Stability of a high-concentration monoclonal antibody solution produced by liquid-liquid phase separation.

Subcutaneous injection of a low volume (<2 mL) high concentration (>100 mg/mL) formulation is an attractive administration strategy for monoclonal antibodies (mAbs) and other biopharmaceutical proteins. Using concentrated solutions may also be beneficial at various stages of bioprocessing. However, concentrating proteins by conventional techniques, such as ultrafiltration, can be time consuming and challenging. Isolation of the dense fraction produced by macroscopic liquid-liquid phase separation (LLPS) has been suggested as a means to produce high-concentration solutions, but practicality of this method, and the stability of the resulting protein solution have not previously been demonstrated. In this proof-of-concept study, we demonstrate that LLPS can be used to concentrate a mAb solution to >170 mg/mL. We show that the structure of the mAb is not altered by LLPS, and unperturbed mAb is recoverable following dilution of the dense fraction, as judged by 1H nuclear magnetic resonance spectroscopy. Finally, we show that the physical properties and stability of a model high concentration protein formulation obtained from the dense fraction can be improved, for example through the addition of the excipient arginine·glutamate. This results in a stable high-concentration protein formulation with reduced viscosity and no further macroscopic LLPS. Concentrating mAb solutions by LLPS represents a simple and effective technique to progress toward producing high-concentration protein formulations for bioprocessing or administration.AbbreviationsArginine·glutamate (Arg·Glu), Carr-Purcell-Meiboom-Gill (CPMG), critical temperature (TC), high-performance size-exclusion chromatography (HPSEC), liquid-liquid phase separation (LLPS), monoclonal antibody (mAb), nuclear magnetic resonance (NMR), transverse relaxation rate (R2).

Comprehensive Assessment of Protein and Excipient Stability in Biopharmaceutical Formulations Using 1H NMR Spectroscopy.

Biopharmaceutical proteins are important drug therapies in the treatment of a range of diseases. Proteins, such as antibodies (Abs) and peptides, are prone to chemical and physical degradation, particularly at the high concentrations currently sought for subcutaneous injections, and so formulation conditions, including buffers and excipients, must be optimized to minimize such instabilities. Therefore, both the protein and small molecule content of biopharmaceutical formulations and their stability are critical to a treatment's success. However, assessing all aspects of protein and small molecule stability currently requires a large number of analytical techniques, most of which involve sample dilution or other manipulations which may themselves distort sample behavior. Here, we demonstrate the application of 1H nuclear magnetic resonance (NMR) spectroscopy to study both protein and small molecule content and stability in situ in high-concentration (100 mg/mL) Ab formulations. We show that protein degradation (aggregation or fragmentation) can be detected as changes in 1D 1H NMR signal intensity, while apparent relaxation rates are specifically sensitive to Ab fragmentation. Simultaneously, relaxation-filtered spectra reveal the presence and degradation of small molecule components such as excipients, as well as changes in general solution properties, such as pH. 1H NMR spectroscopy can thus provide a holistic overview of biopharmaceutical formulation content and stability, providing a preliminary characterization of degradation and acting as a triaging step to guide further analytical techniques.

Application of ER Stress Biomarkers to Predict Formulated Monoclonal Antibody Stability.

For a therapeutic monoclonal antibody (mAb) to reach the clinic, the molecule must be produced at an appropriate yield and quality, then formulated to maintain efficacy and stability. The formation of subvisible particles (SVPs) can impact product stability and is monitored during formulation development; however, the potential of a mAb to form such species can be influenced throughout the whole bioprocess. The levels of intracellular endoplasmic reticulum (ER) stress perceived by Chinese hamster ovary (CHO) cell lines, the day of mAb harvest, and the relationship with subsequent product stability of two mAbs (denoted A and B), as determined by the SVP content after accelerated stability studies, are reported here. Here, it is shown that the propensity of mAb A to form SVPs can be predicted by transcript expression of biomarkers of cellular ER stress, heavy/light-chain transcript and polypeptide amounts, and harvest day. Further, mAb A material harvested on day 9 of culture was more stable, in terms of SVP formation, than material harvested on day 13. These data suggest that ER stress perceived by CHO cells can reflect the stability of a mAb, and that biomarkers of such stress could help define culture harvest time as a tool to control SVP formation in formulated mAbs.