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Background The prostate cancer microenvironment is highly immunosuppressive; immune cells stimulated in the periphery by systemic immunotherapies will be rendered inactive once entering this environment. Immunotherapies for prostate cancer need to break this immune tolerance. We have previously identified interleukin-15 (IL-15) as the only cytokine tested that activates and expands immune cells in the presence of prostate cancer cells. In the current study, we aimed to identify a method of boosting the efficacy of IL-15 in prostate cancer. Methods We engineered, by conjugation to a myristoylated peptide, a membrane-localising form of IL-15 (cyto-IL-15) and the checkpoint inhibitor antibodies cytotoxic T lymphocyte antigen 4 (CTLA-4) and programmed death ligand 1 (PD-L1) (cyto-abs) to enable them to bind to cell surfaces by non-specific anchoring to the phospholipid bilayer. The efficacy of these agents was investigated by intratumoral administration either alone (cyto-IL-15 or cyto-abs) or in combination (cyto-combo) in subcutaneous TRAMP-C2 prostate tumors in C57BL/6J mice and compared with their non-modified equivalents in vivo. Following the survival endpoint, histological analyses and RNA sequencing were performed on the tumors. Results Intratumoral injection of cyto-IL-15 or cyto-combo delayed tumor growth by 50% and increased median survival to 28 and 25 days, respectively, compared with vehicle (17 days), whereas non-modified IL-15 or antibodies alone had no significant effects on tumor growth or survival. Histological analysis showed that cyto-IL-15 and cyto-combo increased necrosis and infiltration of natural killer (NK) cells and CD8 T cells in the tumors compared with vehicle and non-modified agents. Overall, the efficacy of cyto-combo was not superior to that of cyto-IL-15 alone. Conclusion We have demonstrated that intratumoral injection of cyto-IL-15 leads to prostate cancer growth delay, induces tumor necrosis and increases survival. Hence, cytotopic modification in combination with intratumoral injection appears to be a promising novel approach for prostate cancer immunotherapy.

Prostate cancer is the second most commonly diagnosed cancer in men with mortality rates, overtaking those for breast cancer in the last 2 years in the UK. Despite advances in prostate cancer treatments, over 25% of men do not survive over 5 years with advanced disease. Due to the success of immunotherapies in treating other cancers, this treatment modality has been investigated for Prostate cancer, however, the sole FDA approved immunotherapy so far (Provenge™) only extends life by a few months. Therefore, finding immunotherapeutic agents to treat prostate cancer is of major interest. Our group has previously shown that Interleukin-15 (IL-15), unlike other therapeutic cytokines such as IL-2 and IL-12, can stimulate expansion and activity of CD8 T cells and NK cells in vitro when they are exposed to prostate cancer cells, while studies in mice have shown a 50% reduction in tumor size with no apparent toxicity. In this study, we aim to examine potencies of IL-15 in combination with a cyclic dinucleotide (CDN) that activates the Stimulator of Interferon-Gene (STING) receptor. Selected CDNs (also known as STING agonists) have previously been shown to activate both T cells and dendritic cells through STING. We hypothesize that the combination of STING agonists and IL-15 can additively increase NK and T cell activity as they act to increase type I interferons (IFNs) through STING activation and IFN-γ through IL-15. In prostate cancer-lymphocyte co-cultures we now show that combination of IL-15 and the STING agonist ADU-S100 analog induces a marked killing of cancer cells above that seen with IL-15 or ADU-S100 alone. We show that this is related to a potent activation of NK cells resulting in increased perforin and CD69 expression, and up to a 13-fold increase in IFNγ secretion in the co-cultures. NK cells are responsible for killing of the cancer cells, as shown by a lack of cytotoxicity in NK depleted lymphocyte-tumor cell co-cultures, or in co-cultures of B and T cells with tumor cells. In summary, we propose that the combination of IL-15 and the sting agonist ADU-S100 analog may be potently effective in treatment of prostate cancer.

Interleukin-15 (IL-15) is a cytokine that has been shown to expand CD8 T cell and natural killer (NK) cell populations, and therefore has potential for potentiating adoptive immune cell therapy for cancer. Previously, IL-15 has been shown to induce proliferation of CD8 memory T cells through activation of telomerase. Here, we investigated whether telomerase is also activated during the IL-15 mediated proliferation of NK and NKT-like (CD56+CD3+) cells. We also examined the extent that each of the three signaling pathways known to be stimulated by IL-2/IL-15 (JAK-STAT, PI3K-AKT Ras-RAF/MAPK) were activated and involved in the telomerase expression in the three cell types NK, NKT, or CD8 T cells. To assess cell proliferation and doubling, peripheral blood mononuclear cells (PBMCs) or isolated NK, NKT-like or CD8 T cells were incubated with varying concentrations of IL-15 or IL-2 for 7 days. CD8 T, NK, and NKT cell expansion was determined by fluorophore-conjugated antibody staining and flow cytometry. Cell doubling was investigated using carboxyfluorescein-succinimidyl-ester (CFSE). Telomerase expression was investigated by staining cells with anti-telomerase reverse transcriptase (anti-TERT). Telomerase activity in CD56+ and CD8 T cells was also measured via Telomerase Repeat Amplification Protocol (TRAP). Analysis of cellular expansion, proliferation and TERT expression concluded that IL-15 increased cellular growth of NK, NKT, and CD8 T cells more effectively than IL-2 using low or high doses. IL-15, increased TERT expression in NK and NKT cells by up to 2.5 fold, the same increase seen in CD8 T cells. IL-2 had effects on TERT expression only at high doses (100–1000 ng/ml). Proteome profiling identified that IL-15 activated selected signaling proteins in the three pathways (JAK-STAT, PI3K-AKT, Ras-MAPK) known to mediate IL-2/IL-15 signaling, more strongly than IL-2. Evaluation by signaling pathway inhibitors revealed that JAK/STAT and PI3K/AKT pathways are important in IL-15’s ability to upregulate TERT expression in NK and NKT cells, whereas all three pathways were involved in CD8 T cell TERT expression. In conclusion, this study shows that IL-15 potently stimulates TERT upregulation in NK and NKT cells in addition to CD8 T cells and is therefore a valuable tool for adoptive cell therapies.

