint blockade on cell viability.In the contemporary era of cancer immunotherapy, an abundance of studies have demonstrated that combination RT and IC inhibitors (ICIs) are effective in the immunomodulation of many cancer subtypes, with many related clinical trials ongoing. Although surgical excision and elimination of tumour cells by chemotherapy or chemoradiotherapy remains the gold standard approach in OAC, the propagation of anti-tumour immune responses is rapidly garnering increased support in the curative setting. The aim of this body of work was to immunophenotype OAC patients' IC expression with and without radiation and to establish the impact of checkpoint blockade on cell viability. This study was a hybrid combination ofWe identified that conventional dosing and hypofractionated approaches resulted in increased IC expression (PD-1, PD-L1, TIM3, TIGIT)The findings of the current study demonstrate synergistic potential for the use of ICIs and ionising radiation to potentiate established anti-tumour responses in the neoadjuvant setting and is of particular interest in those with advanced disease, adverse features of tumour biology and poor treatment responses to conventional therapies.

Introduction: The majority of oesophageal adenocarcinoma (OAC) patients do not respond to multimodal treatment regimens and face dismal survival rates. Natural killer (NK) cells are crucial anti-tumour immune cells, and this study investigated the susceptibility of treatment-resistant OAC cells to these potent tumour killers.Methods: Natural killer receptor (NKR) ligand expression by OE33CisP (cisplatin-sensitive) and OE33CisR (cisplatin-resistant) cells was investigated. The immunomodulatory effects of OE33CisP and OE33CisR cells on NK cell phenotype and function were assessed. Finally, the impact of chemotherapy regimens on NKR ligand shedding was examined.Results: Our data revealed significantly less surface expression of activating ligands B7-H6, MICA/B, ULBP-3 and activating/inhibitory ligands PVRL-1 and PVRL-4 by OE33CisR cells, compared to OE33CisP cells. Co-culture with OE33CisR cells reduced the frequencies of Nkp30+ and NKp46+ NK cells and increased frequencies of TIGIT+, FasL+ and TRAIL+ NK cells. Frequencies of IFN-γ-producing NK cells increased while frequencies of TIM-3+ NK cells decreased after culture with OE33CisP and OE33CisR cells. Frequencies of circulating NKP30+ NK cells were significantly lower in OAC patients with the poorest treatment response and in patients who received FLOT chemotherapy. B7-H6 shedding by OAC tumour cells was induced by FLOT.Conclusion: OE33CisR cells express less activating NKR ligands than OE33CisP cells and have differential effects on NKR expression by NK cells. However, neither cell line significantly dampened NK cell cytokine production, death receptor expression or degranulation. Finally, our data indicate that FLOT chemotherapy and obesity may promote B7-H6 shedding and immune evasion with detrimental consequences in OAC patients.

Aim Visceral obesity is a key risk factor in the development of oesophagogastric junctional adenocarcinoma (OGJ), predominantly via generation of systemic low grade inflammation. Obesity-induced inflammation promotes resistance to current standards of care, enhancing tumour cell growth and survival. This study investigates the effect of the visceral adipose tissue secretome from OGJ patients with early versus advanced tumours on T-cell immunity and the role of immune checkpoint blockade in enhancing anti-tumour immunity. Methods and results Visceral adipose conditioned media (ACM) from both early and late-stage OGJ patients significantly altered T cell activation status, upregulating co-stimulatory marker CD27 on T cells. ACM from both early and late-stage OGJ patients significantly altered immune checkpoint expression profiles downregulating immune checkpoints (ICs) on the surface of dual Th1/17-like and Th17-like cells and upregulating ICs on the surface of Th1-like cells and Treg cells. ACM derived from early-stage OGJ patients but not late-stage OGJ patients increased IFN-γ production by T cells. The addition of immune checkpoint blockers (ICBs) did not increase IFN-γ production by T cells in the presence of late-stage ACM, collectively highlighting the dichotomous immunostimulatory effect of early-stage ACM and immune-inhibitory effect of late-stage ACM. Interestingly, ACM from early-stage OGJ patients was more pro-inflammatory than ACM from late-stage patients, reflected by decreased levels of IL-17A/F, TNF-α, IL-1RA and IL-5. Conclusion The ACM-induced upregulation of ICs on T cells highlights a therapeutic vulnerability that could be exploited by ICBs to harness anti-cancer immunity and improve clinical outcomes for OGJ patients. Graphical Abstract Schematic workflow – (A) visceral adipose tissue was taken from OAC patients at time of surgery and cultured for 72 h in media. (B) The harvested ACM was co-cultured with healthy donor PBMCs that were concurrently activated with anti-CD3/28 for 48 h and T cell immunophenotyping was carried out by flow cytometry. Key findings – (A) Early and late stage ACM enhanced a Th1-like phenotype and upregulated CTLA-4 on Th1-like cells. A Th17-like phenotype was also enhanced in addition with a Treg-like phenotype. CTLA-4 and PD-L1 were upregulated on the surface of Treg-like cells. (B) ICB-attenuated IL-17 production by T cells. However, ACM attenuated ICB-mediated reduction in IL-10 production by T cells. Higher levels of pro-inflammatory factors were found in early stage ACM compared with late stage ACM.

