Enzyme-Activated Orthogonal Proteolysis Chimeras for Tumor Microenvironment-Responsive Immunomodulation.

Area of Science:

• Biochemistry
• Molecular Biology
• Cancer Research

Background:

• Tumor microenvironment (TME) modulation is crucial for effective cancer therapy.
• Proteolysis-targeting chimeras (PROTACs) offer a promising approach for targeted protein degradation.
• Current PROTACs face challenges in selectivity, synthesis, and in vivo efficacy due to their complex structures.

Purpose of the Study:

• To develop a novel TME-responsive, enzyme-activated clickable PROTAC system.
• To overcome limitations of conventional PROTACs, including selectivity and tumor penetration.
• To investigate the potential of these PROTACs in cancer therapy and immunomodulation.

Main Methods:

• Design and synthesis of enzyme-activated clickable PROTACs utilizing a peptide-tagged pomalidomide derivative and a cyanobenzothiazole-labeled epigenetic protein-ligand.
• Tumor-specific cleavage by cathepsin protease leading to in situ degrader formation.
• Systematic protein profiling and proteomic analysis to assess target degradation and off-target effects.
• In vitro and in vivo evaluation of PROTAC efficacy, including tumor penetration and PD-L1 downregulation.

Main Results:

• The clickable PROTACs demonstrated tumor-specific cleavage and degradation of epigenetic proteins within the TME.
• Achieved superior tumor penetration compared to conventional high-molecular-weight PROTACs.
• Efficiently downregulated programmed death-ligand 1 (PD-L1), a key immune checkpoint, both in vitro and in vivo.

Conclusions:

• Enzyme-activated clickable PROTACs represent a novel strategy for targeted cancer therapy.
• This approach enhances drug delivery and efficacy by leveraging TME-specific activation.
• The developed PROTACs show significant potential for remodeling the TME and improving anti-tumoral immunomodulation.