Charge Variant and Aggregation Analysis of Innovator and Biosimilars of Rituximab

Importance of the Topic

Monoclonal antibodies (mAbs) are critical biotherapeutics in oncology and autoimmune diseases. Biosimilars offer cost-effective alternatives but require rigorous characterization of critical quality attributes (CQAs) such as charge variants and aggregation to ensure safety and efficacy.

Study Objectives and Overview

This work compares two rituximab biosimilars against the innovator reference product using two analytical LC workflows: weak cation exchange for charge variant profiling and size-exclusion chromatography coupled with light scattering for aggregation assessment. High reproducibility and clear detection of differences are demonstrated.

Methodology and Instrumentation

• Agilent 1260 Infinity II Bio-inert LC system: Pump, Multisampler, Multicolumn Thermostat, Diode Array Detector
• Agilent Bio MAb WCX column (2.1×250 mm, 5 µm PEEK) for charge separation
• Agilent AdvanceBio SEC column (7.8×300 mm, 2.7 µm) for aggregate analysis
• Agilent MultiDetector Suite with dual-angle static and dynamic light scattering detectors
• OpenLab CDS 2.3, Buffer Advisor, and Bio-SEC software for method development and data processing

Main Results and Discussion

• Charge variant separation achieved baseline resolution of acidic, main and basic forms within 16 min with intraday RSD <0.3% (RT) and <1% (area).
• Biosimilar 1 closely matched the innovator (main peak ~65%, acidic ~14.5%, basic ~20%), while biosimilar 2 showed reduced main form (~29%) and elevated basic variants (~63%) suggesting incomplete lysine truncation.
• Aggregation profiling resolved monomer, high-molecular-weight (HMWS) and low-molecular-weight species (LMWS) in 20 min with RT RSD <0.1% and area RSD <2%; biosimilars maintained monomer content >98% with HMWS up to 0.94% and LMWS variation.
• DLS analysis provided consistent average molecular weight (~147.5 kDa) and hydrodynamic radius (~5.4 nm) with RSD <7%.
• Peak Explorer in OpenLab CDS facilitated rapid trend analysis and comparative review across samples.

Benefits and Practical Applications

• The workflows provide robust, high-throughput assessment of rituximab biosimilarity, meeting regulatory CQA requirements.
• Excellent precision and ease of operation support routine QC and batch release in biopharma laboratories.
• Integrated software streamlines method development, data review and reporting in batch mode.

Future Trends and Opportunities

• Integration with mass spectrometry for deeper post-translational modification and peptide mapping analyses.
• Advanced data analytics and machine learning for automated anomaly detection and trend monitoring.
• Emerging microflow and ultrahigh-pressure LC approaches to minimize solvent use and boost resolution.

Conclusion

This study demonstrates that Agilent’s LC-based charge variant and aggregation workflows reliably differentiate innovator rituximab from biosimilars with high precision and streamlined data handling, supporting efficient biosimilarity evaluation.

Reference

1. Dϋbel S., Reichert J. M. Handbook of Therapeutic Antibodies, 2nd ed.
2. U.S. Public Health Service Act section 351(k).
3. ICH Q6B: Specifications: Test Procedures and Acceptance Criteria for Biotechnological/Biological Products.
4. Suresh Babu C. V. Charge Heterogeneity Analysis of Rituximab Innovator and Biosimilar mAbs, Agilent Technologies Application Note 5991-5557EN.
5. Lee K. H., et al. Analytical Similarity Assessment of Rituximab Biosimilar CT-P10 to Reference Medicinal Product. MAbs 2018, 10(3), 380–396.