Serial Coupling of Ion-Exchange and Size-Exclusion Chromatography to Determine Aggregation Levels in mAbs in The Presence of a Proteinaceous Excipient, Recombinant Human Serum Albumin

Serially coupled column liquid chromatography: An alternative separation tool

Despite the rapid development of liquid chromatography (LC) in recent decades, it remains a challenge to achieve the desired chromatographic separation of complex matrices using a single column. Multi-column LC techniques, particularly serially coupled column LC (SCC-LC), have emerged as a promising solution to overcome this challenge. While more attention has been focused on heart-cutting or comprehensive two-dimensional LC, reviews specifically focusing on SCC-LC, which offers advantages in terms of precision and facile instrumentation, are scarce. Here, our concerns are devoted to the progress summary regarding the instrumentation and applications of SCC-LC. Emphasis is placed on column selection aiming to enlarge peak capacity, selectivity, or both through the optimization of combination types (e.g. RPLC-RPLC, -RPLC-HILIC, and achiral-chiral LC), connection devices (e.g. zero dead volume connector, tubing, and T-type connector), elution program (i.e. isocratic or gradient) and detectors (e.g. mass spectrometer, ultraviolet detector, and fluorescence detector). The application of SCC-LC in pharmaceutical, biological, environmental, and food fields is also reviewed, and future perspectives and potential directions for SCC-LC are discussed. We envision that the review can give meaningful information to analytical scientists when facing heavy chromatographic separation tasks for complicated matrices.

Biophysical Characterization of Binary Therapeutic Monoclonal Antibody Mixtures

Coformulations containing two therapeutic monoclonal antibodies (mAbs) could offer various benefits like enhanced therapeutic efficacy and better patient compliance. However, there are very few published studies on coformulations and binary mixtures of mAbs. It remains unclear to what extent mAbs with different physicochemical properties can be combined in solution without detrimental effects on protein stability. Here, we present a study including six model mAbs of the IgG1 subclass that are commercially available. In silico and biophysical characterization shows that the proteins have different physicochemical properties. Thus, their combinations represent various scenarios for coformulation development. We prepared all possible binary mixtures of the six mAbs and determined several biophysical parameters that are assessed during early-stage protein drug product development. The measured biophysical parameters are indicative of the conformational protein stability (inflection points of the thermal protein unfolding transitions) and the colloidal protein stability (aggregation onset temperatures and interaction parameter k_D from dynamic light scattering). Remarkably, all 15 binary mAb mixtures do not exhibit biophysical parameters that indicate inferior conformational or colloidal stability compared to the least stable mAb in the mixture. Our findings suggest that the coformulation of some therapeutic monoclonal antibodies of the IgG1 subclass could be possible in a straightforward way as severe detrimental effects on the stability of these proteins in binary mixtures were not observed.

Science and art of protein formulation development

Protein pharmaceuticals have become a significant class of marketed drug products and are expected to grow steadily over the next decade. Development of a commercial protein product is, however, a rather complex process. A critical step in this process is formulation development, enabling the final product configuration. A number of challenges still exist in the formulation development process. This review is intended to discuss these challenges, to illustrate the basic formulation development processes, and to compare the options and strategies in practical formulation development.

Unraveling the mysteries of modern size exclusion chromatography - the way to achieve confident characterization of therapeutic proteins

Modern size exclusion chromatography (SEC) can be defined by the use of relatively small columns (e.g., 150 × 4.6 mm) packed with sub-3 μm particles, allowing a 3- to 5-fold increase in method throughput compared to that of conventional SEC. The quick success of the first sub-2 μm SEC column introduced in 2010 led to the development of numerous ultra-high performance (UHP)-SEC columns for the analysis of therapeutic monoclonal antibody (mAb)-based products. Aggregates also known as high-molecular-weight species (HMWS) are indeed one of the most important critical quality attributes (CQAs) of mAbs, as HMWS may decrease the product efficacy or cause immunogenicity effects. Therefore, the confident characterization of mAbs requires strong knowledge of not only modern SEC performance (i.e., selectivity and efficiency) but also the inherent limitations caused by non-specific interactions more likely to occur with complex antibody drug conjugates (ADCs) and some commercial mAb products. This review discusses the importance of liquid chromatographic (LC) instrumentation in order to exploit the full potential of modern SEC columns and current trends to hyphenate SEC to mass spectrometry (MS). Recent applications for antibody-based products (i.e., mAbs, ADCs, Fc-Fusion proteins and bispecific antibodies) are presented. Finally, tips and tricks are provided to further optimize SEC separations and maintaining their performance over time with better understanding of unexpected SEC results.