Mapping the colorectal tumor microbiota

The gut microbiome in patients with colorectal cancer (CRC) is different than that of healthy controls. Previous studies have profiled the CRC tumor microbiome using a single biopsy. However, since the morphology and cellular subtype vary significantly within an individual tumor, the possibility of sampling error arises for the microbiome within an individual tumor. To test this hypothesis, seven biopsies were taken from representative areas on and off the tumor in five patients with CRC. The microbiome composition was strikingly similar across all samples from an individual. The variation in microbiome alpha-diversity was significantly greater between individuals' samples then within individuals. This is the first study, to our knowledge, that shows that the microbiome of an individual tumor is spatially homogeneous. Our finding strengthens the assumption that a single biopsy is representative of the entire tumor, and that microbiota changes are not limited to a specific area of the neoplasm.

An Antibody Targeting ICOS Increases Intratumoral Cytotoxic to Regulatory T-cell Ratio and Induces Tumor Regression

The immunosuppressive tumor microenvironment constitutes a significant hurdle to immune checkpoint inhibitor responses. Both soluble factors and specialized immune cells, such as regulatory T cells (Treg), are key components of active intratumoral immunosuppression. Inducible costimulatory receptor (ICOS) can be highly expressed in the tumor microenvironment, especially on immunosuppressive Treg, suggesting that it represents a relevant target for preferential depletion of these cells. Here, we performed immune profiling of samples from tumor-bearing mice and patients with cancer to demonstrate differential expression of ICOS in immune T-cell subsets in different tissues. ICOS expression was higher on intratumoral Treg than on effector CD8 T cells. In addition, by immunizing an Icos knockout transgenic mouse line expressing antibodies with human variable domains, we selected a fully human IgG1 antibody called KY1044 that bound ICOS from different species. We showed that KY1044 induced sustained depletion of ICOS^high T cells but was also associated with increased secretion of proinflammatory cytokines from ICOS^low effector T cells (T_eff). In syngeneic mouse tumor models, KY1044 depleted ICOS^high Treg and increased the intratumoral T_Eff:Treg ratio, resulting in increased secretion of IFNγ and TNFα by T_Eff cells. KY1044 demonstrated monotherapy antitumor efficacy and improved anti-PD-L1 efficacy. In summary, we demonstrated that using KY1044, one can exploit the differential expression of ICOS on T-cell subtypes to improve the intratumoral immune contexture and restore an antitumor immune response.

A therapeutic antibody targeting osteoprotegerin attenuates severe experimental pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare but fatal disease. Current treatments increase life expectancy but have limited impact on the progressive pulmonary vascular remodelling that drives PAH. Osteoprotegerin (OPG) is increased within serum and lesions of patients with idiopathic PAH and is a mitogen and migratory stimulus for pulmonary artery smooth muscle cells (PASMCs). Here, we report that the pro-proliferative and migratory phenotype in PASMCs stimulated with OPG is mediated via the Fas receptor and that treatment with a human antibody targeting OPG can attenuate pulmonary vascular remodelling associated with PAH in multiple rodent models of early and late treatment. We also demonstrate that the therapeutic efficacy of the anti-OPG antibody approach in the presence of standard of care vasodilator therapy is mediated by a reduction in pulmonary vascular remodelling. Targeting OPG with a therapeutic antibody is a potential treatment strategy in PAH.

Pulmonary arterial hypertension (PAH) is characterised by progressive pulmonary vascular remodelling. Here, Arnold et al. develop a therapeutic antibody targeting osteoprotegerin and find it attenuates pulmonary vascular remodelling in multiple rodent models of PAH, alone or in combination with standard of care vasodilator therapy.

Abstract 4953: Differential expression of ICOS on circulating immune cells and tumor infiltrating lymphocytes in patient with solid tumors

Background: The Inducible T-cell costimulator (ICOS/CD278) is upregulated during T cell activation and is an important regulator of the immune response against pathogens and cancer cells. When engaged by its ligand, the activation of ICOS signaling improves the survival of ICOS+ effector (TEff) and regulatory T cells (TReg). In addition, depending on the T cell subtypes expressing ICOS, activation of the signaling pathway induces the expression and secretion of either pro- (by TEff) or anti-inflammatory (by TReg) cytokines. ICOS has been reported to be upregulated in the tumor microenvironment (TME) of most tumor indications. However, the variability in ICOS expression levels on ICOS expressing T cells (TEff and TReg) and their relative abundance in different tumor types is still poorly understood. The aim of this study was to take advantage of multiple analytical platforms to assess the expression of ICOS on immune cells in the periphery and on tumor infiltrating lymphocytes (TILs) from cancers known to express high levels of ICOS, based on previous TCGA analyses.

Methods: We analysed ICOS expression on peripheral blood mononuclear cell (PBMCs) and TILs by FACS, ChipcytometryTM and by single cell RNAseq. The analysis aimed to compare the expression of ICOS on different immune T cell subtypes. This comparison was performed on samples isolated from treatment naive non-small cell lung cancer (NSCLC) patients. In parallel, we established dual immunohistochemistry staining protocols supplemented by digital pathology to quantify and compare the expression of ICOS in the context of either FOXP3 or CD8 positive cells in NSCLC, gastric, esophageal, cervical, bladder and head and neck tumor samples.

Results and conclusion: Using these approaches, we confirmed high ICOS expression in several solid tumor types. ICOS expression was also shown to be higher on immune cells in the TME compared to the periphery. Finally, ICOS expression was found to be more abundant on the surface of intratumoral TReg than on CD8+ T effector cells, confirming the data obtained in preclinical syngeneic tumor models (AACR2018 abstract #2792). Importantly, this work highlighted variability in the abundance and ratio of the different ICOS+ T cells subtypes (TEff and TReg) between different ICOSHigh tumors. Altogether, the variability in the intratumoral ratio of ICOS positive T cells observed in different tumor types could differentially affect their response to antibodies targeting ICOS. This work suggests that understanding the expression of ICOS in the context of different immune T cell subtypes may improve selection of patients with higher potential to respond to anti-ICOS therapies such as KY1044.

