F-star is a clinical-stage biopharmaceutical company developing bispecific antibody immuno-oncology products selected for their potential to transform the treatment of cancer. F-star is the only biotechnology company able to create bispecific antibodies where the second binding site is in the constant Fc region of an antibody (mAb2). Their Modular Antibody Technology™ platform, offers unprecedented ease in the development and manufacturing of genuine bispecific antibody products.
BioPharmaSpec performed on-line Liquid Chromatography with Electrospray-Mass Spectrometric detection (LC/ES-MS, Q-TOF)) of proteolytic digests of F-star mAb2 samples (plus MSe and MS/MS as required). Different digestion strategies were used depending on the objectives for the data. A single digestion strategy would typically provide >90% sequence coverage and yield good data for basic characterization studies. A more extensive digestion strategy would allow an assessment of disulfide bridges and post translational modifications (PTMs) such as glycosylation, deamidation, oxidation, N- terminal pyroglutamination and heavy chain C-terminal Lysine clipping.
Technical Considerations – Deamidation
Although not the case with this project or F-star’s mAb2 products, changes to the pH or temperature of the sample can cause deamidation. This is a chemical change where the amide group of the side chains of the amino acids asparagine or glutamine is converted to a carboxylic acid. Deamidation is a chemical instability event and can result in isomerization (i.e. the isomerization of aspartate to isoaspartate residues) or truncation (i.e. peptide chain cleavage).
Although its effects can be drastic to the stability of your biopharmaceutical, deamidation is a small change which will result in a mass difference of only 1Da. This mass change is similar to that seen in natural isotopic variation and so it is important to apply analytical techniques to understand the basis of the charge differential.
At BioPharmaSpec, we use state-of-the-art mass spectrometry instrumentation and decades of data interpretation experience to provide our clients with quality data that can be relied upon to support their development projects.
“I appreciate the fast turnaround times that BioPharmaSpec provide us with. These become especially important when we need to make key development decisions and require data for consideration at internal meetings .” – Senior Scientist, F-Star Biotechnology Ltd.