Objectives To identify cytokines that can activate and expand NK cells in the presence of prostate cancer cells in order to determine whether these agents may be useful in future intra-tumoural administration in pre-clinical and clinical prostate cancer trials. Materials and methods Lymphocytes isolated from normal donor blood were set up in co-cultures with either cancer or non-cancerous prostate cell lines, together with each of the cytokines interleukin (IL)-2, IL-12, IL-15, interferon (IFN)-γ or IL-21 for a period of 7 days. Then, expansion of NK cells, NKT cells and CD8 T cells was measured by flow cytometry and compared with the expansion of the same cells in the absence of prostate cells. The cytotoxic activity of NK cells, as measured by perforin and tumour cell killing, was also assessed. NK cell receptors and their corresponding ligands on prostate tumour cells were analysed to determine whether any of these were modulated by co-culture. The role of the tumour-secreted heat shock proteins HSP90 and HSP70 in the expansion of NK cells in the co-cultures was also investigated because of their effects on NK and CD8 T-cell activation. Results We showed that, among a panel of cytokines known to cause NK cell activation and expansion, only IL-15 could actively induce expansion of NK, NKT and CD8 T cells in the presence of prostate cancer cell lines. Furthermore, the expansion of NK cells was far greater (up to 50% greater) in the presence of the cancer cells (LNCaP, PC3) than when lymphocytes were incubated alone. In contrast, non-cancerous cell lines (PNT2 and WPMY-1) did not exert any expansion of NK cells. The cytolytic activity of the NK cells, as measured by perforin, CD107a and killing of tumour cells, was also greatest in co-cultures with IL-15. Examination of NK cell receptors shows that NKG2D is upregulated to a greater degree in the presence of prostate cancer cells, compared with the upregulation with IL-15 in lymphocytes alone. However, blocking of NKG2D does not inhibit the enhanced expansion of NK cells in the presence of tumour cells. Conclusions Among a panel of NK cell-activating cytokines, IL-15 was the only cytokine that could stimulate expansion of NK cells in the presence of prostate cancer cells; therefore IL-15 may be a good candidate for novel future intra-tumoural therapy of the disease.

Background:WFDC1/Prostate stromal 20 (ps20) is a small secreted protein highly expressed within the prostate stroma. WFDC1/ps20 expression is frequently downregulated or lost in prostate cancer (PCa) and ps20 has demonstrated growth-suppressive functions in numerous tumour model systems, although the mechanisms of this phenomenon are not understood.Methods:Ps20 was cloned and overexpressed in DU145, PC3, LNCaP and WPMY-1 cells. Cellular growth, cell cycle and apoptosis were characterised. WPMY-1 stromal cells expressing ps20 were characterised by transcriptome microarray and the function of WPMY-1 conditioned media on growth of PCa cell lines was assessed.Results:Prostrate stromal 20 expression enhanced the proliferation of LNCaP cells, whereas stromal WPMY-1 cells were inhibited and underwent increased apoptosis. Prostrate stromal 20-expressing WPMY-1 cells secrete a potently proapoptotic conditioned media. Prostrate stromal 20 overexpression upregulates expression of cyclooxygenase-2 (COX-2) in LNCaP and WPMY-1 cells, and induces expression of a growth-suppressive phenotype, which inhibits proliferation of PCa cells by ps20-expressing WPMY-1 conditioned media. This growth suppression was subsequently shown to be dependent on COX-2 function.Conclusions:This work posits that expression of ps20 in the prostate stroma can regulate growth of epithelial and other tissues through the prostaglandin synthase pathway, and thereby restricts development and progression of neoplasms. This provides a rational for selective pressure against ps20 expression in tumour- associated stroma.

The immunosuppressive prostate cancer microenvironment renders most infiltrating effector immune cells anergic or regulatory. Immunotherapeutic agents localized to the prostate can break this immune tolerance, leading to greater efficacy and less toxicity than systemically administered drugs. We have previously shown that cytotopic modification of interleukin-15 (cyto-IL-15) can activate NK and CD8+ T-cells in the presence of prostate cancer cells. In the present study, we used this cyto-IL-15 and two immuno-checkpoint blocking antibodies modified in a similar approach (these antibodies have previously exhibited antitumor response in clinical trials) to investigate their efficacy when used alone or in combination in a syngeneic murine model of prostate cancer. IL-15 and antibodies were modified by conjugation to a myristoylated peptide that enables them to adhere to cell membranes (patents pending), and thus localize to any potential site of injection. The cytotopically modified IL-15 and antibodies were injected intratumorally either alone (cyto-IL-15 or cyto-abs) or in combination (cyto-combo) in subcutaneous TRAMP C2 prostate tumors in C57BL/6 mice and compared with their nonmodified equivalents and with a vehicle-treated control group. Histopathologic analysis and immunohistochemistry were performed on sections from excised frozen tumors in order to quantify necrosis (haematoxylin and eosin staining) and immune cell infiltration. Intratumoral injection of cyto-IL15, combo or cyto-combo significantly delayed tumor growth at day 14 post-treatment by 50%. However, only cyto-IL15 and cyto-combo significantly increased median survival after treatment to 28 (p < 0.05) and 24 days (p < 0.05) respectively, compared with 17 days in the vehicle group. Nonmodified IL15 or antibodies alone had no effect on tumor growth or survival. Mice showed no adverse effects or weight loss with either of the treatments. Moreover, histologic analysis showed that cyto-IL-15 increased necrosis and infiltration of NK cells and CD8+ T cells in the tumors compared with the vehicle- and nonmodified-IL-15-treated groups. We have demonstrated that cytotopically modified immunotherapeutic agents can lead to tumor growth delay in an in vivo murine model of prostate cancer, induce tumor cell death and increase mouse survival. Hence, cytotopic modification in combination with direct injection of the agents directly into the tumor site appears to be a promising novel approach for prostate cancer immunotherapy. Citation Format: Efthymia Papaevangelou, Dorota Smolarek, Oussama Elhage, Richard A. Smith, Prokar Dasgupta, Christine Galustian. Targeting prostate cancer using novel cytotopically modified immunotherapies intratumorally in a syngeneic murine model [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A11.

