Cell Line Characterization

What is cell line characterization and why is it important?

• Identity testing confirms the cell is as described in the submission
• Purity testing ensures that the cell does not contain any adventitious microbial or viral contaminants. It also determines if there is any contamination from other cell lines.
• Stability testing generally focuses on the genetic stability of the cell line and ensures that the cells act in the proposed manner across the expected lifetime.

Mammalian cells used for biologic production must be tested for these three categories across a simulated lifetime for the Master and Working Cell Banks (MCB/WCB), as well as the cells at the end of a production run. This ensures that any endogenous or occulted contaminating virus do not emerge unexpectedly. Genetic stability testing across this lifetime also provides assurance that the quality and yield of the biopharmaceutical product can be maintained by the manufacturer.

Classical cell line testing packages use a range of in vitro and in vivo cultivation assays as well as a number of other molecular assays for the detection of any contamination. Genetic stability can use a mix of Sanger sequencing, PCR and cytological methods such as FISH. A full characterization package can typically take anywhere between 3 to 6 months.

NGS based approaches to cell line characterization developed and validated by PathoQuest can provide a number of advantages to developers, especially where traditional testing proves to be challenging. NGS can provide results much faster than traditional approaches and can provide a viable alternative if there is a compatibility issue with the traditional approach (for example a lack of neutralizing antibody or available sample volume). NGS can also provide a higher level of information, especially when it comes to characterizing any genetic modifications or insertions of sequences into the cell line.

Finally, using an NGS testing strategy can provide a rapid way to screen to identify favorable candidates during the cell line selection process.