The Experts below are selected from a list of 99 Experts worldwide ranked by ideXlab platform
Yasushi Arano - One of the best experts on this subject based on the ideXlab platform.
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Renal Brush Border Enzyme-Cleavable Linkages for Low Renal Radioactivity Levels of Radiolabeled Antibody Fragments
2013Co-Authors: Hiromichi Akizawa, Mitsuo Imajima, Hirofumi Hanaoka, Tomoya Uehara, Satoshi Satake, Yasushi AranoAbstract:We previously demonstrated that Fab fragments labeled with 3′-[131I]iodohippuryl Nε-maleoyl-l-lysine ([131I]HML) showed low renal radioactivity from early postinjection time, due to a liberation of m-[131I]Iodohippuric Acid by the action of renal brush border enzymes. Since there are lots of enzymes on renal brush border membrane, peptide linkages other than the glycyl-l-lysine were evaluated as the cleavable linkages to explore the chemical design. In this study, we evaluated four peptide linkages with a general formula of m-iodobenzoyl-glycyl-X (X: l-tyosine O-methyl, l-asparagine, l-glutamine, and Nε-Boc-l-lysine). In vitro studies using renal brush border membrane vesicles (BBMVs) demonstrated that 3′-[125I]iodohippuryl O-methyl-l-tyrosine (2c) liberated the highest amount of m-[125I]Iodohippuric Acid among the four substrates and the change in the linkage structure altered enzyme species responsible for the hydrolysis reaction. To further assess the applicability of the linkage, a radioiodination reagent containing a glycyl-tyrosine linkage, 3′-[125I]iodohippuryl O-((2-maleimidoethyl)carbamoyl)methyl-l-tyrosine (HMT, 12c), was designed, synthesized, and subsequently conjugated to an Fab fragment. [125I]HMT-Fab exhibited renal radioactivity levels similar to and significantly lower than [125I]HML-Fab and directly radioiodinated Fab, while the blood clearance rates of the three were similar. The analyses of urine for 24 h postinjection of [125I]HMT-Fab showed that m-[125I]Iodohippuric Acid was excreted as the major radiometabolite. The findings indicated that glycyl-tyrosine linkage is also available to reduce renal radioactivity levels of radioiodinated Fab fragments, due to liberation of m-Iodohippuric Acid by the action of enzymes present on renal brush border membrane. These findings suggest that an appropriate selection of peptide linkages would allow the liberation of a designed radiolabeled compound from covalently conjugated polypeptides to prepare radiolabeled polypeptides of low renal radioactivity levels. For the selection of the most appropriate peptide linkage, the in vitro system using BBMVs would be useful to narrow the candidates to just a few
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Design, synthesis, and evaluation of [188Re]organorhenium-labeled antibody fragments with renal enzyme-cleavable linkage for low renal radioactivity levels.
Bioconjugate chemistry, 2007Co-Authors: Tomoya Uehara, Hiromichi Akizawa, Miho Koike, Hideo Nakata, Hiroshi Hanaoka, Yasuhiko Iida, Kazuyuki Hashimoto, Keigo Endo, Yasushi AranoAbstract:Renal localization of radiolabeled antibody fragments constitutes a problem in targeted imaging and radiotherapy. We have reported that Fab fragments labeled with 3'-[131I]iodohippuryl Nepsilon-maleoyl-lysine (HML) showed markedly low renal radioactivity levels even shortly after injection, due to a rapid and selective release of m-[131I]Iodohippuric Acid by the action of brush border enzymes. To estimate the applicability of the molecular design to metallic radionuclides, [188Re]tricarbonyl(cyclopentadienylcarbonate)rhenium ([188Re]CpTR-COOH) was conjugated with Nepsilon-tert-butoxycarbonyl-glycyl-lysine or Nepsilon-maleoyl-glycyl-lysine to prepare [188Re]CpTR-GK-Boc or [188Re]CpTR-GK. The cleavage of the glycyl-lysine linkage of the two compounds generates a glycine conjugate of [188Re]CpTR-COOH ([188Re]CpTR-Gly), which possesses in vivo behaviors similar to those of m-Iodohippuric Acid. The hydrolysis rate of the peptide bond in [188Re]CpTR-GK-Boc was compared with that in 3'-[125I]iodohippuryl Nepsilon-Boc-lysine ([125I]HL-Boc) using brush border membrane vesicles (BBMVs) prepared from rat kidneys. [188Re]CpTR-GK was conjugated to thiolated Fab fragments to prepare [188Re]CpTR-GK-Fab. The biodistribution of radioactivity after injection of [188Re]CpTR-GK-Fab was compared with that of [125I]HML-Fab and [188Re]CpTR-Fab prepared by conjugating N-hydroxysuccinimidyl ester of [188Re]CpTR-COOH with antibody fragments. While [188Re]CpTR-GK-Boc liberated [188Re]CpTR-Gly in BBMVs, [125I]HL-Boc liberated m-[125I]Iodohippuric Acid at a much faster rate. In addition, although [125I]HL-Boc was hydrolyzed by both metalloenzymes and nonmetalloenzymes, metalloenzymes were responsible for the cleavage of the peptide linkage in [188Re]CpTR-GK-Boc. In biodistribution studies, [188Re]CpTR-GK-Fab exhibited significantly lower renal radioactivity levels than did [188Re]CpTR-Fab. However, the renal radioactivity levels of [188Re]CpTR-GK-Fab were slightly higher than those of [125I]HML-Fab. The analysis of urine samples collected for 6 h postinjection of [188Re]CpTR-GK-Fab showed that [188Re]CpTR-Gly was the major radiometabolite. In tumor-bearing mice, [188Re]CpTR-GK-Fab significantly reduced renal radioactivity levels without impairing the radioactivity levels in tumor. These findings indicate that the molecular design of HML can be applied to metallic radionuclides by using a radiometal chelate of high inertness and by designing a radiometabolite of high urinary excretion when released from antibody fragments following cleavage of a glycyl-lysine linkage. This study also indicates that a change in chemical structure of a radiolabel attached to a glycyl-lysine linkage significantly affected enzymes involved in the hydrolysis reaction. Since there are many kinds of enzymes that cleave a variety of peptide linkages on the renal brush border membrane, selection of a peptide linkage optimal to a radiometal chelate of interest may provide radiolabeled antibody fragments that exhibit renal radioactivity levels similar to those of [131I]HML-labeled ones. The in vitro system using BBMVs might be useful for selecting an appropriate peptide linkage.
