An improved method for labeling monoclonal antibodies with samarium-153: use of the bifunctional chelate 2-(p-isothiocyanatobenzyl)-6- methyldiethylenetriaminepentaacetic acid.
Samarium-153 (153Sm) radioimmunoconjugates of the monoclonal antibody K-1-21 were produced using the bifunctional chelate 2-(p-isothiocyanatobenzyl)-6- methyldiethylenetriaminepentaacetic acid (Mx-DTPA). The specific activity (up to 150 MBq mg-1) and percent retained immunoreactivity (greater than 75%) were similar to that of 153Sm-K-1-21 conjugates formed with cyclic DTPA anhydride (cDTPAa). In vivo biodistribution studies showed specific localization of 153Sm-Mx-DTPA-K-1-21 to target antigen implants and higher blood pool and lower uptake in liver, spleen, kidney, and bone when compared to 153Sm-cDTPAa-K-1-21. The improved in vivo distribution of 153Sm-Mx-DTPA-K-1-21 should result in lower radiotoxicity to nontarget tissues when used for radioimmunotherapy purposes.
Izard
M E
ME
Biomedicine and Health Program, ANSTO, Lucas Heights, New South Wales, Australia.
Boniface
G R
GR
Hardiman
K L
KL
Brechbiel
M W
MW
Gansow
O A
OA
Walkers
K Z
KZ
D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid; D007553:Isotope Labeling; D008297:Male; D004369:Pentetic Acid / Q000031:analogs & derivatives* / Q000737:chemistry*; D011868:Radioisotopes; D051381:Rats; D011916:Rats, Inbred F344; D012493:Samarium; D014018:Tissue Distribution
D000911:Antibodies, Monoclonal; D011868:Radioisotopes; C077295:2-(4-isothiocyanatobenzyl)-6-methyldiethylenetriaminepentaacetic acid; D012493:Samarium; D004369:Pentetic Acid