Locally advanced rectal cancer is treated with neoadjuvant-chemoradiotherapy, however only 22% of patients achieve a complete response. Resistance mechanisms are poorly understood. Radiation-induced Bystander Effect (RIBE) describes the effect of radiation on neighbouring unirradiated cells. We investigated the effects of ex vivo RIBEinduction from normal and rectal cancer tissue on bystander cell metabolism, mitochondrial function and metabolomic profiling. We correlated bystander events to patient clinical characteristics. Ex vivo RIBE-induction caused metabolic alterations in bystander cells, specifically reductions in OXPHOS following RIBE-induction in normal (p = 0.01) and cancer tissue (p = 0.03) and reduced glycolysis following RIBE-induction in cancer tissue (p = 0.01). Visceral fat area correlated with glycolysis (p = 0.02) and ATP production (p = 0.03) following exposure of cells to TCM from irradiated cancer biopsies. Leucine levels were reduced in the irradiated cancer compared to the irradiated normal secretome (p = 0.04). ROS levels were higher in cells exposed to the cancer compared to the normal secretome (p = 0.04).

RIBE-induction ex vivo causes alterations in the metabolome in normal and malignant rectal tissue along with metabolic alterations in bystander cellular metabolism. This may offer greater understanding of the effects of RIBE on metabolism, mitochondrial function and the secreted metabolome.

Ulcerative colitis (UC) is a chronic relapsing remitting inflammatory disease of the colon. The lifetime risk of presentation with acute severe ulcerative colitis (ASUC) is 15%.¹ Patients with ASUC receive first line therapy with intravenous corticosteroids, however, approximately 30% have corticosteroid-refractory disease.²,3 In this situation, rescue medical therapy options include the anti-tumor necrosis factor (TNF) monoclonal antibody infliximab (IFX) or the calcineurin inhibitor ciclosporin.² A significant proportion of patients fail to respond to IFX therapy with reported colectomy rates at 1 year of 35%.⁴ Biomarkers which identify patients with corticosteroid-refractory ASUC, with a reduced likelihood of IFX response, would significantly advance clinical care for these patients.

Radiotherapy is used in the treatment of approximately 50% of all malignancies including gastrointestinal cancers. Radiation can be given prior to surgery (neoadjuvant radiotherapy) to shrink the tumour or after surgery to kill any remaining cancer cells. Radiotherapy aims to maximize damage to cancer cells, while minimizing damage to healthy cells. However, only 10–30% of patients with rectal cancer or oesophageal cancer have a pathological complete response to neoadjuvant chemoradiation therapy, with the rest suffering the negative consequences of toxicities and delays to surgery with no clinical benefit. Furthermore, in pancreatic cancer, neoadjuvant chemoradiation therapy results in a pathological complete response in only 4% of patients and a partial pathological response in only 31%. Resistance to radiation therapy is polymodal and associated with a number of biological alterations both within the tumour itself and in the surrounding microenvironment including the following: altered cell cycle" repopulation by cancer stem cells" hypoxia" altered management of oxidative stress" evasion of apoptosis" altered DNA damage response and enhanced DNA repair" inflammation" and altered mitochondrial function and cellular energetics. Radiosensitizers are needed to improve treatment response to radiation, which will directly influence patient outcomes in gastrointestinal cancers. This article reviews the literature to identify strategies — including DNA-targeting agents, antimetabolic agents, antiangiogenics and novel immunotherapies — being used to enhance radiosensitivity in gastrointestinal cancers according to the hallmarks of cancer. Evidence from radiosensitizers from in vitro and in vivo models is documented and the action of radiosensitizers through clinical trial data is assessed.

The clinical management of locally advanced oesophageal adenocarcinoma (OAC) involves neoadjuvant chemoradiotherapy (CRT), but as radio resistance remains a major clinical challenge, complete pathological response to CRT only occurs in 20–30% of patients. In this study we used an established isogenic cell line model of radioresistant OAC to detect proteomic signatures of radio resistance to identify novel molecular and cellular targets of radio resistance in OAC. A total of 5785 proteins were identified of which 251 were significantly modulated in OE33R cells, when compared to OE33P. Gene ontology and pathway analysis of these significantly modulated proteins demonstrated altered metabolism in radioresistant cells accompanied by an inhibition of apoptosis. In addition, inflammatory and angiogenic pathways were positively regulated in radioresistant cells compared to the radiosensitive cells. In this study, we demonstrate, for the first time, a comprehensive proteomic profile of the established isogenic cell line model of radioresistant OAC. This analysis provides insights into the molecular and cellular pathways which regulate radio resistance in OAC. Furthermore, it identifies pathway specific signatures of radio resistance that will direct studies on the development of targeted therapies and personalised approaches to radiotherapy.

