POS0495 CYTOKINE SYNERGY ENHANCES SYNOVIAL FIBROBLAST ACTIVATION IN CHILDREN WITH DOWN’S SYNDROME-ASSOCIATED ARTHRITIS

Background

We have previously shown that children with Down’s syndrome-associated arthritis (DA) display a more aggressive form of inflammatory arthritis compared to that of Juvenile Idiopathic Arthritis (Shih et al., 2019). DA is associated with an increase in polyfunctional T-cells coexpressing TNF-α DA is associated with an increase in polyfunctional T-cells coexpressing TNF-fibroblasts (FLS) (Foley et al., 2019).

Objectives

In this study we examine the effect of cytokine synergy on primary DA FLS function.

Methods

Primary DA FLS were cultured and stimulated with TNF-α (0.1 and 1ng/ml), IL-17A (20 and 50ng/ml), IFN-ɣ (10 and 50ng/ml) and GM-CSF (20 and 100ng/ml) or a combination of these cytokines and the following functional experiments performed. Chemokine and adhesion molecule cell surface expression were quantified by flow cytometry, in addition to quantification of leukocyte-DA-FLS adhesion assays. Gene and protein expression of proinflammatory and metabolic mediators were quantified by ELISA and RT-PCR. Furthermore, real-time metabolic activity in response to cytokine stimulation was assessed by measuring the two major energy pathways: glycolysis (ECAR) and oxidative phosphorylation (OCR), by the Seahorse XFe96 Analyser.

Results

We examined the effects of T cell derived cytokines, TNF-α, IL-17A, IFN-γ and GM-CSF, alone and in combination on DA FLS function. TNF-α, IL-17A and IFN-γ induced IL-6, RANTES and MCP-1 production, with no effect observed for GM-CSF. Furthermore, TNF-α, IFN-ɣ and IL-17A increased leukocyte adhesion to DA FLS. TNF-α and IFN-ɣ induced cell surface expression of CXCR3, CXCR4, ICAM-1 and VCAM-1 on DA FLS. Next, we investigated the potential synergistic relationship that these cytokines could have on proinflammatory mediators. IL-17A and IFN-ɣ potentiated the effects TNF-α on IL-6 and MCP-1 secretion compared to stimulation alone. Furthermore, cytokine synergy significantly induced IL-6, IL-8, RANTES and LDHA mRNA expression compared to basal. IL-17A and IFN-αL-17A and IFN- eeased ts TNF-α on IL-6 and MCP-1 secretion compared to stimulation alone. Additionally, IFN the ECAR:OCR ratio demonstrating a shift in the metabolic profile of DA FLS to glycolysis. Overall DA FLS are transformed from a quiescent metabolic state to an energetic phenotype.

Conclusion

TNF-αNF-lusion:OCR ratio demonstrating a shift in the metabolhe aggressive phenotype of DA FLS through increased cytokine, adhesion molecule and chemokine expression, which is pathways for the treatment of DA.

References

[1]Foley, C. et al. (2019) ‘Increased T cell plasticity with dysregulation of T follicular helper, T peripheral helper and T regulatory cell responses in children with JIA and Down syndrome-associated arthritis’, Arthritis & Rheumatology, pp. 0–1. doi: 10.1002/art.41150.

[2]Shih, Y. J. et al. (2019) ‘Enthesitis-related arthritis is the most common category of juvenile idiopathic arthritis in Taiwan and presents persistent active disease’, Pediatric Rheumatology. Pediatric Rheumatology. doi: 10.1186/s12969-019-0363-0.

Disclosure of Interests

None declared.

CD4 T cell dynamics shape the immune response to combination oncolytic herpes virus and BRAF inhibitor therapy for melanoma

BACKGROUND

Combination herpes simplex virus (HSV) oncolytic virotherapy and BRAF inhibitors (BRAFi) represent promising immunogenic treatments for BRAF mutant melanoma, but an improved understanding of the immunobiology of combinations is needed to improve on the benefit of immune checkpoint inhibitors (ICI).

METHODS

Using a BRAFV600E-driven murine melanoma model, we tested the immunogenicity of HSV/BRAFi in immunocompetent C57BL mice. In addition to standard FACS analysis, we used the 'Timer of Cell Kinetics and Activity' system, which can analyze the temporal dynamics of different T cell subsets. This immune data was used to inform the selection of ICI for triple combination therapy, the effects of which were then further characterized using transcriptomics.

