Abstract Text: Modified T-cells are currently being rapidly developed for use as immunotherapies, with chimeric antigen receptor (CAR) T-cells currently being used to treat patients with B-cell malignancies, via CD19 targeting. However, despite their success CAR T-cells are limited by their exclusive recognition of proteins present on the cell surface. One way to expand the range of target antigens is to utilise T-cell receptor (TCR) mediated recognition. The TCR interacts with peptides presented by MHC molecules allowing the recognition of intracellular as well as cell surface proteins. For efficient expression in T cells, the TCRα/β chains form a complex with four CD3 chains, one of these being CD3ζ which is key in promoting signalling after TCR binding. Here we explore whether modifications to the CD3ζ chain can enhance TCR signalling and T cell function. These modifications include the addition of the co-stimulatory domains CD28 or 4-1BB, at the membrane proximal or the membrane distal position of the intracellular tail of CD3ζ. Our preliminary results show that the CD28 can improve TCR signalling and enhance T cell effector function. We will present a detailed analysis of how CD28 and 4-1BB signalling domains incorporated into two different positions of the CD3ζ chain affect TCR stimulation and T cell effector function. The modification of the CD3ζ chain provides an opportunity to improve TCR gene therapy by incorporating the conventional TCR signal 1 and co-stimulatory signal 2 in one molecular complex.
