High-resolution microPET imaging of carcinoembryonic antigen-positive xenografts by using a copper-64-labeled engineered antibody fragment

Wu, Anna M.; Yazaki, Paul J.; Tsai, Shih‐Wei; Nguyen, Khoi; Anderson, Aaron S.; McCarthy, Deborah W.; Welch, Michael J.; Shively, John E.; Williams, Lawrence E.; Raubitschek, Andrew; Wong, Jeffrey Y.C.; Toyokuni, Tatsushi; Phelps, Michael E.; Gambhir, Sanjiv S.

doi:10.1073/pnas.150228297

Cited by 193 publications

(106 citation statements)

References 27 publications

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“…We have shown that SarAr conjugation to both murine and chimerized mAb can be accomplished under nearly physiological conditions with no adverse affect on immunoreactivity. Incubation of the immunoconjugate with 64 Cu 2ϩ for 10-30 min results in nearly quantitative uptake of 64 Cu 2ϩ without the need for additional HPLC purification, yielding specific activities of Ϸ10 Ci/ g (Ϸ37 MBq/100 g), 2-3 times greater than previously published results using other chelating agents (9,25,26). Furthermore, these high specific activities were achieved without the need for postlabeling purification, as is required with other chelators.…”

Section: Discussionmentioning

confidence: 76%

“…The bifunctional chelators most commonly used for labeling proteins with copper radionuclides are based on the tetraazamacrocyclic chelators DOTA and TETA (5). Copper is, however, lost from these ligands in vivo with concomitant accumulation in the liver (9,27), where it is incorporated into endogenous copper-binding proteins, such as ceruloplasmin and superoxide dismutase (10,28). Copper plays an important role in many normal physiological processes and, hence, is bound by a variety of circulating and intracellular proteins such as copper transporting ATPases, cytochrome oxidase, and superoxide dismutase.…”

Section: Discussionmentioning

confidence: 99%

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Positron emission tomography (PET) imaging of neuroblastoma and melanoma with ⁶⁴ Cu-SarAr immunoconjugates

Voss¹,

Smith

DiBartolo

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

135

123

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The advancement of positron emission tomography (PET) depends on the development of new radiotracers that will complement 18 F-FDG. Copper-64 ( 64 Cu) is a promising PET radionuclide, particularly for antibody-targeted imaging, but the high in vivo lability of conventional chelates has limited its clinical application. The objective of this work was to evaluate the novel chelating agent SarAr (1-N-(4-aminobenzyl)-3, 6,10,13,16,19-hexaazabicyclo[6.6.6]-eicosane-1,8-diamine) for use in developing a new class of tumorspecific 64 Cu radiopharmaceuticals for imaging neuroblastoma and melanoma. The anti-GD2 monoclonal antibody (mAb) 14.G2a, and its chimeric derivative, ch14.18, target disialogangliosides that are overexpressed on neuroblastoma and melanoma. Both mAbs were conjugated to SarAr using carbodiimide coupling. Radiolabeling with 64 Cu resulted in >95% of the 64 Cu being chelated by the immunoconjugate. Specific activities of at least 10 Ci/ g (1 Ci ‫؍‬ 37 GBq) were routinely achieved, and no additional purification was required after 64 Cu labeling. Solid-phase radioimmunoassays and intact cell-binding assays confirmed retention of bioactivity. Biodistribution studies in athymic nude mice bearing s.c. neuroblastoma (IMR-6, NMB-7) and melanoma (M21) xenografts showed that 15-20% of the injected dose per gram accumulated in the tumor at 24 hours after injection, and only 5-10% of the injected dose accumulated in the liver, a lower value than typically seen with other chelators. Uptake by a GD2-negative tumor xenograft was significantly lower (<5% injected dose per gram). MicroPET imaging confirmed significant uptake of the tracer in GD-2-positive tumors, with minimal uptake in GD-2-negative tumors and nontarget tissues such as liver. The 64 Cu-SarAr-mAb system described here is potentially applicable to 64 Cu-PET imaging with a broad range of antibody or peptide-based imaging agents.

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Section: Discussionmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 99%

Positron emission tomography (PET) imaging of neuroblastoma and melanoma with ⁶⁴ Cu-SarAr immunoconjugates

Voss¹,

Smith

DiBartolo

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

135

123

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“…This can be accomplished through the use of molecularly engineered antibodies against the HA sequence. Engineered antibodies have been produced that maintain their bivalency, clear the blood more rapidly than intact antibodies 40,41 and have been radiolabeled for nuclear imaging of tumors. 41 Thus, imaging gene transfer with 99m Tc-labeled anti-HA engineered antibodies should improve the current approach.…”

