Host Antitumour Immune Responses Research Articles

Therapeutic Potential of Clostridium novyi NT in Cancer: Current Knowledge and Future Perspectives.

Resistance to conventional antitumour therapies and Hypoxia in patients with advanced solid tumours are two major reasons for the failure of conventional anti-tumour therapies. Therefore, it is important to find a new therapeutic method that can overcome these problems. An attenuated anaerobic bacterium, Clostridium novyi- NT, could target Hypoxic and Necrotic areas of tumours causing tumour lysis and stimulating a host anti-tumour immune response. To the best of our knowledge, the combination of bacterial anti-tumour therapy, chemotherapy, radiotherapy and immunotherapy may promote tumour regression, inhibit metastasis and develop a new strategy for the treatment of solid tumours. However, the possible molecular mechanisms of the combined therapies are still the biggest challenge. This review provides an overview of the history of bacterial cancer therapy and the development of a non-lethal strain of Clostridium novyi. Below is a precise definition of Hypoxic conditions in solid tumour tissue. To understand the anticancer effect of Clostridium novyi- NT spores, possible cell death mechanisms were summarised by the enzyme phospholipase C (nt01cx0979), which is secreted by Clostridium novyi- NT spores after germination in tumour tissue. The function of Clostridium novyi- NT spores in stimulating the host immune system to elicit anti-tumour responses was reviewed. Then, the results of anti-tumour combination therapies based on Clostridium novyi- NT spores were compiled. Identifying the molecular mechanisms of Clostridium novyi- NT in treating tumours and inducing cell death in invasive cancer cells, ultimately leading to tumour regression, may develop promising clinical strategies in the combined treatment of solid tumours.

Targeting Triple Negative Breast Cancer With Oncolytic Adenoviruses.

Breast cancer (BC) is the most common cancer globally, accounting for 685,000 deaths in 2020. Triple-negative breast cancers (TNBC) lack oestrogen (ER) and progesterone (PR) hormone receptor expression and HER2 overexpression. TNBC represent 10–15% of all BC with high incidence in women under 50-years old that have BRCA mutations, and have a dismal prognosis. African American and Hispanic women are at higher risk partly due to the common occurrence of BRCA mutations. The standard treatment for TNBC includes surgery, radiotherapy, and chemotherapy although, resistance to all standard-of-care therapies eventually develops. It is crucial to identify and develop more efficacious therapeutics with different mechanisms of action to improve on survival in these women. Recent findings with oncolytic adenoviruses (OAds) may generate a new strategy to improve on the outcomes for women afflicted by TNBC and other types of BC. OAds are genetically engineered to selectively lyse, eliminate and recruit the host antitumour immune responses, leaving normal cells unharmed. The most common modifications are deletions in the early gene products including the E1B55 KDa protein, specific regions of the E1A protein, or insertion of tumour-specific promoters. Clinical trials using OAds for various adenocarcinomas have not yet been sufficiently evaluated in BC patients. Preclinical studies demonstrated efficacy in BC cell lines, including TNBC cells, with promising novel adenoviral mutants. Here we review the results reported for the most promising OAds in preclinical studies and clinical trials administered alone and in combination with current standard of care or with novel therapeutics. Combinations of OAds with small molecule drugs targeting the epidermal growth factor receptor (EGFR), androgen receptor (AR), and DNA damage repair by the novel PARP inhibitors are currently under investigation with reported enhanced efficacy. The combination of the PARP-inhibitor Olaparib with OAds showed an impressive anti-tumour effect. The most promising findings to date are with OAds in combination with antibodies towards the immune checkpoints or expression of cytokines from the viral backbone. Although safety and efficacy have been demonstrated in numerous clinical trials and preclinical studies with cancer-selective OAds, further developments are needed to eliminate metastatic lesions, increase immune activation and intratumoural viral spread. We discuss shortcomings of the OAds and potential solutions for improving on patient outcomes.

