In silico selection of therapeutic antibodies for development: viscosity, clearance, and chemical stability.

For mAbs to be viable therapeutics, they must be formulated to have low viscosity, be chemically stable, and have normal in vivo clearance rates. We explored these properties by observing correlations of up to 60 different antibodies of the IgG1 isotype. Unexpectedly, we observe significant correlations with simple physical properties obtainable from antibody sequences and by molecular dynamics simulations of individual antibody molecules. mAbs viscosities increase strongly with hydrophobicity and charge dipole distribution and decrease with net charge. Fast clearance correlates with high hydrophobicities of certain complementarity determining regions and with high positive or high negative net charge. Chemical degradation from tryptophan oxidation correlates with the average solvent exposure time of tryptophan residues. Aspartic acid isomerization rates can be predicted from solvent exposure and flexibility as determined by molecular dynamics simulations. These studies should aid in more rapid screening and selection of mAb candidates during early discovery.

Increasing parvovirus filter throughput of monoclonal antibodies using ion exchange membrane adsorptive pre-filtration.

Pre-filtration using ion exchange membrane adsorbers can improve parvovirus filter throughput of monoclonal antibodies (mAbs). The membranes work by binding trace foulants, and although some antibody product also binds, yields > or =99% are easily achieved by overloading. Results show that foulant adsorption is dependent on pH and conductivity, but independent of scale and adsorber brand. The ability to use ion exchange membranes as pre-filters is significant because it provides a clean, well defined, chemically stable option for enhancing throughput. Additionally, ion exchange membranes facilitate characterization of parvovirus filter foulants. Examination of adsorber elution samples using sedimentation velocity analysis and SEC-MALS/QELS revealed the presence of high molecular weight species ranging from 8 to 13 nm in hydrodynamic radius, which are similar in size to parvoviruses and thus would be expected to plug the pores of a parvovirus filter. A study of two identical membranes in-series supports the hypothesis that the foulants are soluble, trace level aggregates in the feed. This study's significance lies in a previously undiscovered application of membrane chromatography, leading to a more cost effective and robust approach to parvovirus filtration for the production of monoclonal antibodies.

The spectrum of Trp- mutants isolated as 5-fluoroanthranilate-resistant clones in Saccharomyces bayanus, S. mikatae and S. paradoxus.

5-Fluoroanthranilic acid (FAA)-resistant mutants were selected in homothallic diploids of three Saccharomyces species, taking care to isolate mutants of independent origin. Mutations were assigned to complementation groups by interspecific complementation with S. cerevisiae tester strains. In all three species, trp3, trp4 and trp5 mutants were recovered. trp1 mutants were also recovered if the selection was imposed on a haploid strain. Thus, FAA selection may be more generally applicable than was previously described.