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In Vitro System To Estimate Renal Brush Border Enzyme-Mediated Cleavage of Peptide Linkages for Designing Radiolabeled Antibody Fragments of Low Renal Radioactivity Levels
Bioconjugate chemistry, 2005Co-Authors: Yasushi Fujioka, Hiromichi Akizawa, Hideo Saji, Takahiro Mukai, Tomoya Uehara, Satoshi Satake, Kazuma Ogawa, Keigo Endo, Yasushi AranoAbstract:Renal localization of radiolabeled antibody fragments presents a problem in targeted imaging and radiotherapy. We recently reported that Fab fragments labeled with 3‘-[131I]iodohippuryl Ne-maleoyl-l-lysine (HML) demonstrated markedly low renal radioactivity levels from early postinjection in mice. Previous studies suggested that low renal radioactivity levels were attributable to cleavage of the glycyl-lysine sequence in HML by the action of renal brush border enzymes, followed by urinary excretion of the resulting m-Iodohippuric Acid. In this study, an in vitro system using brush border membrane vesicles (BBMVs) isolated from the rat kidney cortex was developed to estimate renal brush border enzyme(s)-mediated cleavage of the peptide linkage. Low molecular weight HML derivatives, 3‘-[125I]iodohippuryl l-lysine (HL), 3‘-[125I]iodohippuryl Ne-tert-butoxycarbonyl-l-lysine (HBL), and their d-amino Acid counterparts, were synthesized and incubated in BBMVs. Both [125I]HL and [125I]HBL generated m-[125I]iodohi...
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Renal metabolism of 3'-iodohippuryl N(epsilon)-maleoyl-L-lysine (HML)-conjugated Fab fragments.
Bioconjugate chemistry, 2001Co-Authors: Yasushi Fujioka, Yasushi Arano, Masahiro Ono, Takahiro Mukai, Tomoya Uehara, Kazuma Ogawa, Shinji Namba, Tsuneo Saga, Yuji Nakamoto, Junji KonishiAbstract:Renal localization of radiolabeled antibody fragments constitutes a problem in targeted imaging and radiotherapy. Recently, we reported use of a novel radioiodination reagent, 3'-[131I]iodohippuryl N(epsilon)-maleoyl-L-lysine (HML), that liberates m-Iodohippuric Acid before antibody fragments are incorporated into renal cells. In mice, HML-conjugated Fab demonstrated low renal radioactivity levels from early postinjection times. In this study, renal metabolism of HML-conjugated Fab fragments prepared by different thiolation chemistries and by direct radioiodination were investigated to determine the mechanisms responsible for the low renal radioactivity levels. Fab fragments were thiolated by 2-iminothiolane modification or by reduction of disulfide bonds in the Fab fragments, followed by conjugation with radioiodinated HML to prepare [131I]HML-IT-Fab and [125I]HML-Fab, respectively. In biodistribution studies in mice, both [131I]HML-IT-Fab and [125I]HML-Fab demonstrated significantly lower renal radioactivity levels than those of [125I]Fab. In subcellular distribution studies, [125I]Fab showed migration of radioactivity from the membrane to the lysosomal fraction of the renal cells from 10 to 30 min postinjection. On the other hand, the majority of the radioactivity was detected only in the membrane fraction at the same time points after injection of both [131I]HML-IT-Fab and [125I]HML-Fab. In metabolic studies, while [125I]Fab remained intact at 10 min postinjection, both HML-conjugated Fab fragments generated m-Iodohippuric Acid as a radiometabolite at the same postinjection time. [131I]HML-IT-Fab registered two radiometabolites (intact [131I]HML-IT-Fab and m-Iodohippuric Acid), whereas additional radiometabolites were observed with [125I]HML-Fab. This suggested that metabolism of both HML-conjugated Fab fragments would occur in the membrane fractions of the renal cells. The findings of this study reinforced our previous hypothesis that radiochemical design of antibody fragments that liberate radiometabolites that are excreted into the urine by the action of brush border enzymes would constitute a useful strategy to reduce renal radioactivity levels from early postinjection times.
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Chemical Design of Radiolabeled Antibody Fragments for Low Renal Radioactivity Levels
Cancer Research, 1999Co-Authors: Yasushi Arano, Kouji Wakisaka, Hiromichi Akizawa, Morio Nakayama, Harumi Sakahara, Junji Konishi, Masahiro Ono, Tomoya Uehara, Yasushi Fujioka, Hideo SajiAbstract:ABSTRACT The renal uptake of radiolabeled antibody fragments presents a prob-lem in targeted imaging and therapy. We hypothesized that the renalradioactivity levels of radiolabeled antibody fragments could be reduced ifradiolabeled compounds of urinary excretion were released from glo-merularly filtered antibody fragments before they were incorporated intorenal cells by the action of brush border enzymes, present on the lumen ofrenal tubules. 3*-[ 131 I]Iodohippuryl N e -maleoyl- L -lysine ([ 131 I]HML) wasconjugated with a thiolated Fab fragment because the glycyl-lysine se-quence in HML is a substrate for a brush border enzyme and meta-Iodohippuric Acid is released by cleavage of the linkage. Fab fragmentswere also radiolabeled by direct radioiodination ( 125 I-Fab) or by conju-gation with meta-[ 125 I]-Iodohippuric Acidvia an amide bond [N-(5-male-imidopentyl) 3*-Iodohippuric Acid amide ([ 125 I]MPH-Fab)] or an esterbond [maleimidoethy 3*-iodohippurate ([ 125 I]MIH-Fab)] by proceduressimilar to those used for [
Hiromichi Akizawa - One of the best experts on this subject based on the ideXlab platform.
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Renal Brush Border Enzyme-Cleavable Linkages for Low Renal Radioactivity Levels of Radiolabeled Antibody Fragments
2013Co-Authors: Hiromichi Akizawa, Mitsuo Imajima, Hirofumi Hanaoka, Tomoya Uehara, Satoshi Satake, Yasushi AranoAbstract:We previously demonstrated that Fab fragments labeled with 3′-[131I]iodohippuryl Nε-maleoyl-l-lysine ([131I]HML) showed low renal radioactivity from early postinjection time, due to a liberation of m-[131I]Iodohippuric Acid by the action of renal brush border enzymes. Since there are lots of enzymes on renal brush border membrane, peptide linkages other than the glycyl-l-lysine were evaluated as the cleavable linkages to explore the chemical design. In this study, we evaluated four peptide linkages with a general formula of m-iodobenzoyl-glycyl-X (X: l-tyosine O-methyl, l-asparagine, l-glutamine, and Nε-Boc-l-lysine). In vitro studies using renal brush border membrane vesicles (BBMVs) demonstrated that 3′-[125I]iodohippuryl O-methyl-l-tyrosine (2c) liberated the highest amount of m-[125I]Iodohippuric Acid among the four substrates and the change in the linkage structure altered enzyme species responsible for the hydrolysis reaction. To further assess the applicability of the linkage, a radioiodination reagent containing a glycyl-tyrosine linkage, 3′-[125I]iodohippuryl O-((2-maleimidoethyl)carbamoyl)methyl-l-tyrosine (HMT, 12c), was designed, synthesized, and subsequently conjugated to an Fab fragment. [125I]HMT-Fab exhibited renal radioactivity levels similar to and significantly lower than [125I]HML-Fab and directly radioiodinated Fab, while the blood clearance rates of the three were similar. The analyses of urine for 24 h postinjection of [125I]HMT-Fab showed that m-[125I]Iodohippuric Acid was excreted as the major radiometabolite. The findings indicated that glycyl-tyrosine linkage is also available to reduce renal radioactivity levels of radioiodinated Fab fragments, due to liberation of m-Iodohippuric Acid by the action of enzymes present on renal brush border membrane. These findings suggest that an appropriate selection of peptide linkages would allow the liberation of a designed radiolabeled compound from covalently conjugated polypeptides to prepare radiolabeled polypeptides of low renal radioactivity levels. For the selection of the most appropriate peptide linkage, the in vitro system using BBMVs would be useful to narrow the candidates to just a few
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Design, synthesis, and evaluation of [188Re]organorhenium-labeled antibody fragments with renal enzyme-cleavable linkage for low renal radioactivity levels.
