SLIM IMS-MS for Characterization of Antibody Drug Conjugates (ADCs)

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Rapid and Simultaneous Characterization of Drug Conjugation in Heavy and Light Chains of a Monoclonal Antibody Revealed by High-Resolution Ion Mobility Separations in SLIM


Gabe Nagy, Isaac K. Attah, Christopher R. Conant, Weijing Liu, Sandilya V.B. Garimella, Harsha P. Gunawardena, Jared B. Shaw, Richard D. Smith, and Yehia M. Ibrahim


Antibody–drug conjugates (ADCs) display great promise for human therapeutics and an alternative to chemotherapy for cancer. Crucial metrics for ADC efficacy, safety, and selectivity are their drug–antibody ratios (DARs). However, DAR characterization through traditional analytical methods remains challenging due to the heterogeneity of drug conjugation as well as the numerous post-translational modifications possible in the monoclonal antibody. This paper explores how MOBILion's HRIM-MS technique (aka SLIM IMS-MS) was used for the characterization of antibody drug conjugates (ADCs).

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The paper, published in Analytical Chemistry concludes:

  • The use of SLIM IMS-MS for the rapid and simultaneous characterization of the drug load profile (i.e., stoichiometric distribution of the number of conjugated drugs present on the mAb), determination of the weighted average DAR in both the heavy and light chains of a model antibody−drug conjugate, and calculation of the overall DAR of the ADCs.
  • Critical to evaluating the toxicity and efficacy of ADCs is the characterization of their drug-to-antibody ratios (DARs) or average number of drugs conjugated to mAb. This has been so much of an issue that the FDA has declared the use of novel analytical techniques for mAb and ADC characterization a top priority.
  • However, DAR determination remains analytically challenging owing to the heterogeneous distribution of drug molecules conjugated along the monoclonal antibody (i.e., the drug load profile), as well as the complexities due to the many possible mAb post-translational modifications (e.g., glycosylation, deamidation, or oxidation).
  • Existing IMS-MS separations have not been integrated into the pharmaceutical pipeline for ADC analysis, largely due to insufficient IMS resolution of, for example, conformational or positional differences based on drug conjugation.
  • HRIMS separations utilizing traveling waves (TW) in SLIM) coupled to mass spectrometry (i.e., SLIM IMS-MS) have been developed to study the ADCs.
  • HRIM-MS separations benefit from long serpentine paths and the option to route ions to even longer path lengths through serpentine ultralong paths with extended routing (SUPER) multipass capabilities.
  • These advancements have provided greatly increased resolving power (Rp) of IMS measurements (>1000), especially as compared to commercially available IMS platforms, as well as benefiting from the ability to inject “in-SLIMâ€
SLIM IMS-MS for Characterization of Antibody Drug Conjugates (ADCs)

Analytical Chemistry 2020 92 (7), 5004-5012 DOI: 10.1021/acs.analchem.9b05209

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