Glycoform Separation and Characterization of Cetuximab Variants by Middle-up Off-Line Capillary Zone Electrophoresis-UV/Electrospray Ionization-MS.

Monoclonal antibodies (mAbs) are highly complex glycoproteins that present a wide range of microheterogeneities that requires multiple analytical methods for full structure assessment and quality control. Capillary zone electrophoresis-mass spectrometry (CZE-MS) couplings, especially by electrospray ionization (ESI), appear to be really attractive methods for the characterization of biological samples. However, due to the presence of non- or medium volatile salts in the background electrolyte (BGE), online CZE-ESI-MS coupling is difficult to implement for mAbs isoforms separation. Here, we report an original strategy to perform off-line CZE-ESI-MS using CZE-UV/fraction collection technology to perform CZE separation, followed by ESI-MS infusion of the different fractions using the capillary electrophoresis-electrospray ionization (CESI) interface as the nanoESI infusion platform. As the aim is to conserve electrophoretic resolution and complete compatibility with ESI-MS without sample treatment, hydroxypropylcellulose (HPC) coated capillary was used to prevent analyte adsorption and asymmetric CZE conditions involving different BGE at both ends of the capillary have been developed. The efficiency of our strategy was validated with the separation of Cetuximab charge variant by the middle-up approach. Molecular weights were measured for six charge variants detected in the CZE separation of Cetuximab subunits. The first three peaks correspond to Fc/2 variants with electrophoretic resolution up to 2.10, and the last three peaks correspond to F(ab')2 variants with average electrophoretic resolution of 1.05. Two Fc/2 C-terminal lysine variants were identified and separated. Moreover, separation of Fc/2 fragments allowed the glycoprofiling of the variants with the characterization of 7 different glycoforms. Regarding the F(ab')2 domain, 8 glycoforms were detected and separated in three different peaks following the presence of N-glycolyl neuraminic acid residues in some glycan structures. This work highlights the potential of CZE technology to perform separation of mAbs especially when they carry sialic acid carbohydrates.

Antibody drug separation using thermoresponsive anionic polymer brush modified beads with optimised electrostatic and hydrophobic interactions.

Antibody drugs play an important role in biopharmaceuticals, because of the specificity for target biomolecules and reduction of side effects. Thus, separation and analysis techniques for these antibody drugs have increased in importance. In the present study, we develop functional chromatography matrices for antibody drug separation and analysis. Three types of polymers, poly(N-isopropylacrylamide (NIPAAm)-co-2-acrylamido-2-methylpropanesulfonic acid (AMPS)-co-N-phenyl acrylamide (PhAAm)), P(NIPAAm-co-AMPS-co-n-butyl methacrylate (BMA)), and P(NIPAAm-co-AMPS-co-tert-butylacrylamide (tBAAm)), were modified on silica beads through atom transfer radical polymerisation. Rituximab elution profiles were observed using the prepared beads-packed column. Rituximab adsorption at high temperature and elution at low temperature from the column were observed, as a result of the temperature-modulated electrostatic and hydrophobic interactions. Using the column, rituximab purification from contaminants was performed simply by changing the temperature. Additionally, three types of antibody drugs were separated using the column through temperature-modulated hydrophobic and electrostatic interactions. These results demonstrate that the temperature-responsive column can be applied for the separation and analysis of biopharmaceuticals through a simple control of the column temperature.

Roadmap for the Development and Clinical Translation of Optical Tracers Cetuximab-800CW and Trastuzumab-800CW.