Bioconjugate chemistry, 2007Co-Authors: Tomoya Uehara, Hiromichi Akizawa, Miho Koike, Hideo Nakata, Hiroshi Hanaoka, Yasuhiko Iida, Kazuyuki Hashimoto, Keigo Endo, Yasushi AranoAbstract:Renal localization of radiolabeled antibody fragments constitutes a problem in targeted imaging and radiotherapy. We have reported that Fab fragments labeled with 3'-[131I]iodohippuryl Nepsilon-maleoyl-lysine (HML) showed markedly low renal radioactivity levels even shortly after injection, due to a rapid and selective release of m-[131I]Iodohippuric Acid by the action of brush border enzymes. To estimate the applicability of the molecular design to metallic radionuclides, [188Re]tricarbonyl(cyclopentadienylcarbonate)rhenium ([188Re]CpTR-COOH) was conjugated with Nepsilon-tert-butoxycarbonyl-glycyl-lysine or Nepsilon-maleoyl-glycyl-lysine to prepare [188Re]CpTR-GK-Boc or [188Re]CpTR-GK. The cleavage of the glycyl-lysine linkage of the two compounds generates a glycine conjugate of [188Re]CpTR-COOH ([188Re]CpTR-Gly), which possesses in vivo behaviors similar to those of m-Iodohippuric Acid. The hydrolysis rate of the peptide bond in [188Re]CpTR-GK-Boc was compared with that in 3'-[125I]iodohippuryl Nepsilon-Boc-lysine ([125I]HL-Boc) using brush border membrane vesicles (BBMVs) prepared from rat kidneys. [188Re]CpTR-GK was conjugated to thiolated Fab fragments to prepare [188Re]CpTR-GK-Fab. The biodistribution of radioactivity after injection of [188Re]CpTR-GK-Fab was compared with that of [125I]HML-Fab and [188Re]CpTR-Fab prepared by conjugating N-hydroxysuccinimidyl ester of [188Re]CpTR-COOH with antibody fragments. While [188Re]CpTR-GK-Boc liberated [188Re]CpTR-Gly in BBMVs, [125I]HL-Boc liberated m-[125I]Iodohippuric Acid at a much faster rate. In addition, although [125I]HL-Boc was hydrolyzed by both metalloenzymes and nonmetalloenzymes, metalloenzymes were responsible for the cleavage of the peptide linkage in [188Re]CpTR-GK-Boc. In biodistribution studies, [188Re]CpTR-GK-Fab exhibited significantly lower renal radioactivity levels than did [188Re]CpTR-Fab. However, the renal radioactivity levels of [188Re]CpTR-GK-Fab were slightly higher than those of [125I]HML-Fab. The analysis of urine samples collected for 6 h postinjection of [188Re]CpTR-GK-Fab showed that [188Re]CpTR-Gly was the major radiometabolite. In tumor-bearing mice, [188Re]CpTR-GK-Fab significantly reduced renal radioactivity levels without impairing the radioactivity levels in tumor. These findings indicate that the molecular design of HML can be applied to metallic radionuclides by using a radiometal chelate of high inertness and by designing a radiometabolite of high urinary excretion when released from antibody fragments following cleavage of a glycyl-lysine linkage. This study also indicates that a change in chemical structure of a radiolabel attached to a glycyl-lysine linkage significantly affected enzymes involved in the hydrolysis reaction. Since there are many kinds of enzymes that cleave a variety of peptide linkages on the renal brush border membrane, selection of a peptide linkage optimal to a radiometal chelate of interest may provide radiolabeled antibody fragments that exhibit renal radioactivity levels similar to those of [131I]HML-labeled ones. The in vitro system using BBMVs might be useful for selecting an appropriate peptide linkage.
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In Vitro System To Estimate Renal Brush Border Enzyme-Mediated Cleavage of Peptide Linkages for Designing Radiolabeled Antibody Fragments of Low Renal Radioactivity Levels
Bioconjugate chemistry, 2005Co-Authors: Yasushi Fujioka, Hiromichi Akizawa, Hideo Saji, Takahiro Mukai, Tomoya Uehara, Satoshi Satake, Kazuma Ogawa, Keigo Endo, Yasushi AranoAbstract:Renal localization of radiolabeled antibody fragments presents a problem in targeted imaging and radiotherapy. We recently reported that Fab fragments labeled with 3‘-[131I]iodohippuryl Ne-maleoyl-l-lysine (HML) demonstrated markedly low renal radioactivity levels from early postinjection in mice. Previous studies suggested that low renal radioactivity levels were attributable to cleavage of the glycyl-lysine sequence in HML by the action of renal brush border enzymes, followed by urinary excretion of the resulting m-Iodohippuric Acid. In this study, an in vitro system using brush border membrane vesicles (BBMVs) isolated from the rat kidney cortex was developed to estimate renal brush border enzyme(s)-mediated cleavage of the peptide linkage. Low molecular weight HML derivatives, 3‘-[125I]iodohippuryl l-lysine (HL), 3‘-[125I]iodohippuryl Ne-tert-butoxycarbonyl-l-lysine (HBL), and their d-amino Acid counterparts, were synthesized and incubated in BBMVs. Both [125I]HL and [125I]HBL generated m-[125I]iodohi...
