1. Labeling of monoclonal antibodies with samarium-153 for combined radioimmunoscintigraphy and radioimmunotherapy.
- Author
-
Boniface GR, Izard ME, Walker KZ, McKay DR, Sorby PJ, Turner JH, and Morris JG
- Subjects
- Animals, Immunoglobulin G metabolism, Immunoglobulin G therapeutic use, Immunotoxins metabolism, Immunotoxins therapeutic use, Indium Radioisotopes metabolism, Indium Radioisotopes therapeutic use, Iodine Radioisotopes metabolism, Iodine Radioisotopes therapeutic use, Male, Pentetic Acid pharmacokinetics, Pentetic Acid therapeutic use, Rats, Rats, Inbred F344, Time Factors, Tissue Distribution, Antibodies, Monoclonal metabolism, Antibodies, Monoclonal therapeutic use, Radioisotopes metabolism, Radioisotopes therapeutic use, Samarium metabolism, Samarium therapeutic use
- Abstract
The labeling of a monoclonal antibody K-1-21 with 153Sm has been investigated using the bifunctional chelate cyclic diethylenetriaminepentaacetic acid (DTPA) anhydride. Labeling efficiencies greater than 60% were obtained using high specific activity [153Sm]chloride and a cDTPAa:MAb conjugation ratio of 20:1. The resultant labeled antibody had a s.a. greater than 150 MBq.mg-1 and a % retained immunoreactivity greater than 90%. Imaging and biodistribution studies in a rat model demonstrated that specific uptake of 153Sm-K-1-21 into s.c. implants of the target antigen could be clearly detected in scintigrams at 6 days p.i. The specific uptake (1.90 +/- 0.45% ID/g, 19.95 +/- 2.20 Implant:Blood ratio) compared favorably to 131I- and 111In-labeled K-1-21 (2.52 +/- 0.20 and 3.33 +/- 0.20% ID/g, 7.69 +/- 0.45 and 10.10 +/- 0.60 I:B, respectively). Labeling of MAbs with 153Sm for combined scintigraphy/therapy is feasible at clinically appropriate specific activities using cDTPAa, with the resultant conjugates retaining immunoreactivity and in vivo antigen localization.
- Published
- 1989