In Silico-Driven THIOMAB Approach for Stable PROTAC Conjugates by Docking Payloads in Antibody Cavities

Area of Science:

• Bioconjugation Chemistry
• Antibody-Drug Conjugates
• Proteolysis Targeting Chimeras (PROTACs)

Background:

• PROTACs offer targeted protein degradation with advantages over traditional toxins.
• High hydrophobicity of PROTAC payloads can compromise antibody stability and in vivo performance.

Purpose of the Study:

• To evaluate the THIOMAB approach for mitigating hydrophobicity in PROTAC-antibody conjugates.
• To maintain therapeutic potency while improving conjugate stability.

Main Methods:

• Utilized an in silico method for selecting optimal antibody conjugation sites.
• Employed a stable tetrapeptide-aminomethoxy linker for PROTAC payload conjugation.
• Constructed a degrader-antibody conjugate (J591 DAC) using a hydrophobic PROTAC (GNE-987).

Main Results:

• The J591 DAC demonstrated antigen-dependent BRD4 degradation.
• Achieved potent cytotoxic activity in PSMA-positive cancer cells.
• Exhibited prolonged blood retention and strong antitumor efficacy in mouse models.

Conclusions:

• The THIOMAB approach successfully stabilized antibody conjugates with hydrophobic PROTACs.
• Homogeneous and stable conjugation is crucial for effective in vivo performance of such conjugates.
• This study provides a framework for designing antibody conjugates with challenging hydrophobic payloads.