SO-10 The prognostic role of microarchitecture in tumour-positive lymph nodes in oesophageal cancer patients: Results from the UK MRC OE02 trial

Patients with resectable oesophageal cancer (OeC) have a 25-47% 5-year overall survival (OS). The strongest prognostic factor is pathological lymph node (LN) status. Regional tumour-draining LNs play an important role in the host anti-tumour immune response. We previously demonstrated that the microarchitecture in tumour-negative LNs (LNneg) changes after chemotherapy and predicts OS. It is currently unknown whether neoadjuvant chemotherapy induces microarchitectural changes in regional tumour-positive LNs (LNpos) which might impact patient's OS. We hypothesized that (1) LNpos in OeC patients treated with chemotherapy and surgery contain fewer germinal centres compared to patients treated by surgery alone and (2) that patients with an activated anti-tumour immune response (e.g. more germinal centres and more lymphocytes) in the regional LNpos have a better OS. Digitized haematoxylin/eosin-stained sections of 129 OE02 trial patients with at least one LNpos were analyzed (70 treated with surgery alone (S patients), 59 treated with chemotherapy and surgery (CS patients)). The area of the different histological components (lymphocytes, germinal centres, histiocytes, tumour tissue) of the largest LNpos per patient was manually quantified by point counting as surrogate of LNpos microarchitecture. The %area of individual immune features in the tumour-free LN area and %area of tumour were calculated. The relationship between individual histological LN components, largest LNpos diameter, treatment and clinicopathological variables was analyzed. Kaplan Meier method was applied for univariate OS from time of surgery and Cox proportional hazard model for multivariate survival analysis including (y)pT status in the model. There was no difference in LNpos microarchitecture between treatment arms. Combined analysis showed that tumour tissue occupied (median(range)) 8.9% of the largest LNpos area (0.01-44.4%). Lymphocytes occupied most of the tumour-free LNpos area (median (range) 65.2% LN area (2.1%-87.7%), followed by histiocytes (9.7% LN area (0%-59.3%)) and germinal centres (1.8% LN area (0%-16.9%)). No relationship between individual LNpos components and clinicopathological parameters was found. S patients with a high %area of histiocytes in the LNpos had a poorer survival in univariate (p=0.008; HR 1.05 95% CI (1.01-1.09)) and in multivariate analysis (p=0.04; HR 1.06 (1.02-1.09)). CS patients with a larger area of tumour in the LNpos showed decreased OS in univariate (p=0.04; HR 2.27 (1.29-3.99)) and in multivariate analysis (p=0.01; HR 2.11 (1.19-3.75). No other relationships with survival were seen. This is the first study to quantify LNpos microarchitecture on haematoxylin/eosin-stained sections and show that LNpos microarchitecture is similar between oesophageal cancer patients treated with chemotherapy and surgery or surgery alone. This might indicate that chemotherapy does not alter the quantitative immune response in tumour-positive lymph nodes of oesophageal cancer patients. Nevertheless, there are differences in prognostic value of histiocytes in tumour-positive lymph nodes in surgery alone patients and residual tumor burden in tumour-positive lymph nodes in chemotherapy patients. The underlying molecular mechanisms of these novel findings warrant further investigations by for example detailed immune-cell phenotyping within lymph nodes and matched primary tumour. Our results need to be confirmed in a second independent series to translate findings into post-surgery patient treatment decisions in the future.

SO-6 Microarchitectural changes in regional lymph nodes after chemotherapy in oesophageal cancer: Results from the UK MRC OE02 trial

Patients with resectable oesophageal cancer (OeC) have a 5-year overall survival of 25-47%. One of the strongest prognostic factors is lymph node (LN) status. The regional tumour draining LNs play an important role in the host anti-tumour immune response. It has been suggested that LN microarchitecture (number of germinal centres, sinus histiocytosis, expansion of the paracortex or medulla) changes in response to exposure to tumour antigens. However, it is currently not known whether there are specific morphological changes in regional LNs after neoadjuvant cytotoxic chemotherapy.

