NR-LU-10/streptavidin-copper 64-(1,4,7,10-tetraazacyclododecane-N,N′,N′′,N′′′-tetraacetic acid)-biotin

NR-LU-10/SA-64Cu-DOTA-biotin

The MICAD Research Team.

Publication Details

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In vitro Rodents

Background

[PubMed]

Radiolabeled monoclonal antibodies (mAbs) have shown very promising results for cancer imaging. Nevertheless, because of their slow blood clearance, they do not localize in solid tumors in sufficient quantities to provide high contrast for positron emission tomography (PET) imaging. To overcome this problem, the innovative concept of antibody “pretargeting” can be used. This approach, first proposed by Goodwin et al. (1) 15 years ago, involves the administration of an unlabeled mAb construct that accumulates in tumors, followed by the administration of a radiolabeled molecule that binds rapidly with high affinity to the construct (2).

64Cu-DOTA-biotin can be labeled to high specificity with 64Cu and may be used as part of a mAb pretargeting approach, for example with pretreatment of the mAb-streptavidin (SA) conjugate NR-LU-10/SA (and the synthetic clearing agent biotin-GalNAc16) (3). The very rapid tumor uptake and blood clearance of 64Cu-DOTA-biotin make it possible to obtain a much higher PET imaging contrast than conventional imaging because of the increased permeability of the small, radiolabeled substrate.

The pretargeting strategy using the system NR-LU-10/SA -64Cu-DOTA-biotin takes advantage of the very high affinity between avidin (or streptavidin) and biotin (the dissociation constant Kd of the avidin/biotin complex is about 1015m); this characteristic has already been used in a wide range of in vitro and in vivo applications (4-6). Avidin and streptavidin have similar binding properties, although some of their chemical and physical properties are different. Streptavidin is often preferred to avidin, because of the slower blood clearance of the mAb conjugate (7).

Synthesis

[PubMed]

DOTA-biotin can be synthesized using the method from Lewis et al. (3). The labeling of DOTA-biotin with 64Cu can be performed using a modified protocol described previously in the literature (3, 8). Briefly, 0.114 μmol of DOTA-biotin (in 46.0 µl of 0.2 m ammonium acetate, pH 5.0) is added to 102 MBq (2.76 mCi) of 64Cu in 164 µl of 0.2 m ammonium acetate, pH 5.0, containing 1 mg/ml of gentisic acid). The reaction mixture is then incubated at 80°C for 1 h. The radiochemical purity of 64Cu-DOTA-biotin obtained by this method is between 95% and 100% (measured by thin-layer chromatography (TLC)).

In Vitro Studies: Testing in Cells and Tissues

[PubMed]

64Cu-DOTA-biotin can be assayed using a method described by Lewis et al. (3) and which involves mixing the radiolabeled compound with 4% streptavidin-agarose beads at room temperature. The amounts of 64Cu-DOTA-biotin that bound specifically to the immobilized streptavidin were found to be typically in the range of 98.4%-98.8%, whereas the immunoreactivity of 64Cu-DOTA-NR-LU-10 averaged 80%. In the experiments performed by Lewis et al. (3), direct labeling of DOTA-NR-LU-10 mAb, either through the binding of DOTA to the antibody or through the copper labeling procedure, appeared to decrease the immunoreactivity.

Animal Studies

Rodents

[PubMed]

Biodistribution studies of NR-LU-10/SA-pretargeted 64Cu-DOTA-biotin in athymic nude mice bearing SW1222 human colorectal carcinoma xenografts were performed by Lewis et al. (3). Experimental data showed a very rapid accumulation of 64Cu-DOTA-biotin in tumor, reaching a tumor/blood ratio of 1.37 at 5 min after injection and a peak tumor uptake at 1 h with a tumor/blood ratio of 18.9. The blood and renal clearances of radioactivity were very rapid (from 20.8 % injected dose (ID)/g at 5 min to 3.40 % ID/g (P = 0.002) at 1 h for the kidneys). Other tissues that showed significant clearance (from 5 min to 48 h) were bone (P = 0.003) and the small intestine (P = 0.001).