Citation Format: Richard C. Sainson, Miha Kosmac, Rachael Kimber, Joana Carvalho, Gwenoline Bohris, Anil Thotakura, David Melvin, Matthew McCourt. Differential expression of ICOS on circulating immune cells and tumor infiltrating lymphocytes in patient with solid tumors [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 4953.

Abstract 2792: The combination of immune checkpoint blockers with the anti-ICOS KY1044 antibody results in a strong tumor response

The last few years have shown a strong paradigm shift in cancer therapies with the approval of antibodies targeting immune checkpoints (CTLA-4, PD-1 and PD-L1). These immune checkpoint blockers (ICBs) are associated with a strong and long-lasting response in patients suffering from different malignancies. However, there is still a high proportion of patients showing intrinsic or acquired resistance to ICBs. Although the mechanisms associated with the lack of immune response are multiple, the presence of highly anti-inflammatory regulatory T cells (TRegs) in the tumour microenvironment (TME) is known to negatively affect the response to these therapies. Similarly, high TReg levels in the TME have been associated with poor prognosis in several cancers. Together, this highlights the potential of targeting and depleting TRegs to enhance anti-tumour responses.

The Inducible T-cell costimulator (ICOS/CD278) is related to the CD28 superfamily and is induced when T cells get activated. ICOS expression levels vary in different immune cell subtypes and in different tissues. In preclinical mouse tumour models, TRegs (CD4+/FOXP3+) constitutively express ICOS on their surface and the expression of ICOS on TRegs is significantly higher than that on effector T cells (TEffs). In addition, ICOS expression on TRegs is higher in the TME than in the blood or spleen, which makes it a strong candidate for preferential depletion of TRegs in tumours. By immunizing Kymice™ in which the endogenous Icos gene has been knocked out, we identified a novel, fully human antibody called KY1044 that cross-reacts with mouse ICOS. KY1044 is an anti-ICOS subclass G1 kappa monoclonal antibody that selectively binds to dimeric ICOS (Fc fusion) with an affinity of less than 2nM. Using in vitro and in vivo approaches we demonstrate that KY1044 has a dual mechanism of action: (1) it promotes the preferential depletion of intratumoural ICOShigh TRegs resulting in an increase in the TEff:TReg ratio in the TME; and (2) it stimulates ICOSLow TEff cells. Using the mouse effector enabled version of KY1044 (mIgG2a) we confirm, using syngeneic models, a strong anti-tumour efficacy as monotherapy or in combination with surrogates of ICBs. We also demonstrated a tumour antigen specific immunity, as highlighted by the rejection of the original tumour cells in animals cured of the disease and re-challenged by the same cell line. Noteworthy, Pharmacodynamic studies demonstrate long-term depletion of TRegs and a significant increase in the TEff:TReg ratio in response to KY1044. In summary, our data demonstrate that targeting ICOS with KY1044 is a valid approach for manipulating the immune system and for inducing a strong anti-tumour response in several indications. The data presented here also warrant the assessment of KY1044 in cancer patients in a clinical trial.

Citation Format: Richard C. Sainson, Matthew McCourt, Anil Thotakura, Nahida Parveen, Miha Kismac, Gwenoline Borhis, Joana Carvalho, Tracey Myers, Robert Rowlands, Hanif Ali, Hannah Craig, Vivian Wong, Qi Liang, Volker Germaschewski. The combination of immune checkpoint blockers with the anti-ICOS KY1044 antibody results in a strong tumor response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2792.

Rational Selection of Syngeneic Preclinical Tumor Models for Immunotherapeutic Drug Discovery

Murine syngeneic tumor models are critical to novel immuno-based therapy development, but the molecular and immunologic features of these models are still not clearly defined. The translational relevance of differences between the models is not fully understood, impeding appropriate preclinical model selection for target validation, and ultimately hindering drug development. Across a panel of commonly used murine syngeneic tumor models, we showed variable responsiveness to immunotherapies. We used array comparative genomic hybridization, whole-exome sequencing, exon microarray analysis, and flow cytometry to extensively characterize these models, which revealed striking differences that may underlie these contrasting response profiles. We identified strong differential gene expression in immune-related pathways and changes in immune cell-specific genes that suggested differences in tumor immune infiltrates between models. Further investigation using flow cytometry showed differences in both the composition and magnitude of the tumor immune infiltrates, identifying models that harbor "inflamed" and "non-inflamed" tumor immune infiltrate phenotypes. We also found that immunosuppressive cell types predominated in syngeneic mouse tumor models that did not respond to immune-checkpoint blockade, whereas cytotoxic effector immune cells were enriched in responsive models. A cytotoxic cell-rich tumor immune infiltrate has been correlated with increased efficacy of immunotherapies in the clinic, and these differences could underlie the varying response profiles to immunotherapy between the syngeneic models. This characterization highlighted the importance of extensive profiling and will enable investigators to select appropriate models to interrogate the activity of immunotherapies as well as combinations with targeted therapies in vivo Cancer Immunol Res; 5(1); 29-41. ©2016 AACR.

Identification and Characterization of MEDI4736, an Antagonistic Anti-PD-L1 Monoclonal Antibody

Programmed cell-death 1 ligand 1 (PD-L1) is a member of the B7/CD28 family of proteins that control T-cell activation. Many tumors can upregulate expression of PD-L1, inhibiting antitumor T-cell responses and avoiding immune surveillance and elimination. We have identified and characterized MEDI4736, a human IgG1 monoclonal antibody that binds with high affinity and specificity to PD-L1 and is uniquely engineered to prevent antibody-dependent cell-mediated cytotoxicity. In vitro assays demonstrate that MEDI4736 is a potent antagonist of PD-L1 function, blocking interaction with PD-1 and CD80 to overcome inhibition of primary human T-cell activation. In vivo MEDI4736 significantly inhibits the growth of human tumors in a novel xenograft model containing coimplanted human T cells. This activity is entirely dependent on the presence of transplanted T cells, supporting the immunological mechanism of action for MEDI4736. To further determine the utility of PD-L1 blockade, an anti-mouse PD-L1 antibody was investigated in immunocompetent mice. Here, anti-mouse PD-L1 significantly improved survival of mice implanted with CT26 colorectal cancer cells. The antitumor activity of anti-PD-L1 was enhanced by combination with oxaliplatin, which resulted in increased release of HMGB1 within CT26 tumors. Taken together, our results demonstrate that inhibition of PD-L1 function can have potent antitumor activity when used as monotherapy or in combination in preclinical models, and suggest it may be a promising therapeutic approach for the treatment of cancer. MEDI4736 is currently in several clinical trials both alone and in combination with other agents, including anti-CTLA-4, anti-PD-1, and inhibitors of IDO, MEK, BRAF, and EGFR.