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Chemical Design of Radiolabeled Antibody Fragments for Low Renal Radioactivity Levels
Cancer Research, 1999Co-Authors: Yasushi Arano, Kouji Wakisaka, Hiromichi Akizawa, Morio Nakayama, Harumi Sakahara, Junji Konishi, Masahiro Ono, Tomoya Uehara, Yasushi Fujioka, Hideo SajiAbstract:ABSTRACT The renal uptake of radiolabeled antibody fragments presents a prob-lem in targeted imaging and therapy. We hypothesized that the renalradioactivity levels of radiolabeled antibody fragments could be reduced ifradiolabeled compounds of urinary excretion were released from glo-merularly filtered antibody fragments before they were incorporated intorenal cells by the action of brush border enzymes, present on the lumen ofrenal tubules. 3*-[ 131 I]Iodohippuryl N e -maleoyl- L -lysine ([ 131 I]HML) wasconjugated with a thiolated Fab fragment because the glycyl-lysine se-quence in HML is a substrate for a brush border enzyme and meta-Iodohippuric Acid is released by cleavage of the linkage. Fab fragmentswere also radiolabeled by direct radioiodination ( 125 I-Fab) or by conju-gation with meta-[ 125 I]-Iodohippuric Acidvia an amide bond [N-(5-male-imidopentyl) 3*-Iodohippuric Acid amide ([ 125 I]MPH-Fab)] or an esterbond [maleimidoethy 3*-iodohippurate ([ 125 I]MIH-Fab)] by proceduressimilar to those used for [
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ASSESSMENT OF THE RADIOCHEMICAL DESIGN OF ANTIBODIES WITH A METABOLIZABLE LINKAGE FOR TARGET-SELECTIVE RADIOACTIVITY DELIVERY
Bioconjugate chemistry, 1998Co-Authors: Yasushi Arano, Kouji Wakisaka, Hiromichi Akizawa, Morio Nakayama, Harumi Sakahara, Junji Konishi, Masahiro Ono, Keiichi Kawai, Hideo SajiAbstract:Interposition of a metabolizable linkage has been performed to reduce the hepatic radioactivity levels of radiolabeled antibodies. To estimate the validity of this strategy, a radioiodination reagent (HML) that provides a stable attachment for m-Iodohippuric Acid with proteins in plasma while facilitating rapid and selective release of the compound after lysosomal proteolysis in the liver was conjugated with a monoclonal antibody (mAb) against osteogenic sarcoma (OST7, IgG1). Radiolabeled OST7 conjugates with a plasma-labile ester bond for releasing m-Iodohippuric Acid (MIH), plasma-stable amide bonds for releasing radiometabolites of hepatobiliary excretion (MPH), or slow elimination rates from hepatocytes ([111In]EMCS-Bz-EDTA) were prepared with similar conjugation chemistry. The four radiolabeled OST7 conjugates were characterized both in vitro and in vivo. All the radiolabeled OST7 conjugates had similar radiochromatograms on size-exclusion HPLC and similar antigen binding affinities. While MIH-OST7 indicated accelerated clearance of radioactivity from the blood due to the release of m-iodohippurate, the rest of the three radiolabeled OST7 conjugates remained stable in serum incubation studies and had similar radioactivity elimination from the blood in vivo. When injected into normal mice, HML-OST7 demonstrated tissue-to-blood ratios of radioactivity similar to those of MIH-OST7 and significantly lower than those of the other two radiolabeled OST7 conjugates. In biodistribution studies in nude mice, both HML-OST7 and MIH-OST7 exhibited tumor-to-liver or tumor-to-intestine ratios of radioactivity higher than those of [111In]EMCS-Bz-EDTA-OST7 or MPH-OST7, respectively. HML-OST7, MPH-OST7, and [111In]EMCS-Bz-EDTA-OST7 indicated there were no changes in the radioactivity levels in the tumor between 24 and 48 h postinjection, whereas MIH-OST7 significantly decreased the radioactivity levels in the tumor at these time points. HML reduced the radioactivity levels in nontarget tissues without impairing the tumor radioactivity levels delivered by OST7. These findings indicated that the design of a radiolabeled mAb that is stable in plasma and liberates the radiometabolite of rapid urinary excretion constitutes an effective strategy for achieving target-selective radioactivity delivery.
Junji Konishi - One of the best experts on this subject based on the ideXlab platform.
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Renal metabolism of 3'-iodohippuryl N(epsilon)-maleoyl-L-lysine (HML)-conjugated Fab fragments.
Bioconjugate chemistry, 2001Co-Authors: Yasushi Fujioka, Yasushi Arano, Masahiro Ono, Takahiro Mukai, Tomoya Uehara, Kazuma Ogawa, Shinji Namba, Tsuneo Saga, Yuji Nakamoto, Junji KonishiAbstract:Renal localization of radiolabeled antibody fragments constitutes a problem in targeted imaging and radiotherapy. Recently, we reported use of a novel radioiodination reagent, 3'-[131I]iodohippuryl N(epsilon)-maleoyl-L-lysine (HML), that liberates m-Iodohippuric Acid before antibody fragments are incorporated into renal cells. In mice, HML-conjugated Fab demonstrated low renal radioactivity levels from early postinjection times. In this study, renal metabolism of HML-conjugated Fab fragments prepared by different thiolation chemistries and by direct radioiodination were investigated to determine the mechanisms responsible for the low renal radioactivity levels. Fab fragments were thiolated by 2-iminothiolane modification or by reduction of disulfide bonds in the Fab fragments, followed by conjugation with radioiodinated HML to prepare [131I]HML-IT-Fab and [125I]HML-Fab, respectively. In biodistribution studies in mice, both [131I]HML-IT-Fab and [125I]HML-Fab demonstrated significantly lower renal radioactivity levels than those of [125I]Fab. In subcellular distribution studies, [125I]Fab showed migration of radioactivity from the membrane to the lysosomal fraction of the renal cells from 10 to 30 min postinjection. On the other hand, the majority of the radioactivity was detected only in the membrane fraction at the same time points after injection of both [131I]HML-IT-Fab and [125I]HML-Fab. In metabolic studies, while [125I]Fab remained intact at 10 min postinjection, both HML-conjugated Fab fragments generated m-Iodohippuric Acid as a radiometabolite at the same postinjection time. [131I]HML-IT-Fab registered two radiometabolites (intact [131I]HML-IT-Fab and m-Iodohippuric Acid), whereas additional radiometabolites were observed with [125I]HML-Fab. This suggested that metabolism of both HML-conjugated Fab fragments would occur in the membrane fractions of the renal cells. The findings of this study reinforced our previous hypothesis that radiochemical design of antibody fragments that liberate radiometabolites that are excreted into the urine by the action of brush border enzymes would constitute a useful strategy to reduce renal radioactivity levels from early postinjection times.
