Positron emission tomography imaging of CD105 expression during tumor angiogenesis

  • Hao Hong
  • Yunan Yang
  • Yin Zhang
  • Jonathan W. Engle
  • Todd E. Barnhart
  • Robert J. Nickles
  • Bryan R. Leigh
  • Weibo CaiEmail author
Original Article



Overexpression of CD105 (endoglin) correlates with poor prognosis in many solid tumor types. Tumor microvessel density (MVD) assessed by CD105 staining is the current gold standard for evaluating tumor angiogenesis in the clinic. The goal of this study was to develop a positron emission tomography (PET) tracer for imaging CD105 expression.


TRC105, a chimeric anti-CD105 monoclonal antibody, was conjugated to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and labeled with 64Cu. FACS analysis and microscopy studies were performed to compare the CD105 binding affinity of TRC105 and DOTA-TRC105. PET imaging, biodistribution, blocking, and ex vivo histology studies were performed on 4T1 murine breast tumor-bearing mice to evaluate the ability of 64Cu-DOTA-TRC105 to target tumor angiogenesis. Another chimeric antibody, cetuximab, was used as an isotype-matched control.


FACS analysis of human umbilical vein endothelial cells (HUVECs) revealed no difference in CD105 binding affinity between TRC105 and DOTA-TRC105, which was further validated by fluorescence microscopy. 64Cu labeling was achieved with high yield and specific activity. Serial PET imaging revealed that the 4T1 tumor uptake of the tracer was 8.0 ± 0.5, 10.4 ± 2.8, and 9.7 ± 1.8%ID/g at 4, 24, and 48 h post-injection, respectively (n = 3), higher than most organs at late time points which provided excellent tumor contrast. Biodistribution data as measured by gamma counting were consistent with the PET findings. Blocking experiments, control studies with 64Cu-DOTA-cetuximab, as well as ex vivo histology all confirmed the in vivo target specificity of 64Cu-DOTA-TRC105.


This is the first successful PET imaging study of CD105 expression. Fast, prominent, persistent, and CD105-specific uptake of the tracer in the 4T1 tumor was observed. Further studies are warranted and currently underway.


CD105/Endoglin Positron emission tomography (PET) Tumor angiogenesis 64Cu RadioimmunoPET TRC105 



This work is supported, in part, by the Wisconsin Partnership Program, the University of Wisconsin Carbone Cancer Center, NCRR 1UL1RR025011, a Susan G. Komen Postdoctoral Fellowship (to H. Hong), and a DOD PCRP IDEA Award.

Conflicts of interest

BRL is an employee of TRACON Pharmaceuticals, Inc. The other authors declare that they have no conflict of interest.


