Conjugates of COL-1 monoclonal antibody and β-D-galactosidase can specifically kill tumor cells by generation of 5-fluorouridine from the prodrug β-D-galactosyl-5-fluorouridine

Abstract

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).

Molecular logistics using cytocleavable polyrotaxanes for the reactivation of enzymes delivered in living cells

“…6)33. The 5-FUR shows dose-dependent cytotoxicity against HeLa cells, whereas negligible cytotoxicity was observed for 5-FUR-β-gal (Fig.…”

D-Galactose as a Vector for Prodrug Design

“…The growth inhibiting effects of the drug and prodrug alone or in combination with the COL-1--GAL conjugate have been evaluated in a variety of tumor cell lines in vitro. Gal-FUrd, for instance, is activated specifically on tumor cells by the COL-1--GAL conjugate and kills the cells at significantly lower concentrations than does the prodrug [59]. …”

Highly regioselective glucosylation of 2′-deoxynucleosides by using the crude β-glycosidase from bovine liver

“…It was reported that glycosylated derivatives of many active compounds could mask their toxicity and/or improve their pharmacokinetic properties. For instance, the toxicity of 5 -O-␤-dgalactosyl-5-fluorouridine was more than 100-fold less than the parent compound to bone marrow cells in Balb/c mice (Abraham et al, 1994). In addition, it has been demonstrated that the cellular uptake of many active components could be significantly enhanced after glycosylation modification, due to the active absorption mediated by glucose transport system (Mizuma et al, 1992).…”