Site-specific antibody fragment conjugates for targeted imaging

Area of Science:

• Bioconjugation Chemistry
• Molecular Imaging
• Protein Engineering

Background:

• Antibody fragments are crucial for targeted therapies and diagnostics.
• Site-specific labeling is essential for developing high-quality imaging agents.
• Unnatural amino acids (UAAs) offer unique functionalities for bioconjugation.

Purpose of the Study:

• To develop site-specifically labeled antibody Fab fragments using UAA incorporation.
• To create novel antibody fragment conjugates as advanced imaging agents.
• To evaluate the in vivo bio-distribution and imaging potential of these conjugates.

Main Methods:

• Amber suppression-mediated genetic incorporation of UAAs (p-azido-l-phenylalanine and p-acetyl-l-phenylalanine).
• Preparation of antibody fragment conjugates.
• Positron emission tomography (PET) imaging of immune-checkpoint protein PD-L1.
• Near-infrared fluorescent imaging of cancer-related biomarkers using switchable antibody conjugates.

Main Results:

• Successfully generated site-specifically labeled antibody Fab fragments.
• Demonstrated optimal stability, efficacy, and pharmacological properties of conjugates.
• Showcased potential for probing in vivo bio-distributions of protein targets.
• Validated utility in PET imaging of PD-L1 and fluorescent imaging of cancer biomarkers.

Conclusions:

• Site-specific UAA incorporation is a powerful strategy for developing advanced antibody-based imaging agents.
• These novel Fab conjugates offer significant potential for preclinical and clinical applications in molecular imaging.
• The developed methods enable precise labeling for enhanced diagnostic and research capabilities.