Section: Discussionmentioning

confidence: 99%

Non-invasive gamma camera imaging of gene transfer using an adenoviral vector encoding an epitope-tagged receptor as a reporter

et al. 2003

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“…Numerous chelators have been reported for complexing copper [5][6][7][8][9][10][11][12][13][14][15][16] and several of these have been functionalized to allow attachment to antibodies [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] and are now commercially available. The choice of antibody/BFC combination will affect efficacy as an imaging or therapy agent.…”

Section: Introductionmentioning

confidence: 99%

Comparison of ⁶⁴Cu-Complexing Bifunctional Chelators for Radioimmunoconjugation: Labeling Efficiency, Specific Activity, and in Vitro/in Vivo Stability

et al. 2012

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High radiolabeling efficiency, preferably to high specific activity, and good stability of the radioimmunoconjugate are essential features for a successful immunoconjugate for imaging or therapy. In this study, the radiolabeling efficiency, in vitro stability and biodistribution of immunoconjugates with eight different bifunctional chelators labeled with 64 Cu were compared. The anti-CD20 antibody, rituximab, was conjugated to four macrocyclic bifunctional chelators (p-SCN-Bn-DOTA, p- , three DTPA derivatives (p-SCN-Bn-DTPA, p-SCN-CHX-A"-DTPA and ITC-2B3M-DTPA) and a macrobicyclic hexamine ("sarcophagine") chelator (sar-CO 2 H) = (1-NH 2 -8-NHCO(CH 2 ) 3 CO 2 H)sar where sar = sarcophagine = 3, 6,10,13,16,19-hexaazabicyclo[6.6.6]icosane). Radiolabeling efficiency under various conditions, in vitro stability in serum at 37°C and in vivo biodistribution and imaging in normal mice over 48 h were studied. All chelators except sar-CO 2 H were conjugated to rituximab by thiourea bond formation with an average of 4.9 +/− 0.9 chelators per antibody molecule. Sar-CO 2 H was conjugated to rituximab by amide bond formation with 0.5 chelators per antibody molecule. Efficiencies of 64 Cu radiolabeling were dependent on the concentration of immunoconjugate. Notably, the 64 Cu-NOTA-rituximab conjugate demonstrated highest radiochemical yield (95%) under very dilute conditions (31 nM NOTA-rituximab conjugate). Similarly, sar-CO-rituximab, containing 1/10 th the number of chelators per antibody compared to other conjugates retained high labeling efficiency (98 %) at an antibody concentration of 250 nM. In contrast to the radioimmunoconjugates containing DTPA derivatives, which demonstrated poor serum stability, all macrocyclic radioimmunoconjugates were very stable in serum with <6 % dissociation of 64 Cu over 48 h. In vivo biodistribution profiles in normal female Balb/C mice were similar for all the macrocyclic radioimmunoconjugates with most of the activity remaining in the blood pool up to 48 h. Whilst all the macrocyclic bifunctional chelators are suitable for molecular imaging using 64 Cu-labeled antibody conjugates, NOTA and sar-CO 2 H show significant advantages over the others in that they can be radiolabeled rapidly at room temperature, under dilute conditions resulting in high specific activity. Europe PMC Funders Group

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High-resolution microPET imaging of carcinoembryonic antigen-positive xenografts by using a copper-64-labeled engineered antibody fragment

Cited by 193 publications

References 27 publications

Positron emission tomography (PET) imaging of neuroblastoma and melanoma with ⁶⁴ Cu-SarAr immunoconjugates

Positron emission tomography (PET) imaging of neuroblastoma and melanoma with ⁶⁴ Cu-SarAr immunoconjugates

Non-invasive gamma camera imaging of gene transfer using an adenoviral vector encoding an epitope-tagged receptor as a reporter

Comparison of ⁶⁴Cu-Complexing Bifunctional Chelators for Radioimmunoconjugation: Labeling Efficiency, Specific Activity, and in Vitro/in Vivo Stability

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High-resolution microPET imaging of carcinoembryonic antigen-positive xenografts by using a copper-64-labeled engineered antibody fragment

Cited by 193 publications

References 27 publications

Positron emission tomography (PET) imaging of neuroblastoma and melanoma with 64 Cu-SarAr immunoconjugates

Positron emission tomography (PET) imaging of neuroblastoma and melanoma with 64 Cu-SarAr immunoconjugates

Non-invasive gamma camera imaging of gene transfer using an adenoviral vector encoding an epitope-tagged receptor as a reporter

Comparison of 64Cu-Complexing Bifunctional Chelators for Radioimmunoconjugation: Labeling Efficiency, Specific Activity, and in Vitro/in Vivo Stability

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Positron emission tomography (PET) imaging of neuroblastoma and melanoma with ⁶⁴ Cu-SarAr immunoconjugates

Positron emission tomography (PET) imaging of neuroblastoma and melanoma with ⁶⁴ Cu-SarAr immunoconjugates

Comparison of ⁶⁴Cu-Complexing Bifunctional Chelators for Radioimmunoconjugation: Labeling Efficiency, Specific Activity, and in Vitro/in Vivo Stability