Aim Use of immune checkpoint blockade to enhance T cell-mediated immunity within the hostile tumour microenvironment (TME) is an attractive approach in oesophageal adenocarcinoma (OAC). This study explored the effects of the hostile TME, including nutrient deprivation and hypoxia, on immune checkpoint (IC) expression and T cell phenotypes, and the potential use of nivolumab to enhance T cell function under such conditions. Methods and Results ICs were upregulated on stromal immune cells within the tumour including PD-L2, CTLA-4 and TIGIT. OAC patient-derived PBMCs co-cultured with OE33 OAC cells upregulated LAG-3 and downregulated the co-stimulatory marker CD27 on T cells, highlighting the direct immunosuppressive effects of tumour cells on T cells. Hypoxia and nutrient deprivation altered the secretome of OAC patient-derived PBMCs, which induced upregulation of PD-L1 and PD-L2 on OE33 OAC cells thus enhancing an immune-resistant phenotype. Importantly, culturing OAC patient-derived PBMCs under dual hypoxia and glucose deprivation, reflective of the conditions within the hostile TME, upregulated an array of ICs on the surface of T cells including PD-1, CTLA-4, A2aR, PD-L1 and PD-L2 and decreased expression of IFN-γ by T cells. Addition of nivolumab under these hostile conditions decreased the production of pro-tumorigenic cytokine IL-10. Conclusion Collectively, these findings highlight the immunosuppressive crosstalk between tumour cells and T cells within the OAC TME. The ability of nivolumab to suppress pro-tumorigenic T cell phenotypes within the hostile TME supports a rationale for the use of immune checkpoint blockade to promote anti-tumour immunity in OAC. Graphical abstract Study schematic: (A) IC expression profiles were assessed on CD45+ cells in peripheral whole blood and infiltrating tumour tissue from OAC patients in the treatment-naïve setting. (B) PBMCs were isolated from OAC patients and expanded ex vivo for 5 days using anti-CD3/28 + IL-2 T cell activation protocol and then co-cultured for 48 h with OE33 cells. T cell phenotypes were then assessed by flow cytometry. (C) PBMCs were isolated from OAC patients and expanded ex vivo for 5 days using anti-CD3/28 + IL-2 T cell activation protocol and then further cultured under conditions of nutrient deprivation or hypoxia for 48 h and T cell phenotypes were then assessed by flow cytometry. Key findings: (A) TIGIT, CTLA-4 and PD-L2 were upregulated on CD45+ immune cells and CTLA-4 expression on CD45+ cells correlated with a subsequent decreased response to neoadjuvant regimen. (B) Following a 48 h co-culture with OE33 cells, T cells upregulated LAG-3 and decreased CD27 co-stimulatory marker. (C) Nutrient deprivation and hypoxia upregulated a range of ICs on T cells and decreased IFN-γ production by T cells. Nivolumab decreased IL-10 production by T cells under nutrient deprivation-hypoxic conditions.

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 fractalkine’s diverse biological functions.

BACKGROUND AND AIMS The FLOT4-AIO trial established the FLOT regimen as a compelling option for gastric, junctional and esophageal adenocarcinoma. Data on FLOT with en-bloc transthoracic esophagectomy (TTE) are limited. This study explored operative complications, tolerance, toxicity, physiological impact, and oncologic outcomes. STUDY DESIGN An observational cohort study on consecutive patients at 3 tertiary centers undergoing FLOT and TTE. Toxicity, operative complications (per ECCG definitions), tumor regression grade (TRG), recurrences and survival were documented, as well as pre and post FLOT assessment of sarcopenia and pulmonary physiology. RESULTS 175 patients (cT2-4a, Nany) commenced treatment, 84% male, median age 65, 94% cT3/T4a, 73% cN+. 89% completed 4 preoperative cycles, and 35% all cycles. Grade 3/4 toxicities included neutropenia (12%), diarrhoea (13%), and infection (15%). Sarcopenia increased from 18% to 37% (P = 0.020), and diffusion capacity (DLCO) decreased by 8% (-34% + 25%; P < 0.010). On pathology, ypT3/4 was 59%, and ypN+54%, with 10% TRG 1, 14% TRG 2, and 76% TRG3-5, and R0 95%. 161 underwent TTE, with an in-hospital mortality of 0.6%, 24%-pneumonia, 11%-anastomotic leak, and Clavien Dindo ≥III in 27%. At a median follow up of 12 months (1-85), 33 relapsed, 8 (5%) locally, and 3yr survival was 60%. CONCLUSION FLOT and en bloc TTE was safe, with no discernible impact on operative complications, with 24% having a major pathologic response. Caveats include a limited pathologic response in the majority, and negative impact on muscle mass and lung physiology, and low use of adjuvant cycles. These data may provide a real-world benchmark for this complex care pathway.

Esophageal adenocarcinoma (EAC) is associated with visceral obesity (VO). Non-alcoholic fatty liver disease (NAFLD) is common within this phenotype; however, its incidence and clinical significance in EAC have not been studied.A total of 559 patients with hepatic stetatosis (HS) defined by unenhanced CT were enrolled. In a sub-study, in 140 consecutive patients a liver biopsy was taken intraoperatively to study HS and non-alcoholic steatohepatitis (NASH). Postoperative complications were defined as per the Esophageal Complications Consensus Group (ECCG). Liver biochemistry was measured peri-operatively, with an ALT 5 defined as acute liver injury (ALI). Mann-Whitney U test or Fisher's exact test was utilized and the Kaplan-Meier method for survival.42% (n = 234/559) of patients had CT-defined HS. HS was associated with VO in 56% of cases, metabolic syndrome (Met S) in 37% and type 2 diabetes in 25%, compared with 44, 21, and 15% in non-HS patients (p 0.01). Pathologic HS was present in 32% (45/140) and graded as mild, moderate, and severe in 73, 24, and 3%, respectively, with NASH reported in 16% and indefinite/borderline NASH in 42% of HS cases. Postoperative ALI was similar (p = 0.88) in both HS (10%) and non-HS cohorts (11%). Operative complication severity was similar in both cohorts. 5-yr survival was 53% (HS) vs 50% (p = 0.890).This study establishes for the first time the incidence and clinical impact of NAFLD in EAC patients undergoing surgery and highlights no major impact on oncologic outcomes, nor in the severity of complications.