RESULTS

Adding BRAFi treatment to HSV improved anti-tumor effects in vivo but not in vitro. Immune characterization showed HSV or dual therapy led to fewer intratumoral Treg, although with a more activated phenotype, together with more effector CD8 +T cells. Tocky analysis further showed that HSV/BRAFi dual treatment reduced the Tocky signal (reflecting engagement with cognate antigen), in both Treg and conventional subsets of CD4+, but not in CD8 +cells. However, a higher percentage of Treg than of conventional CD4 +maintained frequent engagement with antigens on treatment, reflecting a predominance of suppressive over effector function within the CD4 +compartment. The only T cell subset which correlated with a reduction in tumor growth was within Tocky signal positive conventional CD4+, supporting their therapeutic role. Targeting CD25 high, antigen-engaged Treg with a depleting anti-CD25 ICI, achieved complete cures in 100% of mice with triple therapy. Transcriptomic analysis confirmed reduction in Foxp3 on addition of anti-CD25 to HSV/BRAFi, as well as increases in expression of genes reflecting interferon signaling and cytotoxic activity.

CONCLUSIONS

Combination HSV/BRAFi is an immunogenic therapy for BRAF mutant melanoma, but cannot fully control tumors. Dual therapy results in changes in T cell dynamics within tumors, with relatively maintained antigen signaling in Treg compared with conv CD4+. Antigen-engaged CD4 +effectors correlate with tumor growth control, and depletion of Treg by addition of an anti-CD25 ICI, releasing suppression of conventional CD4 +effectors by Treg, enhances survival and activates immune signaling within tumors.

POS0069 INCREASED T CELL RESPONSES, METABOLIC ACTIVITY AND FIBROBLAST INVASIVE CAPACITY IN CHILDREN WITH DOWN’S SYNDROME-ASSOCIATED ARTHRITIS COMPARED TO JUVENILE IDIOPATHIC ARTHRITIS

Background:

Juvenile idiopathic arthritis (JIA) was thought to be the most common inflammatory arthritis in children (Shih et al., 2019). However an aggressive, erosive arthritis of little-known immunologic mechanism occurs 20 times more frequently in children with Down’s syndrome (Foley et al., 2019).

Objectives:

This study was undertaken to characterize immune cell responses and synovial fibroblast invasiveness in children with Down’s syndrome-associated arthritis (DA).

Methods:

Multiparametric flow cytometric analysis was used to examine peripheral blood T cell, B cell and monocyte populations. In addition, T cell cytokine responses and their metabolic profile in children with DA, JIA, Down’s Syndrome (trisomy 21 [T21]), and in healthy controls were assessed. The function of DA primary synovial fibroblasts (FLS) was assessed in response to stimulation with pro-inflammatory mediators alone and in combination (TNF-α, IL-17a, IFN-γ, GM-CSF). The two major energy pathways glycolysis (ECAR) and oxidative phosphorylation (OCR) were quantified by the Seahorse XFe96 Analyser. Migration, adhesion, invasion and cytokine/chemokine secretion were quantified by wound repair scratch assays, Transwell collagen invasion chambers, adhesion binding assays, and ELISAs.

Results:

T cell frequencies were higher in DA compared to JIA and T21 in contrast to B cell frequencies which were decreased. T cell responses in DA were characterized by increased frequencies of CD4+ and CD8+ TNF- α, IFN- γ and GM-CSF producing T cells. The frequency of T peripheral helper (Tph) cells were elevated in children with DA compared to all other groups. In parallel, an increase in their metabolic profile evident by higher phosphorylation of mTOR pathway components AKT, mTOR and S6. Comparison of DA and JIA FLS demonstrated that DA FLS display a more invasive/migratory capacity and are more metabolically active. Based on the increased cytokine responses in DA T cells, we next examined the effect T cell derived cytokines TNF-α, IL-17A, IFN-γ and GM-CSF alone and in combination on DA FLS function. TNF-α, IL-17a and IFN-γ induced IL-6, RANTES and MCP-1 secretion, with no effect observed for GM-CSF. Furthermore, TNF-α and IL-17A induced DA FLS migration and PBMC adhesion to DA FLS. Finally IL17A and IFN-γ potentiated the effect of TNF-α on IL-6 and MCP-1 secretion compared to stimulations alone.

Conclusion:

DA is a more common and aggressive form of arthritis compared to JIA. It is characterized by increased T cell responses and a more invasive FLS phenotype compared to that of JIA, with T cell derived cytokine alone and in combination further inducing DA FLS pathogenic mechanisms. These effects mirror the increased erosive disease observed clinically.