Preclinical characterisation of the GM-CSF receptor as a therapeutic target in rheumatoid arthritis

Objective

Previous work has suggested that the granulocyte macrophage colony stimulating factor (GM-CSF)–GM-CSF receptor α axis (GM-CSFRα) may provide a new therapeutic target for the treatment of rheumatoid arthritis (RA). Therefore, we investigated the cellular expression of GM-CSFRα in RA synovial tissue and investigated the effects of anti-GM-CSFRα antibody treatment in vitro and in vivo in a preclinical model of RA.

Methods

We compared GM-CSFRα expression on macrophages positive for CD68 or CD163 on synovial biopsy samples from patients with RA or psoriatic arthritis (PsA) to disease controls. In addition, we studied the effects of CAM-3003, an anti-GM-CSFR antibody in a collagen induced arthritis model of RA in DBA/1 mice. The pharmacokinetic profile of CAM-3003 was studied in naïve CD1(ICR) mice (see online supplement) and used to interpret the results of the pharmacodynamic studies in BALB/c mice.

Results

GM-CSFRα was expressed by CD68 positive and CD163 positive macrophages in the synovium, and there was a significant increase in GM-CSFRα positive cells in patients in patients with RA as well as patients with PsA compared with patients with osteoarthritis and healthy controls. In the collagen induced arthritis model there was a dose dependent reduction of clinical arthritis scores and the number of F4/80 positive macrophages in the inflamed synovium after CAM-3003 treatment. In BALB/c mice CAM-3003 inhibited recombinant GM-CSF mediated margination of peripheral blood monocytes and neutrophils.

Conclusions

The findings support the ongoing development of therapies aimed at interfering with GM-CSF or its receptor in various forms of arthritis, such as RA and PsA.

Protein engineering and preclinical development of a GM-CSF receptor antibody for the treatment of rheumatoid arthritis

BACKGROUND AND PURPOSE

For antibody therapies against receptor targets, in vivo outcomes can be difficult to predict because of target-mediated clearance or antigen 'sink' effects. The purpose of this work was to engineer an antibody to the GM-CSF receptor α (GM-CSFRα) with pharmacological properties optimized for chronic, s.c. treatment of rheumatoid arthritis (RA) patients.

EXPERIMENTAL APPROACH

We used an in silico model of receptor occupancy to guide the target affinity and a combinatorial phage display approach for affinity maturation. Mechanism of action and internalization assays were performed on the optimized antibody in vitro before refining the modelling predictions of the eventual dosing in man. Finally, in vivo pharmacology studies in cynomolgus monkeys were carried out to inform the predictions and support future clinical development.

KEY RESULTS

Antibody potency was improved 8600-fold, and the target affinity was reached. The refined model predicted pharmacodynamic effects at doses as low as 1 mg kg(-1) and a study in cynomolgus monkeys confirmed in vivo efficacy at 1 mg kg(-1) dosing.

CONCLUSIONS AND IMPLICATIONS

This rational approach to antibody drug discovery enabled the isolation of a potent molecule compatible with chronic, s.c. self-administration by RA patients. We believe this general approach enables the development of optimal biopharmaceuticals.

Th1 cytokines are more effective than Th2 cytokines at licensing anti-tumour functions in CD40-activated human macrophages in vitro

CD40 agonists are showing activity in early clinical trials in patients with advanced cancer. In animal models, CD40 agonists synergise with T-cell-activating therapies to inhibit tumour growth by driving tumour macrophage repolarisation from an immunosuppressive to a Th1 immunostimulatory, tumouricidal phenotype. We therefore tested the hypothesis that T-cell-derived cytokines license anti-tumour functions in CD40-activated human macrophages. CD40 ligand (CD40L) alone activated macrophages to produce immunosuppressive IL-10, in a similar fashion to bacterial LPS, but failed to promote anti-tumour functions. The Th1 cytokine IFN-γ optimally licensed CD40L-induced macrophage anti-tumour functions, inducing a switch from IL-10 to IL-12p70 production, promoting macrophage-mediated Th1 T-cell skewing and enhancing tumouricidal activity. We found that even the Th2 cytokines IL-4 and IL-13 promoted IL-12p70 production (albeit without inhibiting IL-10 production) and enhanced Th1 T-cell skewing by CD40L-activated macrophages. However, IL-4 and IL-13 did not enhance tumouricidal activity in CD40L-activated macrophages. Thus, while both Th1 and Th2 cytokines biased macrophages to a Th1 immunostimulatory phenotype, only Th1 cytokines promoted tumouricidal activity in CD40L-activated macrophages. The presence of tumour-infiltrating Th1 or Th2 cells might therefore be predictive for patient response to CD40 agonism.