The KHP PCaBB was established in 2013 and recruits donors from the Urology or Oncology Departments at Guy’s Hospital in London (UK). Prostate cancer patients may be approached to give their consent for biobanking at any point in their treatment pathway, which allows residual material from their earlier diagnosis to be transferred and used by the Biobank. Currently, patients are specifically asked to donate samples of blood and surplus prostate tissue as well as permitting access to their clinical and pathological data that continues to be added throughout the course of their disease. Between 2013 and 2015, 549 prostate cancer patients gave their consent to the biobank and, the tissue repository collected 489 blood samples, 120 frozen prostate tissue samples and 1064 formalin fixed paraffin embedded diagnostic blocks. Prostate cancer has become a chronic disease in a large proportion of men, with many men receiving multiple subsequent treatments, and their treatment trajectory often spanning over decades. Therefore, this resource aims to provide an ideal research platform to explore potential variations in treatment response as well as disease markers in the different risk categories for prostate cancer. A recent audit of the KHP PCaBB revealed that between 2013 and 2015, 1796 patients were diagnosed with prostate cancer at King’s Health Partners (KHP), out of which 549 (30.6%) gave their consent to KHP PCaBB. Comparisons between demographic and clinical characteristics of patients who had consented compared to the total patient population revealed that the KHP PCaBB is demographically representative of the total prostate cancer patient population seen in Guy’s and St Thomas’ NHS Foundation Trust (GSTT). We observed no differences in distribution of ethnicity (p = 0.507) and socioeconomic status (p = 0.097). Some differences were observed in clinical characteristics, specifically with treatment type – which differed significantly between the patients who had given consent and total patient population. The KHP PCaBB has thereby amassed a rich data and tissue repository that is largely reflective of both the demographic and clinical diversity within the total prostate cancer patient population seen at KHP, making it an ideal platform for prostate cancer research.

Introduction & Objectives: Prostate cancer (PC) is the second most commonly diagnosed cancer in men and the eighth leading cause of cancer-related mortality in the world. The only successful immunotherapy for the disease (ProvengeTM) only extends life by a few months. Therefore the finding of immunotherapeutic agents for the treatment of PC is of major interest. It has been previously shown by our group that Interleukin-15 (IL-15), unlike other therapeutic cytokines such as IL-2 and IL-12, can stimulate expansion and activity of CD8 and NK cells in vitro when they are exposed to prostate cancer cells, while studies in mice have shown a reduction in tumor size by 50% with no apparent toxicity. In this study, we aim to examine potencies of IL-15 in combination with a cyclic dinucleotide (CDN) that activates the Stimulator of Interferon-Gene (STING) receptor. CDNs have previously been shown to activate both T cells and Dendritic cells through STING. We hypothesize that combination of CDNs and IL-15 can additively increase NK and T cell activity as they act to increase type 1 interferons through STING activation and IFN gamma through IL-15. Material & Methods: Peripheral blood mononuclear cells (PBMCs) were isolated and co-cultured with cancer cells (LNCaP, ATCC® CRL-1740™) in the presence of either IL-15, the CDN 2’3’-c-di-AM(PS)2, or a mixture of IL-15 with CDN. Control experiments were also prepared in which IL-15 was replaced by PBS and the CDN by a linear dinucleotide. Co-cultures were incubated for 48 hours at 37°C and 5% CO2. After this period, all cells from each well were collected and stained with fluorophore conjugated anti-CD3, -CD8 and -CD56 to identify CD8 T cells and NK cells, and anti-NKG2D and -perforin to analyze activation of NK and T lymphocytes. Tumor cell death was also evaluated and quantified using Live/Dead staining. All samples were acquired on FACS Canto. Results We observed that 1µg/ml of 2’3’-c-di-AM(PS)2 in combination with 2.5 ng/ml of IL-15 caused 81% of LNCaP killing in prostate cancer-lymphocyte co-cultures, while IL-15 by itself led to approximately 45% of cancer cell death. Little or no cancer cell killing was seen without IL-15 or CDN. Interestingly, the mixture of IL-15 with the CDN did not expand NK cells more than IL-15 alone. This suggests that the activity of NK cells is increased despite lack of their expansion. Preliminary data suggests that the level of perforin is increased by up to 35% in NK cells cultured with the mixture of both therapeutic drugs when compared to IL-15 alone in the cocultures. Of note, cell culture of either LNCaP or PMBCs with 1µg/ml of CDN did not affect cell growth. Conclusion: The combination of two immunotherapeutic drugs, IL-15 and 2’3’-c-di-AM(PS)2, lead to an increase in the activity of NK cells, with an apparent increase in the levels of perforin and doubling of cell death mediated by immune effector cells compared with IL-15 alone. Citation Format: Ana M. Esteves, Efthymia Papaevangelou, Prokar Dasgupta, Richard A.G. Smith, Christine Galustian. Combination of Interleukin-15 with a STING (Stimulator of Interferon Gene) agonist: A potential immunotherapy for prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4070.

