A phase I study of ABT-510 plus bevacizumab in advanced solid tumors.

Our laboratory focuses on transforming growth factor-ß (TGF-ß) superfamily signal transduction pathways, and specifically, the role of these pathways in cancer biology. The TGF-ß superfamily is comprised of a number of polypeptide growth factors, including TGF-βs, bone morphogenetic proteins (BMPs) and activin) that regulate growth, differentiation and morphogenesis in a cell and context specific manner. TGF-ß and the TGF-ß signaling pathway have a dichotomous role in cancer biology, as both tumor-suppressor genes (presumably as regulators of cellular proliferation, differentiation and apoptosis) and as tumor promoters (presumably as regulators of cellular motility, adhesion, angiogenesis and the immune system). This dichotomy of TGF-ß function remains a fundamental problem in the field both in terms of understanding the mechanism of action of the TGF-ß pathway, and directly impacting our ability to target this pathway for the chemoprevention or treatment of human cancers. Resistance to the tumor suppressor effects of TGF-ß is also a common feature of epithelial-derived human cancers (breast, colon, lung, pancreatic, prostate), however, mechanisms for TGF-ß resistance remain undefined in the majority of cases. TGF-ß regulates cellular processes by binding to three high affinity cell surface receptors, the type I, type II, and type III receptors. Recent studies by our laboratory and others have established the type III TGF-ß receptor (TßRIII)  as a critical mediator/regulator of TGF-ß signaling. Specifically we have demonstrated that regulating TßRIII expression levels is sufficient to regulate TGF-ß signaling, and that decreased TßRIII expression is a common phenomenon in human cancers, resulting in cancer progression. TßRIII is also shed from the surface to generate soluble TßRIII, which we have demonstrated has a role in creating an immunotolerant tumor microenvironment. The role of TßRIII and soluble TßRIII in the tumor immune microenvironment is currently being investigated using a multidisciplinary approach.

Activin receptor-like kinase 4 (ALK4) is a type I transforming growth factor-β (TGF-β) superfamily receptor that mediates signaling for several TGF-β superfamily ligands, including activin, Nodal and GDF5. We have demonstrated that mutation or copy number loss of ALK4 occurs in 35% of pancreatic cancer patients, with loss of ALK4 expression associated with a poorer prognosis. ALK4 has also been identified in an unbiased screen as a gene whose disruption enhances Ras mediated pancreatic tumorigenesis in vivo. We have demonstrated that loss of ALK4 expression increases canonical TGF-β signaling to increase cancer invasion and metastasis in vivo. We are currently investigating the mechanism by which loss of ALK4 regulates TGF-β signaling, how it may effect other signaling pathways, and how to use this knowledge to treat pancreatic cancer patients with loss of ALK4 function.

We are studying the use of immune therapies to treat various cancers, including gastrointestinal, breast, and lung cancers and melanoma. These therapies include vaccines based on dendritic cells developed in our laboratory as well as vaccines based on peptides, viral vectors, and DNA plasmids. Our group is also a national leader in the development and use of laboratory assays for demonstrating immunologic responses to cancer vaccines. Finally, we are developing immunotherapies based on adoptive transfer of tumor and viral antigen-specific T cells.

Our current clinical trials include phase I and II studies of immunotherapy for: patients with metastatic malignancies expressing CEA, pancreatic cancer, colorectal cancer, breast cancer, and ovarian cancer, and leukemias following HSCT. My clinical area of expertise is in gastrointestinal oncology, in particular, the treatment of hepatic malignancies, and malignant melanoma.

Key words: dendritic cells, immunotherapy, vaccines, T cells, gastrointestinal oncology, melanoma, hepatoma

Andrew Nixon, PhD, MBA (Professor of Medicine) is Director of the Phase I Biomarker Laboratory, which brings together clinical, translational and basic research to pursue the development of novel biomarkers defining mechanisms of sensitivity, resistance, and toxicity to given therapeutic drug classes, particularly anti-angiogenic agents. Additionally, the laboratory has been appointed as a Molecular Reference Laboratory for the Alliance oncology cooperative group, a national clinical trial research group sponsored by the National Cancer Institute. The laboratory has quality control procedures in place to address many of the issues involved in clinical trial research including determination of sample quantity, sample integrity, and sample heterogeneity. We have spent considerable time developing robust assays that utilize limited amounts of specimen while providing high quality data. Multiplex ELISA and gene expression arrays are used to analyze serially collected blood and paraffin samples archived from cancer patient clinical trials. This work has the potential to improve the efficacy and toxicity of current therapies and to guide the development of the next generation of anti-angiogenesis therapies for cancer and other diseases.

Classification and Predictive Models
Design and Analysis of Biomarker Clinical Trials
Genomics
Pathway Analysis