Site-specific conjugation of chain-terminal chelating polymers to Fab' fragments of anti-CEA mAb: effect of linkage type and polymer size on conjugate biodistribution in nude mice bearing human colorectal carcinoma.
Polylysine-based chelating polymers were used for site-specific modification of anti-CEA mAb Fab' fragments via their SH group distal to the antigen-binding site of the antibody molecule. Conjugation was performed using chain-terminal (pyridyldithio)propionate or 4-(p-maleimidophenyl)butyrate moieties to form reducible (S-S) or stable (S-C) bonds between a polymer and Fab' molecule, respectively. One S-S conjugate (S-S9) and two different S-C conjugates (S-C3 and S-C9) were prepared using 3- and 9-kDa molecular weight polymers. No significant loss of immunoreactivity was observed in solid-phase immunoassay, 90-95% of 111In-labeled conjugates being bound to CEA-coated Sepharose beads. After labeling with 111In, the conjugates had a specific radioactivity of 90-120 microCi/micrograms. Injected in nude mice bearing LS 174T carcinoma, the conjugates produced different biodistribution patterns. S-S9 was practically unable to accumulate in tumor and produced very rapid blood clearance of radioactivity and high uptake of radioactivity in liver, spleen, and especially kidneys (225% ID/g 24 h postinjection). S-C3 and S-C9 produced practically the same blood clearances (much slower than that of S-S9) and significant tumor uptake (9-10% ID/g at 24 h). S-C3 gave significantly lower radioactivity in spleen, skin, and bones, and cleared more rapidly from liver and kidneys. Renal uptake for S-C3 and S-C9 was rather high (45% ID/g at 24 h), but much lower than for S-S9.
Slinkin
M A
MA
Laboratoire Biophysique-Cancerologie, INSERM U.211, Nantes, France.
Curtet
C
C
Sai-Maurel
C
C
Gestin
J F
JF
Torchilin
V P
VP
Chatal
J F
JF
D000230:Adenocarcinoma / Q000209:etiology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000276:immunology; D002272:Carcinoembryonic Antigen / Q000276:immunology*; D002614:Chelating Agents; D002851:Chromatography, High Pressure Liquid; D015179:Colorectal Neoplasms; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry* / Q000276:immunology; D007074:Immunoglobulin G / Q000737:chemistry / Q000276:immunology; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D011108:Polymers / Q000138:chemical synthesis; D013379:Substrate Specificity
D000911:Antibodies, Monoclonal; D002272:Carcinoembryonic Antigen; D002614:Chelating Agents; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D011108:Polymers