The structure-function relationship of disulfide bonds in etanercept

Area of Science:

• Biopharmaceutical development
• Protein chemistry
• Immunology

Background:

• Etanercept is a biologic therapy for rheumatic diseases and psoriasis.
• Process development of biosimilars can reveal critical quality attributes.
• Reduced potency in etanercept was linked to structural abnormalities.

Purpose of the Study:

• Investigate the molecular basis of reduced etanercept potency.
• Identify novel structure-function relationships in etanercept.
• Assess the clinical relevance of identified structural variants.

Main Methods:

• Physicochemical analysis of process fractions.
• Functional assays to determine drug potency.
• Redox condition studies to assess variant reversibility.

Main Results:

• A correlation was found between incorrect disulfide bridging and reduced etanercept potency.
• This structural defect was identified as the cause of lower potency in some Enbrel® batches.
• Incorrect disulfide bridging was reversible under physiological redox conditions, restoring potency.

Conclusions:

• Incorrect disulfide bridging is a critical quality attribute for etanercept functionality.
• The redox-dependent reversibility suggests limited clinical impact of these variants.
• Monitoring and control of disulfide bridging are essential for ensuring patient safety and drug efficacy.