Affibody Molecules as Targeting Vectors for PET Imaging.

Area of Science:

• Biotechnology
• Molecular Imaging
• Protein Engineering

Background:

• Affibody molecules are small, engineered scaffold proteins with high affinity for various targets.
• Their size and affinity make them suitable as targeting vectors in molecular imaging.
• High-affinity affibody binders have been developed for several cancer-associated molecular targets.

Purpose of the Study:

• To provide an overview of affibody molecules for molecular imaging.
• To discuss factors influencing their biodistribution and targeting properties.
• To review the chemistry of labeling affibody molecules with positron emitters.

Main Methods:

• Selection of high-affinity affibody binders for cancer targets.
• Preclinical studies evaluating radiolabeled affibody molecule imaging.
• Phase I/II clinical trial assessing 68Ga-labeled affibody molecules for HER2 expression measurement.

Main Results:

• Radiolabeled affibody molecules demonstrate specific and sensitive imaging.
• Delayed imaging (next day) can enhance sensitivity for certain targets.
• Clinical trials confirm accurate and specific HER2 expression measurement in breast cancer metastases.

Conclusions:

• Affibody molecules are effective targeting vectors for molecular imaging.
• Their properties can be optimized for enhanced diagnostic accuracy.
• Labeling chemistry with positron emitters is crucial for their application.