In the last few years there have been concerted attempts at using the power of the immune system as an effective treatment option for cancer. This has become possible since our understanding of the workings of the immune system improved. Tumours form because of failure of the organism to destroy a rogue, mutated cell in an appropriate way.This article is protected by copyright. All rights reserved.

BACKGROUND In this study, we investigated the effects of combining lenalidomide and docetaxel on in vitro and in vivo models of prostate cancer as a potential strategy for treatment of castrate resistant prostate cancer (CRPC). METHODS The effects of combining lenalidomide and docetaxel on proliferation, apoptosis, invasive potential, anchorage independent growth, and p53 activation in the PC3 and DU145 prostate cell lines were investigated. The effects of the lenalidomide and docetaxel combination on LNCaP prostate cancer cell growth and invasiveness in vitro was also studied. The combination of these two agents was finally tested on a xenograft model of PC3 tumor growth in nude mice. RESULTS Lenalidomide decreased the IC50 of docetaxel by up to 50% (P

Prostate adenocarcinoma is present in over 80% of men over the age of 80 and is by far the most common cancer of men. Although radical prostatectomy is curative in early disease, the risks of incontinence and impotence can affect the quality of life of patients. Early intervention with localized immunotherapy represents a potential solution as lymphocyte infiltration does occur in prostate cancer lesions, and immunotherapy with dendritic cell vaccines can significantly increase survival in late stage disease. However, lymphocytic infiltrates in the cancerous prostates have an anergic character arising from the suppressive effects of the microenvironment resulting from a conversion of effector cells into regulatory T-cells. Although TGFβ (transforming growth factor β) and IL-10 (interleukin-10) are known to be strong suppressor molecules associated with prostate cancer, they are among many possible suppressive factors. We discuss the possible role of alternative suppressor molecules, including the WAP (whey acidic protein) homologue ps20 that is expressed on prostate stroma and other WAP domain-containing proteins in the immunosuppressive prostate cancer milieu and discuss novel immunotherapeutic strategies to combat this disease.

Lenalidomide (REVLIMID®) CC-5013 (Celgene, NJ, USA) is approved, in both the USA and Europe, in combination with dexamethasone for the treatment of multiple myeloma patients who have received at least one prior therapy, and is rapidly being accepted worldwide for this condition. Lenalidomide is also approved in the USA and Canada for use in transfusion-dependent anemia in patients with low- and intermediate-1-risk myelodysplastic syndromes associated with del (5q) abnormality with or without additional abnormalities. Lenalidomide is an IMiD® immunomodulatory compound, incorporating structural modification of the drug thalidomide, which is active against a wide variety of autoimmune Th-2-dependent disorders, including erythema nodosum of leprosy, leishmaniasis, as well as severe ulcerative disorders such as Behcet’s syndrome. Unfortunately, long-term use of thalidomide is limited, particularly by neurotoxicity. To date, results suggest that lenalidomide is more active than thalidomide and does not cause the neurotoxicity seen with thalidomide. Lenalidomide has multiple properties, including anti-inflammatory, antiangiogenic and costimulatory effects, as well as being able to inhibit T-regulatory cells, all of which are properties deemed desirable for anticancer activity. This article covers the evidence that lenalidomide may have a major role in the treatment and control of many cancer types other than del (5q) myelodysplastic syndrome and multiple myeloma.

Recent years have seen improvements in strategies to treat pancreatic cancer. Pancreatic cancer is a leading cause of cancer-related death in the world, and is characterised by rapid disease progression, highly invasive tumour phenotype and resistance to chemotherapy. Patient prognosis is extremely grim, with a one-year survival rate of just 10% and only a 5% chance of surviving beyond five years. There has been little change in the treatment regimen, with 5-FU-based therapies being the usual route. Gemcitabine has also offered some relief over the past two decades, with modest improvements in median survival. This lack of choice has increased the call for new treatments, and indeed, novel drugs are now being investigated for their use in pancreatic cancer. These include those agents classically applied to other indications such as doxycycline and doxorubicin, as well as dietary components such as curcumin and genistein. Each of these drugs possesses different levels of activity both as single agents and in combinatorial approaches with gemcitabine. This review will discuss the difficulties in treating pancreatic cancer, and will summarise the progress and latest development in drugs used within this field of cancer.

T-regulatory cells suppress anti-tumour immunity in cancer patients and in murine tumour models. Furthermore, their activity is likely to have an effect on the effectiveness of immunotherapeutic treatments for cancer. Here we describe the current status of developing clinical strategies for modulating Treg activity in cancer patients.