Abstract 363: Activin receptor-like kinase 1 (Alk1) ligands modulate endothelial cell function in vitro and in vivo

The TGF-ß type-1 receptor activin receptor-like kinase 1 (Alk1) is predominantly expressed on endothelial cells, regulates vascular morphogenesis, and has been implicated in pathological angiogenesis. Alk1 expression is increased in the vasculature of a broad range of tumours and agents that disrupt of Alk1 signalling in tumour endothelial cells may be potential therapeutics for the treatment of a variety of solid tumours. Alk1 has been described as a receptor for the bone morphogenic proteins, BMP9 and BMP10. In order to study the effects of Alk1 signalling in endothelial cells in vitro and in the vasculature in vivo we used a soluble antagonist Alk1-Fc protein consisting of the extracellular domain of the Alk1 protein fused to the Fc domain of IgG1. In vitro, Alk1-Fc inhibited BMP9-dependent Alk1 signalling via phosphorylation and nuclear translocation of SMAD1/5 in endothelial cells and modulated endothelial cell functions such as an ability to form tube- like structures. In mice, physiological levels of BMP9 could be detected in serum by ELISA, consistent with detectable levels of phosphorylated SMAD1/5 in the lung, a site of high Alk1 vascular expression. In mice, the administration of Alk1-Fc effectively blocked SMAD1/5 phosphorylation in the lung, suggesting that in this tissue Alk1 ligands are the predominant driver of lung SMAD1/5 activation and that signalling is efficiently antagonised by Alk1-Fc. Despite suppression of Alk1 signalling in the lung and expression of Alk1 on the vasculature associated with tumours, Alk1-Fc did not have profound effects on tumour size or microvessel density in mice bearing tumours, however administration of Alk1-Fc in neonatal mice did cause defects in angiogenesis of the retinal vasculature demonstrating that in some contexts Alk1 ligands play an important role in regulating the angiogenic process.

Citation Format: Gareth C. Davies, James A. Harper, Richard C. Sainson, Lee Brown, Grace Opoku-Ansah, Alison Smith, Matthew McCourt, James W. Legg. Activin receptor-like kinase 1 (Alk1) ligands modulate endothelial cell function in vitro and in vivo. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 363. doi:10.1158/1538-7445.AM2013-363

Abstract 1616: Survivin regulates endothelial cell proliferation, survival and angiogenesis

Background - Survivin is a member of the inhibitor of apoptosis protein (IAP) family, and is reported to be overexpressed in a number of human cancers with high unmet medical need including breast, non-small-cell lung (NSCLC), colorectal, gastric, glioblastoma, and pancreatic cancers. Multiple studies have described survivin as a key regulator of tumour cell proliferation, survival and drug resistance, which has led to the advancement of survivin inhibitors, including antisense and small molecule drugs, and cancer vaccines, into clinical testing. In the tumour micro-environment, survivin overexpression has also been reported in tumour blood vessels and conditional deletion of survivin in endothelial cells results in murine embryonic lethality secondary to haemorrhage and defective vascular development. We therefore hypothesised that inhibition of survivin function in endothelial cells could have anti-angiogenic or vascular disruptive effects.

Methods and Results - To better understand the role of survivin in primary endothelial cells we designed siRNAs capable of targeting multiple isoforms of human survivin. Using high content imaging assays we demonstrated that the siRNA were highly selective for survivin, inhibited the expression of multiple survivin splice variants, and had potent in vitro effects on endothelial cells. Survivin knockdown resulted in inhibition of cell cycle progression with the formation of enlarged, multi-nucleated cells, and in reduced endothelial cell survival. Survivin knockdown also impaired the formation of tube-like networks in vitro when co-cultured with human fibroblasts, but did not disrupt more established networks.

Conclusion These data show an important role for survivin in primary endothelial cells, and suggest that targeted inhibition of survivin may have anti-angiogenic effects, but may not disrupt more established blood vessels.

Citation Format: Cath Eberlein, Grace Opoku-Ansah, James Legg, Tim London, Frank Gebhardt, Gareth Davies, Natalie Tigue, Matthew McCourt, Julia White, Darren Cross, Ute Schaeper, Viia E. Valge-Archer. Survivin regulates endothelial cell proliferation, survival and angiogenesis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1616. doi:10.1158/1538-7445.AM2013-1616

Abstract 1562: Choosing the right preclinical model for cancer immunotherapy: The “SyngenOmic” toolbox

Recent FDA approvals of ipilimumab and sipuleucel-T for the treatment of metastatic melanoma and castrate-resistant prostate cancer respectively have validated the approach to modulate the immune system for the clinical treatment of cancer. MedImmune Oncology, has an extensive pipeline and expertise in investigational Immune Mediated Therapy in Cancer (IMT-C) drugs (e.g. tremelimumab and MEDI4736), and is heavily invested in this novel era of cancer therapeutics. Pre-clinical assessment of the validity of potential IMT-C drugs can be enabled by the use of syngeneic tumours established in immuno-competent animals. MedImmune's pharmacology team has lead efforts to develop such models, to a point that a panel of 15 different validated syngeneic tumour types is available in house for studies to progress projects. The intention of selecting relevant models and of minimizing animal experimentation, reduces the number of models tested for each project, and allows for detailed genetic and proteomic characterization of treatment dependent effects within our models. Utilising both in vitro and in vivo approaches, we have generated transcriptomic and genomic data for our cell lines, the resulting implanted tumours and for the relevant lymphatic organs (draining lymph node and spleen). Using key proteomic/cell markers through IHC and FACS analysis, we are also evaluating the immune profile/status of our tumour bearing animals in parallel. Finally, in order to establish the disease relevance and prognostic value of our models we are analyzing our cell panel for the presence of somatic mutations in 50 genes previously implicated in human cancers. Once completed, the resulting dataset will hopefully help pre-clinical scientists to refine their in vivo plans and deliver more clinically-relevant pharmacology packages for the progression of cancer immunotherapy drug candidates.

Citation Format: James A. Harper, John Prime, Athula Herath, Jane Howell, Marianna Papaspyridonos, Amy Popple, Judith Anderton, Michelle Morrow, Arthur Lewis, Liz Henley, Matthew McCourt, Richard Sainson. Choosing the right preclinical model for cancer immunotherapy: The “SyngenOmic” toolbox. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1562. doi:10.1158/1538-7445.AM2013-1562

Changes in outcome and management of perforated diverticulitis over a 10 year period

INTRODUCTION

Aggressive non-operative intervention and evolving surgical strategies have altered the treatment of perforated diverticulitis in the acute setting. These strategies have predominantly been implemented over the last decade. The aim of this study was to assess the impact of this on patient outcome during their index admission and subsequently.