The role of NK cells in oncolytic viral therapy: a focus on hepatocellular carcinoma.

Natural killer (NK) cells have a key role in host anti-tumour immune responses via direct killing of tumour cells and promotion of adaptive immune responses. They are therefore attractive targets to promote the anti-tumour efficacy of oncolytic viral therapies. However, NK cells are also potent components of the host anti-viral immune response, and therefore have the potential for detrimental anti-viral responses, limiting the spread and persistence of oncolytic viruses. Oncolytic viruses are currently being investigated for the treatment of hepatocellular carcinoma (HCC), a leading cause of cancer-related death with a high unmet clinical need. In this review, we highlight the role of NK cells in oncolytic virus therapy, their potential for improving treatment options for patients with HCC, and discuss current and potential strategies targeting NK cells in combination with oncolytic viral therapies.

The progress and challenge of anti-PD-1/PD-L1 immunotherapy in treating non-small cell lung cancer.

The use of programmed cell-death protein 1 (PD-1)/programmed cell-death ligand 1 (PD-L1) inhibitors is the standard therapy for the first-line or second-line treatment of patients with non-small-cell lung cancer (NSCLC). In contrast to current traditional treatments such as chemotherapy or radiotherapy, anti-PD-1 and anti-PD-L1 treatments can directly attenuate tumour-mediated exhaustion and effectively modulate the host anti-tumour immune response in vivo. In addition, compared with traditional therapy, PD-1/PD-L1 inhibitor monotherapy can significantly prolong survival without obvious side effects in the treatment of advanced NSCLC. Ideally, several biomarkers could be used to monitor the safety and effectiveness of anti-PD-1 and anti-PD-L1 treatments; however, the current lack of optimal prognostic markers remains a widespread limitation and challenge for further clinical applications, as does the possibility of immune-related adverse events and drug resistance. In this review, we aimed to summarise the latest progress in anti-PD-1/anti-PD-L1 treatment of advanced NSCLC, worldwide, including in China. An exploration of underlying biomarker identification and future challenges will be discussed in this article to facilitate translational studies in cancer immunotherapy.

A phase II, open-label study of durvalumab in combination with stereotactic body radiotherapy in androgen-intact patients with oligometastatic prostate cancer.

TPS263 Background: With the introduction of Ga68-PSMA PET, a new cohort of androgen-intact men with oligometastatic prostate cancer (PCa) recurrence has been identified. These men have normal traditional imaging and a disease-free interval usually measured in years from their definitive treatment. Recent data supports the use of metastasis-directed stereotactic body radiotherapy (SBRT) in oligometastatic PCa. Based on our institutional data in 57 patients treated with SBRT alone in the PSMA era, the median PSA progression free survival (PFS) is 11 months. Despite 100% local control, 80% relapsed by 18 months. Improving the PFS for these men is an important clinical need. Achieving this without the introduction of androgen deprivation therapy (ADT) will likely improve quality of life and minimise the adverse consequences of androgen deprivation. Radiotherapy results in cell stress and release of damage associated molecular patterns (DAMPs) with activation of antigen presenting cells. This stimulates a tumour antigen specific T-cell response and abscopal effect which can be heightened with PD-(L)1 inhibition. Most PD-(L)1 inhibition trials in PCa are in men with a high burden of castrate resistant disease. However, data suggests the castrate state can impair host anti-tumour immune response. PD-(L)1 inhibition combined with SBRT in androgen-intact men may result in improved PFS compared with our historical cohort treated with SBRT alone. Methods: This is a non-randomized, open label, phase II study of durvalumab (1500 mg IV every 4 weeks) starting 1 month prior to SBRT in men with recurrent PCa not immediately requiring ADT and with Ga68-PSMA PET detected oligometastasis. SBRT will be delivered with 30Gy/3# to lymph nodes or 24Gy/2# to bone metastasis. Durvalumab will be continued to a maximum of 12 months. Primary outcomes will be freedom from biochemical failure and toxicity. Secondary objectives include biochemical response rate, magnitude of response, overall survival, time and response to subsequent treatments and quality of life. The study is recruiting at Royal North Shore Hospital in Sydney with 18 of the planned 30 patients enrolled. Clinical trial information: ACTRN12619000097145.

