The Role of MegaMolecule Antibody Structure in Internalization and Signaling

Area of Science:

• Biotechnology
• Molecular Biology
• Immunology

Background:

• The human epidermal growth factor receptor 2 (HER2/ERBB2) is a key target in cancer therapy.
• Antibody-based therapeutics, like trastuzumab, are crucial for HER2-targeted treatments.
• Developing novel antibody scaffolds with enhanced properties is essential for improving therapeutic outcomes.

Purpose of the Study:

• To synthesize and characterize megamolecule-based antibody scaffolds targeting HER2.
• To compare the biological activities of these novel scaffolds with the parent monoclonal antibody trastuzumab.
• To investigate the impact of scaffold valency and epitope targeting on HER2-mediated cellular processes.

Main Methods:

• Synthesis of 26 megamolecule antibody scaffolds with varying valencies (mono-, bi-, trivalent) and domain types (Fab, nanobody).
• Assessment of cell binding, internalization rates, and cytotoxicity of the scaffolds compared to trastuzumab.
• Evaluation of HER2 epitope targeting effects using biparatopic scaffolds.

Main Results:

• Scaffold valency modulation showed modest effects on binding efficiency and no significant increase in internalization rate.
• Biparatopic scaffolds targeting multiple HER2 epitopes significantly increased internalization rates (approx. 3-fold) compared to trastuzumab.
• Scaffold valency did not impact the inhibition of cell proliferation, while biparatopic scaffolds showed variable effects on proliferation.

Conclusions:

• The megamolecule approach enables the generation of diverse, structurally defined antibody mimics for HER2 targeting.
• Scaffold structural characteristics, particularly biparatopic targeting, critically influence biological activities like internalization and proliferation.
• Novel antibody scaffolds offer potential for developing advanced HER2-targeted therapies with modulated cellular responses.