References:

[1]Foley, C. et al. (2019) ‘Increased T cell plasticity with dysregulation of T follicular helper, T peripheral helper and T regulatory cell responses in children with JIA and Down syndrome-associated arthritis’, Arthritis & Rheumatology, pp. 0–1. doi: 10.1002/art.41150.

[2]Shih, Y. J. et al. (2019) ‘Enthesitis-related arthritis is the most common category of juvenile idiopathic arthritis in Taiwan and presents persistent active disease’, Pediatric Rheumatology. Pediatric Rheumatology. doi: 10.1186/s12969-019-0363-0.

Disclosure of Interests:

None declared.

Vulval acne: a case series describing clinical features and management

Intermittent inflammation of the vulval pilosebaceous units is common and usually self-limiting, but some patients experience recurrent and more troublesome symptoms. There is a scarcity of information on this problem. We describe the clinical and histological features in these patients and the response to treatment. A retrospective, observational study of 16 patients with this phenomenon of recurrent, protracted folliculocentric inflammation of the vulval pilosebaceous unit was performed. Details on the clinical features, histology and response to treatment were collected. Mean age at presentation was 32 years (range 21-45). All patients reported recurrent painful papules and pustules on the labia majora and labia minora. Nine patients reported a cyclical pattern to the development of lesions, with premenstrual exacerbation being most common. Histological examination of these lesions showed a folliculocentric microabscess formation surrounded by an acute and chronic inflammatory cell infiltrate, with a focal foreign-body granulomatous reaction. All our patients responded well to tetracycline, antiandrogenic or retinoid therapy. We propose the term 'vulval acne' for this condition and propose a stepwise approach to its management. We hope to highlight this as a common but underreported entity.

SOX11 promotes epithelial/mesenchymal hybrid state and alters tropism of invasive breast cancer cells

SOX11 is an embryonic mammary epithelial marker that is normally silenced prior to birth. High SOX11 levels in breast tumours are significantly associated with distant metastasis and poor outcome in breast cancer patients. Here, we show that SOX11 confers distinct features to ER-negative DCIS.com breast cancer cells, leading to populations enriched with highly plastic hybrid epithelial/mesenchymal cells, which display invasive features and alterations in metastatic tropism when xenografted into mice. We found that SOX11+DCIS tumour cells metastasize to brain and bone at greater frequency and to lungs at lower frequency compared to cells with lower SOX11 levels. High levels of SOX11 leads to the expression of markers associated with mesenchymal state and embryonic cellular phenotypes. Our results suggest that SOX11 may be a potential biomarker for breast tumours with elevated risk of developing metastases and may require more aggressive therapies.

Combining BRAF inhibition with oncolytic herpes simplex virus enhances the immune-mediated antitumor therapy of BRAF-mutant thyroid cancer

BACKGROUND

The aggressive clinical behavior of poorly differentiated and anaplastic thyroid cancers (PDTC and ATC) has proven challenging to treat, and survival beyond a few months from diagnosis is rare. Although 30%-60% of these tumors contain mutations in the BRAF gene, inhibitors designed specifically to target oncogenic BRAF have shown limited and only short-lasting therapeutic benefits as single agents, thus highlighting the need for improved treatment strategies, including novel combinations.

METHODS

Using a BRAFV600E-driven mouse model of ATC, we investigated the therapeutic efficacy of the combination of BRAF inhibition and oncolytic herpes simplex virus (oHSV). Analyses of samples from tumor-bearing mice were performed to immunologically characterize the effects of different treatments. These immune data were used to inform the incorporation of immune checkpoint inhibitors into triple combination therapies.

RESULTS

We characterized the immune landscape in vivo following BRAF inhibitor treatment and detected only modest immune changes. We, therefore, hypothesized that the addition of oncolytic virotherapy to BRAF inhibition in thyroid cancer would create a more favorable tumor immune microenvironment, boost the inflammatory status of tumors and improve BRAF inhibitor therapy. First, we showed that thyroid cancer cells were susceptible to infection with oHSV and that this process was associated with activation of the immune tumor microenvironment in vivo. Next, we showed improved therapeutic responses when combining oHSV and BRAF inhibition in vivo, although no synergistic effects were seen in vitro, further confirming that the dominant effect of oHSV in this context was likely immune-mediated. Importantly, both gene and protein expression data revealed an increase in activation of T cells and natural killer (NK) cells in the tumor in combination-treated samples. The benefit of combination oHSV and BRAF inhibitor therapy was abrogated when T cells or NK cells were depleted in vivo. In addition, we showed upregulation of PD-L1 and CTLA-4 following combined treatment and demonstrated that blockade of the PD-1/PD-L1 axis or CTLA-4 further improved combination therapy.

