Single-cell analysis of bone marrow CD8+ T cells in Myeloid Neoplasms reveals pathways associated with disease progression and response to treatment with Azacitidine.

CD8+ T cells are crucial for antitumor immunity. In higher-risk myelodysplastic neoplasms (HR-MDS) and acute myeloid leukemia (AML), CD8+ T cells exhibit altered functionality. To address their role in the course of the disease, we performed in-depth immunophenotypic analysis of 104 pre-treatment bone marrow (BM) samples using mass and flow cytometry and observed an increased frequency of the CD57+CXCR3+ subset of CD8+ T cells in patients who failed azacitidine (AZA) therapy. Furthermore, an increased baseline frequency (>29%) of the CD57+CXCR3+CD8+ T cell subset was correlated with poor overall survival. We performed scRNA-seq to assess the transcriptional profile of BM CD8+ T cells from treatment-naive patients. The response to AZA was positively associated with the enrichment of IFN-mediated pathways, whereas an enhanced TGF-β signaling signature was observed in non-responders. Our results suggest that targeting CD8+ T cells with inhibitors of TGF-β signaling in combination with AZA is a potential therapeutic strategy for HR-MDS and AML.