OBJECTIVE: Colorectal cancer is immunogenic. However, it is also associated with suppression of host immunity. Identifying the mechanisms involved in immune suppression is necessary to develop future immunotherapeutic strategies. The aim of this study was to assess immune cell function in colorectal cancer patients. METHOD: A total of 80 colorectal cancer patients (41 male) prior to treatment and 38 matched controls (21 male) were recruited. Venous blood samples were taken. White blood cell composition was determined using monoclonal antibodies. Levels of cytokines IFN-gamma, TNF-alpha, IL-2, IL-10, IL-4 and IL-6 were measured from the supernatants of activated peripheral blood mononuclear cells (PBMC) following thawing and re-suspension. Peripheral blood mononuclear proliferation was measured using 3H-Thymidine. RESULTS: Stage I-III cancer patients had elevated percentages of CD8 T cell (P = 0.004) whilst stage IV patients had low total lymphocyte percentages (P = 0.016). Monocyte and NKT cell percentage decreased with advanced tumour stages (P = 0.013 and P = 0.038). Patients had lower PBMC proliferation and production of the TH1 cytokines (IFN-gamma and TNF-alpha) (P < 0.001) than that of the controls. IL-6 and IL-4 production were not significantly different. IFN-gamma and TNF-alpha concentrations reduced with tumour vascular invasion (P = 0.011 and P = 0.019). CONCLUSION: Colorectal cancer induces an immunological response, shifting the cytokine balance. The most profound changes are seen once disease has spread systemically.

Over the past 5 years, lenalidomide (Revlimid, Celgene Co., Summit, NJ, USA), a member of a class of drugs termed immunomodulatory drugs, has emerged as a significant weapon in the arsenal of cancer-therapeutics. It is a lead therapeutic in multiple myeloma and del-5q myelodysplastic syndromes and has also been trialed for acute leukaemia and chronic lymphocytic leukaemia, relapsed or refractory Hodgkin's lymphoma, T-cell non-Hodgkin's lymphoma, prostate cancer, non-small cell lung cancer, malignant melanoma, renal cancer, advanced ovarian and peritoneal carcinoma. The most significant development for lenalidomide has been its FDA approval (US and Europe) for previously treated multiple myeloma in combination with dexamethasone. The following review describes key clinical and mechanistic breakthroughs that have made lenalidomide a leading cancer therapeutic.

Lenalidomide (Revlimid; CC-5013) and pomalidomide (CC-4047) are IMiDs proprietary drugs having immunomodulatory properties that have both shown activity in cancer clinical trials; lenalidomide is approved in the United States for a subset of MDS patients and for treatment of patients with multiple myeloma when used in combination with dexamethasone. These drugs exhibit a range of interesting clinical properties, including anti-angiogenic, anti-proliferative, and pro-erythropoietic activities although exact cellular target(s) remain unclear. Also, anti-inflammatory effects on LPS-stimulated monocytes (TNF-alpha is decreased) and costimulatory effects on anti-CD3 stimulated T cells, (enhanced T cell proliferation and proinflammatory cytokine production) are observed. These drugs also cause augmentation of NK-cell cytotoxic activity against tumour-cell targets. Having shown that pomalidomide confers T cell-dependent adjuvant-like protection in a preclinical whole tumour-cell vaccine-model, we now show that lenalidomide and pomalidomide strongly inhibit T-regulatory cell proliferation and suppressor-function. Both drugs inhibit IL-2-mediated generation of FOXP3 positive CTLA-4 positive CD25high CD4+ T regulatory cells from PBMCs by upto 50%. Furthermore, suppressor function of pre-treated T regulatory cells against autologous responder-cells is abolished or markedly inhibited without drug related cytotoxicity. Also, Balb/C mice exhibit 25% reduction of lymph-node T regulatory cells after pomalidomide treatment. Inhibition of T regulatory cell function was not due to changes in TGF-beta or IL-10 production but was associated with decreased T regulatory cell FOXP3 expression. In conclusion, our data provide one explanation for adjuvant properties of lenalidomide and pomalidomide and suggest that they may help overcome an important barrier to tumour-specific immunity in cancer patients.

Hairy and enhancer of split homolog-1 (HES1) is a part of an extensive family of basic helix-loop-helix (bHLH) proteins and plays a crucial role in the control and regulation of cell cycle, proliferation, cell differentiation, survival and apoptosis in neuronal, endocrine, T-lymphocyte progenitors as well as various cancers. HES1 is a transcription factor which is regulated by the NOTCH, Hedgehog and Wnt signalling pathways. Aberrant expression of these pathways is a common feature of cancerous cells. There appears to be a fine and complicated crosstalk at the molecular level between the various signalling pathways and HES1, which contributes to its effects on the immune response and cancers such as leukaemia. Several mechanisms have been proposed, including an enhanced invasiveness and metastasis by inducing epithelial mesenchymal transition (EMT), in addition to its strict requirement for tumour cell survival. In this review, we summarize the current biology and molecular mechanisms as well as its use as a clinical target in cancer therapeutics.

Cells used in adoptive cell-transfer immunotherapies against cancer include dendritic cells (DCs), natural-killer cells, and CD8+ T-cells. These cells may have limited efficacy due to their lifespan, activity, and immunosuppressive effects of tumor cells. Therefore, increasing longevity and activity of these cells may boost their efficacy. Four cytokines that can extend immune effector-cell longevity are IL-2, IL-7, IL-21, and IL-15. This review will discuss current knowledge on effector-cell lifespans and the mechanisms by which IL-2, IL-7, IL-15, and IL-21 can extend effector-cell longevity. We will also discuss how lifespan and efficacy of these cells can be regulated to allow optimal clinical benefits.