Background: Combining immunostimulatory chemotherapies with immunotherapy is an attractive strategy to enhance treatment responses in oesophagogastric junctional adenocarcinoma (OGJ). Methods: This study investigates the immunostimulatory properties of FLOT, CROSS and MAGIC chemotherapy regimens in the context of OGJ using in vitro and ex vivo models of the treatment-naïve and post-chemotherapy treated tumour microenvironment. Results: FLOT and CROSS chemotherapy regimens increased the surrogate markers of immunogneic cell death, HMGB1 and HLA-DR, whereas the MAGIC treatment regimen decreased HMGB1 and HLA-DR on OGJ cells, markedly so for epirubicin. Tumour-infiltrating and circulating T cells had significantly lower CD27 expression and significantly higher CD69 expression post-FLOT and post-CROSS treatment. Similarly, the supernatant from FLOT- and CROSS-treated OGJ cell lines and from FLOT- and CROSS-treated OGJ biopsies cultured ex vivo also decreased CD27 and increased CD69 expression on T cells. Following 48h treatment with post-FLOT and post-CROSS tumour conditioned media the frequency of CD69+ T cells in culture negatively correlated with the levels of soluble immunosuppressive pro-angiogenic factors in the conditioned media from ex vivo explants. Supernatant from FLOT- and CROSS-treated OGJ cell lines also increased the cytotoxic potential of healthy donor T cells and enhanced OGJ patient-derived lymphocyte mediated-killing of OE33 tumour cells. Conclusions: Collectively, this data suggests that the FLOT and CROSS chemotherapy regimens may be more appropriate immunostimulatory partners than MAGIC to combine with immunotherapy to boost anti-tumour immunity for treating OGJ patients.

Background CROSS regimen (41.4Gy;carboplatin&paclitaxel) is a standard trim-modality treatment for locally advanced oesophageal adenocarcinoma (OAC). The addition of adjuvant immunotherapy targeting PD-L1 may improve outcomes, hence the impact of radiation therapy on the tumour microenvironment is of considerable interest. The dosing has not been studied in this context, especially hypofractionation, and this study explored immunogenic cell death, specifically Damage Associated Molecular Pattern (DAMPs) release,and the impact of immune checkpoint blockade(ICB). Methods The ability of CROSS-regimen (3×1.8Gy) and hypo-fractionation (3×4Gy) to induce immunogenic cell death was assessed by flow cytometry of DAMPs calreticulin&HMGB-1.Expression of DAMPs were evaluated on OAC tumour and whole blood samples (n=10) pre and post conventional therapies versus hypofractionation. The immunostimulatory effect of CROSS and hypofractionation using post-treatment tumour cell secretomes with/without ICB on the cytolytic ability of OAC-donor lymphocytes was interrogated by CCK8-assay. Results The expression of Calreticulin&HMGB1 was significantly higher on tumour tissue compared to whole blood post chemo(radio)therapy(p Conclusions The current CROSS regimen radiation for OAC is immunogenic,however,hypo-fractionated doses boosted the immune response to OAC, and was synergistic with ICB. This may warrant further exploration in a clinical and translational trial.

Background Adjuvant immunotherapy for oesophageal cancer is set to become a standard of care following the Checkmate-577 trial proving the efficacy of adjuvant nivolumab. Scientifically, the key mechanisms are unclear. This study profiled systemic anti-/pro-tumour immunity and circulating pro-metastatic factors perioperatively in patients, and the impact of immune checkpoint blockade on key pathways. Methods Systemic immunity in oesophageal cancer patients (n=14) was immunophenotyped prior to surgery (postoperative day(POD)-0) and POD-1,3,7 and week-6, using flow cytometry. Longitudinal serological profiling was conducted by multiplex ELISA characterising systemic immunity and pro-metastatic signalling. The cytolytic ability of circulating lymphocytes against oesophageal cancer cell lines was assessed with and without immunotherapies; nivolumab/ipililmumab. Results PD-1+ and CTLA-4+ T-cells peaked on POD-1, significantly decreasing by week 6(p Conclusions Major oesophageal cancer surgery promotes a switch from Th1 to Th2 cellular immunity, dampening the cytolytic ability of T-lymphocytes. In an ex-vivo model, PD-1/CTLA-4 inhibition induced a shift to a Th1-like cytotoxic phenotype, highlighting a potential pathway through which such therapies can effect minimal residual disease, and a need to study optimal timing of adjuvant therapy.

The FLOT protocol and the CROSS trimodality regimen represent current standards in the management of locally advanced esophageal adenocarcinoma. In the absence of published Randomised Controlled Trial data, this propensity-matched comparison evaluated tolerance, toxicity, impact on sarcopenia and pulmonary physiology, operative complications, and oncologic metrics.Two hundred and twenty-two patients, 111 in each arm, were included from 2 high-volume centers. Computed tomography-measured sarcopenia, and pulmonary function (forced expiratory volume in first second/forced vital capacity/diffusion capacity for carbon monoxide) were compared pretherapy and posttherapy. Operative complications were defined as per the Esophageal Complications Consensus Group (ECCG) criteria, and severity per Clavien-Dindo. Tumor regression grade and R status were measured, and survival estimated per Kaplan-Meier.A total of 83% were male, cT3/cN+ was 92%/68% for FLOT, and 86%/60% for CROSS. The full prescribed regimen was tolerated in 40% of FLOT patients versus 92% for CROSS. Sarcopenia increased from 16% to 33% for FLOT, and 14% to 30% in CROSS ( P0.01 between arms). Median decrease in diffusion capacity for carbon monoxide was -8.25% (-34 to 25) for FLOT, compared with -13.8%(-38 to 29), for CROSS ( P =0.01 between arms). Major pathologic response was 27% versus 44% for FLOT and CROSS, respectively ( P =0.03). In-hospital mortality, respectively, was 1% versus 2% ( P =0.9), and Clavien DindoIII 22% versus 27% ( P =0.59), however, respiratory failure was increased by CROSS, at 13% versus 3% ( P0.001). Three-year survival was similar at 63% (FLOT) and 60% (CROSS) ( P =0.42).Both CROSS and FLOT resulted in equivalent survival. Operative outcomes were similar, however, the CROSS regimen increased postoperative respiratory failure and atrial fibrillation. Less than half of patients received the prescribed FLOT regimen, although toxicity rates were acceptable. These data support clinical equipoise, caution, however, may be advised with CROSS in patients with greatest respiratory risk.