CONCLUSIONS

The combination of oHSV and BRAF inhibition significantly improved survival in a mouse model of ATC by enhancing immune-mediated antitumor effects, and triple combination therapies, including either PD-1 or CTLA-4 blockade, further improved therapy.

Combination therapy with oncolytic viruses and immune checkpoint inhibitors

Introduction: Immune checkpoint inhibitors (ICI) have dramatically improved the outcome for cancer patients across multiple tumor types. However the response rates to ICI monotherapy remain relatively low, in part due to some tumors cultivating an inherently 'cold' immune microenvironment. Oncolytic viruses (OV) have the capability to promote a 'hotter' immune microenvironment which can improve the efficacy of ICI.Areas covered: In this article we conducted a literature search through Pubmed/Medline to identify relevant articles in both the pre-clinical and clinical settings for combining OVs with ICIs and discuss the impact of this approach on treatment as well as changes within the tumor microenvironment. We also explore the future directions of this novel combination strategy.Expert opinion: The imminent results of the Phase 3 study combining pembrolizumab with or without T-Vec injection are eagerly awaited. OV/ICI combinations remain one of the most promising avenues to explore in the success of cancer immunotherapy.

ATR Inhibition Potentiates the Radiation-induced Inflammatory Tumor Microenvironment

PURPOSE

ATR inhibitors (ATRi) are in early phase clinical trials and have been shown to sensitize to chemotherapy and radiotherapy preclinically. Limited data have been published about the effect of these drugs on the tumor microenvironment.Experimental Design: We used an immunocompetent mouse model of HPV-driven malignancies to investigate the ATR inhibitor AZD6738 in combination with fractionated radiation (RT). Gene expression analysis and flow cytometry were performed posttherapy.

RESULTS

Significant radiosensitization to RT by ATRi was observed alongside a marked increase in immune cell infiltration. We identified increased numbers of CD3+ and NK cells, but most of this infiltrate was composed of myeloid cells. ATRi plus radiation produced a gene expression signature matching a type I/II IFN response, with upregulation of genes playing a role in nucleic acid sensing. Increased MHC I levels were observed on tumor cells, with transcript-level data indicating increased antigen processing and presentation within the tumor. Significant modulation of cytokine gene expression (particularly CCL2, CCL5, and CXCL10) was found in vivo, with in vitro data indicating CCL3, CCL5, and CXCL10 are produced from tumor cells after ATRi + RT.

CONCLUSIONS

We show that DNA damage by ATRi and RT leads to an IFN response through activation of nucleic acid-sensing pathways. This triggers increased antigen presentation and innate immune cell infiltration. Further understanding of the effect of this combination on the immune response may allow modulation of these effects to maximize tumor control through antitumor immunity.

Impaired calcineurin signaling in myeloid cells results in downregulation of pentraxin-3 and increased susceptibility to aspergillosis

Treatment of post-transplant patients with immunosuppressive drugs targeting the calcineurin-nuclear factor of activated T cells (NFAT) pathway, including cyclosporine A or tacrolimus, is commonly associated with a higher incidence of opportunistic infections, such as Aspergillus fumigatus, which can lead to severe life-threatening conditions. A component of the A. fumigatus cell wall, β-glucan, is recognized by dendritic cells (DCs) via the Dectin-1 receptor, triggering downstream signaling that leads to calcineurin-NFAT binding, NFAT translocation, and transcription of NFAT-regulated genes. Here, we address the question of whether calcineurin signaling in CD11c-expressing cells, such as DCs, has a specific role in the innate control of A. fumigatus. Impairment of calcineurin in CD11c-expressing cells (CD11c^crecnb1^loxP) significantly increased susceptibility to systemic A. fumigatus infection and to intranasal infection in irradiated mice undergoing bone marrow transplant. Global expression profiling of bone marrow-derived DCs identified calcineurin-regulated processes in the immune response to infection, including expression of pentraxin-3, an important antifungal defense protein. These results suggest that calcineurin inhibition directly impairs important immunoprotective functions of myeloid cells, as shown by the higher susceptibility of CD11c^crecnb^loxP mice in models of systemic and invasive pulmonary aspergillosis, including after allogeneic bone marrow transplantation. These findings are relevant to the clinical management of transplant patients with severe Aspergillus infections.