METHODS

Consecutive patients admitted with acute diverticulitis between 1999 and 2010 were identified. Patient demographics, treatment strategies and outcomes were collected and analysed. Patients who had an episode of perforated diverticulitis during their index admission were followed.

RESULTS

739 patients were admitted with acute diverticulitis. Of these, 115 (15.7%) had perforated diverticulitis. 53 (47.8%) underwent an intervention. There was a reduction in the mean age of patients admitted with acute diverticulitis of 8.9% over the study period (p = 0.002). There was a significant increase in the use of CT scanning pre-operatively (p < 0.001). 'Non-resectional' interventions have emerged in the form of laparoscopic lavage (n = 5) and percutaneous abscess drainage (n = 14). There was associated improved length of stay (p < 0.001).

CONCLUSION

Outcomes for patients with perforated diverticulitis have improved, contributed to in part by an increased use of non-resectional management strategies.

Improved drug-like properties of therapeutic proteins by directed evolution

Many natural human proteins have functional properties that make them useful as therapeutic drugs. However, not all these proteins are compatible with large-scale manufacturing processes or sufficiently stable to be stored for long periods prior to use. In this study, we focus on small four-helix bundle proteins and employ ribosome display in conjunction with three parallel selection pressures to favour the isolation of variant proteins with improved expression, solubility and stability. This in vitro evolution strategy was applied to two human proteins with known drug development issues, granulocyte colony-stimulating factor (G-CSF) and erythropoietin (EPO). In the case of G-CSF, the soluble expression levels in Escherichia coli were improved 1000-fold, while for EPO the level of aggregation in an accelerated shelf-life study was reduced from over 80% to undetectable levels. These results exemplify the general utility of our in vitro evolution strategy for improving the drug-like properties of therapeutic proteins.

Abstract LB-158: MEDI4736: Delivering effective blockade of immunosupression to enhance tumour rejection: Monoclonal antibody discovery and preclinical development

Cancerous cells emerge within the body following accumulation of deleterious genetic mutations. These mutations alter the phenotype of a cancer cell marking it as distinct from the surrounding host; an immunological state termed “altered self”. These cells, like other non-self entities such as viruses and bacteria, are recognised by the immune system and marked for destruction, a process known as “immune surveillance”. B7-H1 expression by tumour cells is believed to aid tumours in evading detection and elimination by the immune system. B7-H1 functions in this respect via several alternative mechanisms including driving exhaustion and anergy of tumour infiltrating T lymphocytes, stimulating secretion of immune repressive cytokines into the tumour micro-environment, stimulating repressive regulatory T cell function and protecting B7-H1 expressing tumour cells from lysis by tumour cell specific cytotoxic T cells.

Using hybridoma technology and high throughput screening MedImmune has identified a series of fully human antibodies specific for human B7-H1. Further characterisation of these antibodies led to the identification of a single high affinity antibody, MEDI 4736, with the ability to relieve B7-H1 mediated suppression of T cell activation in vitro and to enhance sub-optimal T cell activation in a mixed lymphocyte reaction. In vitro testing shows that MEDI 4736 does not trigger non-specific cytokine release in whole blood, and is only able to activate T cells in the context of an active T cell receptor signal.

A surrogate anti-mouse B7-H1 antibody shows significant anti-tumour activity in a syngeneic model when dosed in combination with chemotherapy. Similarly MEDI 4736 is able to inhibit tumour growth in a novel in vivo xenograft model, via a mechanism that is dependent on the presence of tumour specific human T cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-158. doi:10.1158/1538-7445.AM2011-LB-158

An unusual presentation of Fournier's gangrene

INTRODUCTION

Fournier's gangrene is a rare severe necrotising fasciitis of the genitalia.

CASE

A case of Fournier's gangrene caused by perforated sigmoid diverticulitis in a patient with systemic lupus erythematosus is presented along with a review of the relevant literature.

Rectal cancer

Surgery is the cornerstone of rectal cancer treatment. Oncological cure and overall survival continue to be the main goals, but sparing of the anal sphincter mechanism and functional results are also important. The modern management of rectal cancer is a multidisciplinary approach, and pre-operative staging is of crucial importance when planning treatment in these patients. Pre-operative staging is used to determine the indication for neoadjuvant therapy prior to surgical resection or to determine whether local excision is an option in carefully selected patients with early rectal cancer. Surgery in the form of total mesorectal excision (TME) has become the standard of care for mid and distal rectal cancers. Early rectal cancers do not require neoadjuvant therapy. For locally advanced cancers of the lower two-thirds of the rectum, the combination of surgical resection with chemoradiotherapy decreases local recurrence rates and probably improves overall survival. Whereas in the past local excision was only contemplated in patients who were unfit for radical surgery or for local palliation in cases of metastatic disease, over the last number of years there has been increasing interest in local treatment with curative intent in early rectal cancer.

Combining TGF-β inhibition and angiotensin II blockade results in enhanced antifibrotic effect

BACKGROUND

Although angiotensin II (Ang II) blockade is rapidly becoming standard antifibrotic therapy in renal diseases, current data suggest that Ang II blockade alone cannot stop fibrotic disease. New therapies, such as antibodies to transforming growth factor-beta (TGF-beta), or drug combinations will be required to further slow or halt disease progression. Here, using the anti-Thy1 model of glomerulonephritis, the maximally therapeutic dose of the TGF-beta neutralizing mouse monoclonal antibody (1D11) was determined and compared with the maximally effective dose of enalapril. Then, the effect of combining both treatments at maximal doses was determined.

METHODS

After disease induction with the anti-Thy1 antibody, OX-7, increasing doses of 1D11 were given intraperitoneally (IP) on days 1, 3, and 5. Enalapril was administered in drinking water from day 1. The fibrotic response was assessed at day 6.