Historically, high negative appendicectomy rates (NAR) were acceptable to offset the risks of perforation, previously exceeding 20%. With improved imaging and clinical scoring algorithms, there is growing demand for lower negative appendicectomy rates. The objectives were to (1) establish the NAR in our institution and (2) correlate clinical parameters and imaging modalities with histological findings. Patients undergoing an appendicectomy between January 2012 and June 2018 were identified using a prospectively maintained pathology database. Histology findings were cross referenced against our radiology system, and anonymised data was collected for gender, age, WCC, Neutrophil and CRP level. One thousand one hundred fifty-three patients met the inclusion criteria. Fifty-three percent were males (n = 610), with 81% (n = 933) of histology reports classified as appendicitis. Sixty patients had a histologically normal appendix equating to a 5.2% NAR. If lymphoid hyperplasia, fibrosis and atrophy are included, it equates to a NAR of 14.57%. (p < 0.0001). Sixty-six percent of patients had no pre-operative imaging. CT imaging demonstrated a higher sensitivity (93.33%) and positive predictive value (99.60%) compared to ultrasonography. WCC and CRP are statistically significant in predicting appendicitis (p < 0.0001). There is no consensus on defining a negative appendicectomy or for imaging modality utilisation. CT imaging is the most sensitive and should be used in cases of diagnostic uncertainty. A standardised algorithm regarding the workup of patients with RIF pain along with a consensus on the use of imaging will further reduce negative appendicectomy rates.

Oesophageal cancer is the 6th most common cause of cancer related death worldwide. The current standard of care for oesophageal adenocarcinoma (OAC) focuses on neoadjuvant therapy with chemoradiation or chemotherapy, however the 5-year survival rates remain at

Chemotherapy upregulates immune checkpoint (IC) expression on the surface of tumour cells and IC-intrinsic signalling confers a survival advantage against chemotherapy in several cancer-types including oesophageal adenocarcinoma (OAC). However, the signalling pathways mediating chemotherapy-induced IC upregulation and the mechanisms employed by ICs to protect OAC cells against chemotherapy remain unknown.Longitudinal profiling revealed that FLOT-induced IC upregulation on OE33 OAC cells was sustained for up to 3 weeks post-treatment, returning to baseline upon complete tumour cell recovery. Pro-survival MEK signalling mediated FLOT-induced upregulation of PD-L1, TIM-3, LAG-3 and A2aR on OAC cells promoting a more immune-resistant phenotype. Single agent PD-1, PD-L1 and A2aR blockade decreased OAC cell viability, proliferation and mediated apoptosis. Mechanistic insights demonstrated that blockade of the PD-1 axis decreased stem-like marker ALDH and expression of DNA repair genes. Importantly, combining single agent PD-1, PD-L1 and A2aR blockade with FLOT enhanced cytotoxicity in OAC cells. These findings reveal novel mechanistic insights into the immune-independent functions of IC-intrinsic signalling in OAC cells with important clinical implications for boosting the efficacy of the first-line FLOT chemotherapy regimen in OAC in combination with ICB to not only boost anti-tumour immunity but also to suppress IC-mediated promotion of key hallmarks of cancer that drive tumour progression.

Chemotherapy upregulates immune checkpoint (IC) expression on the surface of tumour cells and IC-intrinsic signalling confers a survival advantage against chemotherapy in several cancer-types including oesophageal adenocarcinoma (OAC). However, the signalling pathways mediating chemotherapy-induced IC upregulation and the mechanisms employed by ICs to protect OAC cells against chemotherapy remain unknown. Longitudinal profiling revealed that FLOT-induced IC upregulation on OE33 OAC cells was sustained for up to 3 weeks post-treatment, returning to baseline upon complete tumour cell recovery. Pro-survival MEK signalling mediated FLOT-induced upregulation of PD-L1, TIM-3, LAG-3 and A2aR on OAC cells promoting a more immune-resistant phenotype. Single agent PD-1, PD-L1 and A2aR blockade decreased OAC cell viability, proliferation and mediated apoptosis. Mechanistic insights demonstrated that blockade of the PD-1 axis decreased stem-like marker ALDH and expression of DNA repair genes. Importantly, combining single agent PD-1, PD-L1 and A2aR blockade with FLOT enhanced cytotoxicity in OAC cells. These findings reveal novel mechanistic insights into the immune-independent functions of IC-intrinsic signalling in OAC cells with important clinical implications for boosting the efficacy of the first-line FLOT chemotherapy regimen in OAC in combination with ICB, to not only boost anti-tumour immunity but also to suppress IC-mediated promotion of key hallmarks of cancer that drive tumour progression.

Supplemental Digital Content is available in the text.

Background Immunotherapy is being intensively investigated for its utilisation in the curative setting as a single agent and in the multimodal setting, however, the most appropriate time to incorporate ICIs remains unknown. Our study profiles systemic anti-tumour immunity perioperatively to provide a rationale for adjuvant immunotherapy. Methods Systemic immunity was immunophenotyped pre and post-oesophagectomy on days 0, 1, 3, 7 and week 6 by flow cytometry (n = 14). The frequency of circulating lymphocytes, T cells, cytotoxic and helper T lymphocytes was profiled longitudinally including the proportion of T cell subsets in circulation. This study also profiled immune checkpoint expression on circulating T cells including: PD-1, CTLA-4, TIGIT, TIM-3, LAG-3, PD-L1 and PD-L2. Markers of immunogenicity (calreticulin, HMGB1 and MIC-A/B) were also assessed. Results The frequency of circulating CD27 + T cells increases sequentially in the immediate post-operative period peaking on day 7 in OAC patients. (p Conclusions We observed increased T cell activation and immune checkpoints immediately post-surgery with returns to baseline by week 6. These results suggest that immune checkpoint inhibitors such as anti-PD-1 may be beneficial immediately post-surgery to maintain T cell activation and prevent exhaustion of this increased population of activated T cells observed immediately post-surgery.