Vessel co-option is common in human lung metastases and mediates resistance to anti-angiogenic therapy in preclinical lung metastasis models

Anti‐angiogenic therapies have shown limited efficacy in the clinical management of metastatic disease, including lung metastases. Moreover, the mechanisms via which tumours resist anti‐angiogenic therapies are poorly understood. Importantly, rather than utilizing angiogenesis, some metastases may instead incorporate pre‐existing vessels from surrounding tissue (vessel co‐option). As anti‐angiogenic therapies were designed to target only new blood vessel growth, vessel co‐option has been proposed as a mechanism that could drive resistance to anti‐angiogenic therapy. However, vessel co‐option has not been extensively studied in lung metastases, and its potential to mediate resistance to anti‐angiogenic therapy in lung metastases is not established. Here, we examined the mechanism of tumour vascularization in 164 human lung metastasis specimens (composed of breast, colorectal and renal cancer lung metastasis cases). We identified four distinct histopathological growth patterns (HGPs) of lung metastasis (alveolar, interstitial, perivascular cuffing, and pushing), each of which vascularized via a different mechanism. In the alveolar HGP, cancer cells invaded the alveolar air spaces, facilitating the co‐option of alveolar capillaries. In the interstitial HGP, cancer cells invaded the alveolar walls to co‐opt alveolar capillaries. In the perivascular cuffing HGP, cancer cells grew by co‐opting larger vessels of the lung. Only in the pushing HGP did the tumours vascularize by angiogenesis. Importantly, vessel co‐option occurred with high frequency, being present in >80% of the cases examined. Moreover, we provide evidence that vessel co‐option mediates resistance to the anti‐angiogenic drug sunitinib in preclinical lung metastasis models. Assuming that our interpretation of the data is correct, we conclude that vessel co‐option in lung metastases occurs through at least three distinct mechanisms, that vessel co‐option occurs frequently in lung metastases, and that vessel co‐option could mediate resistance to anti‐angiogenic therapy in lung metastases. Novel therapies designed to target both angiogenesis and vessel co‐option are therefore warranted. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Abstract 4105: Dissecting the mechanisms of hepatocyte replacement in breast cancer liver metastases

The liver is a common site of metastasis in metastatic breast cancer and is associated with significant mortality. Histopathological examination of human breast cancer liver metastases (BCLMs) reveals that the majority of these tumours present with a ‘replacement growth pattern.’ In this growth pattern, the breast cancer cells freely invade the liver parenchyma and replace the resident hepatocytes. In advanced BCLMs, breast cancer cells can eventually replace a significant volume of the liver parenchyma which, ultimately, leads to organ failure and death. However, the mechanism through which breast cancer cells replace the resident hepatocytes is unknown.

Here we set out to establish how this replacement of hepatocytes by breast cancer cells occurs in BCLMs. To do so, we established two in vivo models of advanced BCLM: (a) an ER+PR+HER2- model using the MCF7 cell line, and (b) a triple negative patient-derived xenograft model using breast cancer cells isolated from a pleural effusion. We have also established an in vitro co-culture system, where MCF7 cells are co-cultured with HepG2 cells, which is designed to mimic the breast cancer cell-hepatocyte interaction observed in vivo.

Both in vivo models exhibit a histology that closely mimics the replacement growth pattern of human BCLMs, where breast cancer cells replace hepatocytes at the tumour-liver interface. To address whether hepatocytes are killed by adjacent breast cancer cells in vivo, we evaluated hepatocyte death by apoptosis using appropriate markers (cleaved-PARP and cleaved-caspase-3). Surprisingly, although extensive apoptotic death of breast cancer cells in the tumour mass could be observed, no evidence for apoptotic death of hepatocytes could be found. However, we observed extensive cell-in-cell invasion at the tumour-liver interface, where live breast cancer cells enter the cytoplasm of adjacent hepatocytes. We also observe a similar process of cell-in-cell invasion within in vitro cultures of MCF-7 cells with HepG2 cells.

Although cell-in-cell invasion has been described as a mechanism of non-apoptotic cell death in breast cancer cells, the role of cell-in-cell invasion between breast cancer cells and hepatocytes in BCLMs has not been investigated. Our current studies are focused in two areas: (a) we are using intra-vital microscopy and time-lapse microscopy to investigate whether cell-in-cell invasion between breast cancer cells and hepatocytes mediates non-apoptotic death of hepatocytes both in vivo and in vitro, and (b) we are investigating the molecular mechanisms that mediate cell-in-cell invasion between breast cancer cells and hepatocytes.

