New strategies to improve adoptive cell therapy (ACT) protocols are now emerging to enhance in vivo persistence of adoptively transferred tumor epitope specific T cells and overcome tumor-induced immunosuppression. Our preliminary data suggests that there is a direct correlation between the long-lived central memory T cells (Tcm) and its anti-oxidant capacity. Overexpression of thioredoxin-1 (Trx), a key molecule that regulates cell-surface thiols (c-SH), resulted in increased Tcm phenotype in T cells obtained from TCR transgenic mouse crossbred with Trx transgenic mouse, or engineering human T cells with retroviral vector with TCR and Trx together. Further, a quantification of the metabolites within Pmel vs. Pmel-Trx cells showed that metabolites from pentose-phosphate pathway (PPP) and tricarboxylic acid cycle (TCA) intermediate alpha-ketoglutarate (?-KG) were significantly higher in Pmel-Trx T cells as compared to Pmel cells. While reductive intermediates generated by PPP are important to overcome oxidative stress, recent reports have shown that ?-KG is important in extending the cellular lifespan and regulating pluripotency of stem cells. These preliminary observations lead us to hypothesize that ?the presence of Trx drives tumor reactive T cells to a c-SHhi phenotype, which not only exhibits enhanced anti-oxidant phenotype, but regulates a combination of events including post-translational modifications, and epigenetic stability that lead to metabolically fit anti-tumor T cells?. We propose the following specific aims: 1) To determine how the level of thiol/thioredoxin on the surface of T cells regulates the generation of tumor reactive Tcm/Tscm cells in vivo, 2) To determine how changes in the metabolic pathways and metabolites in T cells regulate the generation of tumor reactive Tcm/Tscm in vivo, 3) To determine if modulation of reduced thiols and/or metabolites results in generation of tumor reactive TCR transduced human T cells with functional memory phenotype. We believe that our studies are innovative and will uncover important aspects that need to be considered when generating tumor specific Tcm/Tscm cells for ACT.
Adoptive T cell immunotherapy studies predominantly comprise of terminally differentiated T cells with effector memory (Tem) phenotype, which have a limited life span. We believe higher expression of thioredoxin and thioredoxin regulated thiols is key to the central memory (Tcm) phenotype, which has been associated with better tumor control. This proposal will comprehensively establish thioredoxin regulated thiols and antioxidant capacity as biomarker for identifying T cells that persist longer in vivo and will also emphasize that `anti-oxidant help' is central in generation of robust anti-tumor memory T cell response - which is of immediate translational significance.
