Chimeric Antigen Receptor T Cell Research For Clinical Applications

Abstract

Genetically engineered T cells are a promising therapeutic tool for the treatment of cancer or infectious diseases. The generation of potent chimeric antigen receptor (CAR) T cells for clinical use, however, is associated with a plurality of challenges covering medical, economical as well as scientific aspects. Therefore, the present study focusses on specific medical and technical difficulties limiting the dissemination of adoptive cellular therapies (ACT). Furthermore, strategies aiming to improve the potential of CAR modified T cells, especially in a solid tumor setting, were investigated. To this effect, our work initially focused on the generation of a novel CD20-directed CAR which we evaluated in newly established in vitro and in vivo assays. After confirming the potency of the anti-CD20 CAR T cells, we focused on the manufacturing and consequently demonstrated that a current good manufacturing practice (cGMP)-compliant, automated T cell Transduction (TCT) Process is both reliable and applicable to manufacture CAR T cells in a clinically relevant scale and quality. Despite varying starting material, different operators or the use of other devices, the developed manufacturing process yielded a robust formulated product with regard to cellular composition, T cell phenotype or anti-tumor potency. Overall, the high reproducibility of the TCT Process proved the suitability to manufacture CD20-directed CAR T cells which are intended to be used in two clinical trials. In addition, this work focused on strategies to enhance the CAR-based immune response in a melanoma model by co-expressing a CAR and a chimeric co-stimulatory receptor (CCR) in the same T cell. This two-receptor approach includes a second generation CAR specific for chondroitin sulfate proteoglycan 4 (CSPG4) and a CCR that recognizes CD20. Here we show that, dependent on intracellular CCR design, only a simultaneous activation of both co-expressed chimeric receptors CAR as well as CCR resulted in a significantly enhanced immune response. Altogether, this data supports the idea of using an anti-CD20 CCR as a tool to increase the potential of CAR T cells.