  1. 1.
    Carmeliet P. Angiogenesis in life, disease and medicine. Nature 2005;438:932–6.PubMedCrossRefGoogle Scholar
  2. 2.
    Folkman J. Angiogenesis in cancer, vascular, rheumatoid and other disease. Nat Med 1995;1:27–31.PubMedCrossRefGoogle Scholar
  3. 3.
    Cai W, Chen X. Multimodality imaging of vascular endothelial growth factor and vascular endothelial growth factor receptor expression. Front Biosci 2007;12:4267–79.PubMedCrossRefGoogle Scholar
  4. 4.
    Cai W, Niu G, Chen X. Imaging of integrins as biomarkers for tumor angiogenesis. Curr Pharm Des 2008;14:2943–73.PubMedCrossRefGoogle Scholar
  5. 5.
    Dijkgraaf I, Boerman OC. Radionuclide imaging of tumor angiogenesis. Cancer Biother Radiopharm 2009;24:637–47.PubMedCrossRefGoogle Scholar
  6. 6.
    Barbara NP, Wrana JL, Letarte M. Endoglin is an accessory protein that interacts with the signaling receptor complex of multiple members of the transforming growth factor-beta superfamily. J Biol Chem 1999;274:584–94.PubMedCrossRefGoogle Scholar
  7. 7.
    Gougos A, Letarte M. Primary structure of endoglin, an RGD-containing glycoprotein of human endothelial cells. J Biol Chem 1990;265:8361–4.PubMedGoogle Scholar
  8. 8.
    Fonsatti E, Del Vecchio L, Altomonte M, Sigalotti L, Nicotra MR, Coral S, et al. Endoglin: an accessory component of the TGF-beta-binding receptor-complex with diagnostic, prognostic, and bioimmunotherapeutic potential in human malignancies. J Cell Physiol 2001;188:1–7.PubMedCrossRefGoogle Scholar
  9. 9.
    Wang JM, Kumar S, Pye D, van Agthoven AJ, Krupinski J, Hunter RD. A monoclonal antibody detects heterogeneity in vascular endothelium of tumours and normal tissues. Int J Cancer 1993;54:363–70.PubMedCrossRefGoogle Scholar
  10. 10.
    Burrows FJ, Derbyshire EJ, Tazzari PL, Amlot P, Gazdar AF, King SW, et al. Up-regulation of endoglin on vascular endothelial cells in human solid tumors: implications for diagnosis and therapy. Clin Cancer Res 1995;1:1623–34.PubMedGoogle Scholar
  11. 11.
    Fonsatti E, Jekunen AP, Kairemo KJ, Coral S, Snellman M, Nicotra MR, et al. Endoglin is a suitable target for efficient imaging of solid tumors: in vivo evidence in a canine mammary carcinoma model. Clin Cancer Res 2000;6:2037–43.PubMedGoogle Scholar
  12. 12.
    Wikström P, Lissbrant IF, Stattin P, Egevad L, Bergh A. Endoglin (CD105) is expressed on immature blood vessels and is a marker for survival in prostate cancer. Prostate 2002;51:268–75.PubMedCrossRefGoogle Scholar
  13. 13.
    Dallas NA, Samuel S, Xia L, Fan F, Gray MJ, Lim SJ, et al. Endoglin (CD105): a marker of tumor vasculature and potential target for therapy. Clin Cancer Res 2008;14:1931–7.PubMedCrossRefGoogle Scholar
  14. 14.
    Kumar S, Ghellal A, Li C, Byrne G, Haboubi N, Wang JM, et al. Breast carcinoma: vascular density determined using CD105 antibody correlates with tumor prognosis. Cancer Res 1999;59:856–61.PubMedGoogle Scholar
  15. 15.
    Fonsatti E, Nicolay HJ, Altomonte M, Covre A, Maio M. Targeting cancer vasculature via endoglin/CD105: a novel antibody-based diagnostic and therapeutic strategy in solid tumours. Cardiovasc Res 2010;86:12–9.PubMedGoogle Scholar
  16. 16.
    Cai W, Rao J, Gambhir SS, Chen X. How molecular imaging is speeding up antiangiogenic drug development. Mol Cancer Ther 2006;5:2624–33.PubMedCrossRefGoogle Scholar
  17. 17.
