Investigation of

the CRC primary tumor microenvironment allowed us to uncover the association of favorable outcomes with efficient coordination of the intratumoral immune response. We described four major immune coordination profiles within CRC primary tumors depending on the balance between tumor escape and immune coordination. In conclusion, the density and the immune-cell location within Cilengitide the tumor have a prognostic value that are superior of those of the TNM classifications. Tumor invasion is statistically dependent on the host immune reaction. O144 Regulation of Macrophage Function by the Tumor Microenvironment : Role of Hypoxia and Angiopoietin-2 Claire Lewis 1 , Seth Coffelt1, Craig Murdoch2 1 Department of Infection & Immunity, University of Sheffield Medical School, Sheffield, UK, 2 Department of Oral Pathology, University of Sheffield Dental School, Sheffield, UK Tumor-associated macrophages (TAMs) are abundant in virtually all types of malignant tumour. These highly versatile cells respond to the presence of stimuli in different tumour regions with the release of a distinct repertoire of growth factors, cytokines, chemokines, and enzymes that regulate tumor progression. The distinct tumour MDV3100 nmr microenvironments where TAMs are found include areas of invasion where TAMs promote tumour cell motility; stromal and peri-vascular areas where TAMs may promote metastasis;

and avascular and peri-necrotic areas where they are thought to stimulate angiogenesis. In fact, TAMs accumulate in hypoxic areas of tumours in large numbers and our most recent data show that hypoxia, necrotic debris GSK1120212 clinical trial and/or hypoxia-induced FER cytokines like angiopoietin-2 stimulate expression of important tumour-promoting genes like VEGF, EGF and IL-6 by TAMs. This may explain why high TAM density in these areas correlates with increased tumour angiogenesis and metastasis. Large areas of hypoxia and necrosis form in tumors after administration of chemotherapeutic agents, radiotherapy or drugs that disrupt the tumor vasculature.

This is often accompanied by a marked influx of macrophages into the tumor residue where they are activated to stimulate its revascularisation and re-growth. In this way, macrophages act as a powerful ally in tumor resistance and recovery. We are currently exploiting the natural ability of macrophages to migrate into to such poorly vascularised tumor areas to deliver therapeutic virus. To do this, we have developed a novel technology to genetically manipulate macrophages to synthesise and release therapeutic virus under the control of hypoxia-responsive promoter elements. This restricts viral production (and thus therapeutic gene expression in the virus) to cells in hypoxic/necrotic tumor areas. In this way, the responses of macrophages to tumor hypoxia can be exploited to deliver gene therapy to tumors.