Aim The tumour microenvironment (TME) and tumour-draining lymph node microenvironment (LNME) remain poorly understood. Our study profiles the immune, angiogenic and inflammatory environment of the LNME and the TME of oesophagogastric patients. Methods The prognositc value of nodal status, clinical stage and tumour regression grade (TRG) was evaluated using a cohort of OAC patients (n = 702). Immune checkpoints (ICs) on tumour-draining lymph nodes(TDLNs, n = 6) and tumour tissue(n = 9) at surgical resection was assessed by flow cytometry. We also screened for cytokines, angiogenic mediators and chemokines. Using The Cancer Genome Atlas (TCGA), protein and mRNA levels (n = 72) and mutated versus non-mutated copies(n = 87) of this panel was correlated with survival. Results The frequency of CD3+TIM-3 and PD-1+T cells in TDLNs positively correlated with clinical tumour status as did CD8 + PD-1+TIGIT + T cells with nodal burden. Pro-angiogenic factor bFGF was significantly higher within the TME compared with the LNME. PIGF and SAA mediators of tumour growth were significantly higher in the LNME and levels of SAA in LNME positively correlated with adverse features. High levels of pro inflammatory IL-8,IL-6 and Flt1, mutations in pro-inflammatory genes CCL26,IL-31 and IL-17C and anti-tumour IL-1RN and CCL22 correlated with reduced overall survival. Conclusions The TME is more immunosuppressive than the TDLN, however, certain pro-angiogenic factors were enriched in TDLNs suggesting the priming of a pre-metastatic niche. Given the association of ICs with clinical features and tumour biology this may help to inform novel therapeutic approaches.

Introduction The COVID-19 pandemic has interfered with many aspects of cancer management, including delayed diagnoses, stalled screening programmes, limiting treatment and clinical trials. Colorectal cancer is the second commonest cause of cancer death in Ireland. The objective of the current study is to assess the impact of this pandemic on colorectal cancer diagnoses and surgery, at a national level. Methods Data on endoscopy, emergency and elective colorectal operations nationally in Ireland over a three year period (2018-2020) were obtained from the National Quality Assurance Improvement System. Data relating to cancer surgery only were included and patient demographics, type of surgery (open/laparoscopic), length of stay (LOS), mortality, admission to critical care and re-admission rates were collected and analysed. Results 31.33% less cancers have been diagnosed between March and November 2020 inclusive when compared to the same period over the past two years with 22% less rectal cancers identified. There has been a 34% reduction in colorectal cancer surgeries over the same period with a reduction of 42% at the initial wave during the period March-May and of concern, this trend has continued. Laparoscopic right hemicolectomies have reduced by 41%, anterior resections have reduced by 51% with no change in the number of temporary ileostomies over the three year period. Conclusion The impact of COVID-19 on colorectal cancer surgery nationally has been profound. The reduction in diagnoses and cancer surgery is concerning and may result in increased late or incurable stage disease as a consequence of late presentation and diagnosis.

Background Immune checkpoint inhibitors (ICIs) are being investigated for their role as an adjunct in the multimodal treatment of oesophageal adenocarcinoma (OAC). The most appropriate time to incorporate ICIs remains unknown. Our study profiles systemic anti-tumour immunity perioperatively to help inform the optimal timing of ICIs into current standards of care for OAC patients. Methods Systemic immunity in 11 OAC patients was phenotyped prior to oesophagectomy and on post-operative days (POD) 0, 1, 3, 7 and week 6 using flow cytometry. Longitudinal serological profiling was conducted by 54-plex-ELISA. The frequency of circulating lymphocytes, T cells, T helper cells and cytotoxic T lymphocytes was profiled longitudinally. The activation status of T cells was also assessed using CD69, CD27, CD62L and CD45RA as well as the proportion of T cell subsets in circulation, which included: naive, central memory, effector memory and terminally differentiated effector memory T cells. This study also profiled the longitudinal alteration of immune checkpoint expression on circulating T cells, which included: PD-1, CTLA-4, TIGIT, TIM-3, LAG-3, PD-L1 and PD-L2. Damage-associated molecular patterns (calreticulin, HMGB1 and MIC-A/B) were also assessed. Results The frequency of naive T cells increased in circulation post-oesophagectomy from POD-0 to POD-7 (p Conclusion Our study highlights the prevailing immunophenotype and responses to surgery with a switch in balance towards a Th2 and potentially M2 phenotype and consequently, an immunosuppressive milieu. Therefore, orchestrating M2 reprogramming toward an M1 phenotype and similarly shifting the balance in favour of a Th1 phenotype would offer a potent therapeutic approach for augmenting tumourigenesis and promoting cancer regression. Consequently, this study paves the way for further studies and appropriate trial design are needed to interrogate the use of ICB as a trimodal approach with chemoradiotherapy and chemotherapy alone for locally advanced disease in the neoadjuvant and adjuvant setting to determine the optimal timing and subset of patients for their use in the era of precision targeted therapies. Disclosure Information N.E. Donlon: None. M. Davern: None. A. Sheppard: None. F. O’Connell: None. S. Ramjit: None. C. Hayes: None. M. Mc Clean: None. H. Temperley: None. C. Butler: None. N. Ravi: None. C. Donohoe: None. J. O’ Sullivan: None. M.R. Dunne: None. J.V. Reynolds: None. J. Lysaght: None.