RESULTS

1D11 dose-dependently reduced fibrosis, with the 0.5 and 5 mg/kg doses showing maximal therapeutic effects, reducing period-acid Schiff (PAS) staining by 56% and 45%, respectively. Fibronectin and collagen I staining was reduced by 32% to 36%, respectively. Glomerular mRNA and production of fibronectin, plasminogen activator inhibitor-1 (PAI-1), TGF-beta1, and p-Smad2 protein were also reduced. The maximal therapeutic effects of 1D11 and enalapril alone were very similar. However, combination therapy led to further reduction in disease. Notably, matrix deposition was reduced by 80%.

CONCLUSION

While 1D11 or enalapril at maximal doses reduce fibrosis equally, simultaneous blockade of Ang II and TGF-beta reduces fibrotic disease considerably more, offering hope that such drug combinations may confer a therapeutic advantage over angiotensin blockade alone.

Dopamine attenuates neutrophil–endothelial interaction and is a putative anti-inflammatory cytokine

Background

Activated neutrophil (PMN) adherence to vascular endothelium comprises a key step for both transendothelial migration and initiation of potentially deleterious release of PMN products. Previous work has shown that the biogenic amine dopamine (DA) functions as an anti-inflammatory cytokine by inducing PMN apoptosis. The effect of DA on PMN transendothelial migration and adhesion receptor expression as well as on the endothelial molecules, E-selectin and intercellular adhesion molecule (ICAM) 1, was evaluated.

Methods

PMNs were isolated from healthy controls, stimulated with lipopolysaccharide (LPS) and tumour necrosis factor (TNF) α and treated with DA. CD11b and CD18 PMN adhesion receptor expression was assessed flow cytometrically. In a separate transwell experiment, the effect of the chemo-attractant peptide interleukin (IL) 8 on PMN migration was assessed. Human umbilical vein endothelial cells were stimulated with LPS/TNF-α, incubated with DA, and ICAM-1 and E-selectin endothelial molecule expression was assessed.

Results

There was a significant increase in transendothelial migration in stimulated PMNs as well as in CD11b/CD18, endothelial E-selectin and ICAM-1 expression compared with normal PMNs. DA attenuated these changes. The chemoattractant effect of IL-8 was also abolished.

Conclusion

These results show that DA attenuates the initial interaction between PMNs and endothelium, providing further evidence that it also functions as an anti-inflammatory cytokine.

A molecular orbital study of a model of the Mg2+ coordination complex of the self splicing reaction of ribosomal RNA

Recent discoveries have established the fact that RNA is capable of acting as an enzyme. In this study two different types of molecular orbital calculations, INDO and ab initio, were used in an attempt to assess the structural/functional role of the Mg2+ hydrated complex in ribozyme reactions. Preliminary studies indicate that the reaction is multistep and that the Mg2+ complex exerts a stabilizing effect on the intermediate or midpoint of the reaction.

Activated human neutrophils release hepatocyte growth factor/scatter factor

BACKGROUND

Hepatocyte growth factor or scatter factor (HGF/SF) is a pleiotropic cytokine that has potent angiogenic properties. We have previously demonstrated that neutrophils (PMN) are directly angiogenic by releasing vascular endothelial growth factor (VEGF). We hypothesized that the acute inflammatory response can stimulate PMN to release HGF.

AIMS

To examine the effects of inflammatory mediators on PMN HGF release and the effect of recombinant human HGF (rhHGF) on PMN adhesion receptor expression and PMN VEGF release.

METHODS

In the first experiment, PMN were isolated from healthy volunteers and stimulated with tumour necrosis factor-alpha (TNF-alpha), lipopolysaccharide (LPS), interleukin-8 (IL-8), and formyl methionyl-leucyl-phenylalanine (fMLP). Culture supernatants were assayed for HGF using ELISA. In the second experiment, PMN were lysed to measure total HGF release and HGF expression in the PMN was detected by Western immunoblotting. Finally, PMN were stimulated with rhHGF. PMN CD 11a, CD 11b, and CD 18 receptor expression and VEGF release was measured using flow cytometry and ELISA respectively.

RESULTS

TNF-alpha, LPS and fMLP stimulation resulted in significantly increased release of PMN HGF (755+/-216, 484+/-221 and 565+/-278 pg/ml, respectively) compared to controls (118+/-42 pg/ml). IL-8 had no effect. Total HGF release following cell lysis and Western blot suggests that HGF is released from intracellular stores. Recombinant human HGF did not alter PMN adhesion receptor expression and had no effect on PMN VEGF release.

CONCLUSIONS

This study demonstrates that pro-inflammatory mediators can stimulate HGF release from a PMN intracellular store and that activated PMN in addition to secreting VEGF have further angiogenic potential by releasing HGF.

Taurolidine inhibits tumor cell growth in vitro and in vivo

BACKGROUND

Taurolidine, a derivative of the amino acid taurine, exhibits antiendotoxin, antibacterial, and antiadherence activity. We hypothesized that Taurolidine may inhibit tumor cell growth, both in an in vitro and in vivo setting. Our aim was to examine the effect of Taurolidine on the growth of a rat metastatic colorectal tumor cell line (DHD/K12/TRb) in vitro and in vivo.

METHODS

In the in vitro experiments, DHD/K12/TRb cells were incubated with 5, 10, 15, 25, microg/ml of Taurolidine. Cells incubated in culture medium alone were used as controls. Cell proliferation, cell viability, cell death, and cell apoptosis were measured using commercially available techniques. In the in vivo experiment, BD IX rats were randomized into two groups (n = 10/group). Group A (control) underwent laparotomy and instillation of DHD/K12/TRb tumor cells intraperitoneally followed by phosphate buffered saline (PBS). Group B received Taurolidine (100 mg/kg) instead of PBS. Animals were killed after 24 days and tumor burden assessed by counting the number of tumor nodules in the peritoneal cavity.

RESULTS

Incubation of the tumor cells with Taurolidine resulted in a 4-fold decrease in proliferation rates (25+/-4% vs. 100+/-28% for controls) and a 4-fold increase in cell necrosis as demonstrated by the increase in LDH release (403+/-28% vs. 100+/-26% for controls), at a Taurolidine concentration of 25 microg/ml. A dose-dependent decrease in cell viability was also observed. In the in vivo study, local Taurolidine administration resulted in significant decreases in tumor burden (3+/-1 nodules in Group B animals vs. 649+/-101 nodules in Group A animals).

