Eomes+T-betlow CD8+ T cells are functionally impaired and are associated with poor clinical outcome in patients with acute myeloid leukemia (AML)

Acute myeloid leukemia (AML) is a devastating blood cancer with poor prognosis. Immunotherapy targeting inhibitory pathways to unleash the anti-leukemia T cell response is a promising strategy for the treatment of leukemia, but we must first understand the underlying molecular mechanisms. Eomesodermin (Eomes) and T-bet are both T-box transcription factors that regulate CD8+ T cell responses in a context-specific manner. Here we examined the role of these transcription factors in CD8+ T cell immunity in AML patients. We report that the frequency of Eomes+T-betlow CD8+ T cells increased in newly diagnosed AML. This cell subset produced less cytokines and displayed reduced killing capacity, whereas depletion of Eomes by siRNA reversed these functional defects. Furthermore, Eomes bound the promoter of T cell immunoglobulin and ITIM domain (TIGIT) and positively regulated the expression of this inhibitory receptor on patient-derived T cells. A high frequency of Eomes+T-betlow CD8+ T cells was associated with poor response to induction chemotherapy and shorter overall survival in AML patients. These findings have significant clinical implications as they not only identify a predictive and prognostic biomarker for AML, but they also provide an important target for effective leukemia therapeutics.

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