IL-6 expression promoted by Poly(I:C) in cervical cancer cells regulates cytokine expression and recruitment of macrophages.

Poly(I:C) is a promising adjuvant for cancer treatment vaccines to enhance the host anti‐tumour immune response. However, the roles of poly(I:C) in the cervical cancer microenvironment and local immune reactions are not well understood. In this study, we investigated the roles of poly(I:C) in the cervical cancer. We analysed the cytokine transcription and secretion of cervical cancer cell lines and THP‐1–derived macrophages after poly(I:C) treatment, respectively. These results revealed that IL‐6 was significantly up‐regulated, and this up‐regulation was partly dose dependent. poly(I:C)‐stimulated supernatant of cervical cancer cells promoted M1‐type cytokine IL‐1β and IL‐6 expression of THP‐1–derived macrophages, but inhibited the expression of M2‐type cytokine, IL‐10 and CCL22. The recruitment of THP‐1–derived macrophages by poly(I:C)‐stimulated cervical cancer cell supernatant was also enhanced. Inhibition of IL‐6 expression in cervical cancer cells by siRNA transfection almost completely reversed the effects of poly(I:C) treatment. Finally, we found that phosphorylation of the NF‐κB signalling pathway in cervical cancer cells occurred quickly after poly(I:C) treatment. Moreover, the NF‐κB signalling pathway inhibitor PDTC significantly inhibited poly(I:C)‐induced IL‐6 expression. Taken together, these results suggest that poly(I:C) might regulate the effects of cervical cancer cells on tumour‐infiltrated macrophages, and subsequently promote a pro‐inflammatory tumour microenvironment.

Phase I Dose Escalation Study of Radiotherapy and Durvalumab (MEDI4736) in Relapsed/Refractory Diffuse Large B-Cell Lymphoma (DLBCL): The RaDD Study

Background: Although ~60% of patients with DLBCL are cured with frontline therapy, outcomes for those with relapsed/refractory disease remain poor. Tumour cells exploit immune checkpoint pathways, including the PD1/PDL1 axis, to evade and inhibit host anti-tumour immune responses. PD1/PDL1 expression and cytogenetic 9p24 alterations in some DLBCL subtypes provide additional rationale for PDL1 inhibition (PD-L1i) in DLBCL. Though single agent PD1i yields a disappointing ORR of 10-30% in heavily pre-treated DLBCL, some responses are durable.1 Radiotherapy (RT) is an established mechanism of stimulating anti-tumour immunity via increased circulating tumour antigen, immunogenic cell death and T-cell recruitment and activation in the tumour microenvironment. Synergy between concomitant immune checkpoint inhibition (ICI) and RT has been demonstrated in preclinical studies2 and solid tumours; a recent study in non-small cell lung cancer demonstrated an ORR of 36% with pembrolizumab + RT compared with 18% with pembrolizumab alone.3 RT hypofractionation appears critical to the abscopal effect when used with ICI,4 and concurrent RT and PD-L1i is more successful than sequential treatment.5 RT to multiple sites may broaden the spectrum of tumour antigen released and overcome clonal variation between disease sites; a dose-response relationship between RT and antigen release has yet to be established. This phase I study aims to determine the safety profile of escalating dose and number of sites of RT in combination with Durvalumab (MEDI4736), an anti-PD-L1 monoclonal antibody, in relapsed/refractory DLBCL, including primary refractory DLBCL and transformed follicular lymphoma. Study Design and Methods: RaDD (NCT03610061) includes eligible pts who have received ≥1 prior line of therapy and are ineligible for or relapsed after autologous stem cell transplantation (SCT). Pts with active autoimmune disease, CNS involvement, prior allogeneic SCT or chronic steroid use are excluded. Treatment comprises external beam RT to target site(s) daily for 5 days (Fig 1). Durvalumab 1500mg IV commences on day 2 of RT and continues 4-weekly until disease progression. Pts can continue until a second radiological progression if clinical benefit is ongoing. The primary endpoint is the toxicity, drug pharmacokinetics, maximum tolerated dose (MTD) and recommended phase two dose (RP2D) of simultaneous RT plus durvalumab. Secondary endpoints are response rates; progression free survival; and overall survival. An exploratory PET substudy will employ novel tracers to characterise the local and systemic immune response via assessment of the biodistribution of durvalumab (with 89Zr-Durvalumab) and CD8+ T cells (with 89Zr -Df-IAB22M2C). Biomarker sample collection is synchronised with PET response assessment. A comprehensive translational substudy will apply high throughput technologies to tissue and sequential blood samples to characterise the tumour-immune system interaction and correlate novel host, tumour and tumour microenvironment factors with treatment responses and toxicity. Findings may inform the RP2D. RT dose and site escalation will proceed according to a 3+3 design with 5 dose levels (cohorts 1-5, Fig 2). The dose limiting toxicity assessment window is the first 28 days. Projected enrolment for determination of MTD and RP2D is 6-30 pts pending toxicity. Recruitment will continue to a total of 36 pts to allow for secondary endpoint analysis. 5 pts have been enrolled to date. Acknowledgements: Victorian Cancer Agency (funding), Astra Zeneca (durvalumab and funding), Celgene (funding), Imaginab (89Zr -Df-IAB22M2C)

