Solving selectivity issues in LBAs: case study using Gyrolab to quantify CB307, a bispecific Humabody in human serum.

Aim: Endogenous interferents can cause nonselectivity in ligand binding pharmacokinetic assays, leading to inaccurate quantification of drug concentrations. We describe the development of a Gyrolab immunoassay to quantify a new modality, CB307 and discuss strategies implemented to overcome matrix effects and achieve selectivity at the desired sensitivity.Results: Matrix effects were mitigated using strategies including increasing minimum required dilution (MRD) and lower limit of quantification, optimization of antibody orientation, assay buffer and solid phase.Conclusion: The strategies described resulted in a selective method for CB307 in disease state matrix that met bioanalytical method validation (BMV) guidance and is currently used to support clinical pharmacokinetic sample analysis in the first-in-human POTENTIA clinical study (NCT04839991) as a secondary clinical end point.

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Rational Design and Self-Assembly of Coiled-Coil Linked SasG Protein Fibrils.

Protein engineering is an attractive approach for the self-assembly of nanometer-scale architectures for a range of potential nanotechnologies. Using the versatile chemistry provided by protein folding and assembly, coupled with amino acid side-chain functionality, allows for the construction of precise molecular "protein origami" hierarchical patterned structures for a range of nanoapplications such as stand-alone enzymatic pathways and molecular machines. The Staphyloccocus aureus surface protein SasG is a rigid, rod-like structure shown to have high mechanical strength due to "clamp-like" intradomain features and a stabilizing interface between the G5 and E domains, making it an excellent building block for molecular self-assembly. Here we characterize a new two subunit system composed of the SasG rod protein genetically conjugated with de novo designed coiled-coils, resulting in the self-assembly of fibrils. Circular dichroism (CD) and quartz-crystal microbalance with dissipation (QCM-D) are used to show the specific, alternating binding between the two subunits. Furthermore, we use atomic force microscopy (AFM) to study the extent of subunit polymerization in a liquid environment, demonstrating self-assembly culminating in the formation of linear macromolecular fibrils.