Epstein-Barr virus (EBV)-associated hemophagocytic lymphohistiocytosis (EBV-HLH) is a life-threatening hyperinflammatory syndrome triggered by EBV infection. It often becomes relapsed or refractory (r/r), given that etoposide-based regimens cannot effectively clear the virus. r/r EBV-HLH is invariably lethal in adults without allogeneic hematopoietic stem cell transplantation. Here, we performed a retrospective analysis of 7 r/r EBV-HLH patients who were treated with nivolumab on a compassionate-use basis at West China Hospital. All 7 patients tolerated the treatment and 6 responded to it. Five of them achieved and remained in clinical complete remission with a median follow-up of 16 months (range, 11.4-18.9 months). Importantly, both plasma and cellular EBV-DNAs were completely eradicated in 4 patients. Single-cell RNA-sequencing analysis showed that HLH syndrome was associated with hyperactive monocytes/macrophages and ineffective CD8 T cells with a defective activation program. Nivolumab treatment expanded programmed death protein-1–positive T cells and restored the expression of HLH-associated degranulation and costimulatory genes in CD8 T cells. Our data suggest that nivolumab, as a monotherapy, provides a potential cure for r/r EBV-HLH, most likely by restoring a defective anti-EBV response.

The results demonstrated the great potential of MPC-SNEDDS as an alternative oral strategy for active agents in treating hyperuricemia.

UTX (also known as KDM6A), a histone 3 lysine 27 demethylase, is among the most frequently mutated epigenetic regulators in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Recent studies have suggested that UTX mutations promote MDS and AML by blocking the differentiation of hematopoietic stem and progenitor cells (HSPCs). Here, we performed an epigenetic drug library screening for small molecules able to release the differentiation block on HSPCs induced by UTX deficiency. We found that SP2509, a selective inhibitor of LSD1, specifically promoted the differentiation of Utx -null HSPCs while sparing wild-type HSPCs. Transcriptome profiling showed that Utx loss reduced the expression of differentiation-related and tumor suppressor genes, correlating with their potential roles in HSPC self-renewal and leukemogenesis. In contrast, SP2509 treatment reversed these changes in gene expression in Utx -null HSPCs. Accordingly, Utx loss decreased H3K4 methylation level probably through the COMPASS-like complex, while LSD1 inhibition by SP2509 partially reversed the reduction of H3K4 methylation in Utx -deficient HSPCs. Further, SP2509 promoted the differentiation of Utx -null AML cells in vitro and in vivo and, therefore, extended the survival of these leukemic mice. Thus, our study identified a novel strategy to specifically target both premalignant and malignant cells with Utx deficiency for differentiation therapy and provided insights into the molecular mechanisms underlying the role of Utx in regulating HSPCs and related diseases.

Similar signaling pathways could operate in both normal hematopoietic stem and progenitor cells (HSPCs) and leukemia stem cells (LSCs). Thus, targeting LSCs signaling without substantial toxicities to normal HSPCs remains challenging. SALL1, is a member of the transcriptional network that regulates stem cell pluripotency, and lacks significant expression in most adult tissues, including normal bone marrow (NBM). We examined the expression and functional characterization of SALL1 in NBM and in acute myeloid leukemia (AML) using in vitro and in vivo assays. We showed that SALL1 is expressed preferentially in LSCs- enriched CD34+CD38- cell subpopulation but not in NBM. SALL1 inhibition resulted in decreased cellular proliferation and in inferior AML engraftment in NSG mice and it was also associated with upregulation of PTEN and downregulation of m-TOR, β-catenin, and NF-қB expression. These findings suggest that SALL1 inhibition interrupts leukemogenesis. Further studies to validate SALL1 as a potential biomarker for minimal residual disease (MRD) and to determine SALL1’s role in prognostication are ongoing. Additionally, pre-clinical evaluation of SALL1 as a therapeutic target in AML is warranted.

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