TOX2 coordinates with TET2 to positively regulate central memory differentiation in human CAR T cells

Area of Science:

• Immunology
• Cancer Biology
• Cellular Therapy

Background:

• Chimeric antigen receptor (CAR) T cell therapy shows promise for hematological malignancies but is hampered by T cell exhaustion (T_EX).
• T cell exhaustion occurs at the expense of central memory T cells (T_CM), which are vital for sustained anti-tumor responses.
• T_EX is linked to epigenetic regulators, including TET2, which influences T cell differentiation and function.

Purpose of the Study:

• To investigate the role of TET2 and its downstream targets, TOX and TOX2, in CAR T cell exhaustion and central memory differentiation.
• To explore the potential of modulating TET2, TOX, or TOX2 expression to enhance CAR T cell therapy efficacy.

Main Methods:

• Analysis of TET2 gene reduction in a leukemia patient achieving complete remission.
• Assessment of chromatin accessibility and gene expression of TOX and TOX2 following TET2 loss.
• Experimental manipulation (knockdown) of TOX and TOX2 in T cells to evaluate effects on T_CM differentiation and proliferation.
• Analysis of T_CM gene signatures and TOX2 binding to gene promoters.

Main Results:

• Reduction of TET2 correlated with increased T_CM differentiation in a patient case.
• Loss of TET2 increased chromatin accessibility and expression of TOX2, an exhaustion regulator.
• Knockdown of TOX increased T_CM percentage, while knockdown of TOX2 unexpectedly decreased T_CM percentage and proliferation.
• TOX2 was found to bind to promoters of T_CM genes, suggesting a role in their regulation.

Conclusions:

• Human TOX2, distinct from the exhaustion regulator TOX, acts as a potentiator of CAR T cell central memory differentiation.
• Modulating TOX2 expression may offer a therapeutic strategy to improve CAR T cell cancer therapy by enhancing T_CM populations.