Sorbitol crystallization-induced aggregation in frozen mAb formulations.

Area of Science:

• Biopharmaceutical formulation
• Protein aggregation studies
• Crystallization kinetics

Background:

• Monoclonal antibodies (mAbs) are crucial biotherapeutics.
• Maintaining mAb stability in frozen formulations is challenging.
• Sorbitol crystallization can induce protein aggregation, compromising efficacy.

Purpose of the Study:

• To investigate the impact of sorbitol crystallization on mAb aggregation in frozen states.
• To evaluate the influence of formulation variables (protein concentration, pH) on this aggregation.
• To understand the role of molecular mobility in sorbitol crystallization.

Main Methods:

• Monoclonal antibody (IgG1, IgG2) formulations were studied across a concentration range (0.1-120 mg/mL).
• Protein aggregation was quantified using size-exclusion HPLC (SE-HPLC) and capillary-electrophoresis SDS.
• Sorbitol crystallization was monitored via subambient differential scanning calorimetry and X-ray diffraction.
• Molecular mobility was assessed through glass transition temperature (Tg') and fragility index measurements.

Main Results:

• mAb aggregation induced by sorbitol crystallization was inversely related to protein concentration and pH.
• High protein concentrations suppressed sorbitol crystallization and minimized aggregation, suggesting mAb self-stabilization.
• Increased protein concentration led to higher Tg' and a decreased fragility index, hindering sorbitol crystallization.

Conclusions:

• Formulation strategies involving high protein concentrations and pH can mitigate sorbitol crystallization-induced mAb aggregation.
• mAb self-stabilization plays a key role in preventing aggregation at elevated concentrations.
• Understanding molecular mobility is critical for controlling crystallization and ensuring biopharmaceutical stability.