Hepatocellular carcinoma: Prospects for natural killer cell immunotherapy.

Liver disease is a growing cause of death in the United Kingdom and the incidence of hepatocellular carcinoma (HCC) is rising (http://www.cancerresearchuk.org/). The combination of an immunosuppressive environment within the liver and suboptimal host anti-tumour immune responses may account for the poor survival outcome of HCC. Understanding how tumours evade immune recognition coupled with new insights into the unique immunological environment within the liver will be critical to developing liver-specific immunotherapies.

PD-1-PD-L1 immune-checkpoint blockade in B-cell lymphomas.

Cancer cells can escape T-cell-mediated cellular cytotoxicity by exploiting the inhibitory programmed cell-death protein 1 (PD-1)/programmed cell death 1 ligand 1 (PD-L1) immune checkpoint. Indeed, therapeutic antibodies that block the PD-1-PD-L1 axis induce durable clinical responses against a growing list of solid tumours. B-cell lymphomas also leverage this checkpoint to escape immune recognition, although the outcomes of PD-1-PD-L1 blockade, and the correlations between PD-L1 expression and treatment responses, are less-well elucidated in these diseases than in solid cancers. Nevertheless, in patients with Hodgkin lymphoma, amplification of the gene encoding PD-L1 is commonly associated with increased expression of this protein on Reed-Sternberg cells. Correspondingly, PD-1 blockade with nivolumab has been demonstrated to result in response rates as high as 87% in unselected patients with relapsed and/or refractory Hodgkin lymphoma, leading to the FDA approval of nivolumab for this indication in May 2016. The PD-1/PD-L1 axis is probably also important for immune evasion of B-cell lymphomas with a viral aetiology, including those associated with human immunodeficiency virus (HIV) and Epstein-Barr virus (EBV). This Review is focused on the role of PD-1-PD-L1 blockade in unleashing host antitumour immune responses against various B-cell lymphomas, and summarizes the clinical studies of this approach performed to date.

