Paper Number
BM14 

Session
Biological Macromolecules: Proteins, Cellulosic Biomass and other Biomaterials

Title
Deciphering the thermodynamic underpinnings of increased solution viscosity in crowded monoclonal antibody solutions

Presentation Date and Time
October 12, 2015 (Monday) 5:15

Track / Room
Track 4 / Constellation F

Authors (Click on name to view author profile)

1. Keeling, Rose (The University of Manchester, Chemical Engineering & Analytical Science)
2. Ke, Peng (MedImmune, Formulation Sciences)
3. Curtis, Robin (the University of Manchester, School of Chemical Engineering and Analytical Science)
4. Sarangapani, Prasad S. (MedImmune)
5. Ekizoglou, Sofia (MedImmune)
6. Jones, Ronald L. (National Institute of Standards and Technology, Materials Science and Engineering)
7. Uddin, Shahid (MedImmune, Formulation Sciences)
8. van der Walle, Christopher F. (MedImmune, Formulation Sciences)
9. Pathak, Jai (Medimmune, Formulation Sciences Department)

Author and Affiliation Lines (in printed abstract book)
Rose Keeling¹, Peng Ke², Robin Curtis¹, Prasad S. Sarangapani³, Sofia Ekizoglou², Ronald L. Jones⁴, Shahid Uddin², Christopher F. van der Walle², and Jai Pathak^3
1Chemical Engineering & Analytical Science, The University of Manchester, Manchester, United Kingdom; ²Formulation Sciences, MedImmune, Cambridge, United Kingdom; ³Formulation Sciences Department, Medimmune, Gaithersburg, MD 20878; ⁴Materials Science and Engineering, National Institute of Standards and Technology, Gaithersburg, MD

Speaker / Presenter 
Keeling, Rose

Text of Abstract
Therapeutic protein formulation development could benefit from sound approaches for predicting concentrated solution properties from dilute solution data. Recent studies have suggested a link between dilute and concentrated solution behavior, although notable exceptions exist. We have carried out a detailed investigation of a monoclonal antibody solution using a combination of temperature-resolved dynamic and static light scattering (DLS/SLS), small angle neutron scattering (SANS), and rheological measurements spanning a protein concentration range between 1 g/L and 200 g/L. The systematic measurements have been made on a model IgG1 antibody under seven different solvent conditions (pH and ionic strength) chosen to tune non-specific protein-protein interactions from highly repulsive to strongly attractive. We have identified three solution conditions in D2O, used in SANS to achieve contrast between the macromolecule and the solvent, with similar strength of attractive protein-protein interactions, quantified by the DLS interaction parameter kD and the zero wavevector structure factor S(q) from SANS. These buffer conditions are 25 mM ionic strength in Tris buffer at pH 9, which is close to the protein iso-electric point, citrate buffer at pH 6.5 and an ionic strength of 25 mM, and at a high ionic strength of 275 mM in pH 5 acetate buffer with added chaotropic thiocyanate (SCN-) anions. We expect the range and anisotropy of the protein-protein interaction potential to vary across these conditions. Unlike the similar dilute solution behaviour in each buffer, the thermodynamic properties of the concentrated solutions are markedly different. High ionic strength solutions containing SCN- ion phase separate at a higher temperature due to weaker protein-protein attraction between 50 and 100 g/L. The solutions at low ionic strength are much more viscous than the one with SCN- anions at pH 5.0, suggesting that tuning the range and strength of the interaction potential may affect solution viscosity.