Analytical Similarity Assessment in Biosimilar Studies

Area of Science:

• Biopharmaceutical science
• Regulatory science
• Analytical chemistry

Background:

• The US Food and Drug Administration (FDA) recommends a stepwise approach for assessing biosimilarity.
• This process involves analytical studies to characterize the proposed biosimilar product and compare it to the reference biological product.
• Analytical similarity assessment is crucial for demonstrating the totality-of-the-evidence for biosimilarity.

Purpose of the Study:

• To describe and discuss the debatable issues encountered in the FDA's stepwise approach for analytical similarity assessment.
• To provide clarity on the complexities of classifying critical quality attributes (CQAs) and applying tiered testing strategies.
• To highlight practical challenges in implementing the proposed biosimilarity assessment framework.

Main Methods:

• Identification of critical quality attributes (CQAs) relevant to clinical outcomes.
• Classification of CQAs into three tiers based on criticality and risk ranking.
• Application of tiered testing strategies: equivalence testing (Tier 1), quality range approach (Tier 2), and raw data/graphical presentation (Tier 3).

Main Results:

• The stepwise approach involves detailed analytical characterization and tiered testing of CQAs.
• Different testing methodologies are applied based on the criticality of CQAs.
• The process aims to generate comprehensive evidence for biosimilarity.

Conclusions:

• The FDA's stepwise approach for biosimilarity assessment, while structured, presents practical challenges and debatable issues.
• Effective implementation requires careful consideration of CQA classification and tiered testing strategies.
• Further discussion and refinement may be needed to address complexities in analytical similarity assessment.