Antibodies are a highly successful class of biological drugs, with over 50 such molecules approved for therapeutic use and hundreds more currently in clinical development. Improvements in technology for the discovery and optimization of high-potency antibodies have greatly increased the chances for finding binding molecules with desired biological properties; however, achieving drug-like properties at the same time is an additional requirement that is receiving increased attention. In this work, we attempt to quantify the historical limits of acceptability for multiple biophysical metrics of "developability." Amino acid sequences from 137 antibodies in advanced clinical stages, including 48 approved for therapeutic use, were collected and used to construct isotypematched IgG1 antibodies, which were then expressed in mammalian cells. The resulting material for each source antibody was evaluated in a dozen biophysical property assays. The distributions of the observed metrics are used to empirically define boundaries of drug-like behavior that can represent practical guidelines for future antibody drug candidates.monoclonal antibody | developability | biophysical properties | manufacturability | nonspecificity T arget binding is the predominant first concern in development of any drug. However, once a lead molecule attains the desired potency of biological modification, a suite of characteristics termed "developability" assumes critical importance. For monoclonal antibodies, these properties include high-level expression, high solubility, covalent integrity, conformational and colloidal stability, low polyspecificity, and low immunogenicity. The high cost of failing any of these criteria at a late stage in drug development has led to considerable efforts at predicting developability on the basis of sequence motifs and experimentally determined biophysical properties (1-15).In a landmark study of small-molecule drugs over 2,000 molecules with United States Adopted Names (USAN) designations and known to have oral availability were collected and computationally analyzed (16). A simple set of thresholds, encapsulated as the "Lipinski rule of fives," was formulated and has been used by many to prioritize small molecules for entry into clinical development. To date, analogous guiding principles for antibody drugs have not emerged-we therefore endeavor here to do so. By analogy to the Lipinski effort, we first collected the sequences of antibodies that had reached at least phase-2 trials and had USAN or WHO International Nonproprietary Names (INN) designations (137 in total as of the start of this project). As a common basis for comparison of intrinsic variable domain phenotypes we expressed each antibody as the human IgG1 isotype and formulated them in simple Hepes-buffered saline. Each antibody was then subjected to a battery of 12 different biophysical assays in common use for developability assessment.Unexpectedly, for many of the measures the distribution of values was not symmetrically Gaussian, but instead was lon...

We report the humanization of the glycosylation pathway in the yeast Pichia pastoris to secrete a human glycoprotein with uniform complex N-glycosylation. The process involved eliminating endogenous yeast glycosylation pathways, while properly localizing five active eukaryotic proteins, including mannosidases I and II, N-acetylglucosaminyl transferases I and II, and uridine 5'-diphosphate (UDP)-N-acetylglucosamine transporter. Targeted localization of the enzymes enabled the generation of a synthetic in vivo glycosylation pathway, which produced the complex human N-glycan N-acetylglucosamine2-mannose3-N-acetylglucosamine2 (GlcNAc2Man3GlcNAc2). The ability to generate human glycoproteins with homogeneous N-glycan structures in a fungal host is a step toward producing therapeutic glycoproteins and could become a tool for elucidating the structure-function relation of glycoproteins.

To humanize the glycosylation pathway in the yeast Pichia pastoris, we developed several combinatorial genetic libraries and used them to properly localize active eukaryotic mannosidases and sugar transferases. Here we report the details of the fusion of up to 66 N -terminal targeting sequences of fungal type II membrane proteins to 33 catalytic domains of heterologous glycosylation enzymes. We show that while it is difficult to predict which leader/catalytic domain will result in the desired activity, analysis of the fusion protein libraries allows for the selection of the leader/catalytic domain combinations that function properly. This combinatorial approach, together with a high-throughput screening protocol, has allowed us to humanize the yeast glycosylation pathway to secrete human glycoprotein with complex N -glycosylation.

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