David Willner

Doxorubicin immunoconjugates containing bivalent, lysosomally-cleavable dipeptide linkages

Bivalent doxorubicin (DOX)-dipeptides (16a-c) were prepared and conjugated to the monoclonal antibody BR96. The dipeptides are cleaved by lysosomal proteases following internalization of the resulting immunoconjugates. Conjugate 18b demonstrated antigen-specific in vitro tumor cell killing activity (IC(50)=0.2 microM) that was equipotent to DOX with a near doubling of drug molecules/MAb. Size exclusion chromatography showed 18b to be a noncovalent dimer that was formed immediately upon conjugation.

Synthesis and antitumor activity of the immunoconjugate BR96-Dox

Abstract BR96-Dox is an immunoconjugate (IC) in which doxorubicin (8 equivalents) is linked via an acid-labile hydrazone to the chimeric MAb BR96. It binds to a modified Le y Ag on tumor cells, which then internalize it via endocytosis into lysosomes. There, the acidic milieu hydrolyzes the hydrazone link, releasing free Dox. In vivo, it is more active and less toxic than untargeted Dox, producing complete remissions and many cures of subcutaneous human breast, lung and colon tumors, as well as disseminated lung tumors. In vivo, only BR96 + and not BR96 − tumors respond, and ICs with nonbinding Abs are inactive.

Potential non-dopaminergic gastrointestinal prokinetic agents in the series of substituted benzamides

Abstract A series of 2-substituted-4-amino-5-chloro-N-[2-diethylaminoethyl]benzamides was synthesized and evaluated for gastrointestinal motility enhancing activity in vitro (enhancement of field stimulated guinea pig ileum test) and in vivo (enhancement of rat stomach emptying). A number of compounds were shown to be potent gastrointestinal prokinetic agents yet were devoid of dopaminergic D2-receptor antagonism as shown by their inability to displace [3H]spiperone from brain membranes. The model compound 6b would be expected to have clinical use in a spectrum of upper gastroinstestinal motility disorders but without the central nervous system side effects characteristic of dopaminergic D2-receptor blockade in the brain.