Characterization of stress-exposed granulocyte colony stimulating factor using ELISA and hydrogen/deuterium exchange mass spectrometry

Cutting-edge mass spectrometry methods for the multi-level structural characterization of antibody-drug conjugates

Antibody drug conjugates (ADCs) are highly cytotoxic drugs covalently attached via conditionally stable linkers to monoclonal antibodies (mAbs) and are among the most promising next-generation empowered biologics for cancer treatment. ADCs are more complex than naked mAbs, as the heterogeneity of the conjugates adds to the inherent microvariability of the biomolecules. The development and optimization of ADCs rely on improving their analytical and bioanalytical characterization by assessing several critical quality attributes, namely the distribution and position of the drug, the amount of naked antibody, the average drug to antibody ratio, and the residual drug-linker and related product proportions. Here brentuximab vedotin (Adcetris) and trastuzumab emtansine (Kadcyla), the first and gold-standard hinge-cysteine and lysine drug conjugates, respectively, were chosen to develop new mass spectrometry (MS) methods and to improve multiple-level structural assessment protocols.

Comprehensive Characterization of Relationship Between Higher-Order Structure and FcRn Binding Affinity of Stress-Exposed Monoclonal Antibodies

PURPOSE

In biopharmaceutical development, information regarding higher-order structure (HOS) is important to verify quality and characterize protein derivatives. In this study, we aimed to characterize the association between HOS and pharmacokinetic property of a stress-exposed monoclonal antibody (mAb).

METHODS

Purity, primary structure, thermal stability, and HOS were evaluated for mAbs exposed to heat, photo-irradiation, and chemical oxidation. To investigate conformation of stress-exposed mAbs, hydrogen/deuterium exchange coupled with mass spectrometry (HDX-MS) was utilized.

RESULTS

No distinct difference in secondary or tertiary structure between stress-exposed and non-stressed samples was found by conventional spectroscopic techniques. In binding activity with the neonatal Fc receptor (FcRn), however, a marked decline was observed for force-oxidized mAb and a slight decline was observed for heat- and photodegraded mAbs. Using differential scanning calorimetry, a change in thermal stability was observed in the CH2 domain for all the stress-exposed samples. Using HDX-MS analyses, individual regions with altered conformation could be identified for heat-degraded and force-oxidized samples.

CONCLUSIONS

These findings indicate that comprehensive study is important for detecting conformational changes and helpful for predicting biophysical property, and that the evaluation of HOS using several analytical techniques is indispensable for confirming biopharmaceutical quality.