Middle-up characterization of monoclonal antibodies by online reduction liquid chromatography-mass spectrometry

What is the role of current mass spectrometry in pharmaceutical analysis?

The role of mass spectrometry (MS) has become more important in most application domains in recent years. Pharmaceutical analysis is specific due to its stringent regulation procedures, the need for good laboratory/manufacturing practices, and a large number of routine quality control analyses to be carried out. The role of MS is, therefore, very different throughout the whole drug development cycle. While it dominates within the drug discovery and development phase, in routine quality control, the role of MS is minor and indispensable only for selected applications. Moreover, its role is very different in the case of analysis of small molecule pharmaceuticals and biopharmaceuticals. Our review explains the role of current MS in the analysis of both small-molecule chemical drugs and biopharmaceuticals. Important features of MS-based technologies being implemented, method requirements, and related challenges are discussed. The differences in analytical procedures for small molecule pharmaceuticals and biopharmaceuticals are pointed out. While a single method or a small set of methods is usually sufficient for quality control in the case of small molecule pharmaceuticals and MS is often not indispensable, a large panel of methods including extensive use of MS must be used for quality control of biopharmaceuticals. Finally, expected development and future trends are outlined.

Tetrapeptide-based mimotope affinity monolith for the enrichment and analysis of anti-HER2 antibody and antibody-drug conjugate

Selective enrichment and analysis of therapeutic antibodies in biological fluids are crucial for the development of biopharmaceuticals. Recently, peptide-based affinity chromatography has exhibited fascinating prospects for antibody enrichment due to the high affinity and specificity of small peptides. However, the post-modification approach of peptide ligands on the material surface is complicated and time-consuming. In this study, a methacrylate modified tetrapeptide (m-EDPW) was firstly demonstrated as the affinity ligand of trastuzumab (K_d = 1.91 ± 1.81 μM). Next, the m-EDPW based affinity monolith was prepared using a facile one-step polymerization method, which could overcome the drawbacks of traditional post-modification preparation strategies. Based on the monolith as described above, a simple enrichment approach was developed under the optimal washing and elution conditions. Based on the excellent properties, such as high porosity (53.09%), weak electrostatic interaction and suitable affinity (1.00 ± 2.14 μM for anti-HER2 ADC), this novel monolith exhibited good specificity and recovery for antibodies (91.6% for trastuzumab, 98.37% for anti-HER2 ADC), and low nonspecific adsorption for human serum albumin (DBC_10% = 0.5 mg/g polymer). Particularly, this material was successfully applied to enrich trastuzumab and its related antibody-drug conjugate (ADC) from different cell culture medias. The dynamic tracking analysis of ADC in the critical quality attributes (e.g., charge variants, drug to antibody ratio and subunit conjugation ratio) was also achieved by combining the enrichment approach, capillary electrophoresis or reversed phase liquid chromatography. In summary, the exploited peptide-based mimotope affinity materials showed a great potential for the application in biopharmaceutical analysis.

Bispecific antibody characterization by a combination of intact and site-specific/chain-specific LC/MS techniques

Bispecific antibodies (bsAbs) are considered as an important class of biopharmaceutical drugs, with about 160 products in clinical trials. From an analytical point of view, the correct chain-association is one of the most critical challenge to monitor during bsAbs development and production. In the present study, a full analytical workflow has been developed based on the use of various chromatographic modes: size exclusion chromatography (SEC), ion exchange chromatography (IEX), reversed phase liquid chromatography (RPLC), and hydrophilic interaction chromatography (HILIC), all combined with high resolution mass spectrometry (MS). This analytical strategy was applied to Hemlibra® (emicizumab), which is certainly the most successful commercial bsAb to date. Using this strategy, it was possible to monitor the presence of mispaired bsAb species and detect and identify additional post-translational modifications (PTMs).

Inline electrochemical reduction of NISTmAb for middle-up subunit liquid chromatography-mass spectrometry analysis

Disulfide bond reduction within antibody mass spectrometry workflows is typically carried out using chemical reducing agents to produce antibody subunits for middle-down and middle-up analysis. In this contribution we offer an online electrochemical reduction method for the reduction of antibodies coupled with liquid chromatography (LC) and mass spectrometry (MS), reducing the disulfide bonds present in the antibody without the need for chemical reducing agents. An electrochemical cell placed before the analytical column and mass spectrometer facilitated complete reduction of NISTmAb inter- and intrachain disulfide bonds. Reduction and analysis were carried out under optimal solvent conditions using a trapping column and switching valve to facilitate solvent exchange during analysis. The level of reduction was shown to be affected by electrochemical potential, temperature and solvent organic content, but with optimization, complete disulfide bond cleavage was achieved. The use of an inline electrochemical cell offers a simple, rapid, workflow solution for liquid chromatography mass spectrometry analysis of antibody subunits.

Superheated reversed phase chromatography with ultrashort columns for the analysis of therapeutic proteins

Mild or elevated temperatures are routinely used for the analysis of therapeutic proteins by reversed phase liquid chromatography. Generic conditions can be used for the analysis of monoclonal antibodies, and may be adapted for species derived thereof, for instance their immuno-conjugates. Beyond platform monoclonal antibodies, many novel, non-covalent protein complexes are also frequently pursued as protein therapeutics. These complexes, in reverse phased chromatography, may require extremely harsh, superheated conditions to dissociate and elute as interpretable profiles. In order to minimize on-column degradation under superheated conditions, the analysis time has to be reduced as much as possible. Using ultrashort columns and fast gradients is a promising approach in achieving informative separations within a minute, or even faster. Here the applicability of this approach, which supports maintaining levels of degradation products close to the intrinsic sample composition without further on-column degradation is demonstrated. NISTmAb as conventional IgG, a bispecific homodimer and a bispecific homotetramer were used for demonstrating differences in the elution characteristics and the necessity of using the proposed approach. The analysis of the bispecific homodimer was discussed in detail as a case study.