Conjugates of COL-1 monoclonal antibody and beta-D-galactosidase can specifically kill tumor cells by generation of 5-fluorouridine from the prodrug beta-D-galactosyl-5-fluorouridine.
5'-O-beta-D-galactosyl-5-fluorouridine is a prodrug that can be converted by the enzyme beta-D-galactosidase to the potent antineoplastic drug 5-fluorouridine. The prodrug is more than 100x less toxic than the drug to bone marrow cells in Balb/c mice. The ratio of the IC50 of the prodrug to that of the drug determined on a variety of tumor cell lines in vitro ranged from 500:1-1000:1. An antibody-enzyme conjugate (AEC) was synthesized and purified. Maleimide-substituted COL-1 anti-CEA monoclonal antibody was linked to free thiol groups of beta-D-galactosidase. The conjugate was purified by size exclusion and ion exchange chromatography. It retained full immunoreactivity and enzyme activity. After binding to antigen-positive tumor cells, the conjugate was able to activate the prodrug and specifically kill the cells. We are continuing to investigate this model for its potential use in antibody-directed enzyme prodrug therapy (ADEPT).
Abraham
R
R
IGEN, Inc., Rockville, MD 20852.
Aman
N
N
von Borstel
R
R
Darsley
M
M
Kamireddy
B
B
Kenten
J
J
Morris
G
G
Titmas
R
R
D000230:Adenocarcinoma / Q000628:therapy*; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D000918:Antibody Specificity; D005690:Galactose / Q000031:analogs & derivatives / Q000378:metabolism; D006801:Humans; D018796:Immunoconjugates / Q000302:isolation & purification / Q000627:therapeutic use*; D007124:Immunoenzyme Techniques; D011355:Prodrugs / Q000378:metabolism; D014407:Tumor Cells, Cultured; D014529:Uridine / Q000031:analogs & derivatives / Q000378:metabolism; D001616:beta-Galactosidase / Q000627:therapeutic use*
D000911:Antibodies, Monoclonal; D018796:Immunoconjugates; D011355:Prodrugs; C093357:5'-O-galactosyl-5-fluorouridine; C001943:5-fluorouridine; D001616:beta-Galactosidase; D014529:Uridine; D005690:Galactose