The majority of oesophageal adenocarcinoma (OAC) patients do not respond to multimodal treatment regimens and face dismal survival rates. Natural killer (NK) cells are crucial anti-tumour immune cells, and this study investigated the susceptibility of treatment-resistant OAC cells to these potent tumour killers. Natural killer receptor (NKR) ligand expression by OE33CisP (cisplatin-sensitive) and OE33CisR (cisplatin-resistant) cells was investigated. The immunomodulatory effects of OE33CisP and OE33CisR cells on NK cell phenotype and function were assessed. Finally, the impact of chemotherapy regimens on NKR ligand shedding was examined. Our data revealed significantly less surface expression of activating ligands B7-H6, MICA/B, ULBP-3 and activating/inhibitory ligands PVRL-1 and PVRL-4 by OE33CisR cells, compared to OE33CisP cells. Co-culture with OE33CisR cells reduced the frequencies of NKp30

Immunotherapies are transforming outcomes for many cancer patients and are quickly becoming the fourth pillar of cancer therapy. However, their efficacy of only ∼25% in gastro-oesophageal cancer has been disappointing. This is attributed to factors such as insufficient patient stratification and the pro-tumourigenic immune landscape of gastro-oesophageal tumours. The chemokine profiles of solid tumours and the availability of effector immune cells greatly influence the immune infiltrate, producing 'cold' or 'immune-excluded' tumours in which immunotherapies are unable to reinvigorate the immune response. Other biological functions for chemokines have emerged, such as promoting cell survival, polarising T cell responses, and supporting several hallmarks of cancer. Therefore, chemokine networks may be exploited with therapeutic intent to mobilise and polarise anti-tumour immune cells, with further utility as combination treatments to augment the efficacy of current cancer immunotherapies. Few studies have demonstrated the clinical benefit of chemokine-targeted therapies as monotherapies, and this review proposes their consideration as combination treatments. Herein, we explore the anti-tumour and pro-tumour implications of chemokine signalling in gastro-oesophageal cancer and discuss their value as prognostic and predictive biomarkers in response to treatment.

The perioperative period theoretically is a critical time of opportunity for the progression of pre-existing tumour micrometastasis. Therefore,the timing of introducing cancer therapies including chemotherapy, radiation therapy and immunotherapies in the postoperative period is important. A thorough exploration of the perioperative immune events at a cellular level in combination with an intricate review of available clinical rials was conducted to extrapolate the effects of oncological surgery on the perioperative immune milieu.This is timely in view of the recently published Checkmate-577 trial which demonstrated significant disease-free survival in carcinoma of the gastroesophageal junction with the use of adjuvant anti-programmed cell deathprotein 1(PD-1) immunotherapy.This review focusing in particular on perioperative immunosuppression, identifies potential modifiable factors, the effects of perioperative conditioning and optimisation, the most recent trials in the curative setting for Gastrointestinal malignancies and the new treatment avenues possible in the context of the combination of immunotherapy and major oncological gastrointestinal surgery.

Oesophageal cancer (OC) is an inflammation-associated malignancy linked to gastro-oesophageal reflux disease, obesity and tobacco use. Knowledge of the microenvironment of oesophageal tumours is relevant to our understanding of the development of OC and its biology, and has major implications for understanding the response to standard therapies and immunotherapies, as well as for uncovering novel targets. In this context, we discuss what is known about the TME in OC from tumour initiation to development and progression, and how this is relevant to therapy sensitivity and resistance in the two major types of OC. We provide an immunological characterisation of the OC TME and discuss its prognostic implications with specific comparison with the Immunoscore and immune-hot, -cold, altered-immunosuppressed and -altered-excluded models. Targeted therapeutics for the TME under pre-clinical and clinical investigation in OCs are also summarised. A deeper understanding of the TME will enable the development of combination approaches to concurrently target the tumour cells and TME delivering precision medicine to OC patients.

Radiotherapy remains one of the contemporary cornerstones of cancer treatment in the neoadjuvant, curative, adjuvant and palliative settings, either in isolation or as a multimodal approach. Moreover, recent advances in targeted immune checkpoint therapy have firmly established immunotherapy as the fourth pillar in cancer therapy alongside surgery, chemotherapy and notably radiotherapy. There is emerging evidence to suggest both radioresistance and reduced efficacy of immune checkpoint blockade (ICB) are potentiated by the tumour microenvironment (TME) and in fact modulating aspects of this immunosuppressive milieu is instrumental to unlocking anti-tumour immunity. The response rates of Upper Gastrointestinal (UGI) malignancies to ICB remains modest at 10–15%, compared to melanoma at 20–40%. Harnessing the effects of radiotherapy through remodelling of the TME using ICB as a radiosensitisor is an avenue showing promise. Here we explore the rationale behind combining radiotherapy with ICB, as a symbiotic relationship in shifting the balance in favour of anti-tumour immunity. We discuss the effects of radiotherapy on immunogenic cell death, the concept of the abscopal effect, the importance of the cGAS STING pathway, and their relevance in the context of the tumour microenvironment. Furthermore, dosing and timing of radiotherapy and ICB is now being evaluated for its synergistic effects on host tumour immunity, and we review the ongoing efforts and current available literature for single agent and dual agent ICB in combination multimodal therapy for both locally advanced operable and metastatic disease of the upper gastrointestinal tract.

Tumour acidosis contributes to cancer progression by inhibiting anti-tumour immunity. However, the effect of acidosis on anti-tumour T cell phenotypes in oesophageal adenocarcinoma (OAC) is unknown. Therefore, this study investigated the effect of acidosis on anti-tumour T cell profiles and if immune checkpoint blockade (ICB) could enhance anti-tumour T cell immunity under acidosis. Acidic conditions substantially altered immune checkpoint expression profiles of OAC patient-derived T cells, upregulating TIM-3, LAG-3 and CTLA-4. Severe acidosis (pH 5.5) significantly decreased the percentage of central memory CD4 + T cells, an effect that was attenuated by ICB treatment. ICB increased T cell production of IFN-γ under moderate acidosis (pH 6.6) but not severe acidosis (pH 5.5) and decreased IL-10 production by T cells under severe acidic conditions only. A link between lactate and promotion of angiogenesis was also depicted; circulating lactate levels positively correlated with circulating soluble Tie-2. Our findings establish that acidosis-induced upregulation of immune checkpoints on T cells may potentially contribute to immune evasion in OAC. However, acidic conditions curtailed ICB efficacy, supporting a rationale for utilizing systemic oral buffers to neutralize tumour acidity to improve ICB efficacy. Funding: This work was funded by an Irish Research Council scholarship (GOIPG/2017/1659) and the CROSS cancer research charity. Declaration of Interest: The authors declare that there is no conflict of interest Ethical Approval: Ethical approval was granted from the St James’s Hospital Ethics Committee.

