Half-life extension using serum albumin-binding DARPin® domains

Area of Science:

• Biotechnology
• Protein Engineering
• Pharmacology

Background:

• Therapeutic proteins require a long systemic half-life for efficacy.
• Designed ankyrin repeat domains (DARPin®) are versatile protein scaffolds.
• Enhancing protein half-life is a critical goal in drug development.

Purpose of the Study:

• To engineer serum albumin-binding DARPin® domains to improve pharmacokinetic properties.
• To assess the stability and in vivo performance of these engineered domains.
• To evaluate the potential of these domains in creating multi-functional drugs with extended half-lives.

Main Methods:

• Generation of serum albumin-binding DARPin® domains.
• Affinity assessment using nanomolar binding to serum albumin across species.
• Pharmacokinetic studies in mouse and cynomolgus monkey models.
• Covalent linkage of albumin-binding DARPin® to other target-specific domains.
• Allometric scaling for human half-life extrapolation.

Main Results:

• Engineered DARPin® domains bind serum albumin with high affinity.
• Significant improvement in pharmacokinetic properties (exposure and half-life) in preclinical models.
• Demonstrated high thermal and storage stability.
• Terminal half-life values ranged from 27 h to 80 h in mice and 2.6 to 20 days in cynomolgus monkeys.
• Extrapolated human half-life of 5-50 days.

Conclusions:

• Serum albumin-binding DARPin® domains effectively extend the in vivo half-life of therapeutic proteins.
• These domains possess favorable stability characteristics for drug development.
• DARPin® technology offers a promising platform for generating advanced, long-acting multi-functional drugs.