The Antibody Society is pleased and proud to be affiliated with mAbs, a multi-disciplinary journal dedicated to advancing the art and science of antibody research and development. We hope you enjoy these summaries based on the abstracts of the most read papers published in a recent issue. All the articles are open access; PDFs can be freely downloaded by following the links below.

Issue 11.1 (January 2019)

Evolution of a comprehensive, orthogonal approach to sequence variant analysis for biotherapeutics.
As discussed by Lin et al., a cross-functional team of Pfizer colleagues from the Analytical and Bioprocess Development departments worked closely together for over 6 years to formulate and communicate a practical, reliable sequence variant (SV) testing strategy with state-of-the-art techniques that did not necessitate more resources or lengthen project timelines. The final SV screening strategy relies on next-generation sequencing and amino acid analysis as frontline techniques to identify mammalian cell clones with genetic mutations and recognize cell culture process media/feed conditions that induce misincorporations, respectively. Once an industry-wide challenge, sequence variation is now routinely monitored and controlled at Pfizer (and other biopharmaceutical companies) through increased awareness, dedicated cross-line efforts, smart comprehensive strategies, and advances in instrumentation/software, resulting in even higher product quality standards for biopharmaceutical products.

The first World Health Organization International Standard for infliximab products: A step towards maintaining harmonized biological activity.
In this Brief Report, Metcalfe et al. present a collaborative study designed to assess the suitability of the first international standard (IS) for infliximab to serve as an IS for the in vitro biological activity of infliximab. The IS was developed by the UK’s National Institute for Biological Standards and Control (NIBSC). The study involved participants using in vitro cell-based bioassays (TNF neutralization, antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity) and binding assays. The results of this study showed that the candidate preparation, coded 16/170, is suitable as an IS for infliximab bioactivity. This infliximab IS from NIBSC, is intended to support in vitro bioassay calibration and validation by defining international units of bioactivity

Anti-PD1 ‘SHR-1210ʹ aberrantly targets pro-angiogenic receptors and this polyspecificity can be ablated by paratope refinement.
Finlay et al. report that the combination of receptor proteome screening and optimization of the antibody binding interface succeeded in generating novel, higher-potency, specificity-enhanced therapeutic IgGs from a single, clinically sub-optimal progenitor. They show that highly-specific off-target binding events might be an under-appreciated phenomenon in therapeutic antibody development, but that these unwanted properties can be fully ameliorated by paratope refinement.

Deamidation and isomerization liability analysis of 131 clinical-stage antibodies.
As discussed by Lu et al., knowledge of the chemical stability characteristics of clinical-stage therapeutic monoclonal antibodies (mAbs) is fragmented and lacks comprehensive comparative assessment. To address this knowledge gap, the authors produced 131 mAbs with amino acid sequences corresponding to the variable regions of clinical-stage mAbs, subjected these to low and high pH stresses and identified the resulting modifications at amino acid-level resolution via tryptic peptide mapping. Among this large set of mAbs, relatively high frequencies of asparagine deamidation events were observed in CDRs H2 and L1, while CDRs H3, H2 and L1 contained relatively high frequencies of instances of aspartate isomerization.

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