Thursday, March 27, 2014

BDP Week Day 2: Analytical Technologies for Biotherapeutic Development: Characterization and Measurement Strategies

At the half-way point of the IBC Life Sciences Biopharmaceutical Development and Production Week 2014 conference draws near at the close of Day 2 on March 25th, there remains the last event which is the Beach Party where attendees can unwind and network on the San Diego water front removed from the seminar rooms and exhibit hall. It’s also a chance where information and lessons learned can be further disseminated that were presented by over 80 speakers in five topic session tracks not to mention several two-day training courses and a handful of technology workshops. The session tracks have included Analytical Technologies for Biotherapeutic Development (ATBD), Process Validation and Continued Process Verification, and Antibody Development and Production.

One such presentation in the Analytical Technologies for Biotherapeutic Development session track was by Aston Liu of GlaxoSmithKline, whose talk was titled Localized Conformation Changes from Chemical Modifications and their Impact on the Development of mAb-Based Protein Therapeutics. Amongst the numerous possible chemical modifications that could occur to a mAb, Liu chose to focus on the impact of deamidation and oxidation of methionine on structural conformation. The structural changes to a mAb can be characterized by several analytical techniques. Liu constructed a simple X-Y plot of analytical resolution versus sample throughput to describe and compare the instrumental methods. The objective was to identify a method that had both high resolution and high throughput. NMR has high resolution, but it has low throughput. FT-IR has relatively high throughput, but it has relatively low resolution. The focus of Liu’s talk was on the application of HDX-MS, or hydrogen-deuterium exchange detected by mass spectroscopy, because it lied in the sweet spot of his graph as a technique that had both high resolution and high throughput. HDX can occur as a function of solvent accessibility of the moiety undergoing exchange, secondary structure or conformational dynamics. Deamidation or oxidation of methionine can have an impact on any one or all three of these properties and thus give rise to HDX or a difference in rate of HDX compared to the unmodified mAb. These changes in structure can lead to changes in the stability of the mAb or its propensity for aggregation which can give rise to detrimental effects on safety and efficacy as a biopharmaceutical. Certain amino acids or regions of the mAb can thus be identified as “hot spots” depending on the impact of undergoing chemical modification and thus can be the focus of genetic engineering with respect to optimization of leads. Liu fielded a couple questions from the audience with respect to the correlation of a change in activity with a change in HDX. Liu reported he has determined that a change in HDX correlates to a change in mAb binding activity.

The characterization of protein conformation as a critical quality attribute of biotherapeutics was also the topic of discussion in later presentations, for example given by Robert Karlsson of GE Healthcare Life Sciences in a technology workshop and John Philo of Alliance Protein Laboratories in an ATBD session track. Karlsson spoke in part on a very early stage technology called Epitope Characterizing Reagents which are probes for protein conformation whose utility was described as part of the characterization of changes in binding properties of a mAb upon being subject to forced stress such as extreme pH and oxidation. Philo presented on the application of sedimentation velocity analytical ultracentrifugation, SV-AUC, for example in the comparison or identification of conformational changes that may arise upon a change in the manufacturing process.

Today's post comes from Gregory T Mrachko a Protein Chemist and Enzymologist. He specializes in protein purification, enzymology, high throughput assay/screen conceptualization/development/implementation, analytical biochemistry, biocatalysis, liquid column chromatography, and protein analytics. He is a guest blogger at this year's Biopharmaceutical Development and Production Week and can be reached at

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