Background: Oesophageal Adenocarcinoma (OAC) is the most strongly associated cancer with obesity. Approximately 75% of OAC patients are obese which results in chronic systemic low-grade inflammation, which is believed to drive carcinogenesis as well as influencing radiation treatment response. Adipose tissue is a regulatory organ with many downstream effects which are still not understood. This study aims to elucidate what influence adipose tissue metabolism and secretome have in treatment resistance and whether obesity alters this response. Methods: Following patient consent, ex-vivo Visceral Adipose Tissue (VAT) explants were exposed to increasing doses of radiation with/without Palmitate and Oleate. Agilent Seahorse Xfe24 was used to measure oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) in VAT explants and mitochondrial metabolic parameters in dendritic cells (DCs) following treatment with Adipose Conditioned Media (ACM). Levels of DC maturation following irradiated ACM exposure and Macrophage (Mɸ) polarisation following ACM or Tumour Conditioned Media (TCM) exposure were analyzed by flow cytometry. Irradiated ACM and TCM were analyzed via MSD 54plex ELISA to assess secreted factors on angiogenic, chemokine, cytokine, inflammatory, TH17 or vascular injury panels. Results: VAT explant energy metabolism showed a significant increase for OCR and ECAR with obesity and increasing radiation exposure however OCR was significantly decreased following Palmitate treatment compared with untreated and Oleate treated adipose explants (p Conclusion: We have demonstrated that obesity and increasing radiation doses can significantly alter the immune-metabolic influences of adipose tissue and further studies are profiling the lipidomic and metabolomic landscape of the adipose secretome. Alterations in the secretome of adipose tissue could potentiate the tumor microenvironment and deleteriously affect immune cell function therefore further interrogation is required to fully elucidate the influence adipose tissue may have in treatment response. Citation Format: Fiona O'Connell, Eimear Mylod, Ailsing B. Heeran, Noel E. Donlon, Maria Davern, Christine Butler, Anshul Bhardwaj, Claire Donohoe, Narayanasamy Ravi, John V. Renyolds, Margaret R. Dunne, Helen M. Roche, Jacintha O'Sullivan. Exploring the immune-metabolic mechanisms of adipose tissue in oesophageal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1990.

Background Combining immune checkpoint inhibitors (ICIs) with immunogenic chemotherapies is a promising approach in oesophageal adenocarcinoma (OAC) to convert ‘cold’ tumours to ‘hot’ tumours expanding the efficacy of ICIs to a greater spectrum of patients.1 However, there is a vast array of immune checkpoints (ICs) expressed by T cells and the effect of ICIs in combination with chemotherapy regimens is largely unknown.2 Methods The expression profile of a range of ICs on circulating and tumour-infiltrating T cells was assessed using flow cytometry prior to and post-neoadjuvant treatment and correlated with clinical parameters (n=20). PBMCs isolated from OAC blood were treated with single agent ICIs alone (single agent anti-PD-1, anti-PD-L1, anti-A2aR and anti-TIM-3 inhibition) and in combination with FLOT (5-Fluorouracil, oxaliplatin and docetaxel) and CROSS (carboplatin and paclitaxel) chemotherapy regimens. The production of anti-tumour cytokines by T cells was assessed in vitro by flow cytometry (n=6). Results In the treatment-naive and post-treatment setting, a range of ICs were expressed by circulating T cells and were significantly increased on tumour-infiltrating T cells, which included PD-L1, PD-L2, CD160, PD-1, CTLA-4, TIGIT, TIM-3, LAG-3, A2aR and ICOS (p Conclusions T cells expressing ICs in circulation and infiltrating OAC tissue were adverse prognostic markers in the pre-treatment setting, perhaps due to their role in enabling tumour immune evasion and subsequent tumour progression. In contrast, T cells expressing ICs post-chemotherapy treatment in peripheral circulation were favorable prognostic markers. ICs are typically expressed by ‘hot’ tumours2 therefore, the presence of ICs in the post-treatment setting may be as a result of an induced-anti-tumour immune response following immunogenic chemotherapy/chemoradiotherapy treatment and may be a useful strategy for stratifying patients into chemotherapy/chemoradiotherapy responders or non-responders. A therapeutic rationale is also highlighted for combining ICIs with chemotherapy regimens in OAC patients to enhance anti-tumour T cell-mediated responses and potentially boost response rates to chemotherapy treatment. Acknowledgements We would like to thank all the patients who kindly donated their samples to our research Ethics Approval The work was performed in accordance with the Code of Ethics of the World Medical Association (Declaration of Helsinki) for experiments involving human samples. Consent Patients provided informed consent for sample and data acquisition, and the study received full ethical approval from the St. James’s Hospital/AMNCH Ethical Review Board. References Davern M, Lysaght J. Cooperation between chemotherapy and immunotherapy in gastroesophageal cancers. Cancer Lett 2020. https://doi.org/10.1016/j.canlet.2020.09.014 Emens LA, Middleton G. The interplay of immunotherapy and chemotherapy: harnessing potential synergies. Cancer Immunol Res 2015;3:436–443.

The tumour microenvironment is of critical importance in cancer development and progression and includes the surrounding stromal and immune cells, extracellular matrix, and the milieu of metabolites and signalling molecules in the intercellular space. To support sustained mitotic activity cancer cells must reconfigure their metabolic phenotype. Lactate is the major by-product of such metabolic alterations and consequently, accumulates in the tumour. Lactate actively contributes to immune evasion, a hallmark of cancer, by directly inhibiting immune cell cytotoxicity and proliferation. Furthermore, lactate can recruit and induce immunosuppressive cell types, such as regulatory T cells, tumour-associated macrophages, and myeloid-derived suppressor cells which further suppress anti-tumour immune responses. Given its roles in oncogenesis, measuring intratumoural and systemic lactate levels has shown promise as a both predictive and prognostic biomarker in several cancer types. The efficacies of many anti-cancer therapies are limited by an immunosuppressive TME in which lactate is a major contributor, therefore, targeting lactate metabolism is a priority. Developing inhibitors of key proteins in lactate metabolism such as GLUT1, hexokinase, LDH, MCT and HIF have shown promise in preclinical studies, however there is a corresponding lack of success in human trials so far. This may be explained by a weakness of preclinical models that fail to reproduce the complexities of metabolic interactions in natura. The future of these therapies may be as an adjunct to more conventional treatments.

