Cell Line Characterization

What is cell line characterization and why is it important?

According to regulatory guidance, all cells used directly as a therapy or within the manufacturing process of a biopharmaceutical must be sufficiently tested to confirm:

• 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 does 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 characterization packages use a range of in vitro and in vivo cell assays and other molecular assays for contamination detection. Cell line stability testing can use a mix of Sanger sequencing, PCR, and cytological methods such as FISH. A full biopharmaceutical characterization package can typically take anywhere between 3 to 6 months.

NGS-based approaches to cell line characterization developed and validated by PathoQuest offer several advantages, especially where traditional testing proves challenging. NGS can provide results much faster and is a viable alternative if there is a compatibility issue with the traditional approach (e.g., a lack of neutralizing antibody or available sample volume). NGS also offers a higher level of information, particularly in cell sequencing to characterize genetic modifications or insertions of sequences into the cell line.

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