Synthesis and evaluation of a monoreactive DOTA derivative for indium-111-based residualizing label to estimate protein pharmacokinetics.
The purpose of this study was to develop an indium-111 (111In)-based residualizing label for estimating the pharmacokinetics of proteins. 1,4,7,10-Tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA), which produced a highly stable and hydrophilic 111In chelate, was selected as the chelating site, and the monoreactive DOTA derivative with a tetrafluorophenyl group as the protein binding site (mDOTA) was designed to avoid cross-linkings of proteins. mDOTA was synthesized with an overall yield of 11%. The stability in murine plasma, the radioactivity retention in the catabolic sites of proteins and the radiochemical yields of 111In-labelled proteins via mDOTA were investigated using human serum albumin (HSA), galactosyl-neoglycoalbumin (NGA) and cytochrome c (cyt c) as model proteins. 111In-labelled HSA via mDOTA was highly stable for 5 days after incubation in murine plasma. Long retention of radioactivity in the catabolic sites was observed after injection of 111In-DOTA-NGA in mice, due to the slow elimination of the radiometabolite from the lysosome. At a chelator concentration of 42.2 microM, 111In-DOTA-cyt c was produced with over 91% radiochemical yield. On the other hand, 111In-DOTA-lysine and 111In-DOTA were obtained with high radiochemical yields at lower chelator concentrations. These findings indicated that mDOTA would be an appropriate 111In-labelling agent for estimating protein pharmacokinetics. These findings also suggested that the introduction of a protein binding site at a position distal from the unmodified DOTA structure would be preferable to preparing 111In-DOTA-labelled proteins with higher specific activity.
Department of Nuclear Medicine and Diagnostic Imaging, Graduate School of Medicine, Kyoto University, Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan. tmukai@kuhp.kyoto-u.ac.jp
Takahiro
T
Mukai
Shinji
S
Namba
Yasushi
Y
Arano
Masahiro
M
Ono
Yasushi
Y
Fujioka
Tomoya
T
Uehara
Kazuma
K
Ogawa
Junji
J
Konishi
Hideo
H
Saji
D000818:Animals; D002614:Chelating Agents / Q000138:chemical synthesis* / Q000493:pharmacokinetics*; D006573:Heterocyclic Compounds, 1-Ring / Q000819:agonists / Q000138:chemical synthesis* / Q000493:pharmacokinetics*; D007205:Indium Radioisotopes; D008297:Male; D051379:Mice; D011506:Proteins / Q000378:metabolism / Q000493:pharmacokinetics; D014018:Tissue Distribution
D002614:Chelating Agents; D006573:Heterocyclic Compounds, 1-Ring; D007205:Indium Radioisotopes; D011506:Proteins; C071349:1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid