The Adnectin CT-322 is a novel VEGF receptor 2 inhibitor that decreases tumor burden in an orthotopic mouse model of pancreatic cancer

Division of Surgical Oncology, Department of Surgery, University of Texas Southwestern Medical School, Dallas, TX 75390-8593, USA.
BMC Cancer (Impact Factor: 3.36). 12/2008; 8(1):352. DOI: 10.1186/1471-2407-8-352
Source: PubMed


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.
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).
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.
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.

Download full-text


Available from: Rolf A Brekken,

Click to see the full-text of:

Article: The Adnectin CT-322 is a novel VEGF receptor 2 inhibitor that decreases tumor burden in an orthotopic mouse model of pancreatic cancer

2.78 MB

See full-text
  • Source
    • "The inherent biophysical properties of FN3 domains and the development of strategies for stability and affinity evolution have extended the utility of the scaffold. On the basis of promising preclinical tumor xenograft studies for an anti VEGFR2-FN3 domain (Dineen, et al., 2008), the first FN3-based therapeutic has been evaluated in human patients in a Phase 1 study (Molckovsky & Siu, 2008, Sweeney, et al., 2008). Initial pharmacokinetic studies for a PEGylated anti-VEGFR2 FN3 domain dosed intravenously have demonstrated that the scaffold has a terminal half-life of ~69 hours with a maximum tolerated dose of 2 mg/kg weekly. "

    Protein Engineering, 02/2012; , ISBN: 978-953-51-0037-9
  • Source
    • "Alternative therapeutic options are urgently needed to improve the tumor response and survival. For these reasons, numerous combinations have been assessed in preclinical studies, usually using gemcitabine combined with various drugs such as fluvastatin [12] and antiangiogenic agents [13] [14] [15]. Irinotecan (CPT-11) is a standard therapeutic choice for colorectal cancer, but few phase 1 to 2 clinical studies, combining gemcitabine with irinotecan [16] [17], to treat pancreatic cancer have been undertaken; moreover, a few preclinical studies assessing single drug administration [18] [19] or its combination with GEM231, a second-generation antisense oligonucleotide [20] or TRA-8, an agonistic antibody to death receptor 5 [21], have been recently assessed in pancreas cancer. "
    [Show abstract] [Hide abstract]
    ABSTRACT: To demonstrate the synergistic antiproliferative and proapoptotic activity of irinotecan and axitinib in vitro and the improvement of the in vivo effects on angiogenesis and pancreatic cancer. Proliferation and apoptotic assays were performed on human dermal microvascular endothelial cells and pancreas cancer (MIAPaCa-2, Capan-1) cell lines exposed to SN-38, the active metabolite of irinotecan, axitinib, or their simultaneous combination for 72 hours. ERK1/2 and Akt phosphorylation, the vascular endothelial growth factor (VEGF), VEGF receptor-2, and thrombospondin-1 (TSP-1) concentration were measured by ELISAs. ATP7A and ABCG2 gene expression was performed with real-time polymerase chain reaction and SN-38 intracellular concentrations were measured by high-performance liquid chromatography. Capan-1 xenografts in nude mice were treated with irinotecan and axitinib alone or in simultaneous combination. A strong synergistic effect on antiproliferative and proapoptotic activity was found with the axitinib/SN-38 combination on endothelial and cancer cells. ERK1/2 and Akt phosphorylation were significantly inhibited by lower concentrations of the combined drugs in all the cell lines. Axitinib and SN-38 combined treatment greatly inhibited the expression of the ATP7A and ABCG2 genes in endothelial and cancer cells, increasing the SN-38 intracellular concentration. Moreover, TSP-1 secretion was increased in cells treated with both drugs, whereas VEGFR-2 levels significantly decreased. In vivo administration of the simultaneous combination determined an almost complete regression of tumors and tumor neovascularization. In vitro results show the highly synergistic properties of simultaneous combination of irinotecan and axitinib on endothelial and pancreas cancer cells, suggesting a possible translation of this schedule into the clinics.
    Neoplasia (New York, N.Y.) 03/2011; 13(3):217-29. DOI:10.1593/neo.101334 · 4.25 Impact Factor
  • Source
    • "characterization of biological efficacy in animal models (Dineen et al., 2008; Mamluk et al., 2010); "
    [Show abstract] [Hide abstract]
    ABSTRACT: Adnectins™ are a new family of therapeutic proteins based on the 10th fibronectin type III domain, and designed to bind with high affinity and specificity to therapeutically relevant targets. Adnectins share with antibody variable domains a beta-sheet sandwich fold with diversified loops, but differ from antibodies in primary sequence and have a simpler, single-domain structure without disulfide bonds. As a consequence, Adnectins bind targets with affinity and specificity as high as those of antibodies, but are easier to manipulate genetically and compatible with bacterial expression systems. Adnectins that bind macromolecular targets with nanomolar and picomolar affinity have been selected using in vitro evolution methods, including mRNA display, phage display and yeast display. CT-322, a PEGylated, anti-angiogenic Adnectin that binds vascular endothelial growth factor (VEGF) receptor 2 and blocks its interaction with VEGF A, C and D, is being evaluated in Phase II clinical trials for efficacy in several oncology indications.
    Protein Engineering Design and Selection 11/2010; 24(1-2):3-9. DOI:10.1093/protein/gzq097 · 2.54 Impact Factor
Show more