Comparative study of trastuzumab modification analysis using mono/multi-epitope affinity technology with LC-QTOF-MS

Dual-filler mixed matrix membrane with covalent-organic framework and nano TiO2/polyether sulfone for efficient antibody purification

With the rapid expansion of antibody drug market, most biopharmaceutical industries urgently need to optimize their downstream purification processes to reduce production costs and improve market competitiveness. In this study, a dual-filler polyether sulfone (PES) mixed matrix membrane (MMM) that combines covalent-organic framework (COF) with nano TiO2 was developed to overcome the drawbacks of conventional protein A based purification methods. Firstly, COF@TiO2 dual-filler was prepared by Schiff base reaction. The proposed dual-filler MMM was fabricated via nonsolvent-induced phase separation (NIPS), followed by functionalization with a Fab-specific affinity peptide (m-EDPW) of trastuzumab through atom-transfer radical-polymerization method. The resulting m-EDPW@COF@TiO2/PES affinity membrane effectively integrates the merits of COF and TiO2 and show synergistic effects, demonstrating satisfactory hydrophilicity, anti-fouling ability (BSA rejection rate: 97.7 %), enrichment recovery (90.8 %), binding capacity for trastuzumab (386.6 mg/g), and long-term stability (∼ 21 days). Particularly, this affinity membrane showed good selectivity and specificity, enabling the successful purification of trastuzumab from spiked HCC1937 cancer cell culture medium with satisfactory purity (~ 97.4 %) and preservation of the antibody secondary structure. This study not only developed a novel affinity membrane with satisfactory antibody separation performance but also opened a new route for developing dual-filler or multi-filler MMM for highly efficient downstream protein purification.

In vitro Stability Study of a Panel of Commercial Antibodies at Physiological pH and Temperature as a Guide to Screen Biologic Candidate Molecules for the Potential Risk of In vivo Asparagine Deamidation and Activity Loss

OBJECTIVE

Biologic drug molecules such as antibodies are exposed to the physiological stress conditions of pH 7.4 and 37°C during their long circulation lifetime in vivo. The stress on biologic molecules in vivo is more severe compared to that under typical storage conditions of low pH formulation and cold temperature. Chemical degradation of critical residues such as asparagine may occur in vivo, leading to potential loss of biological activity. This study describes a physiologically relevant and convenient in vitro PBS stress condition of pH 7.4 and 40°C for pre-clinical stability screening of biologic molecules.

METHODS

As benchmarks, multiple commercial antibodies (alirocumab, evolocumab, golimumab, ramucirumab, and trastuzumab) were tested in parallel for formulation stability at storage and accelerated temperature conditions and for physiological stability at pH 7.4 and 40°C stress both for 3-4 weeks. The stressed antibodies were monitored for chemical modification and target binding, without requiring affinity purification.

RESULTS

The major CDR chemical modifications observed in PBS-stressed commercial antibodies were deamidations of asparagine residues. Although slight decreases in target binding were observed for two antibodies, the affinities overall remained strong after PBS stress.

CONCLUSIONS

This benchmarking study of commercial antibodies would be useful as a guide to screen discovery-stage biologic molecules both for drug product stability at formulation pH under storage and accelerated temperature conditions and for physiological stability under in vivo-mimicking pH and temperature stress condition.

Site-Specific Stability Evaluation of Antibody-Drug Conjugate in Serum Using a Validated Liquid Chromatography-Mass Spectrometry Method

Antibody-drug conjugate (ADC) consists of engineered antibodies and cytotoxic drugs linked via a chemical linker, and the stability of ADC plays a crucial role in ensuring its safety and efficacy. The stability of ADC is closely related to the conjugation site; however, no method has been developed to assess the stability of different conjugation sites due to the low response of conjugated peptides. In this study, an integrated strategy was developed and validated to assess the stability of different conjugation sites on ADC in serum. Initial identification of the conjugated peptides of the model drug ado-trastuzumab emtansine (T-DM1) was achieved by the proteomic method. Subsequently, a semiquantitative method for conjugated peptides was established in liquid chromatography-hybrid linear ion trap triple quadrupole mass spectrometry (LC-QTRAP-MS/MS) based on the qualitative information. The pretreatment method of the serum sample was optimized to reduce matrix interference. The method was then validated and applied to evaluate the stability of the conjugation sites on T-DM1. The results highlighted differences in stability among the different conjugation sites on T-DM1. This is the first study to assess the stability of different conjugation sites on the ADC in serum, which will be helpful for the design and screening of ADCs in the early stages of development.