Comparison of Four Bifunctional Chelates for Radiolabeling Monoclonal Antibodies with Copper Radioisotopes: Biodistribution and Metabolism
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- 作者：Buck E. Rogers ; Carolyn J. Anderson ; Judith M. Connett ; Li Wu Guo ; W. Barry Edwards ; Elizabeth L. C. Sherman ; Kurt R. Zinn ; and Michael J. Welch
- 刊名：Bioconjugate Chemistry
- 出版年：1996
- 出版时间：July 1996
- 年：1996
- 卷：7
- 期：4
- 页码：511 - 522
- 全文大小：364K
- 年卷期：v.7,no.4(July 1996)
- ISSN：1520-4812
文摘
The bifunctional chelating agents (BFCs),6-[p-(bromoacetamido)benzyl]-1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid (BAT),6-[p-(isothiocyanato)benzyl]-1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid (SCN-TETA),4-[(1,4,8,11-tetraazacyclotetradec-1-yl)methyl]benzoicacid(CPTA), and1-[(1,4,7,10,13-pentaazacyclopentadec-1-yl)methyl]benzoicacid (PCBA), were synthesizedand conjugated to the anti-colorectal monoclonal antibody (mAb), 1A3,and antibody fragments, 1A3-F(ab')2, for radiolabeling with 64,67Cu andcomparison in animal models. In vivo metabolismstudieswere carried out in liver and kidneys in order to correlate the natureof the metabolites formed to theuptake and retention of the radiolabel in each organ. Animalbiodistribution studies were performedin Golden Syrian hamsters bearing the GW39 human colon cancer tumorsand in normal Sprague-Dawley rats. All conjugates showed good tumor uptake in hamsters.Biodistribution in rats showedthat 64Cu-BAT-2IT-1A3 had the lowest liver and kidneyuptake of the intact 1A3 conjugates (p <0.03), whereas in hamsters, there were no significant differences inliver and kidney uptake betweenthe four intact BFC-1A3 conjugates. Tumor-bearing hamstersinjected with64Cu-CPTA-1A3-F(ab')2and 64Cu-PCBA-1A3-F(ab')2 had from 3 to 7times greater uptake in the kidneys than hamsters given64Cu-labeled BAT and SCN-TETA 1A3-F(ab')2conjugates, while rats injected with64Cu-CPTA-1A3-F(ab')2 and64Cu-PCBA-1A3-F(ab')2 had nearly twice theuptake. The in vivo metabolism of the mAbs1A3 and 1A3-F(ab')2 radiolabeled with 67Cuthrough the SCN-TETA, CPTA, and PCBA BFCs wasinvestigated by excising the livers and kidneys of normal rats from1-5 days post-injection of theradiolabeled conjugates. Liver and kidney homogenates wereanalyzed by size exclusion chromatography and thin layer chromatography (TLC). The size exclusionchromatography data showed thatall of the 67Cu-labeled 1A3-F(ab')2conjugates were >85% degraded in the kidneys to smallmolecularweight metabolites by 1 day post-injection. In contrast, in theliver at 1 day post-injection, greaterthan 70% of the 67Cu-labeled 1A3 conjugates wereunmetabolized. By day 5, a 35 kDa peak appearedin the liver of rats injected with the 67Cu-labeled1A3 conjugates, possibly due to transchelation ofthe 67Cu to proteins. Superoxide dismutasechromatographically elutes at the same retention timeas this 67Cu-labeled metabolite. The TLC dataindicate that the low molecular weight metabolite (<5kDa) of both 67Cu-CPTA-1A3 and67Cu-CPTA-1A3-F(ab')2 conjugatesco-chromatographed with a67Cu-CPTA-
-lysine standard. Our data suggestthat chelate charge and lipophilicity play a largerole in kidney retention of 64/67Cu-labeledBFC-1A3-F(ab')2 conjugates, while transchelation ofthecopper label appears to be the major factor for liver accumulation of64/67Cu-labeled BFC-1A3conjugates.
-lysine standard. Our data suggestthat chelate charge and lipophilicity play a largerole in kidney retention of 64/67Cu-labeledBFC-1A3-F(ab')2 conjugates, while transchelation ofthecopper label appears to be the major factor for liver accumulation of64/67Cu-labeled BFC-1A3conjugates.