The TET2 methylcytosine dioxygenase regulates early and late transitions in exhausted CD8+ T-cell differentiation

Epigenetic reprogramming of CAR T-cells by targeting TET2, a methylcytosine deoxygenase that mediates active DNA demethylation, has shown therapeutic potential; however, the role of TET2 in TEX development is unclear. In both CAR T-cell exhaustion models in vitro and chronic LCMV infection in vivo, TET2 drove the conversion from memory-like, self-renewing TEX progenitors towards effector (TEFF)-like and terminally differentiated TEX. TET2-deficient terminally differentiated TEX retained aspects of TEX progenitor biology, including decreased expression of the transcription factor TOX, suggesting that TET2 is required for terminal exhaustion.