Although the absolute tumor uptake of 64Cu-DOTA-NR-LU-10 was significantly higher than the 64Cu-DOTA-biotin, the pretargeting system exhibited much faster disappearance of radioactivity from the circulation (6 and 18 h were necessary for 64Cu-DOTA-NR-LU-10 levels (in % ID/g) to drop below the level of tumor uptake, and only 5 min was needed for the tumor/blood ratio of 64Cu-DOTA-biotin to exceed 1:1). Studies such as the one by Lewis et al. (3) showed that the antibody pretargeting strategy using NR-LU-10/SA and 64Cu-DOTA-biotin allows rapid clearance, superior tumor/normal tissue ratios, and whole-body radioactivity exposure from blood.

Other Non-Primate Mammals

[PubMed]

No publication is currently available.

Non-Human Primates

[PubMed]

No publication is currently available.

Human Studies

[PubMed]

No publications of human studies involving the system NR-LU-10/SA-64Cu-DOTA-biotin

are currently available. Nevertheless, human data for DOTA-biotin labeled with other radionuclides, as well as clinical studies using the pretargeting system avidin-biotin, can be found in the literature (4, 9-11).

References

1.
Goodwin D , Meares C , Diamanti C , McCall M , Lai C , Torti F , McTigue M , Martin B . Use of specific antibody for rapid clearance of circulating blood background from radiolabeled tumor imaging proteins. Eur J Nucl Med. 1984;9(5):209–215. [PubMed: 6428891]
2.
Wu AM . Tools for pretargeted radioimmunotherapy. Cancer Biother Radiopharm. 2001;16(2):103–108. [PubMed: 11385957]
3.
Lewis MR , Wang M , Axworthy DB , Theodore LJ , Mallet RW , Fritzberg AR , Welch MJ , Anderson CJ . In vivo evaluation of pretargeted 64Cu for tumor imaging and therapy. J Nucl Med. 2003;44(8):1284–1292. [PubMed: 12902420]
4.
Paganelli G , Chinol M . Radioimmunotherapy: is avidin-biotin pretargeting the preferred choice among pretargeting methods? Eur J Nucl Med Mol Imaging. 2003;30(5):773–776. [PubMed: 12557049]
5.
Goodwin DA , Meares CF . Advances in pretargeting biotechnology. Biotechnol Adv. 2001;19(6):435–450. [PubMed: 14538068]
6.
Hnatowich DJ , Virzi F , Rusckowski M . Investigations of avidin and biotin for imaging applications. J Nucl Med. 1987;28(8):1294–1302. [PubMed: 3612292]
7.
Sung C , van Osdol WW , Saga T , Neumann RD , Dedrick RL , Weinstein JN . Streptavidin distribution in metastatic tumors pretargeted with a biotinylated monoclonal antibody: theoretical and experimental pharmacokinetics. Cancer Res. 1994;54(8):2166–2175. [PubMed: 8174124]
8.
de Jong M , Bakker WH , Krenning EP , Breeman WA , van der Pluijm ME , Bernard BF , Visser TJ , Jermann E , Behe M , Powell P , Macke HR . Yttrium-90 and indium-111 labelling, receptor binding and biodistribution of [DOTA0,d-Phe1,Tyr3]octreotide, a promising somatostatin analogue for radionuclide therapy. Eur J Nucl Med. 1997;24(4):368–371. [PubMed: 9096086]
9.
Breitz HB , Fisher DR , Goris ML , Knox S , Ratliff B , Murtha AD , Weiden PL . Radiation absorbed dose estimation for 90Y-DOTA-biotin with pretargeted NR-LU-10/streptavidin. Cancer Biother Radiopharm. 1999;14(5):381–395. [PubMed: 10850323]
10.
Knox SJ , Goris ML , Tempero M , Weiden PL , Gentner L , Breitz H , Adams GP , Axworthy D , Gaffigan S , Bryan K , Fisher DR , Colcher D , Horak ID , Weiner LM . Phase II trial of yttrium-90-DOTA-biotin pretargeted by NR-LU-10 antibody/streptavidin in patients with metastatic colon cancer. Clin Cancer Res. 2000;6(2):406–414. [PubMed: 10690517]
11.
Gruaz-Guyon A , Raguin O , Barbet J . Recent advances in pretargeted radioimmunotherapy. Curr Med Chem. 2005;12(3):319–338. [PubMed: 15723622]