The number of receptors of the 'C-type' lectin family is greater than previously thought with a considerable proportion on cells (dendritic cells and macrophages) critical for innate immunity. Establishing that they bind carbohydrates, unravelling and comparing details of their ligands is crucial for understanding the molecular basis of the cell-cell and cell-pathogen interactions that they mediate. Here we use carbohydrate arrays as a new approach to discovering the ligands of three recently described C-type lectin-type receptors on antigen-presenting cells: murine SIGN-R1, SIGN-R3 and langerin. The arrays encompass an extensive panel including polysaccharides, glycoproteins, oligosaccharides and monosaccharides. These are probed with soluble forms of the receptors (IgG-Fc chimeras). The dominant specificities found for SIGN-R1 and SIGN-R3 are mannose- and fucose-related, as expressed on high mannose type N-glycans and Lewis(a/b)/Lewis(x/y)-type sequences, respectively, with subtle differences between the receptors. The dominant specificity for langerin is unique so far: a Lewisx-related sequence with sulfate at position 6 of the terminal galactose. The polysaccharide dextran, known from classical studies to elicit a T-independent response, and whose cellular uptake has been shown recently to be mediated by membrane-associated SIGN-R1, gave no binding signals with the soluble form of the protein. We highlight here the additional need for cell-based assays for detecting biologically relevant low affinity ligands, for we show with SIGN-R1-transfected cells that dextran is such a low affinity ligand for SIGN-R1 that binding is detectable only with the cell membrane-associated receptor. But there is a close relationship between dextran recognition and mannose/fucose recognition, with dextran- and mannose-conjugates co-localizing in intracellular compartments.

A novel analogue of sialyl Lewis X ganglioside, N -deacetylsialyl Lewis X ganglioside, was synthesized. Methyl 4,7,8,9-tetra- O -acetyl-3,5-dideoxy-5-trifluoroacetamido- d - glycero -α- d - galacto -2-nonulopyranosylonate-(2→3)-2,4,6-tri- O -benzoyl- d -galactopyranosyl trichloroacetimidate was coupled with 2-(trimethylsilyl)ethyl [2-acetamido-6- O -benzyl-2-deoxy-3- O -(4-methoxybenzyl)-β- d -glucopyranosyl]-(1→3)-[2,4,6-tri- O -benzyl-β- d -galactopyranosyl]-(1→4)-2,3,6-tri- O -benzyl-β- d -galactopyranoside to give the desired pentasaccharide in high yield. The glycosylation of the pentasaccharide acceptor, which was derived from its precursor by removal of the 3-methoxybenzyl group, with the phenyl 1-thioglycoside derivative of l -fucose using N -iodosuccinimide–trifluoromethanesulfonic acid as promoter, produced the hexasaccharide. Proper manipulation of the protecting groups of the hexasaccharide afforded the corresponding glycosyl imidate, which was coupled with (2 S ,3 R ,4 E )-2-azido-3- O -benzoyl-4-octadecene-1,3-diol. Selective reduction of the azido group, N -acylation with octadecanoic acid, and the complete removal of the protecting groups gave the desired N -deacetylsialyl Lewis X ganglioside. L-Selectin bound more strongly to N -deacetylsialyl Lewis X ganglioside than to the sialyl Lewis X ganglioside, whereas E- and P-selectins bound equally well to the two gangliosides.

We describe microarrays of oligosaccharides as neoglycolipids and their robust display on nitrocellulose. The arrays are obtained from glycoproteins, glycolipids, proteoglycans, polysaccharides, whole organs, or from chemically synthesized oligosaccharides. We show that carbohydrate-recognizing proteins single out their ligands not only in arrays of homogeneous oligosaccharides but also in arrays of heterogeneous oligosaccharides. Initial applications have revealed new findings, including: (i) among O-glycans in brain, a relative abundance of the Lewis(x) sequence based on N-acetyllactosamine recognized by anti-L5, and a paucity of the Lewis(x) sequence based on poly-N-acetyllactosamine recognized by anti-SSEA-1; (ii) insights into chondroitin sulfate oligosaccharides recognized by an antiserum and an antibody (CS-56) to chondroitin sulfates; and (iii) binding of the cytokine interferon-gamma (IFN-gamma) and the chemokine RANTES to sulfated sequences such as HNK-1, sulfo-Lewis(x), and sulfo-Lewis(a), in addition to glycosaminoglycans. The approach opens the way for discovering new carbohydrate-recognizing proteins in the proteome and for mapping the repertoire of carbohydrate recognition structures in the glycome.

The E-, L- and P-selectins are carbohydrate-recognizing cell-adhesion molecules mediating selective leucocyte recruitment in inflammation. The 3'-sialyl- and 3'-sulpho-oligosaccharides of Lewis(x) (Le(x)) and Lewis(a) (Le(a)) series are bound by them, but for high-avidity binding of P- and L-selectins to the glycoprotein counter-receptor known as P-selectin glycoprotein ligand, PSGL-1, there is a requirement for sulpho-tyrosines neighbouring a sialyl-Le(x) glycan. The two selectins can also bind 3-O- or 6-O-sulphated galacto-lipids (sulphatides). Here we compare some features of the interactions of P- and L-selectins with a novel lipid-linked sulpho-tyrosine probe, and with the sulphatides and neoglycolipids of sialyl- and sulpho-Le(x)/Le(a) fuco-oligosaccharides. The sulpho-tyrosine probe is bound by both selectins. There are close similarities in the interactions of the two selectins with sulpho-tyrosine and the sulphatides; the binding is relatively resistant to chelation of calcium ions, in contrast to the absolute requirement of calcium ions with the long fuco-oligosaccharides, including 6-sulpho-sialyl-Le(x). With both selectins, there is striking synergy in binding signals elicited by the two ligand types when presented as equimolar mixtures on a matrix. Thus, there are two operationally distinct binding sites on both L- and P-selectin; and the binding sites for sulphate groups in the two ligand types are probably distinct. When sulpho-tyrosine and sialyl-Le(x) are presented on liposomes, a potent inhibitory activity is generated toward the binding of P-selectin to HL60 cells, with 50% inhibitory concentration (IC(50)) values in the nanomolar range. These features of the lipid-linked ligand analogues, and the simple approach for their display on liposomes, may have applications in designs and screening of selectin inhibitors as anti-inflammatory compounds.

