Expanded Utility of the β-Glucuronide Linker: ADCs That Deliver Phenolic Cytotoxic Agents

The β-glucuronide linker has been used for antibody-drug conjugates (ADCs) to deliver amine-containing cytotoxic agents. The linker is stable in circulation, hydrophilic and provides ADCs that are highly active in vitro and in vivo. To extend the utility of the β-glucuronide linker toward phenol-containing drugs, an N,N'-dimethylethylene diamine self-immolative spacer was incorporated with the linker for release of the potent cytotoxic phenol psymberin A. Exposure of the drug-linker to β-glucuronidase resulted in facile drug release. The corresponding ADCs were active and immunologically selective against CD30-positive L540cy and CD70-positive Caki-1 cell lines.