In conclusion, we present preliminary evidence for a novel mechanism via which breast cancer cells could replace hepatocytes in BCLMs. Further studies aimed at elucidating the molecular basis of this mechanism may reveal novel targets for preventing the replacement of the liver parenchyma by metastatic breast cancer cells.

Citation Format: Mark R. Nathan, Lefteris Kostaras, Victoria Bridgeman, Shane Foo, Peter Vermeulen, Andrew Reynolds. Dissecting the mechanisms of hepatocyte replacement in breast cancer liver metastases. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4105.

The Initiator Methionine tRNA Drives Secretion of Type II Collagen from Stromal Fibroblasts to Promote Tumor Growth and Angiogenesis

Expression of the initiator methionine tRNA (tRNAi(Met)) is deregulated in cancer. Despite this fact, it is not currently known how tRNAi(Met) expression levels influence tumor progression. We have found that tRNAi(Met) expression is increased in carcinoma-associated fibroblasts, implicating deregulated expression of tRNAi(Met) in the tumor stroma as a possible contributor to tumor progression. To investigate how elevated stromal tRNAi(Met) contributes to tumor progression, we generated a mouse expressing additional copies of the tRNAi(Met) gene (2+tRNAi(Met) mouse). Growth and vascularization of subcutaneous tumor allografts was enhanced in 2+tRNAi(Met) mice compared with wild-type littermate controls. Extracellular matrix (ECM) deposited by fibroblasts from 2+tRNAi(Met) mice supported enhanced endothelial cell and fibroblast migration. SILAC mass spectrometry indicated that elevated expression of tRNAi(Met) significantly increased synthesis and secretion of certain types of collagen, in particular type II collagen. Suppression of type II collagen opposed the ability of tRNAi(Met)-overexpressing fibroblasts to deposit pro-migratory ECM. We used the prolyl hydroxylase inhibitor ethyl-3,4-dihydroxybenzoate (DHB) to determine whether collagen synthesis contributes to the tRNAi(Met)-driven pro-tumorigenic stroma in vivo. DHB had no effect on the growth of syngeneic allografts in wild-type mice but opposed the ability of 2+tRNAi(Met) mice to support increased angiogenesis and tumor growth. Finally, collagen II expression predicts poor prognosis in high-grade serous ovarian carcinoma. Taken together, these data indicate that increased tRNAi(Met) levels contribute to tumor progression by enhancing the ability of stromal fibroblasts to synthesize and secrete a type II collagen-rich ECM that supports endothelial cell migration and angiogenesis.

Preclinical Evidence That Trametinib Enhances the Response to Antiangiogenic Tyrosine Kinase Inhibitors in Renal Cell Carcinoma

Sunitinib and pazopanib are antiangiogenic tyrosine kinase inhibitors (TKI) used to treat metastatic renal cell carcinoma (RCC). However, the ability of these drugs to extend progression-free and overall survival in this patient population is limited by drug resistance. It is possible that treatment outcomes in RCC patients could be improved by rationally combining TKIs with other agents. Here, we address whether inhibition of the Ras-Raf-MEK-ERK1/2 pathway is a rational means to improve the response to TKIs in RCC. Using a xenograft model of RCC, we found that tumors that are resistant to sunitinib have a significantly increased angiogenic response compared with tumors that are sensitive to sunitinib in vivo. We also observed significantly increased levels of phosphorylated ERK1/2 in the vasculature of resistant tumors, when compared with sensitive tumors. These data suggested that the Ras-Raf-MEK-ERK1/2 pathway, an important driver of angiogenesis in endothelial cells, remains active in the vasculature of TKI-resistant tumors. Using an in vitro angiogenesis assay, we identified that the MEK inhibitor (MEKI) trametinib has potent antiangiogenic activity. We then show that, when trametinib is combined with a TKI in vivo, more effective suppression of tumor growth and tumor angiogenesis is achieved than when either drug is utilized alone. In conclusion, we provide preclinical evidence that combining a TKI, such as sunitinib or pazopanib, with a MEKI, such as trametinib, is a rational and efficacious treatment regimen for RCC.

Abstract 2997: Vessel co-option in colorectal cancer liver metastases mediates resistance to VEGF-targeted therapy

The purpose of this study is to: (1) examine whether vessel co-option is associated with a lack of response to anti-angiogenic therapy in advanced colorectal cancer patients, (2) identify whether inhibition of pathways associated with vessel co-option sensitizes to anti-angiogenic therapy in vivo.

