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Applied Biochemistry and Biotechnology


Bio Pharm Intl



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Post-Translational Modifications - Day 2

Conference Proceeding CD Now Available
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Post-Translational Modifications

Day 1  |  Day 2  |  Download Brochure 


8:30 Chairperson’s Remarks

Alistair Kippen, Ph.D., Associate Director, Analytical Biochemistry, MedImmune Ltd.



8:35 Impact of Post-Translational Modifications on Bioassays is Critical for Establishing Comparability Strategy for a Monoclonal Antibody

Monica Brzezinski, Ph.D., Principal Scientist, Biotherapeutics, Analytical Research & Development, Pfizer, Inc.

A comprehensive comparability exercise is performed for monoclonal antibodies in the late stage of development to compare pre-change and post-change product. The importance of using more than one biological assay to evaluate the effects of structural heterogeneity is sometimes overlooked. In this case study, different types of bioassays were used to measure direct binding of a monoclonal antibody to antigen, kinetic binding constants, and functional binding (cell-based method). A specific product-related impurity detected by one of these bioassays will be discussed along with a proposed strategy for bioassay methods to be used in release of Drug Substance and Drug Product.

9:05 Asn Deamidation in the Light Chain CDR1 of a Humanized IgG1 Monoclonal Antibody – Impact on Structure and Function

Josef Vlasak, Ph.D., Senior Research Biochemist, Merck & Co., Inc.

Asn deamidation in the light chain CDR1 of a monoclonal antibody will be described in detail.  Both deamidation products (Asp/isoAsp) were detected and found to be less potent in antigen binding than the intact antibody.  Several experiments such as near-UV CD spectroscopy, limited proteolysis, and differential scanning calorimetry suggested changes in antibody structure of the isoAsp variant.  The kinetics of the reaction at different pH and temperatures will be discussed, including evidence for isomerization of the newly formed isoAsp.

9:35 Analytical Characterization of PTMs to Support Formulation Decisions

Jun Ouyang, Ph.D., Scientist, Protein Analytical Chemistry, Genentech, Inc.

Two PTMs in the complementarity-determining region (CDR) of antibody therapeutics were found to have drastically impacted antibody-antigen binding. In one case, oxidation of a tryptophan was identified using tryptic map coupled with Mascot Error Tolerant Search; the level of oxidized tryptophan was correlated to the potency loss. In the other case, an aspartic acid isomerization was pinpointed using a novel electron-transfer dissociation MS approach. Factors that impacted the rate of isomerization were investigated. In both cases, appropriate assays and formulation strategies were developed to mitigate the stability risk.

9:55 Networking Coffee Break, Poster and Exhibit Viewing

10:40 Manipulation of the Fc Receptor/Immunoglobulin Interaction for the Treatment of IgG-Mediated Autoimmune Diseases

Peter Sondermann, Ph.D., Chief Scientific Officer, SuppreMol GmbH

In IgG-mediated autoimmune diseases, the body’s own tissues are recognized by antibodies and subsequently destroyed by humoral and cellular effector functions that are mediated via the Fc part of the immune complexed IgGs. SM101, a soluble human FcgRIIb interferes with the interaction of such immune complexed IgG with FcgR-expressing cells and complement. This results in an overall down regulation of the immune system. Animal experiments with various models of autoimmune diseases confirm the validity of this approach. SM101 is currently tested in a phase I trial in healthy volunteers. Results of this mono-centric, randomized, double-blind, placebo-controlled study will be presented.


Featured Presentation

11:10 Do it Earlier, Save Big Later! - Chemical Stability Stress Test for Therapeutic mAb Lead Candidates2Boyan ZhangBoyan Zhang, Ph.D., Scientist and Group Leader, Protein Analytical Chemistry, Genentech, Inc.

Early assessment of the stability of recombinant monoclonal antibodies can result in significant time and cost savings downstream in clinical development. A chemical stability stress test is established to assess if antibody candidates contain labile chemical degradation hotspots (i.e. Asp isomerization, Asn deamidation, Met and Trp oxidation) or product variants resulting from amino acid substitutions. A case study on mAb1 will be presented to depict the assays and strategies developed for such a purpose. A second case study will be presented on how a 40% product variation from a Pro replacement by Leu (+16 Da mass shift) was identified in mAb2.

11:40  End of Post-Translational Modifications

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