Cathepsin B-sensitive dipeptide prodrugs. 2. Models of anticancer drugs paclitaxel (Taxol®), mitomycin C and doxorubicin

Substrates containing doxorubicin (DOX), paclitaxel (taxol®), and mitomycin C (MMC) attached to the cathepsin B-sensitive dipeptide Phe-Lys via a self-immolative spacer were prepared as model compounds for internalizing anticancer immunoconjugates. Cathepsin B-mediated release rates of free drug, rat liver lysosomal susceptibility and human plasma stability were measured for each.