Type III TGF-β receptor downregulation generates an immunotolerant tumor microenvironment.

We are interested in understanding the mechanisms that cancers have evolved to suppress the generation of tumor antigen-specific immune responses and how this knowledge can be exploited for the development of novel and more effective cancer immunotherapy strategies. This work involves the utilization of both autochthonous transgenic tumor model systems as well as clinical specimens to develop novel strategies to enhance the efficacy of immunotherapies while also developing predictive biomarkers to better guide the management of cancer patients with these agents. We strive to translate our understanding of the fundamental biochemical and metabolic pathways within the tumor microenvironment that are critical for driving immune evasion and resistance into early phase clinical trial testing.

Our work utilizes a variety of techniques and methodologies that span the breadth of basic biological research. This work integrates studies based on both 1) transgenic mouse tumor models that are monitored using bioluminescence and micro-CT imaging and 2) a variety of clinical specimens.

Our current areas of focus include:

1. Investigating mechanisms of adaptive or acquired immunotherapy resistance in cancer
2. Studying the relationship between EMT pathways and immunotherapy resistance.
3. Elucidating mechanisms of dendritic cell tolerization in the tumor microenvironment and how these processes may contribute to immunotherapy resistance
4. Development of novel pharmacologic and genetic strategies to overcome immunotherapy resistance
5. Investigating mechanisms contributing to select immunotherapy-associated toxicities

Dr. Beasley is an associate professor of surgery in the division of Surgical Oncology at Duke University with a secondary appointment as associate professor in the department of medicine.  After playing 3 years in the women’s NBA, she began medical school. She obtained her MD (2008) and Masters of Health Science in clinical research (2010) from Duke University School of Medicine.  She then completed general surgical residency at Duke University in 2015, during which time she was awarded a traineeship under a long-standing Surgical Oncology T32 grant. She then completed a fellowship in complex surgical oncology at the Ohio State University in 2017. She returned to Duke in 2017 as a faculty member. In 2019, she became co-director of the Duke Melanoma Program.

Dr. Beasley is a surgeon scientist with active involvement in clinical and translational research. Her main clinical and research interests include immunologic aspects of melanoma including oncolytic viral therapy.  She is principal investigator of over 10 therapeutic clinical trials in melanoma including novel intratumoral therapies. Her research focuses on the role of innate immunity in the anti-tumor response. She has authored over 100 publications centered on melanoma. She has received multiple internal and external funding including the Society of Surgical Oncology’s Young Investigator Award, NIH K08 mentored physician scientist award, and Melanoma Research Alliance Grant..  Most recently she was selected to Duke Medical School’s Alpha Omega Alpha and received the American Society for Clinical Investigation Young Physician-Scientist Award.

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

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.