The genomic landscape of breast cancer and its interaction with host immunity

Molecular profiling of thousands of primary breast cancers has uncovered remarkable genomic diversity between breast cancer subtypes, and even within subtypes. Only a few driver genes are recurrently altered at high frequency highlighting great challenges for precision medicine. Considerable evidence also confirms the role of host immunosurveillance in influencing response to therapy and prognosis in HER2+ and triple negative breast cancer. The role of immunosurveillance in ER + disease remains unclear. Advances in both these fields have lead to intensified interest in the interaction between genomic landscapes and host anti-tumour immune responses in breast cancer. In this review, we discuss the potential genomic determinants of host anti-tumour immunity – mutational load, driver alterations, mutational processes and neoantigens – and their relationship with immunity in breast cancer. Significant differences exist in both the genomic and immune characteristics amongst breast cancer subtypes. While ER + disease appears to be less immunogenic than HER2+ and triple negative breast cancer, it displays the greatest degree of heterogeneity. Mutational and neoantigen load appears to incompletely explains immune responses in breast cancer. Driver alterations do not appear to increase immunogenicity. Instead, they could contribute to immune-evasion or an immunosuppressive microenvironment, and therefore represent potential therapeutic targets. Finally, we also discuss the tailoring of immunotherapeutic strategies by genomic alterations, with possible multimodal combination approaches to maximise clinical benefits.

Immunotherapy and stereotactic ablative radiotherapy (ISABR): a curative approach?

Conventional radiotherapy, in addition to its well-established tumoricidal effects, can also activate the host immune system. Radiation therapy modulates tumour phenotypes, enhances antigen presentation and tumour immunogenicity, increases production of cytokines and alters the tumour microenvironment, enabling destruction of the tumour by the immune system. Investigating the combination of radiotherapy with immunotherapeutic agents, which also promote the host antitumour immune response is, therefore, a logical progression. As the spectrum of clinical use of stereotactic radiotherapy continues to broaden, the question arose as to whether the ablative radiation doses used can also stimulate immune responses and, if so, whether we can amplify these effects by combining immunotherapy and stereotactic ablative radiotherapy (SABR). In this Perspectives article, we explore the preclinical and clinical evidence supporting activation of the immune system following SABR. We then examine studies that provide data on the effectiveness of combining these two techniques - immunotherapy and SABR - in an approach that we have termed 'ISABR'. Lastly, we provide general guiding principles for the development of future clinical trials to investigate the efficacy of ISABR in the hope of generating further interest in these exciting developments.

Clinical relevance of host immunity in breast cancer: from TILs to the clinic.

The clinical relevance of the host immune system in breast cancer has long been unexplored. Studies developed over the past decade have highlighted the biological heterogeneity of breast cancer, prompting researchers to investigate whether the role of the immune system in this malignancy is similar across different molecular subtypes of the disease. The presence of high levels of lymphocytic infiltration has been consistently associated with a more-favourable prognosis in patients with early stage triple-negative and HER2-positive breast cancer. These infiltrates seem to reflect favourable host antitumour immune responses, suggesting that immune activation is important for improving survival outcomes. In this Review, we discuss the composition of the immune infiltrates observed in breast cancers, as well as data supporting the clinical relevance of host antitumour immunity, as represented by lymphocytic infiltration, and how this biomarker could be used in the clinical setting. We also discuss the rationale for enhancing immunity in breast cancer, including early data on the efficacy of T-cell checkpoint inhibition in this setting.

P6 The effect of soluble factors derived from the head and neck tumour microenvironment on the proliferation of isolated immune cell populations

