New GMP-Grade, Xeno-Component Free Medium for the Activation and Expansion of T Cells

Abstract 4316

Therapeutic applications of T cells in immunotherapy have recently gained momentum with the promising results in adoptive transfer of antigen-specific T cells for infectious complications after allogeneic stem cell or solid organ transplantation or for immunotherapy of malignant diseases. Activation and expansion of these cells for clinical application under controlled conditions require GMP-grade reagents including appropriate antibodies, cytokines and media. For standardized, reproducible cell cultivation and ex vivo differentiation procedures, a new serum and xeno-component free, GMP-grade medium for clinical use has been developed: High lot-to-lot consistency has been achieved by eliminating protein components not relevant for T cell expansion leaving human serum albumin as the only protein component.

The expansion of T cells in this medium upon polyclonal activation using biotinylated antibodies against CD2, CD3 and CD28 loaded on anti-Biotin coated beads resulted in expansion rates similar to other commercially available serum-free media. Using soluble antibodies against CD3 and CD28, more than 30%-higher expansion rates of viable and functional T cells after 6 days of expansion have been achieved with the new xeno-component free medium compared with other serum-fee media. Transferring the same protocol to a high density cell culture system such as a gas permeable rapid expansion device, high densities of T cells with more than 1.5×10⁷ cells/ mL were reached.

The generation of antigen-specific T cells using the Cytokine Capture System (IFN-gamma) and the serum and xeno-component free T cell medium showed similar results regarding purity, recovery and background stimulation compared to the use of a standard basal medium supplemented with 10% human AB serum. For the automation of such complex procedures, a new cell processing device was developed. All steps for the antigen-specific T cell processing, i.e. antigen-specific re-stimulation, magnetic enrichment, and in vitro expansion with this T cell medium are performed in this fully automated device, in a closed system under sterile conditions.

In conclusion, the newly developed GMP-grade, serum and xeno-component free T cell medium demonstrated high lot-to-lot consistency and was superior in its performance to other commercially available serum-free media in high density cell culture systems. The new medium can be used to replace human AB serum supplementation for the clinical manufacturing of T cells resulting in easier handling and higher consistency.