Features of scFvs that influence tonic signaling of CAR T cells

CAR T cell therapy is a breakthrough in cellular therapy for the treatment of cancer. For this therapy, the patient´s T cells are equipped with a chimeric antigen receptor (CAR) that has an exrtacellular binding domain to bind to target antigens on the surface of tumor cells and subsequently lyse them. These binding domains are typically single chain variable fragments (scFvs) derived from an antibody engineered against the tumor antigen. However, despite tremendous success of this therapy the field currently faces some challenges, mainly the exhaustion of CAR T cells which leads to poor persistence and therapy failure. One reason for this phenomenon is the constant activation of T cells which is known as tonic signaling. However, despite the importance of this topic it is poorly understood how tonic signaling is initiated. There is no assay available to screen scFvs at an early timepoint of development to assess which proteins are suitable and safe for the use in CAR T cells.- In this project, we propose to assess which biochemical features determine the likelihood of an scFv to induce tonic signaling. With this, we aim to identify high throughout assays that can be used for screening purposes in the future.