Introduction The constituents of the head and neck tumour microenvironment are becoming increasingly recognised as being influential on the growth, development and spread of the tumour. Although evidence exists for the presence of a host anti-tumour immune response, this often fails to eradicate the malignancy. Tumour epithelium and associated stromal cells both secrete soluble factors which may influence tumour evasion of host immunity, however which immune cells are affected by these factors are still to be clarified. The effect of both the tumour epithelial, and cancer-associated stromal cell secretome on the proliferation of individual immune cell populations was therefore investigated. Material and methods The conditioned medium (CM) from HNSCC cell lines (laryngeal; UMSCC-11b and oropharyngeal; UMSCC-81b, −4 and −47) and primary tumour-derived fibroblasts (2 oropharyngeal and 2 laryngeal) was collected following three days of incubation under both normoxic and hypoxic conditions. The CM was added to T regulatory cells (CD4 + CD25 + CD127lo), T effector cells (CD4 + CD25−) and cytotoxic T cells (CD8+) isolated, using fluorescence activated cell sorting, from healthy donors ( n = 4), for 48 h before using an MTS Cell Titre 96®Aqueous One Solution cell proliferation assay (Promega). Results Two of the four T regulatory cell samples isolated from healthy PBMC demonstrated an increase in proliferation in response to some of the CM applied: one of the samples significantly increased in proliferation after adding all CM regardless of origin, whereas the other sample only significantly increased in proliferation following the addition of oropharyngeal cell line CM and laryngeal fibroblast CM (collected under both hypoxic and normoxic conditions). A significant increase in proliferation of T effector cells was only seen with a few of the CM: with three of four samples reacting positively to at least one CM. No conclusive effect was observed on CD8+ cells following the addition of the CM. Conclusion The secretome of HNSCC epithelial cells and fibroblasts has the ability to alter the growth of individual sets of immune cells, in particular an increase in T regulatory cells was seen which may represent a mechanism for suppression of localised host anti-tumour immunity.

Measles virus causes immunogenic cell death in human melanoma.

Oncolytic viruses (OV) are promising treatments for cancer, with several currently undergoing testing in randomised clinical trials. Measles virus (MV) has not yet been tested in models of human melanoma. This study demonstrates the efficacy of MV against human melanoma. It is increasingly recognised that an essential component of therapy with OV is the recruitment of host anti-tumour immune responses, both innate and adaptive. MV-mediated melanoma cell death is an inflammatory process, causing the release of inflammatory cytokines including type-1 interferons and the potent danger signal HMGB1. Here, using human in vitro models, we demonstrate that MV enhances innate antitumour activity, and that MV-mediated melanoma cell death is capable of stimulating a melanoma-specific adaptive immune response.

Experimental mouse tumour models: what can be learnt about human cancer immunology?

The recent demonstration that cancer immunotherapy extends patient survival has reinvigorated interest in elucidating the role of immunity in tumour pathogenesis. Experimental mouse tumour models have provided key mechanistic insights into host antitumour immune responses, and these have guided the development of novel treatment strategies. To accelerate the translation of these findings into clinical benefits, investigators need to gain a better understanding of the strengths and limitations of mouse model systems as tools for deciphering human antitumour immune responses.

Tumour-mediated TRAIL-Receptor expression indicates effective apoptotic depletion of infiltrating CD8+ immune cells in clinical colorectal cancer

Expression of apoptosis-related proteins on tumour cells has been shown in several experimental models to be an efficient mechanism for a counterattack against host anti-tumour immune responses in solid tumours. Here we provide a clinical evidence for such a tumour immune escape mechanism by demonstrating tumour to T cell-directed death receptor signalling (TRAIL/TRAIL-Receptor (TRAIL-R)) in colorectal cancer (CRC). In a series of patients with CRC and completed 5-year follow up, we investigated apoptosis and expression levels of apoptosis-related proteins. Gene and protein profiles in the tumours demonstrated intratumoural upregulated gene expression for Fas, Fas-L, TRAIL, TRAIL-R and TNF-α (RT-qPCR). Levels of terminaldeoxynucleotidyl transferase-mediated deoxyuridinetriphosphate nick-end labelling (TUNEL)-positive events were positively correlated with TRAIL-R1-expression on tumour infiltrating immune cells. Among the immune cells, preferentially CD8+ T cells were found to express TRAIL-R1 while serial immunostaining in the same patient tumours showed abundant apoptotic (TUNEL-positive) immune cells. In conclusion, our results in tumour samples from CRC patients suggest TRAIL-R1-mediated apoptotic depletion of infiltrating immune cells (CD8+) in response to TRAIL expression by the tumour itself. This supports the notion of an efficient escape from tumour immune response and thus evasion from the attack of activated CD8+ T cells. These findings may enhance our understanding of tumour progression in CRC and might be helpful for the development of TRAIL and its death receptor-based therapy.

