Histidine Tag-Specific PEGylation Improves the Circulating Half-Life of TIMP2

Area of Science:

• Biotechnology
• Protein Engineering
• Pharmacokinetics

Background:

• Therapeutic biologics often have short serum half-lives, limiting their clinical efficacy.
• Poly(ethylene glycol) (PEG) conjugation is a strategy to improve protein pharmacokinetics (PK).
• Tissue Inhibitor of Metalloproteinases 2 (TIMP2) has therapeutic potential but a short half-life.

Purpose of the Study:

• To improve the circulating half-life of recombinant His-tagged TIMP2 (TIMP2) using PEGylation.
• To compare primary amine conjugation versus site-specific histidine conjugation for TIMP2 PEGylation.

Main Methods:

• Primary amine PEGylation of TIMP2 (TIMP2-a-PEG(n)) and site-specific histidine PEGylation (TIMP2-H-PEG(1), TIMP2-H-PEG(2)).
• Evaluation of PK improvements, stability, and MMP-inhibitory activity of PEGylated TIMP2 variants.

Main Results:

• Primary amine PEGylation improved TIMP2 half-life 11.5-fold but yielded heterogeneous products and affected activity.
• Site-specific histidine PEGylation allowed purification of mono- and di-PEGylated forms.
• TIMP2-H-PEG(1) showed a 6.2-fold increase in half-life, enhanced stability, and maintained MMP-inhibitory activity.

Conclusions:

• Site-specific PEGylation of TIMP2 at the histidine tag is a viable strategy to enhance PK.
• TIMP2-H-PEG(1) demonstrates potential for further preclinical development as a therapeutic biologic.