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Chemical Design of Radiolabeled Antibody Fragments for Low Renal Radioactivity Levels
Cancer Research, 1999Co-Authors: Yasushi Arano, Kouji Wakisaka, Hiromichi Akizawa, Morio Nakayama, Harumi Sakahara, Junji Konishi, Masahiro Ono, Tomoya Uehara, Yasushi Fujioka, Hideo SajiAbstract:ABSTRACT The renal uptake of radiolabeled antibody fragments presents a prob-lem in targeted imaging and therapy. We hypothesized that the renalradioactivity levels of radiolabeled antibody fragments could be reduced ifradiolabeled compounds of urinary excretion were released from glo-merularly filtered antibody fragments before they were incorporated intorenal cells by the action of brush border enzymes, present on the lumen ofrenal tubules. 3*-[ 131 I]Iodohippuryl N e -maleoyl- L -lysine ([ 131 I]HML) wasconjugated with a thiolated Fab fragment because the glycyl-lysine se-quence in HML is a substrate for a brush border enzyme and meta-Iodohippuric Acid is released by cleavage of the linkage. Fab fragmentswere also radiolabeled by direct radioiodination ( 125 I-Fab) or by conju-gation with meta-[ 125 I]-Iodohippuric Acidvia an amide bond [N-(5-male-imidopentyl) 3*-Iodohippuric Acid amide ([ 125 I]MPH-Fab)] or an esterbond [maleimidoethy 3*-iodohippurate ([ 125 I]MIH-Fab)] by proceduressimilar to those used for [
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ASSESSMENT OF THE RADIOCHEMICAL DESIGN OF ANTIBODIES WITH A METABOLIZABLE LINKAGE FOR TARGET-SELECTIVE RADIOACTIVITY DELIVERY
Bioconjugate chemistry, 1998Co-Authors: Yasushi Arano, Kouji Wakisaka, Hiromichi Akizawa, Morio Nakayama, Harumi Sakahara, Junji Konishi, Masahiro Ono, Keiichi Kawai, Hideo SajiAbstract:Interposition of a metabolizable linkage has been performed to reduce the hepatic radioactivity levels of radiolabeled antibodies. To estimate the validity of this strategy, a radioiodination reagent (HML) that provides a stable attachment for m-Iodohippuric Acid with proteins in plasma while facilitating rapid and selective release of the compound after lysosomal proteolysis in the liver was conjugated with a monoclonal antibody (mAb) against osteogenic sarcoma (OST7, IgG1). Radiolabeled OST7 conjugates with a plasma-labile ester bond for releasing m-Iodohippuric Acid (MIH), plasma-stable amide bonds for releasing radiometabolites of hepatobiliary excretion (MPH), or slow elimination rates from hepatocytes ([111In]EMCS-Bz-EDTA) were prepared with similar conjugation chemistry. The four radiolabeled OST7 conjugates were characterized both in vitro and in vivo. All the radiolabeled OST7 conjugates had similar radiochromatograms on size-exclusion HPLC and similar antigen binding affinities. While MIH-OST7 indicated accelerated clearance of radioactivity from the blood due to the release of m-iodohippurate, the rest of the three radiolabeled OST7 conjugates remained stable in serum incubation studies and had similar radioactivity elimination from the blood in vivo. When injected into normal mice, HML-OST7 demonstrated tissue-to-blood ratios of radioactivity similar to those of MIH-OST7 and significantly lower than those of the other two radiolabeled OST7 conjugates. In biodistribution studies in nude mice, both HML-OST7 and MIH-OST7 exhibited tumor-to-liver or tumor-to-intestine ratios of radioactivity higher than those of [111In]EMCS-Bz-EDTA-OST7 or MPH-OST7, respectively. HML-OST7, MPH-OST7, and [111In]EMCS-Bz-EDTA-OST7 indicated there were no changes in the radioactivity levels in the tumor between 24 and 48 h postinjection, whereas MIH-OST7 significantly decreased the radioactivity levels in the tumor at these time points. HML reduced the radioactivity levels in nontarget tissues without impairing the tumor radioactivity levels delivered by OST7. These findings indicated that the design of a radiolabeled mAb that is stable in plasma and liberates the radiometabolite of rapid urinary excretion constitutes an effective strategy for achieving target-selective radioactivity delivery.
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Assessment of radiochemical design of antibodies using an ester bond as the metabolizable linkage: evaluation of maleimidoethyl 3-(tri-n-butylstannyl)hippurate as a radioiodination reagent of antibodies for diagnostic and therapeutic applications.
Bioconjugate chemistry, 1996Co-Authors: Yasushi Arano, Kouji Wakisaka, Takashi Uezono, Hiromichi Akizawa, Chiaki Tanaka, Yoshiro Ohmono, Morio Nakayama, Harumi Sakahara, Junji Konishi, Akira YokoyamaAbstract:Reduction of radioactivity levels in nontarget tissues such as the liver and kidney constitutes a problem to be resolved in diagnostic and therapeutic applications of radiolabeled monoclonal antibodies (mAbs). A new radioiodination reagent with an ester bond to liberate m-Iodohippuric Acid from covalently conjugated proteins, maleimidoethyl 3-(tri-n-butylstannyl)hippurate (MIH), was recently developed. MIH liberated m-Iodohippuric Acid from galactosylneoglycoalbumin in murine liver, and the radiometabolite was rapidly eliminated from the liver into urine as an intact structure. In this study, intact IgG and Fab fragment of a mAb against osteogenic sarcoma were radioiodinated with MIH to further assess the applicability of MIH to radioimmunoimaging and therapy. For comparison, a mAb radioiodinated with N-succinimidyl iodobenzoate (SIB) and indium-111 (111In)-labeled mAbs with diethylenetriaminepentaacetic dianhydride (cDTPA) or 1-[4-[(5-maleimidopentyl)amino]benzyl]-ethylenediaminetetraacetic Acid (EMCS-Bz-EDTA) were used. Size-exclusion HPLC analysis and cell binding assays indicated the preservation of both structure and antigen binding affinity of radioiodinated MIH-OST7 (IgG). In biodistribution studies in mice, [125I]MIH-OST7 (IgG) showed faster systemic clearance of radioactivity after 24 h postinjection than did [131I]SIB- and [111In]EMCS-Bz-EDTA-OST7 (IgG). [125I]MIH-OST7 (IgG) also exhibited much lower radioactivity levels in nontarget tissues such as the liver and kidney, with higher radioactivity levels in the blood up to 72 h postinjection when compared with [111In]cDTPA-OST7 (IgG). Radioactivity excreted from the mice was found in the urine as m-Iodohippuric Acid, following administration of [125I]MIH-OST7 (IgG). In athymic mice bearing osteogenic sarcoma, [131I]MIH-OST7 (IgG) indicated higher tumor-to-nontarget ratios of radioactivity at both 24 and 48 h postinjection than [125I]SIB-OST7 (IgG). Although both radioiodinated OST7s showed similar radioactivity levels in the target at 24 h postinjection, a small but significant decrease in the target radioactivity level was observed with [131I]MIH-OST7 (IgG) at 48 h postinjection. In addition, [131I]MIH-OST7 (Fab) showed very rapid cleavage of the ester bond both in vivo and in vitro. These findings indicated that while MIH may be a useful reagent for radioimmunoimaging using IgG, mAb, its application to smaller molecular weight mAbs and radioimmunotherapy would be hindered due to the labile characteristics of the ester bond in plasma. Thus, while the present study reinforced the usefulness of metabolizable linkages for reducing nontarget radioactivity levels, a development of plasma-stable metabolizable linkages is also warranted for radioimmunotherapy and for smaller molecular weight polypeptides.
