Validating Flow Cytometry Assays for Cell Therapy

Flow cytometry is used in nearly every single cell therapy process, for process characterization, to monitor process parameters, and release of the final product. The assay is inherently variable due to the variety of instruments, the antibody clones, reference setting protocols, assay protocols, and the lack of consistent controls that can be implemented. Lonza Cell and Gene Therapy (CGT) operates under a site agnostic model in order to support the demand and the variety of cell therapy products of our clients. This model requires each site to operate similarly like every other site within the network, and as such, a flow assay should perform consistently, for routine and validation, from site to site. Validation of flow assays can be a difficult process. Lonza uses a phase-appropriate approach to mitigate these challenges. When designing protocols to evaluate accuracy and establishing a validated range, the live/dead population discrimination can prove challenging. Lonza examined two common cell killing methods, ethanol and commercial fixation buffers, that are suitable for flow assay live/dead determination. Each killing method offers pros and cons, depending on the type of sample validated. Lonza continues to strive for consistency and robustness to support our global manufacturing sites. Part of this is achieved through instrument alignment. Lonza has implemented the BD FACSLyric™ Flow Cytometer in CGT Quality Control (QC) laboratories. The unique capability of the BD FACSLyric™ Flow Cytometer to set target MFI as part of the template ensures consistent mean fluorescent intensity of the panel for the same sample from instrument to instrument. This allows flow assays to demonstrate high precision and reproducibility between different QC labs.