Rapid and Reliable: Ensuring Quality Through Release Testing

In cell and gene therapy, every hour matters. The ability to test, qualify, and release a product quickly can directly impact a patient’s access to treatment. At C3i, release testing is designed to deliver fast, reliable results without compromising scientific or regulatory rigour.

C3i’s Quality Control (QC) laboratory oversees every step of product testing, from cellular characterization to sterility and potency. Each assay is validated to ensure it produces trustworthy data while meeting strict compliance standards under Good Manufacturing Practice (GMP) guidelines.

Flow cytometry plays a key role in defining the cellular composition of each cell therapy product. Using validated templates and 21 CFR Part 11–compliant software, the C3i QC team characterizes T cells, NK cells, B cells, monocytes, and CD34+ stem cells. These analyses confirm the purity and identity of each lot while detecting potential contamination. The same data also verify the expression of specific receptors such as CAR-T constructs, ensuring functional precision before infusion.

Potency testing complements cellular analysis by confirming that the therapy performs as intended. Through ELISA and ELISpot assays, the team evaluates cytokine release, proliferation, and cytotoxic activity, indicators of the product’s therapeutic potential. To maintain rapid turnaround, tests are often run in parallel and supported by electronic systems that enable real-time data review.

Sterility testing is equally critical. Rapid detection systems, such as the BacT/ALERT 3D and Endosafe Nexgen-PTS, are validated for use with cellular matrices, reducing testing time from 14 days to just 7 days for microbial detection and to under an hour for endotoxin results (project-specific). Each platform operates under electronic data integrity controls, ensuring compliance from sample to signature.

At C3i, release testing is more than a regulatory checkpoint; it’s an integrated, high-speed process that bridges manufacturing and patient care. By combining advanced technologies, validated methods, and a culture of precision, the QC team ensures that each product is ready for safe delivery when patients need it most.

This article is drawn from material presented during the webinar “Cellular Therapy Product Release Testing within a GMP context“, presented on October 16th 2025, by C3i’s experts Ann Brasey (Principal Scientist), Pauline Cassart (QC Technical Supervisor), and Ludovic Durrieu (QC Operations Manager).