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assessment of radiochemical design of antibodies using an ester bond as the metabolizable linkage evaluation of maleimidoethyl 3 tri n butylstannyl hippurate as a radioiodination reagent of antibodies for diagnostic and therapeutic applications
Bioconjugate Chemistry, 1996Co-Authors: Yasushi Arano, Kouji Wakisaka, Takashi Uezono, Hiromichi Akizawa, Chiaki Tanaka, Yoshiro Ohmono, Morio Nakayama, Harumi Sakahara, Junji Konishi, Akira YokoyamaAbstract:Reduction of radioactivity levels in nontarget tissues such as the liver and kidney constitutes a problem to be resolved in diagnostic and therapeutic applications of radiolabeled monoclonal antibodies (mAbs). A new radioiodination reagent with an ester bond to liberate m-Iodohippuric Acid from covalently conjugated proteins, maleimidoethyl 3-(tri-n-butylstannyl)hippurate (MIH), was recently developed. MIH liberated m-Iodohippuric Acid from galactosylneoglycoalbumin in murine liver, and the radiometabolite was rapidly eliminated from the liver into urine as an intact structure. In this study, intact IgG and Fab fragment of a mAb against osteogenic sarcoma were radioiodinated with MIH to further assess the applicability of MIH to radioimmunoimaging and therapy. For comparison, a mAb radioiodinated with N-succinimidyl iodobenzoate (SIB) and indium-111 (111In)-labeled mAbs with diethylenetriaminepentaacetic dianhydride (cDTPA) or 1-[4-[(5-maleimidopentyl)amino]benzyl]ethylenediaminetetraacetic Acid (EMCS-Bz-...
Hideo Saji - One of the best experts on this subject based on the ideXlab platform.
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In Vitro System To Estimate Renal Brush Border Enzyme-Mediated Cleavage of Peptide Linkages for Designing Radiolabeled Antibody Fragments of Low Renal Radioactivity Levels
Bioconjugate chemistry, 2005Co-Authors: Yasushi Fujioka, Hiromichi Akizawa, Hideo Saji, Takahiro Mukai, Tomoya Uehara, Satoshi Satake, Kazuma Ogawa, Keigo Endo, Yasushi AranoAbstract:Renal localization of radiolabeled antibody fragments presents a problem in targeted imaging and radiotherapy. We recently reported that Fab fragments labeled with 3‘-[131I]iodohippuryl Ne-maleoyl-l-lysine (HML) demonstrated markedly low renal radioactivity levels from early postinjection in mice. Previous studies suggested that low renal radioactivity levels were attributable to cleavage of the glycyl-lysine sequence in HML by the action of renal brush border enzymes, followed by urinary excretion of the resulting m-Iodohippuric Acid. In this study, an in vitro system using brush border membrane vesicles (BBMVs) isolated from the rat kidney cortex was developed to estimate renal brush border enzyme(s)-mediated cleavage of the peptide linkage. Low molecular weight HML derivatives, 3‘-[125I]iodohippuryl l-lysine (HL), 3‘-[125I]iodohippuryl Ne-tert-butoxycarbonyl-l-lysine (HBL), and their d-amino Acid counterparts, were synthesized and incubated in BBMVs. Both [125I]HL and [125I]HBL generated m-[125I]iodohi...
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Chemical Design of Radiolabeled Antibody Fragments for Low Renal Radioactivity Levels
Cancer Research, 1999Co-Authors: Yasushi Arano, Kouji Wakisaka, Hiromichi Akizawa, Morio Nakayama, Harumi Sakahara, Junji Konishi, Masahiro Ono, Tomoya Uehara, Yasushi Fujioka, Hideo SajiAbstract:ABSTRACT The renal uptake of radiolabeled antibody fragments presents a prob-lem in targeted imaging and therapy. We hypothesized that the renalradioactivity levels of radiolabeled antibody fragments could be reduced ifradiolabeled compounds of urinary excretion were released from glo-merularly filtered antibody fragments before they were incorporated intorenal cells by the action of brush border enzymes, present on the lumen ofrenal tubules. 3*-[ 131 I]Iodohippuryl N e -maleoyl- L -lysine ([ 131 I]HML) wasconjugated with a thiolated Fab fragment because the glycyl-lysine se-quence in HML is a substrate for a brush border enzyme and meta-Iodohippuric Acid is released by cleavage of the linkage. Fab fragmentswere also radiolabeled by direct radioiodination ( 125 I-Fab) or by conju-gation with meta-[ 125 I]-Iodohippuric Acidvia an amide bond [N-(5-male-imidopentyl) 3*-Iodohippuric Acid amide ([ 125 I]MPH-Fab)] or an esterbond [maleimidoethy 3*-iodohippurate ([ 125 I]MIH-Fab)] by proceduressimilar to those used for [
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ASSESSMENT OF THE RADIOCHEMICAL DESIGN OF ANTIBODIES WITH A METABOLIZABLE LINKAGE FOR TARGET-SELECTIVE RADIOACTIVITY DELIVERY
Bioconjugate chemistry, 1998Co-Authors: Yasushi Arano, Kouji Wakisaka, Hiromichi Akizawa, Morio Nakayama, Harumi Sakahara, Junji Konishi, Masahiro Ono, Keiichi Kawai, Hideo SajiAbstract:Interposition of a metabolizable linkage has been performed to reduce the hepatic radioactivity levels of radiolabeled antibodies. To estimate the validity of this strategy, a radioiodination reagent (HML) that provides a stable attachment for m-Iodohippuric Acid with proteins in plasma while facilitating rapid and selective release of the compound after lysosomal proteolysis in the liver was conjugated with a monoclonal antibody (mAb) against osteogenic sarcoma (OST7, IgG1). Radiolabeled OST7 conjugates with a plasma-labile ester bond for releasing m-Iodohippuric Acid (MIH), plasma-stable amide bonds for releasing radiometabolites of hepatobiliary excretion (MPH), or slow elimination rates from hepatocytes ([111In]EMCS-Bz-EDTA) were prepared with similar conjugation chemistry. The four radiolabeled OST7 conjugates were characterized both in vitro and in vivo. All the radiolabeled OST7 conjugates had similar radiochromatograms on size-exclusion HPLC and similar antigen binding affinities. While MIH-OST7 indicated accelerated clearance of radioactivity from the blood due to the release of m-iodohippurate, the rest of the three radiolabeled OST7 conjugates remained stable in serum incubation studies and had similar radioactivity elimination from the blood in vivo. When injected into normal mice, HML-OST7 demonstrated tissue-to-blood ratios of radioactivity similar to those of MIH-OST7 and significantly lower than those of the other two radiolabeled OST7 conjugates. In biodistribution studies in nude mice, both HML-OST7 and MIH-OST7 exhibited tumor-to-liver or tumor-to-intestine ratios of radioactivity higher than those of [111In]EMCS-Bz-EDTA-OST7 or MPH-OST7, respectively. HML-OST7, MPH-OST7, and [111In]EMCS-Bz-EDTA-OST7 indicated there were no changes in the radioactivity levels in the tumor between 24 and 48 h postinjection, whereas MIH-OST7 significantly decreased the radioactivity levels in the tumor at these time points. HML reduced the radioactivity levels in nontarget tissues without impairing the tumor radioactivity levels delivered by OST7. These findings indicated that the design of a radiolabeled mAb that is stable in plasma and liberates the radiometabolite of rapid urinary excretion constitutes an effective strategy for achieving target-selective radioactivity delivery.