Esophageal adenocarcinoma (EAC) is increasing exponentially year on year in Western civilisation, linked epidemiologically to GERD and obesity. It is characterized by a highly immunosuppressive tumour microenvironment (TME) and evasion of immune surveillance. A novel treatment option is upregulating immune mediated anti-tumour response via Immune Checkpoint Blockers (ICB). Methods The effects of immune checkpoint blockers were characterised in terms of proliferation, cytolysis and cancer cell viability. The basal expression of immune checkpoints (TIGIT, PD-1, PD-L1, PD-L2) and Damage Associated Molecular Patterns (Calreticulin, HMGB1) in EAC patients was profiled ex vivo using fresh tumor, blood and lymph-node tissue (n = 10) by flow cytometry. In an in-vitro study, T-lymphocytes were isolated and treated with Nivolumab, Pembrolizumab or Atezolizumab, activated and co-cultured for 48 hours with a panel of four esophageal cancer cell lines; OE33P, OE33R, FLO-1, FLO-1LM treated with 1.8Gy and 3.6Gy of radiation (Fig 1). Cytolysis was measured using a CCK8 assay.(n = 6). Results The expression of TIGIT, TIM-3, PD-1 and its ligands (PD-L1, PD-L2) were higher (p Conclusion Fractionated radiation can enhance immunologic function. In combination with ICB, this symbiotic relationship enhances the cytotoxic potential of T lymphocytes with conventional dosing, however, with hypofractionation, this signifies true immunogenicity, and as such this provides a basis for advocating for potential combination strategies with ICB in the multimodal treatment of EAC.

There is extensive literature demonstrating CD8+ T cells are essential for initial tumour control following radiation, however, effects are reduced after time due to T cell exhaustion and a lack of release Damage Associated Molecular Patterns (DAMPS) which are essential for anti-tumour immune responses. In vivo, activated T-cells migrate to the tumour site within the field of irradiation, however translational studies on the effects of radiotherapy on T-cell activation, function and activity are lacking. Methods EAC patient (n = 6) PBMCs were isolated by density centrifugation in Ficoll Paque. T cells were activated and were irradiated at 1.8Gy, 3.6Gy bolus dosing and fractionation for 72 hrs. A panel of immune checkpoints, DAMPS, activation markers, and cytokines were assessed by flow cytometry. To determine the effect of the TME on T cells, PBMCs were cultured under conditions of nutrient deprivation (No Glucose & No Glutamine) under conditions of normoxia and hypoxia. We then ran the aforementioned panel by flow cytometry. We also activated PBMCs with immune checkpoint blockers to determine its effects on T cell expansion and survival. Results 3.6Gy induced a significantly higher expression of DAPMS (Fig 1 p Conclusion This work demonstrates the impact of clinically utilised fractions of radiation, and conditions of the TME on T cell function and activity, with improved T cell expansion and survival in the presence of ICB’s suggesting it may be a feasible combination therapy as an adjunct to radiotherapy.

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

Gastroesophageal cancers (GOCs) represent some of the most common cancers globally and are linked with poor survival rates. The current standard of care includes multimodal chemotherapy, radiotherapy and surgery. However, up to two-thirds of patients fail to derive benefit from these treatments, underscoring the urgent need to develop better, rationally-designed treatment strategies to enhance survival rates. Certain immunogenic chemotherapies can stimulate anti-tumour immune responses in GOC patients; therefore, combining immune checkpoint inhibitors (ICIs) with chemotherapy to prevent immune exhaustion is an attractive putative therapeutic strategy. Emerging studies demonstrate that immune checkpoint-intrinsic signalling in cancer cells supports several cancer hallmarks in addition to immune evasion, including proliferation, metastasis, glycolysis, DNA repair and chemoresistance. Combining ICIs with chemotherapy may therefore potentially enhance chemosensitivity and suppress a range of immune-dependent and -independent tumourigenic processes in GOCs. This review summarises the current clinical trials investigating the efficacy of ICIs in GOCs. The immunogenic effects of chemotherapies and their effects on immune checkpoint expression is discussed, as is the important and emerging study of novel immune-independent functions of immune checkpoints in cancer.

Historically, high negative appendicectomy rates (NAR) were acceptable to offset the risks of perforation, previously exceeding 20%. With improved imaging and clinical scoring algorithms, there is growing demand for lower negative appendicectomy rates. The objectives were to (1) establish the NAR in our institution and (2) correlate clinical parameters and imaging modalities with histological findings.Patients undergoing an appendicectomy between January 2012 and June 2018 were identified using a prospectively maintained pathology database. Histology findings were cross referenced against our radiology system, and anonymised data was collected for gender, age, WCC, Neutrophil and CRP level.One thousand one hundred fifty-three patients met the inclusion criteria. Fifty-three percent were males (n = 610), with 81% (n = 933) of histology reports classified as appendicitis. Sixty patients had a histologically normal appendix equating to a 5.2% NAR. If lymphoid hyperplasia, fibrosis and atrophy are included, it equates to a NAR of 14.57%. (p0.0001). Sixty-six percent of patients had no pre-operative imaging. CT imaging demonstrated a higher sensitivity (93.33%) and positive predictive value (99.60%) compared to ultrasonography. WCC and CRP are statistically significant in predicting appendicitis (p0.0001).There is no consensus on defining a negative appendicectomy or for imaging modality utilisation. CT imaging is the most sensitive and should be used in cases of diagnostic uncertainty. A standardised algorithm regarding the workup of patients with RIF pain along with a consensus on the use of imaging will further reduce negative appendicectomy rates.