In vitro and in vivo comparison of binding of 99m-Tc-labeled anti-CEA MAb F33-104 with 99m-Tc-labeled anti-CEA MAb BW431/26.
OBJECTIVE
The purpose of this study was to assess the potential for radio-immunodetection (RAID) of murine anti-carcinoembryonic antigen (CEA) monoclonal antibody (MAb) F33-104 labeled with technetium-99m (99m-Tc) by a reduction-mediated labeling method.


METHODS
The binding capacity of 99m-Tc-labeled anti-CEA MAb F33-104 with CEA by means of in vitro procedures such as immunoradiometric assay and cell binding assay and the biodistribution of 99m-Tc-labeled anti-CEA MAb F33-104 in normal nude mice and nude mice bearing human colon adenocarcinoma LS180 tumor were investigated and compared with 99m-Tc-labeled anti-CEA MAb BW431/26.


RESULTS
The in vitro binding rate of 99m-Tc-labeled anti-CEA MAb F33-104 with CEA in solution and attached to the cell membrane was significantly higher than 99m-Tc-labeled anti-CEA MAb BW431/261 (31.4 +/- 0.95% vs. 11.9 +/- 0.55% at 100 ng/mL of soluble CEA, 83.5 +/- 2.84% vs. 54.0 +/- 2.54% at 10(7) of LS 180 cells). In vivo, accumulation of 99m-Tc-labeled anti-CEA MAb F33-104 was higher at 18 h postinjection than 99m-Tc-labeled anti-CEA MAb BW431/26 (20.1 +/- 3.50% ID/g vs. 14.4 +/- 3.30% ID/g). 99m-Tc-activity in the kidneys of nude mice bearing tumor was higher at 18 h postinjection than at 3 h (12.8 +/- 2.10% ID/g vs. 8.01 +/- 2.40% ID/g of 99m-Tc-labeled anti-CEA MAb F33-104, 10.7 +/- 1.70% ID/g vs. 8.10 +/- 1.75% ID/g of 99m-Tc-labeled anti-CEA MAb BW431/26).


CONCLUSIONS
99m-Tc-labeled anti-CEA MAb F33-104 is a potential novel agent for RAID of recurrent colorectal cancer.
Watanabe
N
N
Division of Advanced Technology for Medical Imaging, National Institute of Radiological Sciences, Chiba, Japan. w_nao@nirs.go.jp
Oriuchi
N
N
Sugiyama
S
S
Kuroki
M
M
Matsuoka
Y
Y
Tanada
S
S
Murata
H
H
Inoue
T
T
Sasaki
Y
Y
D000230:Adenocarcinoma / Q000000981:diagnostic imaging*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000493:pharmacokinetics; D001666:Binding Sites, Antibody; D003110:Colonic Neoplasms / Q000000981:diagnostic imaging*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D016719:Radioimmunodetection / Q000379:methods*; D012008:Recurrence; D013667:Technetium / Q000493:pharmacokinetics; D014018:Tissue Distribution; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D013667:Technetium