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A novel radioiodination reagent for protein radiopharmaceuticals with L-lysine as a plasma-stable metabolizable linkage to liberate m-Iodohippuric Acid after lysosomal proteolysis.
Journal of medicinal chemistry, 1997Co-Authors: Kouji Wakisaka, Yasushi Arano, Takashi Uezono, Hiromichi Akizawa, Morio Nakayama, Masahiro Ono, Keiichi Kawai, Yoshiro Ohomomo, Hideo SajiAbstract:Radiochemical design of polypeptides using metabolizable linkages would be attractive to enhance target-selective localization of radioactivity for diagnostic and therapeutic nuclear medicine. However, while use of ester bonds as the linkage allows selective release of the designed radiometabolite from covalently conjugated polypeptides after lysosomal proteolysis in nontarget tissues, low plasma stability of ester bonds causes a decrease in radioactivity levels of the target. In pursuit of new metabolizable linkages that provide stable attachment of radiolabels with polypeptide in plasma while facilitating rapid and selective release of designed radiometabolites of rapid urinary excretion in lysosomes, a new radioiodination reagent with l-lysine as the metabolizable linkage to liberate m-Iodohippuric Acid (l-HML) was designed and synthesized. Stabilities of the metabolizable linkage in serum and cleavabilities of the linkage in lysosomal proteolysis in hepatic cells were investigated after conjugation of...
Kouji Wakisaka - One of the best experts on this subject based on the ideXlab platform.
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Chemical Design of Radiolabeled Antibody Fragments for Low Renal Radioactivity Levels
Cancer Research, 1999Co-Authors: Yasushi Arano, Kouji Wakisaka, Hiromichi Akizawa, Morio Nakayama, Harumi Sakahara, Junji Konishi, Masahiro Ono, Tomoya Uehara, Yasushi Fujioka, Hideo SajiAbstract:ABSTRACT The renal uptake of radiolabeled antibody fragments presents a prob-lem in targeted imaging and therapy. We hypothesized that the renalradioactivity levels of radiolabeled antibody fragments could be reduced ifradiolabeled compounds of urinary excretion were released from glo-merularly filtered antibody fragments before they were incorporated intorenal cells by the action of brush border enzymes, present on the lumen ofrenal tubules. 3*-[ 131 I]Iodohippuryl N e -maleoyl- L -lysine ([ 131 I]HML) wasconjugated with a thiolated Fab fragment because the glycyl-lysine se-quence in HML is a substrate for a brush border enzyme and meta-Iodohippuric Acid is released by cleavage of the linkage. Fab fragmentswere also radiolabeled by direct radioiodination ( 125 I-Fab) or by conju-gation with meta-[ 125 I]-Iodohippuric Acidvia an amide bond [N-(5-male-imidopentyl) 3*-Iodohippuric Acid amide ([ 125 I]MPH-Fab)] or an esterbond [maleimidoethy 3*-iodohippurate ([ 125 I]MIH-Fab)] by proceduressimilar to those used for [
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ASSESSMENT OF THE RADIOCHEMICAL DESIGN OF ANTIBODIES WITH A METABOLIZABLE LINKAGE FOR TARGET-SELECTIVE RADIOACTIVITY DELIVERY
Bioconjugate chemistry, 1998Co-Authors: Yasushi Arano, Kouji Wakisaka, Hiromichi Akizawa, Morio Nakayama, Harumi Sakahara, Junji Konishi, Masahiro Ono, Keiichi Kawai, Hideo SajiAbstract:Interposition of a metabolizable linkage has been performed to reduce the hepatic radioactivity levels of radiolabeled antibodies. To estimate the validity of this strategy, a radioiodination reagent (HML) that provides a stable attachment for m-Iodohippuric Acid with proteins in plasma while facilitating rapid and selective release of the compound after lysosomal proteolysis in the liver was conjugated with a monoclonal antibody (mAb) against osteogenic sarcoma (OST7, IgG1). Radiolabeled OST7 conjugates with a plasma-labile ester bond for releasing m-Iodohippuric Acid (MIH), plasma-stable amide bonds for releasing radiometabolites of hepatobiliary excretion (MPH), or slow elimination rates from hepatocytes ([111In]EMCS-Bz-EDTA) were prepared with similar conjugation chemistry. The four radiolabeled OST7 conjugates were characterized both in vitro and in vivo. All the radiolabeled OST7 conjugates had similar radiochromatograms on size-exclusion HPLC and similar antigen binding affinities. While MIH-OST7 indicated accelerated clearance of radioactivity from the blood due to the release of m-iodohippurate, the rest of the three radiolabeled OST7 conjugates remained stable in serum incubation studies and had similar radioactivity elimination from the blood in vivo. When injected into normal mice, HML-OST7 demonstrated tissue-to-blood ratios of radioactivity similar to those of MIH-OST7 and significantly lower than those of the other two radiolabeled OST7 conjugates. In biodistribution studies in nude mice, both HML-OST7 and MIH-OST7 exhibited tumor-to-liver or tumor-to-intestine ratios of radioactivity higher than those of [111In]EMCS-Bz-EDTA-OST7 or MPH-OST7, respectively. HML-OST7, MPH-OST7, and [111In]EMCS-Bz-EDTA-OST7 indicated there were no changes in the radioactivity levels in the tumor between 24 and 48 h postinjection, whereas MIH-OST7 significantly decreased the radioactivity levels in the tumor at these time points. HML reduced the radioactivity levels in nontarget tissues without impairing the tumor radioactivity levels delivered by OST7. These findings indicated that the design of a radiolabeled mAb that is stable in plasma and liberates the radiometabolite of rapid urinary excretion constitutes an effective strategy for achieving target-selective radioactivity delivery.
