What we do is work with a specific vendor, and order as much reagent as possible from a lot that we have precertified and know will work appropriately with our cell line. We then put tests in place to assess new batches as they are produced. Having control charts and mapping out the responses of cells as you are culturing them helps improve and maintain consistency.
Cardinal Health's Wise-Blackman Shares Tips On Cell-Based Assays In GxP Environment
In her role as senior manager of cellular technologies at Cardinal Health's Research Triangle Park, NC, site, Gwendolyn Wise-Blackman develops, optimizes, and validates cell-based assays for the global healthcare company's Pharmaceutical Technologies and Services group.
The PTS group, a contract manufacturing and service provider for pharmaceutical customers, is in the process of being sold to the Blackstone Group, but the sale is not expected to impact its current activities (see related story, this issue).
Wise-Blackman's team has developed a series of process controls to help ensure the optimum performance of cell-based assays in a regulated environment, and she recently shared her expertise in the area in an online seminar hosted by Compliance Online, a web portal dedicated to FDA compliance.
Cell-Based Assay News spoke with Wise-Blackman about the company’s use of cell-based assays for lot release and stability projects in a GxP environment. She also described how implementing process controls can increase the performance of cell-based assays.
Why and how is Cardinal Health using cell-based assays?
The majority of our clients have large molecules that form the basis for their drug product. These are usually either monoclonal antibodies or some kind of protein.
What we traditionally do for our customers are viral clearance, contamination assessment, and potency bioassays. My group specifically does the potency bioassays.
Is this unique?
Yes, because in academic environments and early drug discovery you do not have to follow [US Food and Drug Administration] regulations. Our work has to be done according to the federal regulations for [good manufacturing practices] and [good lab practices].
What technologies do you use for cell-based assays?
We use a variety of technologies. It depends on what the product is supposed to do to an established cell line. With some of our assays, we are looking for growth induction, so we may measure that with a fluorescent dye, for example.
For other assays, we may add a labeled antibody to a material that we expect to be expressed in the cells, and we’ll use a fluorescence microscope to quantify that.
We’ll also do assays where we start the process with a cell-based assay using cells that have been treated with the reagent we are testing, and then we’ll finish with an ELISA. So we actually get the data from an ELISA.
How much testing does Cardinal Health do using cell-based assays compared to biochemical screening?
Our group does not do any biochemical screening. If you are talking about things like HPLC and mass spec, those can be done by our sister group, which is located across the street. Our San Diego facility can do additional assays such as protein mapping and amino acid analysis.
Virtually anything that is required to test a large molecule prior to submission to the FDA can be done at our Research Triangle Park or our San Diego facility.
What do you view as the biggest limitation in cell-based assays now and what are you doing to overcome those limitations?
The biggest limitation is having consistency in the cell prep because the cells tend be variable in their response, depending on where they are in their growth cycle and at what stage you are using them in your testing.
One of the things we do when we are initiating a project is to determine the useful passage range — the usable range from when we take the cells out of liquid nitrogen to when, based on the data, they can no longer be used for this particular assay. We back that up by a few weeks to make sure we stay within the acceptable range.
We occasionally have problems with cells not wanting to grow, so we have to change a particular batch of a critical reagent from an outside vendor.
Some of the material you cannot store long-term, so you have to buy it when it is available. You can have issues with its being consistent necessarily for your cell lines from lot to lot. This inconsistency can mean you have variability in your assay.