ABSTRACT
A series of new prodrugs of daunorubicin and doxorubicin which are candidates for antibody-directed enzyme prodrug therapy (ADEPT) is reported. These compounds (25a,b,c and 32a,b,c) have been designed to generate cytotoxic drugs after activation with beta-glucuronidase. As expected, recovery of the active drug was observed after enzymatic cleavage by Escherichia coli beta-glucuronidase as well as by a fusion protein which has been obtained from human beta-glucuronidase and humanized CEA-specific binding region. The six prodrugs are highly stable and are more than 100-fold less cytotoxic than doxorubicin against murine L1210 cell lines. The ortho-substituted phenyl carbamates 25a,b,c are better substrates for beta-glucuronidase than the corresponding para-substituted analogues. After taking into account additional factors such as stability in plasma and kinetics of enzymatic cleavage, we selected the o-nitro prodrug 25c for clinical trials.
Subject(s)
Antibiotics, Antineoplastic/chemical synthesis , Antibodies, Monoclonal/pharmacology , Daunorubicin/chemistry , Doxorubicin/analogs & derivatives , Doxorubicin/chemistry , Glucuronates/chemical synthesis , Prodrugs/chemical synthesis , Animals , Antibiotics, Antineoplastic/chemistry , Antibiotics, Antineoplastic/metabolism , Antibiotics, Antineoplastic/pharmacology , Antibodies, Monoclonal/immunology , Carcinoembryonic Antigen/genetics , Carcinoembryonic Antigen/immunology , Cell Division/drug effects , Daunorubicin/pharmacology , Doxorubicin/chemical synthesis , Doxorubicin/metabolism , Doxorubicin/pharmacology , Drug Screening Assays, Antitumor , Drug Stability , Escherichia coli/enzymology , Glucuronates/chemistry , Glucuronates/metabolism , Glucuronates/pharmacology , Glucuronidase/genetics , Glucuronidase/pharmacology , Humans , Hydrolysis , Immunoglobulin Fab Fragments/genetics , Immunoglobulin Fab Fragments/immunology , Kinetics , Leukemia L1210/pathology , Mice , Prodrugs/chemistry , Prodrugs/metabolism , Prodrugs/pharmacology , Rats , Recombinant Fusion Proteins/immunology , Recombinant Fusion Proteins/pharmacology , Structure-Activity Relationship , Tumor Cells, CulturedABSTRACT
New prodrugs of daunorubicin, 1c, 1e and 2c, including a galactopyranosyl residue linked to the N-3' of the daunosaminyl moiety through substituted o- or p-benzyloxycarbonyl groups were synthesized. Their low cytotoxicity and high stability in plasma fulfil the conditions for antibody-directed enzyme prodrug therapy (ADEPT). Enzymatic hydrolysis using alpha-D-galactosidase gives rise to daunorubicin by subsequent self-elimination of the spacers. However, elimination clearly depends on the aromatic substitution pattern, as demonstrated especially by comparison with non-substituted analogues.