Development of Cathepsin B-Responsive GalNAc-PROTACs for Hepatocyte-Targeting Protein Degradation

  • J Med Chem. 2026 Jan 8;69(1):517-532. doi: 10.1021/acs.jmedchem.5c02908.
Yunhua Peng  1  2 ,  Tao Li  1 ,  Donghua Liu  3 ,  Wenxin Li  1 ,  Yimeng Zhang  3 ,  Ying Zhao  3 ,  Xuehan Jiang  3 ,  Yaqi Liang  1 ,  Pengxiao Chen  1 ,  Bohan Ma  3 ,  Jing Liu  3  4 ,  He Chen  1
Affiliations
  • 1. Department of Medicinal Chemistry, Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics, School of Pharmacy, Tianjin Medical University, Tianjin 300070, China.
  • 2. Institute of Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
  • 3. Department of Urology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, China.
  • 4. Key Laboratory for Tumor Precision Medicine of Shaanxi Province, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, China.
PMID: 41403144 DOI: 10.1021/acs.jmedchem.5c02908
Abstract

Targeted protein degradation (TPD) has arisen as a therapeutic revolution for eliminating disease-relevant proteins, but its tissue-specific delivery remains a critical challenge. Here, we developed an asialoglycoprotein receptor (ASGPR)-based platform for the selective degradation of target proteins in hepatocytes. By conjugating the ASGPR ligand triantennary N-acetylgalactosamine (tri-GalNAc) with a BRD4-targeted proteolysis targeting chimera (PROTAC) via a Cathepsin B (CTSB)-cleavable Val-Cit-PABC linker, we generated a prototype GalNAc-PROTAC conjugate, TMU454. TMU454 selectively degraded BRD4 in ASGPR-positive hepatocellular carcinoma cells while sparing ASGPR-negative Cancer cells and normal cells. Mechanistic investigations confirmed that TMU454-mediated BRD4 degradation is dependent on the ASGPR-mediated endocytosis, CTSB-mediated linker cleavage, and ubiquitin-proteasome system (UPS). Furthermore, a fluorescein-labeled analogue, TMU670, revealed preferential liver accumulation. Importantly, TMU454 significantly inhibited tumor growth in a Huh7-derived liver Cancer xenograft model without apparent systemic toxicity. Collectively, this study establishes a versatile approach for tissue-selective protein degradation and advances targeted therapies for liver Cancer.

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