    Zhang D, Feng XY, Henning TD, Wen L, Lu WY, Pan H, et al. MR imaging of tumor angiogenesis using sterically stabilized Gd-DTPA liposomes targeted to CD105. Eur J Radiol 2009;70:180–9.PubMedCrossRefGoogle Scholar
  18. 18.
    Bredow S, Lewin M, Hofmann B, Marecos E, Weissleder R. Imaging of tumour neovasculature by targeting the TGF-beta binding receptor endoglin. Eur J Cancer 2000;36:675–81.PubMedCrossRefGoogle Scholar
  19. 19.
    Costello B, Li C, Duff S, Butterworth D, Khan A, Perkins M, et al. Perfusion of 99mTc-labeled CD105 Mab into kidneys from patients with renal carcinoma suggests that CD105 is a promising vascular target. Int J Cancer 2004;109:436–41.PubMedCrossRefGoogle Scholar
  20. 20.
    Korpanty G, Carbon JG, Grayburn PA, Fleming JB, Brekken RA. Monitoring response to anticancer therapy by targeting microbubbles to tumor vasculature. Clin Cancer Res 2007;13:323–30.PubMedCrossRefGoogle Scholar
  21. 21.
    Korpanty G, Grayburn PA, Shohet RV, Brekken RA. Targeting vascular endothelium with avidin microbubbles. Ultrasound Med Biol 2005;31:1279–83.PubMedCrossRefGoogle Scholar
  22. 22.
    Cui S, Lü SZ, Chen YD, He GX, Liu JP, Song ZY, et al. Relationship between intravascular ultrasound imaging features of coronary plaques and soluble CD105 level in patients with coronary heart disease. Chin Med J (Engl) 2007;120:595–7.Google Scholar
  23. 23.
    Lee SY, Hong YD, Felipe PM, Pyun MS, Choi SJ. Radiolabeling of monoclonal anti-CD105 with (177)Lu for potential use in radioimmunotherapy. Appl Radiat Isot 2009;67:1366–9.PubMedCrossRefGoogle Scholar
  24. 24.
    Tsujie M, Tsujie T, Toi H, Uneda S, Shiozaki K, Tsai H, et al. Anti-tumor activity of an anti-endoglin monoclonal antibody is enhanced in immunocompetent mice. Int J Cancer 2008;122:2266–73.PubMedCrossRefGoogle Scholar
  25. 25.
    She X, Matsuno F, Harada N, Tsai H, Seon BK. Synergy between anti-endoglin (CD105) monoclonal antibodies and TGF-beta in suppression of growth of human endothelial cells. Int J Cancer 2004;108:251–7.PubMedCrossRefGoogle Scholar
  26. 26.
    Tsujie M, Uneda S, Tsai H, Seon BK. Effective anti-angiogenic therapy of established tumors in mice by naked anti-human endoglin (CD105) antibody: differences in growth rate and therapeutic response between tumors growing at different sites. Int J Oncol 2006;29:1087–94.PubMedGoogle Scholar
  27. 27.
    Mendelson DS, Gordon MS, Rosen LS, Hurwitz H, Wong MK, Adams BJ, et al. Phase I study of TRC105 (anti-CD105 [endoglin] antibody) therapy in patients with advanced refractory cancer. J Clin Oncol 2010;28:15s.Google Scholar
  28. 28.
    Wang H, Cai W, Chen K, Li ZB, Kashefi A, He L, et al. A new PET tracer specific for vascular endothelial growth factor receptor 2. Eur J Nucl Med Mol Imaging 2007;34:2001–10.PubMedCrossRefGoogle Scholar
  29. 29.
    Cai W, Chen K, He L, Cao Q, Koong A, Chen X. Quantitative PET of EGFR expression in xenograft-bearing mice using 64Cu-labeled cetuximab, a chimeric anti-EGFR monoclonal antibody. Eur J Nucl Med Mol Imaging 2007;34:850–8.PubMedCrossRefGoogle Scholar
  30. 30.
    Cai W, Wu Y, Chen K, Cao Q, Tice DA, Chen X. In vitro and in vivo characterization of 64Cu-labeled Abegrin™, a humanized monoclonal antibody against integrin αvβ3. Cancer Res 2006;66:9673–81.PubMedCrossRefGoogle Scholar
  31. 31.