Multiple organ dysfunction syndrome (MODS) is a term used to describe the sequential failure of single organ systems leading ultimately to a general failure of multiple organs. 1 MODS is responsible for 50% to 80% of all deaths in the surgical intensive care unit and has remained so for the past 20 years. 2–4 It develops secondary to severe systemic inflammation (sepsis), in which the activated neutrophil plays a central role. 4–6 The neutrophil is therefore subject to intensive investigation as a target for modulation in the reduction of MODS. 7–9 Various strategies have been used to reduce neutrophil activation in both experimental and clinical MODS. Because neutrophil activation usually involves ligation of surface receptors, 10 most strategies have tried to target various receptors or ligands. Such strategies have met with limited success clinically, 11–14 which probably reflects the complex nature of neutrophil activation in clinical MODS, where the neutrophil is stimulated by a variety of simultaneous extracellular signals, including various cytokines and endotoxin. A common event occurring as a result of many ligand–receptor interactions is the activation of the transcription factor NFκB (Fig. 1). NFκB is a dimer of two DNA binding subunits (RelA and p50). Inactive NFκB exists in the cytoplasm bound to IκB, which prevents NFκB from translocating to the nucleus and binding DNA. NFκB activation is the process by which NFκB is dissociated from ΙκB and translocated to the nucleus, where it binds DNA and ultimately initiates transcription. This very complex process occurs rapidly (within minutes of extracellular stimulation) and involves phosphorylation, proteolysis, and redox changes. Figure 1. Hypothetical pathway for NFκB activation. Any one of a number of extracellular inducers results in the activation of a number of protein kinases that phosphorylate IκB/p105 (shown in red; RelA, dark blue; p50, light blue). Phosphorylated ... NFκB is rapidly activated in response to many pathologic signals that may be relevant during surgical trauma, including cytokines, 15,16 adhesion molecules, 17,18 endotoxin, 19 hypoxia, 20,21 and shear stress. 22 These stimuli activate several different protein kinases (protein kinase C, MAP kinase, ceramide kinase, IκB kinase) 23 that initiate NFκB activation. It has been postulated that the common mechanism by which these signals result in the activation of NFκB is by a change in the redox status of the cells. 24,25 Increased levels of hydrogen peroxide have been implicated in IκB degradation and NFκB DNA binding. The increase in intracellular reactive oxygen species (hydrogen peroxide) is also accompanied by a depletion of antioxidants such as glutathione. 26 It has been reported that replenishing glutathione levels by treatment with the antioxidant N-acetyl-L-cysteine (NAC) reduces activation of NFκB. 27 Other antioxidants, including pyrrolidine dithiocarbamate (PDTC) and diethyldithiocarbamate (DDTC), have also been shown to abrogate activation of NFκB. 28 Activation of NFκB results in the transcription of genes that can participate in the inflammatory reaction by inducing the production of cytokines, immunoreceptors, and cell adhesion molecules. 29 This transcription factor is therefore a potentially attractive target for immunomodulation. Information on the role of NFκB in human sepsis and MODS is limited but shows that the activity of this transcription factor is increased during inflammation and sepsis. 30,31 There is, however, no published information about neutrophil NFκB status and the development of organ dysfunction. In this study we investigated the role of neutrophil NFκB activation in the development of postsurgical MODS and potential modulation of neutrophil NFκB activation in the prevention of MODS-related neutrophil activation.

We reevaluate here an earlier report of monosaccharide binding by the C-type lectin-like, leukocyte surface protein CD69 in the form of a recombinant soluble dimer, and we examine polysaccharide binding by the protein. We have expressed in Escherichia coli a new construct of the extracellular part (Q 65 -K 199 ) of human CD69. We describe the folding in vitro to produce, in good yield, the protein in a soluble, disulphide-linked, dimeric form, and the results of binding experiments with monosaccharides: glucose, galactose, mannose, fucose, N -acetylglucosamine, and N -acetylgalactosamine, linked to bovine serum albumin. Monosaccharide-binding signals are not detectable. Among the polysaccharides, heparin, chondroitin sulphates A, B, and C, fucoidan, and dextran sulphate, CD69 dimer gives a weak binding signal with fucoidan.

This article is dedicated to Prof. Pierre Sinay on the occasion of his 62nd birthday. His group was the first to synthesize a Lewisx-related sequence41xJacquinet, J-C. and Sinay, P. J. Chem. Soc. Perkin Trans. 1979; 1: 314–318CrossrefSee all References41. The authors are supported by programme grant no. G9601454 from the Medical Research Council.

