Optimizing Therapeutic Proteins Through PEGylation: Key Parameters and Impacts

João Gonçalves
Faculty of Pharmacy
University of Lisbon
Lisbon, Portugal

Paolo Caliceti
Department of Pharmaceutical and Pharmacological Sciences
University of Padova
Padova, Italy

What Is PEGylation and Why Is It Important?
We will begin by examining the clinical uses of therapeutic proteins, and their applications in healthcare. Next, we will discuss the inherent limitations of therapeutic proteins, including challenges such as pharmacokinetic (PK) profiles, protein aggregation during storage, and potential immune responses. The session will then delve into the process of PEGylation, where polyethylene glycol (PEG) is conjugated to functional amino acid groups on the protein surface. This modification may enhance the properties of therapeutic proteins, offering advantages in stability, half-life, and immunogenicity.

Biopharmaceutical and Immunological Properties of PEGylated Proteins
We will explore the biopharmaceutical and immunological properties of PEGylated proteins, focusing on how their unique structure and composition impact their function. We will discuss how each PEGylated protein has distinct properties based on PEG architecture, molecular weight and degree of conjugation that cannot be generalized across different pegylated molecules, highlighting the variability in pharmacokinetic (PK) characteristics such as half-life, absorption, distribution, and elimination. These factors can significantly influence clinical outcomes, including dosing intervals and overall therapeutic effectiveness. We will also address the potential clinical advantages and limitations of PEGylation, with real-world examples to illustrate how these proteins are used in practice.

Immunogenicity Considerations of PEGylated Proteins
We will explore the immunogenicity of PEGylated proteins, examining both the potential benefits and risks associated with PEG modification. While PEGylation can trigger immune responses against PEG itself or the PEGylated protein, it can also help mask epitopes and reduce anti-drug antibodies formation. Drug- and patient-related factors that influence immunogenicity risk will also be covered, along with the prevalence and impact of pre-existing anti-drug antibodies (ADAs).We will discuss the potential clinical consequences of immune reactions to PEG or PEGylated proteins, and how the risk of such responses can vary depending on the unique properties of each PEGylated protein. The session will also address strategies to mitigate anti-PEG immunogenicity, as well as approaches for monitoring immunogenicity across different stages of drug development—from preclinical studies to post-marketing surveillance. Additionally, we will explore tools that may help predict therapeutic responses to PEGylated proteins, touching on potential areas for future research.

Discussion and Conclusion
By the end of the session, participants will gain a comprehensive understanding of:

• How PEGylation represents a major technological advancement in the development and optimization of therapeutic proteins.
• How PEGylation affects both the biopharmaceutical properties and clinical applications of therapeutic proteins
• Immunogenicity in the context of PEGylated proteins and the strategies used to manage and predict immune responses.
• The role of PEGylation in therapeutic outcomes and the future opportunities for innovation in this field.