A Cathepsin B -Cleavable Self-Immolative Linker for the Delivery of Hydroxyl-Containing Payloads in Antibody–Drug Conjugates

In development of antibody–drug conjugates (ADCs), cathepsin B-cleavable linkers have been extensively optimized for amine-containing payloads and successfully translated into clinic practice, whereas effective solutions for hydroxyl-containing payloads remain limited. Here, we report a cathepsin B-cleavable VA-PAB-2-HPCCONH self-immolative linker platform featuring three orthogonal attachment sites that enable modulation of linker–payload hydrophilicity. Using this platform, we designed and synthesized highly water-soluble linker–payload conjugates, incorporating either phenolic hydroxyl payload CPT002 or aliphatic hydroxyl payload DXd, and constructed anti-HER2 and anti-Trop2 ADCs. In addition to excellent plasma stability and efficient enzymatic release, these ADCs showed robust in vitro cytotoxicity. Notably, they achieved in vivo antitumor efficacy and safety on par with the clinical benchmark DS-8201a. Collectively, this work establishes a versatile and generalizable linker strategy that expands the accessible payload space of ADCs and enables efficient, controlled delivery of hydroxyl-containing payloads, highlighting its potential for next-generation ADC development.