    Takahashi N, Haba A, Matsuno F, Seon BK. Antiangiogenic therapy of established tumors in human skin/severe combined immunodeficiency mouse chimeras by anti-endoglin (CD105) monoclonal antibodies, and synergy between anti-endoglin antibody and cyclophosphamide. Cancer Res 2001;61:7846–54.PubMedGoogle Scholar
  32. 32.
    Cai W, Chen K, Mohamedali KA, Cao Q, Gambhir SS, Rosenblum MG, et al. PET of vascular endothelial growth factor receptor expression. J Nucl Med 2006;47:2048–56.PubMedGoogle Scholar
  33. 33.
    Cai W, Ebrahimnejad A, Chen K, Cao Q, Li ZB, Tice DA, et al. Quantitative radioimmunoPET imaging of EphA2 in tumor-bearing mice. Eur J Nucl Med Mol Imaging 2007;34:2024–36.PubMedCrossRefGoogle Scholar
  34. 34.
    Duff SE, Li C, Garland JM, Kumar S. CD105 is important for angiogenesis: evidence and potential applications. FASEB J 2003;17:984–92.PubMedCrossRefGoogle Scholar
  35. 35.
    Fonsatti E, Sigalotti L, Arslan P, Altomonte M, Maio M. Emerging role of endoglin (CD105) as a marker of angiogenesis with clinical potential in human malignancies. Curr Cancer Drug Targets 2003;3:427–32.PubMedCrossRefGoogle Scholar
  36. 36.
    Matsuno F, Haruta Y, Kondo M, Tsai H, Barcos M, Seon BK. Induction of lasting complete regression of preformed distinct solid tumors by targeting the tumor vasculature using two new anti-endoglin monoclonal antibodies. Clin Cancer Res 1999;5:371–82.PubMedGoogle Scholar
  37. 37.
    Wadas TJ, Wong EH, Weisman GR, Anderson CJ. Coordinating radiometals of copper, gallium, indium, yttrium, and zirconium for PET and SPECT imaging of disease. Chem Rev 2010;110:2858–902.PubMedCrossRefGoogle Scholar
  38. 38.
    Völkel T, Hölig P, Merdan T, Müller R, Kontermann RE. Targeting of immunoliposomes to endothelial cells using a single-chain Fv fragment directed against human endoglin (CD105). Biochim Biophys Acta 2004;1663:158–66.PubMedCrossRefGoogle Scholar
  39. 39.
    Müller D, Trunk G, Sichelstiel A, Zettlitz KA, Quintanilla M, Kontermann RE. Murine endoglin-specific single-chain Fv fragments for the analysis of vascular targeting strategies in mice. J Immunol Methods 2008;339:90–8.PubMedCrossRefGoogle Scholar
  40. 40.
    Nettelbeck DM, Miller DW, Jérôme V, Zuzarte M, Watkins SJ, Hawkins RE, et al. Targeting of adenovirus to endothelial cells by a bispecific single-chain diabody directed against the adenovirus fiber knob domain and human endoglin (CD105). Mol Ther 2001;3:882–91.PubMedCrossRefGoogle Scholar
  41. 41.
    Korn T, Müller R, Kontermann RE. Bispecific single-chain diabody-mediated killing of endoglin-positive endothelial cells by cytotoxic T lymphocytes. J Immunother 2004;27:99–106.PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Hao Hong
    • 1
  • Yunan Yang
    • 1
    • 5
  • Yin Zhang
    • 2
  • Jonathan W. Engle
    • 2
  • Todd E. Barnhart
    • 2
  • Robert J. Nickles
    • 2
  • Bryan R. Leigh
    • 3
  • Weibo Cai
    • 1
    • 2
    • 4
    • 6
    Email author
  1. 1.Department of RadiologyUniversity of Wisconsin - MadisonMadisonUSA
  2. 2.Department of Medical PhysicsUniversity of Wisconsin - MadisonMadisonUSA
  3. 3.TRACON Pharmaceuticals, Inc.San DiegoUSA
  4. 4.University of Wisconsin Carbone Cancer CenterMadisonUSA
  5. 5.Department of Ultrasound, Xinqiao HospitalThird Military Medical UniversityChongqingPeople’s Republic of China
  6. 6.Departments of Radiology and Medical Physics, School of Medicine and Public HealthUniversity of Wisconsin - MadisonMadisonUSA

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