Sprouting angiogenesis is the process whereby new blood vessels are induced to sprout from existing vessels. The growth of metastatic tumors is considered to require sprouting angiogenesis. This hypothesis has driven the development and clinical application of vascular endothelial growth factor (VEGF) targeted agents, such as bevacizumab. However, responses to such agents in cancer patients, including metastatic colorectal cancer (CRC), are variable. It is not currently clear why this is the case and we have no way of selecting patients suitable for such therapies.

Importantly, it is now evident that tumors can also utilize a number of putative ‘VEGF-independent’ angiogenesis mechanisms, the existence of which may limit the efficacy of VEGF-targeted therapy. One such mechanism is ‘vessel co-option,’ whereby tumors engulf existing local blood vessels as they invade into surrounding host tissue. Published studies have reported that this mechanism occurs in ∼28-30% of CRC liver metastases.

Here we present data from a retrospective study of patients with CRC liver metatases that were treated with bevacizumab. We demonstrate that, in this patient cohort, the presence of vessel co-option in liver metastases was strongly associated with lack of response to bevacizumab. We also show that a similar result is observed in a mouse model of colorectal cancer liver metastasis. Interestingly, when we disable actin nucleation activity in colorectal cancer cells, vessel co-option is compromised and sensitivity to VEGF-targeted therapy is restored in vivo. These data demonstrate a potential role for vessel co-option as a negative predictive biomarker for anti-angiogenic therapy and also have consequences for the development of novel therapies for targeting tumor angiogenesis.

Citation Format: Sophia Frentzas, Victoria L. Thompson, Peter B. Vermeulen, Shane Foo, Gina Brown, David Cunningham, Andrew R. Reynolds. Vessel co-option in colorectal cancer liver metastases mediates resistance to VEGF-targeted therapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2997. doi:10.1158/1538-7445.AM2014-2997

'It's effective but should I bother?' A study of personal protection measures against Malaria in urban India

OBJECTIVES

Malaria affects millions of people in urban and rural India every year. This study addresses two main gaps in current research: 1) attitudes towards personal protective strategies against Malaria among urban populations; and 2) understanding of the extent to which urban health information seeking preferences shape preventive behaviours.

STUDY DESIGN

Cross-sectional face-to-face surveys using stratified sampling design.

METHODS

A 60-min survey was carried out to 1000 middle-of-pyramid (MOP) population in five main cities in India by trained interviewers. Variables assessed included perceived effectiveness and actual practice of 14 scientific and indigenous personal protection methods, Malaria-related attitudes (susceptibility, severity and response efficacy) and health information seeking preferences.

RESULTS

Actual practice of Malaria preventive behaviours was found to be significantly lower than the perceived effectiveness of each of the fourteen scientific and indigenous methods. Television, newspapers, and mobile phones were reported as the top three preferred media for seeking public health information. Lastly, perceived susceptibility, response efficacy, and health-related media use were found to play significant roles in predicting actual practice behaviours.

CONCLUSIONS

Our study highlights a need for health authorities to focus on translating positive attitudes to actual practice of preventive behaviours. Communication efforts may focus on the use of TV, newspapers and mobile phones for greater reach and efficacy. Other implications for Malaria prevention programs are discussed.

Sequestrated meningocoele within a naevus sebaceous of Jadassohn on the scalp of a child

Sequestrated meningocoele is an uncommon developmental anomaly in which meningothelial elements are found in the skin or subcutaneous tissue without underlying bony defect. By contrast, naevus sebaceous of Jadassohn (NSJ) is a circumscribed hamartomatous lesion occurring in about 0.3% of newborns. We report a child with a histologically confirmed sequestrated meningocoele within an NSJ on his scalp vertex. Such an occurrence has not been reported previously.

Acute stroke patients with high BMI are less likely to have severe disability at initial presentation

This is a prospective study to determine the severity of disability and prognosis of acute stroke patients related to their Body Mass index (BMI). A total of 79 consecutive CT-scan-proven acute stroke patients who were admitted to Hospital Tuanku Ja'afar, Seremban between November 2006 and April 2007 were recruited (male:female 49:30; mean age 62.7 years; ischemic stroke 70, intracerebral bleed 9). The patients were divided according to BMI less than 25 (Group A) and equal or greater than 25 (Group B). Severity of disability was measured between 24-48 hours by modified Rankin's score. Patients were followed up after one month. Thirty-seven patients had severe disability (Rankin Score 5). Twenty-nine patients had adverse outcomes including 11 deaths and 18 rehospitalizations or prolonged hospital/nursing home stay. 34.3% of Group B had severe disability compared to 56.8% of Group A (chi2 P = 0.046). Conversely 42.9% of Group B had adverse events at one month compared to 31.8% of Group A (chi2 P = 0.312). There were no statistical differences between high- and low-BMI groups for gender ratio, smoking, hypertension, diabetes, prior cardiovascular disease, mean age, mean lipid profile and blood pressure. When comparing patients with Rankin Score 1-4 versus 5, age and BMI were statistically significant between the two groups. By multivariate analysis only age is independent predictor for severe disability (P < 0.05). The results of this pilot study should be confirmed in larger prospective multicentre trial.