Optical molecular imaging using fluorescently labeled monoclonal antibodies is of significant added value in guiding surgical or endoscopic procedures. However, development of tracers for clinical trials is complex, and implementation in the clinic is therefore slow. We present a roadmap for development and translation of monoclonal antibody tracers into a drug product compliant with current good manufacturing processes (cGMPs). Methods: The production process for cetuximab-800CW and trastuzumab-800CW was optimized with regard to dye-to-protein ratio and formulation buffer. Promising formulations were produced under cGMP conditions and advanced to a full-scale stability study. Tracers were analyzed for stability by size-exclusion high-pressure liquid chromatography, pH measurement, osmolality, visual inspection, and sterility, as required by the European Pharmacopeia and cGMP guidelines. Results: Seven formulations were investigated for cetuximab-800CW and 10 for trastuzumab-800CW. On the basis of the formulation study results, we chose 2 formulations per antibody for investigation during the full-scale stability study. These formulations all performed well, showing good compliance with the acceptance criteria set for each product. Conclusion: We designed a roadmap to standardize the development, formulation, and cGMP translation of molecular fluorescent tracers. Using our standardized approach, we developed 2 stable antibody-based tracers for clinical use. The proposed roadmap can be used to efficiently develop a cGMP-compliant formulation and improve the translation of newly developed optical tracers to first-in-human use.

Top-down and middle-down approach by fraction collection enrichment using off-line capillary electrophoresis - mass spectrometry coupling: Application to monoclonal antibody Fc/2 charge variants.

The characterization of complex protein mixtures represents one of the biggest challenge in many research fields such as biological or biopharmaceutical sciences. Out of all categories, monoclonal antibodies (mAbs) and related products drawn the most interest due to their strong therapeutic potency and specificity. Because of their intrinsic complexity due to a large number of micro-heterogeneities, there is a crucial need for analytical methods to provide comprehensive in-depth characterization of these proteins. In this work, we developed a methodology using CE-UV/MALDI-MS to perform top-down or middle-down characterization after fraction collection enrichment applied to intact protein and mAbs samples. The performance of the method was evaluated with the rapid separation of three intact protein mixture. Good robustness of CZE separation and quality of MALDI-MS spectra and MALDI-ISD spectra of each protein confirms the usefulness of sample enrichment to obtain adequate quantity of deposed protein for top-down analysis and the proof of principle of the method. In a second step, the method was applied to the middle-down characterization of Fc/2 cetuximab variants. Identification of around 9% sequence coverage of Fc/2 cetuximab fragments allows to conclude on the feasibility of the strategy for middle-down characterization of Fc/2 cetuximab variants using CE-UV/MALDI-MS. Moreover, MALDI-ISD fragmentation of Fc/2 cetuximab variants confirm separation phenomenon based on the formation of Fc/2 dimers with and without C-terminal truncation.

Semi-synthetic vNAR libraries screened against therapeutic antibodies primarily deliver anti-idiotypic binders.

Anti-idiotypic binders which specifically recognize the variable region of monoclonal antibodies have proven to be robust tools for pharmacokinetic studies of antibody therapeutics and for the development of cancer vaccines. In the present investigation, we focused on the identification of anti-idiotypic, shark-derived IgNAR antibody variable domains (vNARs) targeting the therapeutic antibodies matuzumab and cetuximab for the purpose of developing specific capturing ligands. Using yeast surface display and semi-synthetic, CDR3-randomized libraries, we identified several highly specific binders targeting both therapeutic antibodies in their corresponding variable region, without applying any counter selections during screening. Importantly, anti-idiotypic vNAR binders were not cross-reactive towards cetuximab or matuzumab, respectively, and comprised good target recognition in the presence of human and mouse serum. When coupled to magnetic beads, anti-idiotypic vNAR variants could be used as efficient capturing tools. Moreover, a two-step procedure involving vNAR-functionalized beads was employed for the enrichment of potentially bispecific cetuximab × matuzumab antibody constructs. In conclusion, semi-synthetic and CDR3-randomized vNAR libraries in combination with yeast display enable the fast and facile identification of anti-idiotypic vNAR domains targeting monoclonal antibodies primarily in an anti-idiotypic manner.

Quality Control of Therapeutic Monoclonal Antibodies at the Hospital After Their Compounding and Before Their Administration to Patients.

Monoclonal antibodies (mAbs) are widely used in cancer therapy and recently many new mAbs have gained EMA and FDA approvals for oncology indications. Here we describe a highly reproducible CZE method, relying on a cationic coating allowing separation and identification of a complex mixture of four compounded mAbs widely used in cancer therapy (cetuximab, rituximab, bevacizumab, and trastuzumab).