Use of tumor-mediated TRAIL-receptor expression to evaluate apoptotic depletion of infiltrating CD8+ immune cells in clinical colorectal cancer.

e21038 Background: Expression of apoptosis-related proteins on tumour cells has been shown in several experimental models to be an efficient mechanism for a counterattack against host antitumour immune responses in solid tumours. Here we provide clinical evidence for such a tumour immune escape mechanism by demonstrating tumour to T cell directed death receptor signalling (TRAIL/TRAIL-R) in colorectal cancer (CRC). Methods: In a series of patients with CRC and completed 5-year follow up we investigated apoptosis and expression levels of apoptosis-related proteins. Results: Elevated soluble TNF-receptor 1 and 2 levels were found in sera during tumour progression as one of the tumour immune escape mechanisms in the patients. Gene and protein profiles in the tumours demonstrated intratumoral upregulated gene expression for Fas, FasL, TRAIL, TRAIL-R, and TNF-a (RT-qPCR). Levels of TUNEL-positive events were positively correlated with TRAIL-R1-expression on tumour infiltrating immune cells. Among the immune cells, preferentially CD8+ T cells were found to express TRAIL-R1 while serial immunostaining in the same patient tumours showed abundant apoptotic (TUNEL-positive) immune cells. Conclusions: Our results in tumour samples from CRC patients suggest TRAIL-R1-mediated apoptotic depletion of infiltrating immune cells (CD8+) in response to TRAIL expression by the tumour itself. This supports the notion of an efficient escape from tumour immune response and thus evasion from the attack of activated CD8+ T cells. These findings may enhance our understanding of tumour progression in CRC and might be helpful for the development of TRAIL and its death receptor-based therapy. No significant financial relationships to disclose.

Stat3: linking inflammation to epithelial cancer - more than a "gut" feeling?

Inflammation is an important environmental factor that promotes tumourigenesis and the progression of established cancerous lesions, and recent studies have started to dissect the mechanisms linking the two pathologies. These inflammatory and infectious conditions trigger immune and stromal cell release of soluble mediators which facilitate survival and proliferation of tumour cells in a paracrine manner. In addition, (epi-)genetic mutations affecting oncogenes, tumour-suppressor genes, chromosomal rearrangements and amplifications trigger the release of inflammatory mediators within the tumour microenvironment to promote neoplastic growth in an autocrine manner. These two pathways converge in tumour cells and result in activation of the latent signal transducer and activator of transcription 3 (Stat3) which mediates a transcriptional response favouring survival, proliferation and angiogenesis. The abundance of cytokines that activate Stat3 within the tumour microenvironment, which comprises of members of the interleukin (IL) IL6, IL10 and IL17/23 families, underpins a signaling network that simultaneously promotes the growth of neoplastic epithelium, fuels inflammation and suppresses the host's anti-tumour immune response. Accordingly, aberrant and persistent Stat3 activation is a frequent observation in human cancers of epithelial origin and is often associated with poor outcome.Here we summarize insights gained from mice harbouring mutations in components of the Stat3 signaling cascade and in particular of gp130, the shared receptor for the IL6 family of cytokines. We focus on the various feed-back and feed-forward loops in which Stat3 provides the signaling node in cells of the tumour and its microenvironment thereby functionally linking excessive inflammation to neoplastic growth. Although these observations are particularly pertinent to gastrointestinal tumours, we suggest that the tumour's addiction to persistent Stat3 activation is likely to also impact on other epithelial cell-derived cancers. These insights provide clues to the judicious interference of the gp130/Stat3 signaling cascade in therapeutically targeting cancer.