CONCLUSIONS

Taurolidine inhibits the growth of a rat metastatic colorectal tumor cell line in vitro and in vivo and thus may have potential in the prevention of peritoneal metastases.

Proinflammatory mediators stimulate neutrophil-directed angiogenesis

BACKGROUND

Vascular endothelial growth factor (VEGF; vascular permeability factor) is one of the most potent proangiogenic cytokines, and it plays a central role in mediating the process of angiogenesis or new blood vessel formation. Neutrophils (PMNs) recently have been shown to produce VEGF.

HYPOTHESIS

The acute inflammatory response is a potent stimulus for PMN-directed angiogenesis.

METHODS

Neutrophils were isolated from healthy volunteers and stimulated with lipopolysaccharide (LPS), tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), and anti-human Fas monoclonal antibody. Culture supernatants were assayed for VEGF using enzyme-linked immunosorbent assays. Culture supernatants from LPS- and TNF-alpha-stimulated PMNs were then added to human umbilical vein endothelial cells and human microvessel endothelial cells and assessed for endothelial cell proliferation using 5-bromodeoxyuridine labeling. Tubule formation was also assessed on MATRIGEL basement membrane matrix. Neutrophils were lysed to measure total VEGF release, and VEGF expression was detected using Western blot analysis.

RESULTS

Lipopolysaccharide and TNF-alpha stimulation resulted in significantly increased release of PMN VEGF (532+/-49 and 484+/-80 pg/mL, respectively; for all, presented as mean +/- SEM) compared with control experiments (32+/-4 pg/mL). Interleukin 6 and Fas had no effect. Culture supernatants from LPS- and TNF-alpha-stimulated PMNs also resulted in significant increases (P<.005) in macrovascular and microvascular endothelial cell proliferation and tubule formation. Adding anti-human VEGF-neutralizing polyclonal antibody to stimulated PMN supernatant inhibited these effects. Total VEGF release following cell lysis and Western blot analysis suggests that the VEGF is released from an intracellular store.

CONCLUSION

Activated human PMNs are directly angiogenic by releasing VEGF, and this has important implications for inflammation, capillary leak syndrome, wound healing, and tumor growth.

Dopamine induces neutrophil apoptosis through a dopamine D-1 receptor-independent mechanism

BACKGROUND

For the normal resolution of an acute inflammatory response, neutrophil (PMN) apoptosis is essential to maintain immune homeostasis and to limit inappropriate host tissue damage. A delay in PMN apoptosis has been implicated in the pathogenesis of the systemic inflammatory response syndrome (SIRS). Dopamine, a biogenic amine with known cardiovascular and neurotransmitter properties, is used in patients with SIRS to maintain hemodynamic stability. We sought to determine whether dopamine may also have immunoregulatory properties capable of influencing PMN apoptosis, function, and activation state in patients with SIRS.

METHODS

PMNs were isolated from healthy volunteers and patients with SIRS and treated with varying doses of dopamine and a dopamine D-1 receptor agonist, fenoldopam. PMN apoptosis was assessed every 6 hours with use of propidium iodide DNA staining and PMN function was assessed with use of respiratory burst activity, phagocytosis ability, and CD11a, CD11b, and CD18 receptor expression as functional markers.

RESULTS

There was a significant delay in PMN apotosis in patients with SIRS compared with controls. Treatment of isolated PMNs from both healthy controls and patients with SIRS with 10 and 100 mumol/L dopamine induced apoptosis. PMN ingestive and cytocidal capacity were both decreased in patients with SIRS compared with controls. Treatment with dopamine significantly increased phagocytic function. Fenoldopam did not induce PMN apoptosis.

CONCLUSION

Our data demonstrate for the first time that dopamine induces PMN apoptosis and modulates PMN function both in healthy controls and in patients with SIRS. These results indicate that dopamine may be beneficial during SIRS through a nonhemodynamic PMN-dependent proapoptotic mechanism.

Responsibilities, roles & staffing patterns of nurse practitioners in the neonatal intensive care unit

PURPOSE

To describe the unique contribution of the NP in caring for critically ill infants through the study of NP responsibilities, roles, staffing patterns, and patient profiles.

DESIGN

This prospective descriptive study was conducted in conjunction with a regional multi-site outcomes study.

METHODS

Data were collected at five regional level II/III NICUs in Massachusetts and Rhode Island. Twenty-two NPs were surveyed. Existing data on outcomes of 2,146 very low birth weight infants were used to describe patient profiles. NP care was defined as assignment to an NP at admission. Illness severity was measured using the Score of Neonatal Acute Physiology (SNAP).

RESULTS

NP roles included all levels of NICU care as well as antepartal consultation, delivery room management, transport, and outpatient follow-up. NPs were equally involved with patients of all degrees of complexity and birthweights. Patient assignments were most often made by a rotational system with the resident/fellow or by complexity of infant with the NP in some NICUs caring for sicker smaller babies.

CLINICAL IMPLICATIONS

This study documents a blended model of NP MD care in the NICU with each provider bringing unique strengths to the team. Nurse practitioners working in the NICU provide an invaluable contribution in terms of parent support and teaching, post NICU follow-up care, and professional education and research. The NP role in the NICU should not be viewed as a substitution for resident physicians.

Preclinical and clinical studies of MMP inhibitors in cancer

The role of matrix metalloproteinases in tumor angiogenesis and growth is now well recognized for models of both human and animal cancer. Clinical studies currently under way with the prototype matrix metalloproteinase inhibitor, marimastat, will establish whether inhibitors of these enzymes are of benefit in the treatment of different types of human cancer. On chronic therapy in humans, marimastat induces a reversible tendinitis that can also be detected in certain animal species. This paper compares the ability of broad-spectrum and various types of selective matrix metalloproteinase inhibitors to induce tendinitis and to exhibit anticancer effects in an animal cancer model. Under conditions in which both systemic exposure and inhibitor potency are controlled, selective inhibitors are less pro-tendinitic, but are weaker anticancer agents than broad-spectrum agents such as marimastat. The clinical relevance of these findings is discussed.

