Figure 1.

Characterization of Zapadcine-1. (A) Molecular structures of Zapadcine-1. Conjugates were prepared by controlled partial reduction of internal Zaptuzumab disulfides with tris (2-carboxyethyl) phosphine hydrochloride (TCEP), followed by adding various linker-drugs. Stable thioether-linked ADC was formed by the reaction of maleimides in the drug molecules with free sulfhydryl groups in the monoclonal antibodies (mAbs). (B) Hydrophobic interaction chromatography (HIC) analysis of Zapadcine-1 in a butyl-NPR column yielded five predominant peaks corresponding to the ADCs containing zero, one, two, three, four and five toxin molecules. (C) ELISA assay for the binding of Zapadcine-1 with DR5 on the cell surfaces. Naked humanized antibody Zaptuzumab was used as control.