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< 20%. To improve treatment outcomes it is critical to further investigate OAC tumour biology, metabolic phenotype and their metabolic adaptation to different oxygen tensions. In this study, by using human ex-vivo explants we demonstrated using real-time metabolic profiling that OAC tumour biopsies have a significantly higher oxygen consumption rate (OCR), a measure of oxidative phosphorylation compared to extracellular acidification rate (ECAR), a measure of glycolysis (p= 0.0004). Previously, we identified a small molecule compound, pyrazinib which enhanced radiosensitivity in OAC. Pyrazinib significantly inhibited OCR in OAC treatment-naïve biopsies (p= 0.0139). Furthermore, OAC biopsies can significantly adapt their metabolic rate in real-time to their environment. Under hypoxic conditions pyrazinib produced a significant reduction in both OCR (p= 0.0313) and ECAR in OAC treatment-naïve biopsies. The inflammatory secretome profile from OAC treatment-naïve biopsies is heterogeneous. OCR was positively correlated with three secreted factors in the tumour conditioned media: vascular endothelial factor A (VEGF-A), IL-1RA and thymic stromal lymphopoietin (TSLP). Pyrazinib significantly inhibited IL-1β secretion (p= 0.0377) and increased IL-3 (p= 0.0020) and IL-17B (p= 0.0181). Importantly, pyrazinib did not directly alter the expression of dendritic cell maturation markers or reduce T-cell viability or activation markers. We present a new method for profiling the metabolic rate of tumour biopsies in real-time and demonstrate the novel anti-metabolic and anti-inflammatory action of pyrazinib ex-vivo in OAC tumours, supporting previous findings in-vitro whereby pyrazinib significantly enhanced radiosensitivity in OAC.

Background: Colorectal cancer (CRC) is the second most common cause of cancer-related mortality worldwide with one in every five patients diagnosed with metastatic CRC (mCRC). In mCRC cases, the 5-year survival rate remains at approximately 14%, reflecting the lack of effectiveness of currently available treatments such as the anti-VEGF targeting antibody Bevacizumab combined with the chemotherapy folinic acid, fluorouracil and oxaliplatin (FOLFOX). Approximately 60% of patients do not respond to this combined treatment. Furthermore, Bevacizumab inhibits dendritic cell (DC) maturation in poor responders, a key process for tumor eradication.

Method: Following drug treatment, secreted expression levels of angiogenic and inflammatory markers in tumor conditioned media generated from human ex vivo colorectal tumors were measured by ELISA. Dendritic cell phenotypic and maturation markers were assessed by flow cytometry.

Results: Our novel compound, 1,4-dihydroxy quininib, acts in an alternative pathway compared to the approved therapy Bevacizumab. 1,4-dihydroxy quininib alone, and in combination with Bevacizumab or FOLFOX significantly reduced TIE-2 expression which is involved in the promotion of tumor vascularization. Combination treatment with 1,4-dihydroxy quininib significantly increased the expression level of DC phenotypic and maturation markers.

Conclusion: Our results indicate the anti-angiogenic small molecule 1,4-dihydroxy quininib could be an alternative novel treatment in combination therapy for CRC patients.

Oesophageal adenocarcinoma (OAC) is an exemplar model of obesity-associated cancer. Previous work in our group has demonstrated that overweight/obese OAC patients have better responses to neoadjuvant therapy, but the underlying mechanisms are unknown. Unravelling the immune–metabolic signatures of adipose tissue may provide insight for this observation. We hypothesised that different metabolic pathways predominate in visceral (VAT) and subcutaneous adipose tissue (SAT) and inflammatory secretions will differ between the fat depots. Real-time ex vivo metabolic profiles of VAT and SAT from 12 OAC patients were analysed. These samples were screened for the secretion of 54 inflammatory mediators, and data were correlated with patient body composition. Oxidative phosphorylation (OXPHOS) was significantly higher in VAT when compared to SAT. OXPHOS was significantly higher in the SAT of patients receiving neoadjuvant treatment. VEGF-A, VEGF-C, P1GF, Flt-1, bFGF, IL-15, IL-16, IL-17A, CRP, SAA, ICAM-1, VCAM-1, IL-2, IL-13, IFN-γ, and MIP-1β secretions were significantly higher from VAT than SAT. Higher levels of bFGF, Eotaxin-3, and TNF-α were secreted from the VAT of obese patients, while higher levels of IL-23 and TARC were secreted from the SAT of obese patients. The angiogenic factors, bFGF and VEGF-C, correlated with visceral fat area. Levels of OXPHOS are higher in VAT than SAT. Angiogenic, vascular injury and inflammatory cytokines are elevated in VAT versus SAT, indicating that VAT may promote inflammation, linked to regulating treatment response.