Research article
The Adnectin CT-322 is a novel VEGF receptor 2 inhibitor that decreases tumor burden in an orthotopic mouse model of pancreatic cancer
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* Corresponding author: Rolf A Brekken rolf.brekken@utsouthwestern.edu
1 Division of Surgical Oncology, Department of Surgery, University of Texas Southwestern Medical School, Dallas, TX 75390-8593, USA
2 Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical School, Dallas, TX 75390-8593, USA
3 Adnexus, a Bristol-Myers Squibb Company, Waltham, MA 02453, USA
4 Department of Pharmacology, University of Texas Southwestern Medical School, Dallas, TX 75390-8593, USA
BMC Cancer 2008, 8:352 doi:10.1186/1471-2407-8-352
Published: 27 November 2008Abstract
Background
Pancreatic cancer continues to have a 5-year survival of less than 5%. Therefore, more effective therapies are necessary to improve prognosis in this disease. Angiogenesis is required for tumor growth, and subsequently, mediators of angiogenesis are attractive targets for therapy. Vascular endothelial growth factor (VEGF) is a well-characterized mediator of tumor angiogenesis that functions primarily by binding and activating VEGF receptor 2 (VEGFR2). In this study, we evaluate the use of CT-322, a novel biologic (Adnectin). This small protein is based on a human fibronectin domain and has beneficial properties in that it is fully human, stable, and is produced in bacteria. CT-322 binds to and inhibits activation of VEGFR2.
Methods
The efficacy of CT-322 was evaluated in vivo using two orthotopic pancreatic tumor models. The first model was a human tumor xenograft where MiaPaCa-2 cells were injected into the tail of the pancreas of nude mice. The second model was a syngeneic tumor using Pan02 cells injected into pancreas of C57BL/6J mice. In both models, therapy was initiated once primary tumors were established. Mice bearing MiaPaCa-2 tumors were treated with vehicle or CT-322 alone. Gemcitabine alone or in combination with CT-322 was added to the treatment regimen of mice bearing Pan02 tumors. Therapy was given twice a week for six weeks, after which the animals were sacrificed and evaluated (grossly and histologically) for primary and metastatic tumor burden. Primary tumors were also evaluated by immunohistochemistry for the level of apoptosis (TUNEL), microvessel density (MECA-32), and VEGF-activated blood vessels (Gv39M).
Results
Treatment with CT-322 was effective at preventing pancreatic tumor growth and metastasis in orthotopic xenograft and syngeneic models of pancreatic cancer. Additionally, CT-322 treatment increased apoptosis, reduced microvessel density and reduced the number of VEGF-activated blood vessels in tumors. Finally, CT-322, in combination with gemcitabine was safe and effective at controlling the growth of syngeneic pancreatic tumors in immunocompetent mice.
Conclusion
We conclude that CT-322 is an effective anti-VEGFR2 agent and that further investigation of CT-322 for the treatment of pancreatic cancer is warranted.