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Molecular Imaging and Contrast Agent Database (MICAD) [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2004-2013.

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64Cu-1,4,7,10-Tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid-T84.66 scFv-human serum albumin

64Cu-DOTA-T84.66 scFv-HSA
, PhD
National for Biotechnology Information, NLM, NIH, Bethesda, MD
Corresponding author.

Created: ; Last Update: September 2, 2008.

Chemical name:64Cu-1,4,7,10-Tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid-T84.66 scFv-human serum albumin
Abbreviated name:64Cu-DOTA-T84.66 scFv-HSA
Synonym:
Agent category:Antibody fragment
Target:Carcinoembryonic antigen (CEA)
Target category:Antigen
Method of detection:Positron emission tomography (PET)
Source of signal:64Cu
Activation:No
Studies:
  • Checkbox In vitro
  • Checkbox Rodents
Click on protein, nucleotide (RefSeq), and gene for more information about CEA

Background

[PubMed]

Carcinoembryonic antigen (CEA) was first identified from extracts of human colon adenocarcinoma (1) and fetal gut (2). It is a β-glycoprotein, and its predominant expression on the cell surface is increased in a variety of carcinomas and in certain inflammatory conditions such as inflammatory bowel disease (3, 4). CEA has a molecular weight of ~180 kDa, and it can be shed and detected in the serum (5). CEA expression is observed in patients with various carcinomas of the colon, lungs, thyroid, uterus, ovaries, pancreas, and medullary thyroid (6). Radiolabeled monoclonal antibodies (mAbs) have been developed for both the diagnosis and treatment of tumors (7, 8).

Single-chain variable fragments (scFvs) of mAbs with a molecular mass of 25 kDa are cleared very rapidly from the circulation, but they exhibit poor tumor retention because they have a lower affinity than the parent antibody (9). On the other hand, bivalent antibody fragments possess more ideal tumor-targeting characteristics, including rapid tissue penetration, high target retention, and rapid blood clearance. The diabody fragment (a dimer of scFvs; molecular mass = 55 kDa) and the minibody fragment (a dimer of scFvs-CH3 with a linker comprising 18 amino acids; molecular mass = 80 kDa) of a murine/human chimeric anti-CEA T84.66 antibody have been evaluated for targeting in several tumor antigen systems with rapid tumor localization and high-contrast imaging (9, 10). In particular, murine/human chimeric anti-CEA T84.66 diabody and minbody, which retain excellent CEA-binding properties (dissociation constant = 0.01–0.6 nM) (11-13), were developed as CEA imaging agents. However, the pharmacokinetics of radiometal labeled antibodies, with high liver and kidney uptake, are generally not ideal for imaging (14). Albumin is known to accumulate in tumors (15) and has a long blood half-life (16). Furthermore, albumin fusion proteins have been shown to prolong the in vivo circulation of small peptides and proteins (17). A T84.66 single-chain antibody (scFv) was joined with human serum albumin (HSA) using recombinant technology to form T84.66 scFv-albumin fusion protein (T84.66 scFv-HSA), which was radiolabeled with 64Cu for localization of CEA-positive tumors in mice with positron emission tomography (PET) (18).

Synthesis

[PubMed]

The recombinant T84.66 scFv-HSA was conjugated with N-hydroxysuccinimidyl-DOTA in a molar ratio of 1:17 (18). The DOTA-scFv-HSA (~1.8 nmol) was incubated with 32.56 MBq (1.85 mCi) of 64CuCl2 (pH, 5.5) at 43°C for 45 min. 64Cu-DOTA-T84.66 scFv-HSA was isolated with size-exclusion chromatography with a radiolabeling efficiency of ~100%. The specific activity was ~18.5 MBq/nmol (0.5 mCi/nmol) at the end of purification.

In Vitro Studies: Testing in Cells and Tissues

[PubMed]

Radioimmunoreactivity of 64Cu-DOTA-T84.66 scFv-HSA for recombinant CEA was determined to be 87% with high-performance liquid chromatography analysis (18).

Animal Studies

Rodents

[PubMed]

Yazaki et al. (18) performed a preliminary biodistribution study of 64Cu-DOTA-T84.66 scFv-HSA in a nude mouse with the use of a LS174T human colon carcinoma subcutaneous xenograft model. Data were obtained at 48 h after injection. Accumulation of the 64Cu-DOTA-T84.66 scFv-HSA in the CEA-expressing LS174T tumor was 32.3% injected dose (ID)/g. The tumor/blood and tumor/liver ratios were 9.8 and 2.4, respectively. PET imaging with the 64Cu-DOTA-T84.66 scFv-HSA was visualized at 4 h and reached the highest level at 24 h. There was relatively low radioactivity elsewhere (except the liver) in the mice, confirming the biodistribution data. No blocking experiments were performed.

Other Non-Primate Mammals

[PubMed]

No publication is currently available.

Non-Human Primates

[PubMed]

No publication is currently available.

