An improved method for labeling monoclonal antibodies with samarium-153: use of the bifunctional chelate 2-(p-isothiocyanatobenzyl)-6-methyldiethylenetriaminepentaacetic acid

• Published in: Bioconjugate chemistry Vol. 3; no. 4; pp. 346 - 350
• Main Authors: Izard, M. E, Boniface, G. R, Hardiman, K. L, Brechbiel, M. W, Gansow, O. A, Walker, K. Z
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.07.1992
• Subjects: Animals; Antibodies, Monoclonal - chemistry; Antibodies, Monoclonal - isolation & purification; Biological and medical sciences; Chromatography, High Pressure Liquid; Fundamental and applied biological sciences. Psychology; General aspects; Isotope Labeling; Male; Pentetic Acid - analogs & derivatives; Pentetic Acid - chemistry; Radioisotopes; Rats; Rats, Inbred F344; Samarium; Tissue Distribution; Vertebrata; Mammalia; Radiolabelling; Rat; Rodentia; Monoclonal antibody; Conjugated compound; Localization; Biological activity
• ISSN: 1043-1802; 1520-4812
• DOI: 10.1021/bc00016a015

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.