Response of a concentrated monoclonal antibody formulation to high shear.

There is concern that shear could cause protein unfolding or aggregation during commercial biopharmaceutical production. In this work we exposed two concentrated immunoglobulin-G1 (IgG1) monoclonal antibody (mAb, at >100 mg/mL) formulations to shear rates between 20,000 and 250,000 s(-1) for between 5 min and 30 ms using a parallel-plate and capillary rheometer, respectively. The maximum shear and force exposures were far in excess of those expected during normal processing operations (20,000 s(-1) and 0.06 pN, respectively). We used multiple characterization techniques to determine if there was any detectable aggregation. We found that shear alone did not cause aggregation, but that prolonged exposure to shear in the stainless steel parallel-plate rheometer caused a very minor reversible aggregation (<0.3%). Additionally, shear did not alter aggregate populations in formulations containing 17% preformed heat-induced aggregates of a mAb. We calculate that the forces applied to a protein by production shear exposures (<0.06 pN) are small when compared with the 140 pN force expected at the air-water interface or the 20-150 pN forces required to mechanically unfold proteins described in the atomic force microscope (AFM) literature. Therefore, we suggest that in many cases, air-bubble entrainment, adsorption to solid surfaces (with possible shear synergy), contamination by particulates, or pump cavitation stresses could be much more important causes of aggregation than shear exposure during production.

High concentration formulation feasibility of human immunoglubulin G for subcutaneous administration.

The delivery of monoclonal antibodies (mAbs) as subcutaneous (sc) injections hinges on the high dose requirement of these usually low potency molecules. This necessitates their formulation as high concentration solutions or suspensions, which presents a formidable formulation challenge due to the concentration-driven protein aggregation and high solution viscosity generated at these conditions. The objective of this study was to evaluate the feasibility of spray-drying in preparing stable, high concentration formulations of mAbs. A model polyclonal antibody, human immunoglobulin G (IgG) was formulated as dry powder using Nektar's glass stabilization technology. Formulation in sugar glasses stabilized IgG during spray-drying and maintained the protein's secondary structure. Further, in contrast to the bulk material, the glass-stabilized powders successfully reconstituted at 200 mg/mL IgG without loss of the protein monomer. Spectroscopic analysis confirmed that upon high concentration reconstitution, spray-dried glass-stabilized IgG retained both its secondary and tertiary structure. Further, the spray-dried powder reconstituted within a few minutes yielding clear, low viscosity solutions that syringed easily through narrow (28 G) needles. The results of this study suggest that formulation in spray-dried, glass-stabilized powders may enable the development of products suitable for sc administration of mAbs and other low potency protein therapeutics.