Analysis of Charge Variant of Trastuzumab Deruxtecan

Significance of the Topic

Charge variant profiling of antibody–drug conjugates (ADCs) is essential for ensuring product consistency, safety and efficacy. Trastuzumab deruxtecan, a clinically approved ADC, can exhibit microheterogeneity due to subtle modifications in the antibody backbone or conjugated payload. Detailed charge variant analysis supports quality control, stability testing and comparability studies during development and manufacturing.

Study Objectives and Overview

This study demonstrates the use of a Shim-pack Bio IEX SP-NP strong cation exchange column coupled to a Nexera lite inert system for rapid separation of acidic, main and basic charge variants of trastuzumab deruxtecan. Key aims were to evaluate resolution, run time and method robustness under a linear pH gradient.

Methodology

The analytical method employs ion-exchange chromatography in pH gradient mode. A two-buffer system based on MES/HEPES–sodium acetate with acetonitrile was programmed from pH 5 to pH 10 over 10 minutes. Separation is achieved at 30 °C with a 1.0 mL/min flow rate and UV detection at 280 nm. Sample injection volume is 1 µL.

Instrumentation Used

• System: Nexera lite inert
• Column: Shim-pack Bio IEX SP-NP, 50 mm × 4.6 mm ID, 5 μm particle size
• Mobile Phase A: 30 mmol/L MES–HEPES–acetate (pH 5)/acetonitrile 95/5 (v/v)
• Mobile Phase B: 30 mmol/L MES–HEPES–acetate (pH 10)/acetonitrile 95/5 (v/v)
• Gradient: 2% B at 0 min to 100% B at 10–15 min, return to 2% B at 15.1–20 min
• Column Temperature: 30 °C
• Detection: UV at 280 nm
• Vial: Shim-vial H glass

Main Results and Discussion

The method achieved clear baseline separation of acidic, main and basic variants within a 20-minute runtime. Chromatograms show distinct peak clusters corresponding to minor acidic species eluting early, the principal antibody peak at mid‐gradient and basic variants toward higher pH. Reproducibility tests confirmed retention time precision within ±0.1 minute and peak area RSD below 2%.

Benefits and Practical Applications of the Method

• Rapid analysis suitable for high‐throughput QC environments
• High resolution enabling detection of low‐abundance variants
• Robust gradient profile delivering consistent performance
• Minimal solvent consumption and simple mobile phase preparation

Future Trends and Potential Applications

Advances may include integration with mass spectrometry for structural characterization of variants, adoption of shorter or monolithic columns to reduce analysis time further, and automated sample preparation workflows. Emerging buffer chemistries and high‐resolution stationary phases promise enhanced sensitivity for low‐level charge species.

Conclusion

The presented pH gradient ion‐exchange method on the Shim-pack Bio IEX SP-NP column offers a fast, reproducible and high‐resolution approach for charge variant analysis of trastuzumab deruxtecan. It meets key requirements for biopharmaceutical QC and stability testing and can be readily adapted to other ADCs and monoclonal antibodies.