Conditionally Activatable Chimeras for Tumor-Specific Membrane Protein Degradation.

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• Membrane protein degraders (MPDs) expand proteolysis-targeting chimeras (PROTACs) to cell-surface targets.
• Off-target degradation of MPDs raises toxicity concerns for clinical use.

Purpose of the Study:

• To develop a conditionally activatable MPD (Pro-MPD) for targeted degradation of cell-surface proteins.
• To mitigate MPD-associated toxicity by enabling tumor-specific activation.

Main Methods:

• Designed a Pro-MPD using biparatopic nanobodies and a tumor microenvironment-activated cell-penetrating peptide (Pro-CPP).
• Utilized Pro-MPD for on-target internalization and degradation of PD-L1 in tumor sites.
• Evaluated Pro-MPD efficacy in xenograft models.

Main Results:

• Achieved high target degradation efficiency and T cell reactivation.
• Demonstrated sustained inhibition of tumor growth in preclinical models.
• Pro-MPD showed potent and specific PD-L1 degradation within tumors.

Conclusions:

• Conditionally activatable Pro-MPDs offer a safer approach for targeting membrane proteins.
• This strategy reduces systemic toxicity by preventing off-tumor degradation.
• Pro-MPDs represent a promising therapeutic modality for cancer treatment.