Adoptive cell therapy using T cell receptors equipped with ICOS yields durable anti-tumor response

Treatment with adoptively transferred T cells is challenged by limited longevity of therapeutic cells within tumors. To enhance the durability of anti-tumor T cell products, we have created T cell receptors (TCRs) with built-in co-stimulatory molecules. We observed that TCRs coupled to ICOS mediated exceptionally long-term responses including delay of tumor recurrence and cures in a mouse tumor model. TCR:ICOS T cells showed enhanced and antigen-specific production of inflammatory cytokines and resistance to exhaustion. Genetic ablation of ICOS-mediated activation of the PI3K-NFκB pathway neutralized the long-term anti-tumor effects. To translate TCR:ICOS to human T cells, we identified a single amino acid change in the cytosolic tail which was necessary for functional surface expression. Notably, the optimized receptor sustained performance of human T cells upon repeated stimulation across multiple antigen specificities. Collectively, we present a novel and uniformly applicable TCR:ICOS format that supports fitter T cell products for adoptive cell therapy.