Novel spiking methods developed for anion exchange chromatography operating in a continuous process.

Many manufacturers of biopharmaceuticals are moving from batch to continuous processing. While this approach offers advantages over batch processing, demonstration of viral clearance for continuous processes is challenging. Fluctuating output from a continuous process chromatography column results in a nonhomogeneous load for the subsequent column and must be considered when designing viral clearance studies. One approach to clearance studies is to downscale the connected unit operations and introduce virus by in-line spiking. This is challenging to be implemented at the contract research organization performing the clearance study given the complexity of systems and level of expertise required. Alternately, each unit operation could be evaluated in traditional batch mode but the spiking and loading conditions be modified to mimic the variance introduced by the transition between two connected columns. Using a standard chromatography system, we evaluated a flow-through anion exchange chromatography step in a monoclonal antibody (mAb) manufacturing process using five different methods to introduce the virus to the column. Our data show that whether the virus or the mAbs were introduced in concentrated peaks, or as a homogeneous batch, the clearance of mouse minute virus was similar. This study introduces an alternative way to evaluate viral clearance in a continuous process and demonstrates the robustness of anion exchange chromatography unit operating in continuous processing.

A consensus rating method for small virus-retentive filters. I. Method development.

Virus filters are membrane-based devices that remove large viruses (e.g., retroviruses) and/or small viruses (e.g., parvoviruses) from products by a size exclusion mechanism. In 2002, the Parenteral Drug Association (PDA) organized the PDA Virus Filter Task Force to develop a common nomenclature and a standardized test method for classifying and identifying viral-retentive filters. One goal of the task force was to develop a test method for small virus-retentive filters. Because small virus-retentive filters present unique technical challenges, the test method development process was guided by laboratory studies to determine critical variables such as choice of bacteriophage challenge, choice of model protein, filtration operating parameters, target log10 reduction value, and filtration endpoint definition. Based on filtration, DLS, electrospray differential mobility analysis, and polymerase chain reaction studies, a final rating based on retention of bacteriophage PP7 was chosen by the PDA Virus Filter Task Force. The detailed final consensus filter method was published in the 2008 update of PDA Technical Report 41. Virus Filtration.

A consensus rating method for small virus-retentive filters. II. Method evaluation.

Virus filters are membrane-based devices that remove large viruses (e.g., retroviruses) and/or small viruses (e.g., parvoviruses) from products by a size exclusion mechanism. In 2002, the Parenteral Drug Association (PDA) organized the PDA Virus Filter Task Force to develop a common nomenclature and a standardized test method for classifying and identifying viral-retentive filters. A test method based on bacteriophage PP7 retention was chosen based on developmental studies. The detailed final consensus filter method is published in the 2008 update of PDA Technical Report 41: Virus Filtration. Here, we evaluate the method and find it to be acceptable for testing scaled-down models of small virus-retentive filters from four manufacturers. Three consecutive lots of five filter types were tested (Pegasus SV4, Viresolve NFP, Planova 20N and 15N, Virosart CPV). Each passed the criteria specified in the test method (i.e., >4 log10 PP7 retention, >90% intravenous immunoglobulin passage, and passing integrity/installation testing) and was classified as PP7-LRV4.