Advances in the Validation of Chromatographic Processes part3

Resin Lifespan Studies

Resin lifespan studies may be more appropriately carried out concurrently, provided the analytical methods are demonstrated to be sufficiently sensitive and appropriate.¹⁰ Virus clearance by aged resins has been a topic of discussion for several years. Surrogate measurements that replace the need to evaluate virus clearance after repeated use have been proposed for some types of chromatographic steps (i.e., affinity and flow-through mode anion exchange chromatography used in MAb production).^11,12

Conformance Batches and Beyond

Figure 3

Once the process is characterized and scale up verified, 3–5 consecutive batches are run at center point to demonstrate manufacturing consistency. The validation effort does not stop here, however. The level of process understanding increases with manufacturing experience (Figure 3).

Better process understanding may lead to changes to improve process control, increase productivity or reduce costs. Often, implementing such changes is delayed due to concerns about validating changes and submitting regulatory filings. The concept of design space, defined by process development, DoE, empirical studies, and experience, and approval of that space may now enable changes to be made within that space without incurring regulatory delays (see ICH Q8).

Validation Strategy and Activities for A Cation Exchange Step

Although there is no one protocol for process validation for a chromatography step, a strategy and activity plan for validating a cation exchange step in a purification process for a MAb summarizes the key elements (Figure 4 and Table 2).

To validate this step, it is necessary to know why it was designed into the process. Most monoclonal antibodies bind to cation exchangers. This step is used to capture the MAb and remove process impurities such as host cell proteins (HCP), DNA, leached Protein A, other process impurities from cell culture and clarification steps, and product-related impurities. This cation exchange step is also used to enhance overall virus clearance.

Process-related Impurities

Based on the intended use of this cation exchange step, assays are developed and validated. A decision will be made whether to use clearance studies, routine in-process assays, or API testing for removal of HCP, DNA, and Protein A. The choice is dictated by assay sensitivity, the practicality of performing the assay, and relevance of the assay for in-process control.

Product-related Assays

Antibody titer and purity by high performance liquid chromatography (HPLC) are commonly used methods for assessing product quality. Impurities, such as aggregates and other product modifications, may also be detected by the HPLC assay. Other modes of HPLC may be used to detect glycoforms, and isoelectric focusing (IEF) might also be a useful assay.

Viral clearance

Viral clearance studies will be performed in a scaled down model, validated to represent manufacturing scale. Adherence to the ICH guideline for virus validation will be confirmed, which means prospective cation exchanger lifespan studies must be performed.¹³ In the future, it is possible that the surrogate determinations (i.e., removal of a specific impurity, height equivalent to a theoretical plate (HETP), and backpressure) might be acceptable for assessing column performance for a cation exchanger.

Before performing validation studies and conformance runs, column packing is validated. Ranges for process control parameters (e.g., flow rate, load, pH, conductivity) will be established in characterization studies. Engineering runs will be performed at production scale. Before confirming scale up, it will be necessary to determine if any modifications resulting from scale changes might alter the process control parameters or product critical quality attributes.

Column storage will be validated by evaluating packing integrity (e.g., frontal analysis, removal of storage agents, any residues removed by the cleaning effect of storage, and control over bioburden.

Column cleaning will be validated by a combination of small-scale prospective studies and concurrent in-process analysis at manufacturing scale.

Summary

Experience over the last decade in developing and producing biotherapeutics has enabled the development of a structured approach to process validation that begins in development and continues throughout the lifetime of the product. Although process analytical technologies continue to be discussed as a means for achieving better quality and process control, the need for process validation does not appear to be going away. Improvements in analytical methods have improved our understanding of downstream intermediates and final purified products. These analytical tools enhance the value of process validation. Improvements in process validation approaches have resulted in better process understanding that enables better control over variability—the intent of process validation. The use of enhanced analysis and feedback control, process development, statistical analysis, and characterization studies to establish robust processes have led to the ability to define a space in which the process delivers the critical quality attributes.

Acknowledgements

The Polymerase Chain Reaction (PCR) is covered by patents owned by Roche Molecular Systems and F. Hoffman-LaRoche. A license to use the PCR process for certain research and development activities accompanies the purchase of certain reagents from licensed suppliers.

Gustav Rodrigo and Maria Murby, GE Healthcare Life Sciences R&D, Uppsala, Sweden, are gratefully acknowledged for providing the data from the DoE study on Capto S.

All illustrations are reproduced with the permission of GE Healthcare Bio-Sciences AB, a General Electric Company, Bjorkgatan, Uppsala, Sweden.

Gail Sofer is director of regulatory compliance at the life sciences business unit of GE Healthcare, and a member of BioPharm International’s Editorial Advisory Board, 732.457.8000, gail.sofer@ge.com.
Mattias Ahnfelt is senior research engineer and black belt in Six Sigma at the life sciences business unit of GE Healthcare, +46 18 612 1990, mattias.ahnfelt@ge.com.

References

1. International Conference on Harmonization. Q8, pharmaceutical development. Geneva, Switzerland; 2005.

2. International Conference on Harmonization. Q9, quality risk management. Geneva, Switzerland; 2005.

3. Seely JE, Seely RJ. A rational, step wise approach to process characterization. BioPharm Int. 2003;16(8): 24–34.

4. Murtagh J. Development of a bio-derived drug. Contract pharma. 2006;8(3):70–75.

5. Mollah AH. Application of FMEA for process risk assessment. 2005;3(10):12–22.

6. Brorson K, et al. Impact of cell culture process changes on endogenous retroviral expression. Biotechnol. bioeng. 2002;80(3):257–67.

7. Application Note 28-4078-17 AA, Capto S cation exchanger for post-protein A purification of monoclonal antibodies. Chalfont St. Giles, UK; 2006.

8. US Food and Drug Administration. Guidance for industry. General principles of process validation. Rockville, MD; May 2006.

9. Rathore A. Efficiency measurements for chromatography columns. BioPharm Int. 2005;18(8):58–64.

10. US Food and Drug Administration. Therapeutic compliance guide. 7341.001.

11. Norling L, et al. Impact of multiple re-use of anion-exchange chromatography media on virus removal. J Chrom A. 2005;1069(1):79–89.

12. Brorson K, et al. Identification of protein A media performance attributes that can be monitored as surrogates for retrovirus clearance during extended re-use. J Chrom A. 2003;989(1):153–163.

13. International Conference on Harmonization. Q 5A, viral safety evaluation of biotechnology products derived from cell lines of human or animal origin. Geneva, Switzerland; 1997.