At 95% yield, the solvent requirement per unit product purified for the batch process is about 3,000 L solvent per purified
product. Using the ideal recycle process, the solvent requirement can be reduced by a factor of 37 to 80 L/g. Using the MCSGP
process, even more solvent can be saved, and compared to the ideal recycling process, the solvent requirement can be reduced
by a factor of 10 to 8 L/g.
The clear superiority of the MCSGP process with respect to yield, productivity, and solvent requirement compared to the conventional
purification processes result from the principle of countercurrent operation, which strongly improves the process efficiency,
because only a partial separation of the fraction is sufficient to get high yields and purities.
The performance increase as described above by using the MCSGP process has been encountered previously for binary separations
of small molecules when the batch process has been compared to the countercurrent SMB process.8
Summary
The multicolumn countercurrent solvent gradient purification process for the purification of therapeutic proteins has been
presented and the basic principles have been explained. The practical realization in a prototype using only three chromatographic
columns has been done using commercially available chromatographic equipment. The successful application to two industrial
purification problems is discussed. The first is the purification of a MAb from a clarified cell culture supernatant without
using Protein A. Although the feed purity of the supernatant is very low, the experimental results show that the MCSGP process
operated with a preparative cation-exchange resin can obtain purities with 95% recovery comparable to a Protein A purification.
These results underline the potential of the MCSGP process to replace the Protein A purification step in the downstream processing
of MAbs. Second, the separation of three MAb variants on a commercial, preparative weak cation-exchange resin was investigated.
The use of batch chromatography for the purification of the intermediately eluting MAb variant yields only 80% purity at zero
recovery, while the MCSGP process gives 90% purity and 93% yield. This application example clearly shows that the use of continuous,
countercurrent processes such as the MCSGP process can strongly increase the separation efficiency. To evaluate the performance
gain of the MCSGP process quantitatively with respect to the conventional processes (i.e., batch chromatography and batch
chromatography with recycling), a numerical comparison using an industrial polypeptide purification problem has been performed.
This analysis shows that the MCSGP process can increase the productivity by a factor of 10 and reduce the solvent requirement
by 90%.
GUIDO STRÖHLEIN, LARS AUMANN, PhD, THOMAS MÜLLER-SPÄTH, ABHIJIT TARAFDER, PhD, and PROF. MASSIMO MORBIDELLI work at the Institute for Chemical and Bioengineering at the Swiss Federal Institute of Technology (ETH) Zurich, Switzerland,
+41 44 633 45 26, guido.stroehlein@chem.ethz.ch
References
1. Nineteenth International symposium on preparative/process chromatography, ion exchange, adsorption/desorption processes
and related separation techniques, PREP. Baltimore, USA; 2006, May 14–17.
2. 25th International symposium and exhibit on the separation of proteins, peptides and polynucleotides, ISPPP. Florida,
USA; 2005, Nov 6–9.
3. Ströhlein G, Aumann L, Mazzotti M, Morbidelli M. A continuous, countercurrent multicolumn chromatographic process incorporating
modifier gradients for ternary separations. J Chrom A, 2006; 1126(1–2):338–346.
4. Aumann L, Morbidelli M. A continuous multicolumn countercurrent solvent gradient purification process. Submitted to Biotechnology
and Bioengineering.
5. Aumann L, Morbidelli M. European Patent, EP 05405327.7, EP 05405421.8; 2005.
6. Shan Y, Seidel-Morgenstern A. Optimization of gradient elution conditions in multicomponent preparative liquid chromatography,
J Chrom A, 2005; 1093(1–2):47–58.
7. Tarafder A, Ströhlein G, Aumann L, Morbidelli M. Role of recycling in improving the performance of chromatographic solvent
gradient bioseparations. International symposium on preparative and industrial chromatography and allied techniques, SPICA.
Innsbruck, Austria; 2006, Oct 15–18.
8. Miller L, Grill C, Yan T, Dapremont O, Huthmann E, Juza M. Batch and simulated moving bed chromatographic resolution of
a pharmaceutical racemate. J Chrom A, 2003; 1006(1–2):267–280.
|