Acute renal failure in the newborn

Newborns at risk for acute renal failure require immediate diagnosis and treatment. Supportive care must be provided while the kidney heals and begins functioning again. The critical care nurse plays a vital role in early recognition and treatment of signs and symptoms of acute renal failure. As technology improves, a greater number of acutely ill newborns are surviving. The critical care nurse is managing more neonates with acute renal failure. Expertise in caring for these infants has also improved. Quality nursing care plays a crucial role in preventing complications and improving the prognosis of neonates with renal failure.

Acute renal failure in the newborn

Newborns at risk for acute renal failure require immediate diagnosis and treatment. Supportive care must be provided while the kidney heals and begins functioning again. The critical care nurse plays a vital role in early recognition and treatment of signs and symptoms of acute renal failure. As technology improves, a greater number of acutely ill newborns are surviving. The critical care nurse is managing more neonates with acute renal failure. Expertise in caring for these infants has also improved. Quality nursing care plays a crucial role in preventing complications and improving the prognosis of neonates with renal failure.

BB-10010: an active variant of human macrophage inflammatory protein-1 alpha with improved pharmaceutical properties

The stem cell inhibitor, macrophage inflammatory protein-1 alpha (MIP-1 alpha) or LD78, protects multipotent hematopoietic progenitors in murine models from the cytotoxic effects of chemotherapy. Clinical use of human MIP-1 alpha during chemotherapy could therefore lead to faster hematologic recovery and may allow dose intensification. We have also shown that human MIP-1 alpha causes the rapid mobilization of hematopoietic cells, suggesting an additional clinical use in peripheral blood stem cell transplantation. However, the clinical evaluation of human MIP-1 alpha is complicated by its tendency to associate and form high molecular weight polymers. We have produced a variant of rhMIP-1 alpha, BB-10010, carrying a single amino acid substitution of Asp26 > Ala, with a reduced tendency to form large polymers at physiologic pH and ionic strength. This greatly increases its solubility, facilitating its production and clinical formulation. We confirmed the potency of BB-10010 as a human MIP-1 alpha-like agonist in receptor binding, calcium mobilization, inhibition of colony formation, and thymidine suicide assays. The myeloprotective activity of BB-10010 was shown in a murine model of repeated chemotherapy using hydroxyurea. BB-10010 is therefore an ideal variant with which to evaluate the therapeutic potential of recombinant human MIP-1 alpha.

Mobilization of early hematopoietic progenitor cells with BB-10010: a genetically engineered variant of human macrophage inflammatory protein-1 alpha

BB-10010 is a genetically engineered variant of human macrophage inflammatory protein-1 alpha with improved solution properties. We show here that it mobilizes stem cells into the peripheral blood. We investigated the mobilizing effects of BB-10010 on the numbers of circulating 8-day spleen colony-forming units (CFU-S8), CFU-S12, and progenitors with marrow repopulating ability (MRA). A single subcutaneous dose of BB-10010 caused a twofold increase in circulating numbers of CFU-S8, CFU-S12, and MRA 30 minutes after dosing. We also investigated the effects of granulocyte colony-stimulating factor (G-CSF) and the combination of G-CSF with BB-10010 on progenitor mobilization. Two days of G-CSF treatment increased circulating CFU-S8, CFU-S12, and MRA progenitors by 25.7-, 19.8-, and 27.7-fold. A single administration of BB-10010 after 2 days of G-CSF treatment increased circulating CFU-S8, CFU-S12, and MRA even further to 38-, 33-, and 100-fold. Splenectomy resulted in increased circulating progenitor numbers but did not change the pattern of mobilization. Two days of treatment with G-CSF then increased circulating CFU-S8, CFU-S12, and MRA by 64-, 69-, and 32-fold. A single BB-10010 administration after G-CSF treatment further increased them to 85-, 117-, and 140-fold, respectively, compared with control. We conclude that BB-10010 causes a rapid increase in the number of circulating hematopoietic progenitors and further enhances the numbers induced by pretreatment with G-CSF. BB-10010 preferentially mobilized the more primitive progenitors with marrow repopulating activity, releasing four times the number achieved with G-CSF alone. Translated into a clinical setting, this improvement in progenitor cell mobilization may enhance the efficiency of harvest and the quality of grafts for peripheral blood stem cell transplantation.

Grating induction: a new explanation for stationary phantom gratings

The magnitude of brightness variations within test fields of grating induction and phantom grating type displays was measured using a pointwise brightness matching paradigm. A range of test field luminances was sampled which encompassed those reported to give rise to both in-phase phantom and counterphase induced gratings. Results from four observers failed to reveal the existence of stationary "in phase" phantom gratings: at all test field luminances the spatial phase of brightness modulations was consistently opposite to that of the inducing grating. At low or high test field luminances, however, test field luminance matches to the bright or dark half-cycles of induced gratings approximate the luminances of the troughs or peaks of the dark or bright half-cycles of the inducing gratings, respectively. Thus, at low test field luminances the dark half-cycle of the inducing grating may appear to continue across the dark test field, and similarly, at high test field luminances the bright half-cycle may appear continuous with the bright test field. Previously misidentified as being "in-phase" with the inducing grating, the appearance of "phantoms" is suggested to arise due to the apparent brightness continuity of these induction-produced half-cycles of the induced grating across the test field.

At risk for infection: the very-low-birth-weight infant

The very-low-birth-weight (VLBW) infant is at high risk for developing infection during the antenatal, prenatal, and postnatal periods. The six major predisposing factors are perinatal infections, an immature immune system, decreased natural defenses, disease states and disorders leading to infection, side effects of medication, and prolonged hospitalization and iatrogenic complications of lifesaving therapies. Quality nursing care plays a crucial role in recognizing signs and symptoms of sepsis and facilitating a timely diagnostic evaluation. Prevention, prompt diagnosis, and treatment will reduce the high morbidity and mortality rates associated with sepsis in the VLBW infant.