The cell adhesion molecule L-selectin binds to 3'-sialyl-Lewis (Le)x and -Lea and to 3'-sulfo-Lex and -Lea sequences. The binding to 3'-sialyl-Lex is strongly affected by the presence of 6-O-sulfate as found on oligosaccharides of the counter receptor, GlyCAM-1; 6-O-sulfate on the N-acetylglucosamine (6-sulfation) enhances, whereas 6-O-sulfate on the galactose (6'-sulfation) virtually abolishes binding. To extend knowledge on the specificity of L-selectin, we have investigated interactions with novel sulfo-oligosaccharides based on the Lex pentasaccharide sequence. We observe that, also with 3'-sulfo-Lex, the 6-sulfation enhances and 6'-sulfation suppresses L-selectin binding. The 6'-sulfation without 3'-sialyl or 3'-sulfate gives no binding signal with L-selectin. Where the 6-sulfo,3'-sialyl-Lex is on an extended di-N-acetyllactosamine backbone, additional 6-O-sulfates on the inner galactose and inner N-acetylglucosamine do not influence the binding. Although binding to the 6,3'-sulfo-Lex and 6-sulfo, 3'-sialyl-Lex sequences is comparable, the former is a more effective inhibitor of L-selectin binding. This difference is most apparent when L-selectin is in paucivalent form (predominantly di- and tetramer) rather than multivalent. Indeed, as inhibitors of the paucivalent L-selectin, the 3'-sulfo-Lex series are more potent than the corresponding 3'-sialyl-Lex series. Thus, for synthetic strategies to design therapeutic oligosaccharide analogs as antagonists of L-selectin binding, those based on the simpler 3'-sulfo-Lex (and also the 3'-sulfo-Lea) would seem most appropriate.

The human L-selectin is known to bind to immobilized 3'-sialyl-Le(x) and -Le(a) oligosaccharides both under static and physiological flow conditions. Here the reactivities toward 3'-sulfated and 3'-sialyl-Le(a) and -Le(x) pentasaccharides are compared by in-vitro binding and inhibition assays using preparations of human L-selectin-IgG-Fc chimera in which the selectin is predominantly in di- and tetrameric form (paucivalent) or in the form of a complex with anti-IgG (multivalent). Affinity for the sulfated ligands is marginally greater than for the sialyl ligands, as judged by concentrations required to give 50% inhibition of the multivalent selectin binding to the immobilized sulfated and sialyl ligands. There is a striking difference, however, in the avidities of binding of the two L-selectin forms toward the sulfated and sialyl ligands when these are immobilized in the clustered state: the paucivalent selectin gives detectable binding only to the sulfated ligands when these are immobilized as neoglycolipids on plastic microwells (up to 100 pmol immobilized per well) whereas the multivalent L-selectin binds well to both classes of ligand. Moreover, binding of the paucivalent selectin form is effectively inhibited only by the sulfated ligand, although binding of the multivalent selectin is inhibitable by both the sulfated and sialyl ligands. Such striking valency-dependent differences in ligand binding avidity and inhibitability may be manifest in vivo with the membrane-bound L-selectin, as marked variations occur in its density of expression on leukocytes. Thus, for the purpose of selecting inhibitors for development of therapeutic anti-inflammatory compounds, experimental designs based on the paucivalent L-selectin would more clearly single out compounds with broad spectrum anti-adhesive activities toward the both the high- and low-avidity interactions of the cell adhesion protein.

The concept that cancer can be eliminated by the immune system has been put forward over 100 years ago [1]. At this time, it was already thought that immune effector cells can recognize cancer cells as non-self and can eliminate them in the same way as viral or microbial pathogens. Both the innate immune system and the adaptive immune system have a major role in the control of tumor cell growth. The innate immune system consists of nonantigen-specific cells including macrophages, dendritic cells, neutrophils, natural killer cells, gamma delta T cells, and complement. The adaptive immune system consists of cells such as antigen-specific cytotoxic and helper T cells and antibody-producing B cells which can obtain a memory phenotype against specific antigenic challenge. The result is the ability of the different immune cell types to recognize cancer cells as foreign [2]. Antigens produced by tumor cells are known to be recognized by T cells and B cells, and both tumor antigen-specific T cells and antibodies against tumor antigens can be detected in patients with cancers such as melanoma, ovarian cancer, colorectal carcinoma, and hepatocellular cell carcinoma [3, 4]. Tumor-related antigens fall into a number of types including unique patient or shared tumor-specific antigens, antigens which are in both tumors and normal tissues, and antigens derived from tumor-associated viruses. In prostate cancer, a number of antigens are expressed which can be used for prostate cancer diagnosis or monitoring (Table 5.1).

The IMiDs(®) immunomodulatory compounds lenalidomide and pomalidomide are agents with anti-inflammatory, immunomodulatory and anti-cancer activity. An excellent success rate has been shown for multiple myeloma in phase I/II clinical trials leading to Food and Drug Administration approval of lenalidomide. One mechanism by which these drugs could enhance anti-tumour immunity may be through enhanced dendritic cell (DC) function. Thalidomide, a compound structurally related to lenalidomide and pomalidomide, is known to enhance DC function, and we have investigated whether its analogues, pomalidomide and lenalidomide, also have functional effects on DCs. We used mouse bone marrow-derived DCs treated with 5 or 10 μm pomalidomide, or lenalidomide from day 1 of culture. Treatment with IMiD(®) immunomodulatory compounds increased expression of Class I (H2-Kb), CD86, and pomalidomide also increased Class II (I-Ab) expression in bone marrow-derived DCs, as measured by flow cytometry. Fluorescent bead uptake was increased by up to 45% when DCs were treated with 5 or 10 μm pomalidomide or lenalidomide compared with non-treated DCs. Antigen presentation assays using DCs primed with ovalbumin, and syngeneic T cells from transgenic OTI and OTII mice (containing MHC restricted, ovalbumin-specific, T cells) showed that both pomalidomide and lenalidomide effectively increased CD8(+) T-cell cross-priming (by up to 47%) and that pomalidomide alone was effective in increasing CD4(+) T-cell priming (by 30%). Our observations suggest that pomalidomide and lenalidomide enhance tumour antigen uptake by DCs with an increased efficacy of antigen presentation, indicating a possible use of these drugs in DC vaccine therapies.