Abnormal metabolic activation of CD8+ t cells correlates with poor prognosis in acute myeloid leukemia Free

While conferring a superior graft-versus-leukemia (GVL) effect and achieving comparable outcomes to HLA-matched sibling donor transplantation (MSDT), the immune mechanisms underlying haploidentical stem cell transplantation (haplo-HSCT) in acute myeloid leukemia (AML) remain poorly understood. Furthermore, the impact of the AML tumor microenvironment (TME) on T cells, particularly within secondary lymphoid organs, warrants deeper investigation. To address this, we utilized a non-irradiated, AML-ETO-driven mouse model to systematically analyze T-cell dynamics in different MHC contexts, combining dynamic flow cytometry with transcriptomic analysis.

Beyond a significantly shorter survival, our flow cytometry results revealed that although at an early disease stage with identical peripheral blood tumor burden (1%-5% GFP⁺ AML-ETO leukemic cells), the MHC-matched leukemia (ML, aggressive progression) group showed profound alterations in the splenic immune microenvironment compared to the haplomatched leukemia (HL, indolent progression) group, including significant changes in CD4/8⁺ T-cell and NK-cell proportions. To dissect these changes, CD4⁺ and CD8⁺ T cells were sorted from the peripheral blood (PB) and spleen (SP) of ML, HL, and their respective healthy control (MC, HC) groups for RNA-sequencing (RNA-seq).

In the HL group, CD8⁺ T cells retained a robust cytotoxic and cytokine activation profile similar to healthy controls, consistent with effective GVL. In contrast, CD8⁺ T cells from the ML group exhibited a dramatic and unexpected metabolic hyperactivation, with oxidative phosphorylation (OXPHOS) emerging as the most significantly enriched pathway across both PB and SP. Further multi-dimensional comparisons—contrasting the ML group with its late-stage counterpart and with the HL group—confirmed that this aberrant metabolic state is a specific feature of early-stage aggressive AML. Critically, this metabolic activation did not lead to a corresponding enhancement in anti-tumor effector functions. Instead, it was associated with a significant upregulation of exhaustion-related markers in CD8⁺ T cells, indicating that excessive metabolic activation drives T-cell exhaustion. This represents a key reason for the rapid disease progression and shorter survival observed in the ML group.

Based on the enriched metabolic pathways, we summarized the activated metabolic pathways and established a metabolism-associated genes (MAGs) scoring system. We then validated its efficacy for risk stratification and prognosis prediction in multiple dimensions using public bulk (TCGA) and single-cell (GSE223844) RNA-seq datasets. TCGA data revealed that a high MAG score was significantly associated with poor prognosis in AML patients (p=0.018). Furthermore, scRNA-seq analysis revealed that CD8⁺ effector T cells from patients with no response (NR) to chemotherapy exhibited significantly higher MAG scores than those from patients who achieved complete remission (CR). This high MAG score was consistently observed in effector CD8⁺ T cells from patients with adverse clinical outcomes, regardless of transplant history.

In conclusion, our study identifies, for the first time, an abnormally elevated metabolic state in CD8⁺ T cells during early AML progression as a fundamental mechanism driving immune dysfunction and poor prognosis. This work provides a new molecular rationale for the clinical benefits of haplo-HSCT and establishes the MAG score as a robust biomarker for AML risk stratification and a potential therapeutic target to restore T-cell fitness.