Human Studies

[PubMed]

References

1.
Gold P., Freedman S.O. Demonstration of tumor-specific antigens in human colonic carcinomata by immunological tolerance and absorption techniques. The Journal of Experimental Medicine. 1964;121:439–462. [PMC free article: PMC2137957] [PubMed: 14270243]
2.
Krupey J., Gold P., Freedman S.O. Purification and characterization of carcinoembryonic antigens of the human digestive system. Nature. 1967;215(5096):67–8. [PubMed: 6053407]
3.
Kowalsky, R.J., and S.W. Falen, Radiopharmaceuticals in nuclear pharmacy and nuclear medicine2004, American Pharmacists Association: Washington, D.C. p. 733-752.
4.
Wahl R.L., Philpott G., Parker C.W. Monoclonal antibody radioimmunodetection of human-derived colon cancer. Invest Radiol. 1983;18(1):58–62. [PubMed: 6832932]
5.
Primus F.J., Freeman J.W., Goldenberg D.M. Immunological heterogeneity of carcinoembryonic antigen: purification from meconium of an antigen related to carcinoembryonic antigen. Cancer Res. 1983;43(2):679–85. [PubMed: 6401222]
6.
Package Insert. CEA-Scan (Arcitumomab) for the preparation of Tc 99m Arcitumomab1999, Immunomedics, Inc. p. 1-15.
7.
Kenanova V., Wu A.M. Tailoring antibodies for radionuclide delivery. Expert Opin Drug Deliv. 2006;3(1):53–70. [PubMed: 16370940]
8.
Wu A.M., Senter P.D. Arming antibodies: prospects and challenges for immunoconjugates. Nat Biotechnol. 2005;23(9):1137–46. [PubMed: 16151407]
9.
Wu A.M., Chen W., Raubitschek A., Williams L.E., Neumaier M., Fischer R., Hu S.Z., Odom-Maryon T., Wong J.Y., Shively J.E. Tumor localization of anti-CEA single-chain Fvs: improved targeting by non-covalent dimers. Immunotechnology. 1996;2(1):21–36. [PubMed: 9373325]
10.
Viti F., Tarli L., Giovannoni L., Zardi L., Neri D. Increased binding affinity and valence of recombinant antibody fragments lead to improved targeting of tumoral angiogenesis. Cancer Res. 1999;59(2):347–52. [PubMed: 9927045]
11.
Fagerstam L.G., Frostell-Karlsson A., Karlsson R., Persson B., Ronnberg I. Biospecific interaction analysis using surface plasmon resonance detection applied to kinetic, binding site and concentration analysis. J Chromatogr. 1992;597(1-2):397–410. [PubMed: 1517343]
12.
Hefta L.J., Neumaier M., Shively J.E. Kinetic and affinity constants of epitope specific anti-carcinoembryonic antigen (CEA) monoclonal antibodies for CEA and engineered CEA domain constructs. Immunotechnology. 1998;4(1):49–57. [PubMed: 9661814]
13.
Williams L.E., Wu A.M., Yazaki P.J., Liu A., Raubitschek A.A., Shively J.E., Wong J.Y. Numerical selection of optimal tumor imaging agents with application to engineered antibodies. Cancer Biother Radiopharm. 2001;16(1):25–35. [PubMed: 11279795]
14.
Yazaki P.J., Wu A.M., Tsai S.W., Williams L.E., Ikler D.N., Wong J.Y., Shively J.E., Raubitschek A.A. Tumor targeting of radiometal labeled anti-CEA recombinant T84.66 diabody and t84.66 minibody: comparison to radioiodinated fragments. Bioconjug Chem. 2001;12(2):220–8. [PubMed: 11312683]
15.
Wang J., Ueno H., Masuko T., Hashimoto Y. Binding of serum albumin on tumor cells and characterization of the albumin binding protein. J Biochem. 1994;115(5):898–903. [PubMed: 7961605]
16.
Dennis M.S., Zhang M., Meng Y.G., Kadkhodayan M., Kirchhofer D., Combs D., Damico L.A. Albumin binding as a general strategy for improving the pharmacokinetics of proteins. J Biol Chem. 2002;277(38):35035–43. [PubMed: 12119302]
17.
Dennis M.S., Jin H., Dugger D., Yang R., McFarland L., Ogasawara A., Williams S., Cole M.J., Ross S., Schwall R. Imaging tumors with an albumin-binding Fab, a novel tumor-targeting agent. Cancer Res. 2007;67(1):254–61. [PubMed: 17210705]
18.
Yazaki P.J., Kassa T., Cheung C.W., Crow D.M., Sherman M.A., Bading J.R., Anderson A.L., Colcher D., Raubitschek A. Biodistribution and tumor imaging of an anti-CEA single-chain antibody-albumin fusion protein. Nucl Med Biol. 2008;35(2):151–8. [PMC free article: PMC3195408] [PubMed: 18312824]

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