IPSC-derived anti-KIT CAR-T cell generation: functional optimization and in vivo application in a transplantable mouse gastrointestinal stromal tumor (GIST) model

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Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the gastrointestinal tract. 85-90% of GIST patients harbor activating mutations in cKIT or PDGFRA, allowing the application of tyrosine kinase inhibitors (TKI). In patients with primary or secondary TKI resistance, therapeutic options are limited. In vitro and in vivo mice data as well as preliminary patient observations imply that immunotherapeutic approaches might be successful in GIST patients, including adoptive T cell transfer using chimeric antigen receptors (CAR-T cells). However, CAR-T cell therapies are often restricted by low numbers of generated T cells, which frequently present with an unfavorable phenotype. This might be circumvented by generating CAR-T cells from inducible pluripotent stem cells (iPSCs). In previous studies, CAR-T cells originating from iPSCs possessed a phenotype resembling -T cells with diminished antitumoral activity. The aim of the present research proposal is to improve antitumoral functionality by generating CAR-T cells targeting cKIT from iPSC. The generated anti-KIT CAR-T-iPSCs will be investigated for their phenotype and metabolism, as it has been demonstrated that CAR-T cell activity strongly depends on these profiles. By variations of culture conditions, cytokines, drugs or genetic/epigenetic modifications, functionally optimized CAR-T-iPSCs will be generated. To prove their in vitro and in vivo antitumoral activity, these cells will be tested in GIST cell co-cultures and a mouse xenograft GIST model. Finally, the anti-KIT CAR-T iPSCs will be further improved by targeted knockout of HLA-antigens and the T cell receptor to reduce allorejection and graft-versus-host-disease.