Profiling, Relative Quantification, and Identification of Sialylated N-Linked Oligosaccharides by UPLC-FLR-ESI/MS After Derivatization with Fluorescent Anthranilamide.

The presence of sialic acids is one characteristic of glycosylated therapeutic proteins. The presence of these charged monosaccharides is critical for the immunogenicity properties and structural properties of the proteins. Profiling of the N-glycans and their charge state is a requisite for complete protein characterization. Two analytical methods developed on released N-glycans are described in this chapter, allowing for the determination of the sialoglycosylation with different levels of details. In the first method (AEX-HILIC/FLR), N-glycans are separated based on their charge and the average charge state can be determined from the fluorescence profile. In the second method (AEX-RP-FLR-MS), N-glycans are also separated based on their charge and the sialylation level is determined based on the fluorescence signal. In addition, in this method, the N-glycans are also separated by type and identified with the hyphenated MS. For both methods, an optimized protocol with fast and high-throughput sample preparation and purification is presented.

Orthogonal liquid chromatography-mass spectrometry methods for the comprehensive characterization of therapeutic glycoproteins, from released glycans to intact protein level.

Proteins are increasingly used as therapeutics. Their characterization is challenging due to their size and inherent heterogeneity notably caused by post-translational modifications, among which glycosylation is probably the most prominent. The glycosylation profile of therapeutic proteins must therefore be thoroughly analyzed. Here, we illustrate how the use of a combination of various cutting-edge LC or LC/MS(/MS) methods, and operating at different levels of analysis allows the comprehensive characterization of both the N- and O-glycosylations of therapeutic proteins without the need for other approaches (capillary electrophoresis, MALDI-TOF). This workflow does not call for the use of highly specialized/custom hardware and software nor an extensive knowledge of glycan analysis. Most notably, we present the point of view of a contract research organization, with the constraints associated to the work in a regulated environment (GxP). Two salient points of this work are i) the use of mixed-mode chromatography as a fast and straightforward mean of profiling N-glycans sialylation as well as an orthogonal method to separate N-glycans co-eluting in the HILIC mode; and ii) the use of widepore HILIC/MS to analyze challenging N/O-glycosylation profiles at both the peptide and subunit levels. A particular attention was given to the sample preparations in terms of duration, specificity, versatility, and robustness, as well as the ease of data processing.

Therapeutic antibody glycosylation analysis: a contract research organization perspective in the frame of batch release or comparability support.

Glycosylation of the Fc moiety of a monoclonal antibody is a heterogeneous posttranslational process considered as a critical quality attribute of the purified drug substance due to its major impact on safety and efficacy (i.e., immunogenicity, CDC or ADCC effector functions, etc.). Glycosylation should thus be addressed for batch-to-batch comparability and for drug substance characterization, in terms of identity and/or purity testing. We present below a set of efficient, performing and complementary analytical tests that can be used alone or in combination, depending on the information needed and available laboratory instrumentation. The results obtained using these techniques for "global" glycosylation profile, N-glycans profiling, monosaccharides, and sialic acids determination are presented for the Trastuzumab (Herceptin)-humanized mAb produced in CHO.