Quantification of surrogate monoclonal antibodies in mouse serum using LC-MS/MS.

Background: Surrogate monoclonal antibodies (mAbs) used in preclinical in vivo studies can be challenging to quantify due to lack of suitable immunoaffinity reagents or unavailability of the mAb protein sequence. Generic immunoaffinity reagents were evaluated to develop sensitive LC-MS/MS assays. Peptides of unknown sequence can be used for selective LC-MS quantification. Results: anti-mouse IgG1 was found to be an effective immunoaffinity reagent, enabling quantification of mouse IgG1 mAbs in mouse serum. Selective peptides of unknown sequence were applied for multiplex LC-MS quantification of two rat mAbs co-dosed in mouse. Conclusion: Generic anti-mouse IgG subtype-specific antibodies can be used to improve assay sensitivity and peptides of unknown sequence can be used to quantify surrogate mAbs when the mAb protein sequence in unavailable.

Application of the Gyrolab microfluidic platform to measure picomolar affinity of a PD-L1-binding Adnectin™ radioligand for positron emission tomography.

Advances in in vitro display and protein engineering yield therapeutics with affinities in the picomolar range. The Gyrolab® microfluidics platform uses the kinetic exclusion assay principle to measure subnanomolar solution affinities. This work describes application of the Gyrolab solution affinity module and the new multi-curve analysis feature to determine affinity of the PD-L1 Adnectin™ positron emission tomography radioligand, which was measured as 20 pM for human PD-L1. We also report key parameters that affect assay signal-to-background ratio and data quality, such as detection reagent concentration. Gyrolab offers the necessary throughput for rapid assay development with low sample consumption, as demonstrated in this study, which also provides helpful tips for assay optimization for solution affinity measurement.