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A novel radioiodination reagent for protein radiopharmaceuticals with L-lysine as a plasma-stable metabolizable linkage to liberate m-Iodohippuric Acid after lysosomal proteolysis.
Journal of medicinal chemistry, 1997Co-Authors: Kouji Wakisaka, Yasushi Arano, Takashi Uezono, Hiromichi Akizawa, Morio Nakayama, Masahiro Ono, Keiichi Kawai, Yoshiro Ohomomo, Hideo SajiAbstract:Radiochemical design of polypeptides using metabolizable linkages would be attractive to enhance target-selective localization of radioactivity for diagnostic and therapeutic nuclear medicine. However, while use of ester bonds as the linkage allows selective release of the designed radiometabolite from covalently conjugated polypeptides after lysosomal proteolysis in nontarget tissues, low plasma stability of ester bonds causes a decrease in radioactivity levels of the target. In pursuit of new metabolizable linkages that provide stable attachment of radiolabels with polypeptide in plasma while facilitating rapid and selective release of designed radiometabolites of rapid urinary excretion in lysosomes, a new radioiodination reagent with l-lysine as the metabolizable linkage to liberate m-Iodohippuric Acid (l-HML) was designed and synthesized. Stabilities of the metabolizable linkage in serum and cleavabilities of the linkage in lysosomal proteolysis in hepatic cells were investigated after conjugation of...
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Assessment of radiochemical design of antibodies using an ester bond as the metabolizable linkage: evaluation of maleimidoethyl 3-(tri-n-butylstannyl)hippurate as a radioiodination reagent of antibodies for diagnostic and therapeutic applications.
Bioconjugate chemistry, 1996Co-Authors: Yasushi Arano, Kouji Wakisaka, Takashi Uezono, Hiromichi Akizawa, Chiaki Tanaka, Yoshiro Ohmono, Morio Nakayama, Harumi Sakahara, Junji Konishi, Akira YokoyamaAbstract:Reduction of radioactivity levels in nontarget tissues such as the liver and kidney constitutes a problem to be resolved in diagnostic and therapeutic applications of radiolabeled monoclonal antibodies (mAbs). A new radioiodination reagent with an ester bond to liberate m-Iodohippuric Acid from covalently conjugated proteins, maleimidoethyl 3-(tri-n-butylstannyl)hippurate (MIH), was recently developed. MIH liberated m-Iodohippuric Acid from galactosylneoglycoalbumin in murine liver, and the radiometabolite was rapidly eliminated from the liver into urine as an intact structure. In this study, intact IgG and Fab fragment of a mAb against osteogenic sarcoma were radioiodinated with MIH to further assess the applicability of MIH to radioimmunoimaging and therapy. For comparison, a mAb radioiodinated with N-succinimidyl iodobenzoate (SIB) and indium-111 (111In)-labeled mAbs with diethylenetriaminepentaacetic dianhydride (cDTPA) or 1-[4-[(5-maleimidopentyl)amino]benzyl]-ethylenediaminetetraacetic Acid (EMCS-Bz-EDTA) were used. Size-exclusion HPLC analysis and cell binding assays indicated the preservation of both structure and antigen binding affinity of radioiodinated MIH-OST7 (IgG). In biodistribution studies in mice, [125I]MIH-OST7 (IgG) showed faster systemic clearance of radioactivity after 24 h postinjection than did [131I]SIB- and [111In]EMCS-Bz-EDTA-OST7 (IgG). [125I]MIH-OST7 (IgG) also exhibited much lower radioactivity levels in nontarget tissues such as the liver and kidney, with higher radioactivity levels in the blood up to 72 h postinjection when compared with [111In]cDTPA-OST7 (IgG). Radioactivity excreted from the mice was found in the urine as m-Iodohippuric Acid, following administration of [125I]MIH-OST7 (IgG). In athymic mice bearing osteogenic sarcoma, [131I]MIH-OST7 (IgG) indicated higher tumor-to-nontarget ratios of radioactivity at both 24 and 48 h postinjection than [125I]SIB-OST7 (IgG). Although both radioiodinated OST7s showed similar radioactivity levels in the target at 24 h postinjection, a small but significant decrease in the target radioactivity level was observed with [131I]MIH-OST7 (IgG) at 48 h postinjection. In addition, [131I]MIH-OST7 (Fab) showed very rapid cleavage of the ester bond both in vivo and in vitro. These findings indicated that while MIH may be a useful reagent for radioimmunoimaging using IgG, mAb, its application to smaller molecular weight mAbs and radioimmunotherapy would be hindered due to the labile characteristics of the ester bond in plasma. Thus, while the present study reinforced the usefulness of metabolizable linkages for reducing nontarget radioactivity levels, a development of plasma-stable metabolizable linkages is also warranted for radioimmunotherapy and for smaller molecular weight polypeptides.
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assessment of radiochemical design of antibodies using an ester bond as the metabolizable linkage evaluation of maleimidoethyl 3 tri n butylstannyl hippurate as a radioiodination reagent of antibodies for diagnostic and therapeutic applications
Bioconjugate Chemistry, 1996Co-Authors: Yasushi Arano, Kouji Wakisaka, Takashi Uezono, Hiromichi Akizawa, Chiaki Tanaka, Yoshiro Ohmono, Morio Nakayama, Harumi Sakahara, Junji Konishi, Akira YokoyamaAbstract:Reduction of radioactivity levels in nontarget tissues such as the liver and kidney constitutes a problem to be resolved in diagnostic and therapeutic applications of radiolabeled monoclonal antibodies (mAbs). A new radioiodination reagent with an ester bond to liberate m-Iodohippuric Acid from covalently conjugated proteins, maleimidoethyl 3-(tri-n-butylstannyl)hippurate (MIH), was recently developed. MIH liberated m-Iodohippuric Acid from galactosylneoglycoalbumin in murine liver, and the radiometabolite was rapidly eliminated from the liver into urine as an intact structure. In this study, intact IgG and Fab fragment of a mAb against osteogenic sarcoma were radioiodinated with MIH to further assess the applicability of MIH to radioimmunoimaging and therapy. For comparison, a mAb radioiodinated with N-succinimidyl iodobenzoate (SIB) and indium-111 (111In)-labeled mAbs with diethylenetriaminepentaacetic dianhydride (cDTPA) or 1-[4-[(5-maleimidopentyl)amino]benzyl]ethylenediaminetetraacetic Acid (EMCS-Bz-...