Identification of a histamine H4 receptor on human eosinophils--role in eosinophil chemotaxis

Eosinophils are recruited to sites of inflammation via the action of a number of chemical mediators, including PAF, leukotrienes, eotaxins, ECF-A and histamine. Although many of the cell-surface receptors for these mediators have been identified, histamine-driven chemotaxis has not been conclusively attributed to any of the three known histamine receptor subtypes, suggesting the possibility of a 4th histamine-responsive receptor on eosinophils. We have identified and cloned a novel G protein-coupled receptor (GPCR), termed Pfi-013, from an IL-5 stimulated eosinophil cDNA library which is homologous to the human histamine H3 receptor, both at the sequence and gene structure level. Expression data indicates that Pfi-013 is predominantly expressed in peripheral blood leukocytes, with lower expression levels in spleen, testis and colon. Ligand-binding studies using Pfi-013 expressed in HEK-293Galpha15 cells, demonstrates specific binding to histamine with a Kd of 3.28 +/- 0.76 nM and possesses a unique rank order of potency against known histaminergic compounds in a competitive ligand-binding assay (histamine > clobenpropit > iodophenpropit > thioperamide > R-alpha-methylhistamine > cimetidine > pyrilamine). We have therefore termed this receptor human histamine H4. Chemotaxis studies on isolated human eosinophils have confirmed that histamine is chemotactic and that agonists of the known histamine receptors (H1, H2, and H3) do not induce such a response. Furthermore, studies employing histamine-receptor antagonists have shown an inhibition of chemotaxis only by the H3 antagonists clobenpropit and thioperamide. Since these compounds are also antagonists of hH4 we postulate that the receptor mediating histaminergic chemotaxis is this novel histamine H4 receptor.

Complex partial seizures in young children

We retrospectively analyzed the clinical manifestations of complex partial seizures (CPS) in children aged < or = 10 years using video and EEG telemetry and evaluated their course, investigations, management, and seizure status at follow-up. Seventeen patients with CPS were studied at the Prince of Wales Children's Hospital (POWCH) and Prince Henry Hospital (PHH) between 1987 and 1992. Because 15 of the 17 patients had intractable seizures, the population was selective. Mean age was 6.5 years; 4 patients were aged < or = 2 years. Clinical features were normal or mild intellectual handicap (13); hemiplegia (5); and infantile spasms preceding CPS (4); of these, 2 also had simple partial motor seizures. Structural abnormalities were noted on scanning in 9 patients. Eighty-seven seizures were reviewed. Mean duration of each clinical seizure was 59.7 s (total population), 108 s (subgroup 1, aged < or = 2 years), and 48.5 s (subgroup 2, aged > 2 years). Major ictal manifestations were auras (9), staring (9), autonomic changes (6), and automatisms (17). In subgroup 1, automatisms were simple and mainly oroalimentary and gestural. Two patients had no change in surface ictal recordings, and 2 had normal interictal EEGs. At follow-up, 8 patients were seizure-free for 6 months, 1 was partially controlled (more than two seizures a month), and 8 had intractable seizures (two or more seizures a month). Seven patients underwent operation for intractable epilepsy, and 4 achieved a class 1A outcome (Engel classification).

Simplified pressure method for respirator fit testing

A simplified pressure method has been developed for fit testing air-purifying respirators. In this method, the air-purifying cartridges are replaced by a pressure-sensing attachment and a valve. While wearers hold their breath, a small pump extracts air from the respirator cavity until a steady-state pressure is reached in 1 to 2 sec. The flow rate through the face seal leak is a unique function of this pressure, which is determined once for all respirators, regardless of the respirator's cavity volume or deformation because of pliability. The contaminant concentration inside the respirator depends on the degree of dilution by the flow through the cartridges. The cartridge flow varies among different brands and is measured once for each brand. The ratio of cartridge to leakflow is a measure of fit. This flow ratio has been measured on human subjects and has been compared to fit factors determined on the same subjects by means of photometric and particle count tests. The aerosol tests gave higher values of fit.