Venous thromboembolism (VTE) is common among older individuals, but provoking factors are not identified in many cases. Patients with myeloid malignancies, especially myeloproliferative neoplasms (MPNs), are at increased risk for venous thrombosis. Clonal hematopoiesis of indeterminate potential (CHIP), a precursor state to myeloid malignancies, is common among older individuals and may similarly predispose to venous thrombosis. We evaluated overall and genotype-specific associations between CHIP and prevalent and incident VTE in >400 000 samples from the UK Biobank. CHIP was modestly associated with incident VTE with a hazard ratio (HR) of 1.17 (95% confidence interval [CI], 1.09-1.3; P = .002) but was not significantly associated with prevalent VTE with an odds ratio (OR) of 1.02 (95% CI, 0.81-1.23; P = .81). TET2-mutant CHIP was associated with incident VTE with a HR of 1.33 (95% CI, 1.05-1.69; P = .02). JAK2 mutations were highly associated with both prevalent and incident VTE risk, with an OR of 6.58 (95% CI, 2.65-16.29; P = 4.7 × 10-5) and a HR of 4.2 (95% CI, 2.18-8.08; P = 1.7 × 10-5), respectively, consistent with the thrombophilia associated with JAK2-mutant MPN. The association between JAK2-mutant CHIP and VTE remained significant after excluding potential undiagnosed MPN based on laboratory parameters. JAK2-mutant CHIP was more strongly associated with VTE but was less common than heterozygous factor V Leiden and heterozygous prothrombin gene mutation. These results indicate that most individuals with CHIP do not have an altered risk of thrombosis, but individuals with JAK2-mutant CHIP have a significantly elevated risk of VTE.

The specification of megakaryocytic (Mk) or erythroid (E) lineages from primary human megakaryocytic-erythroid progenitors (MEPs) is crucial for hematopoietic homeostasis, yet the underlying mechanisms regulating fate specification remain elusive. In this study, we identify RUNX1 as a key modulator of gene expression during MEP fate specification. Overexpression of RUNX1 in primary human MEPs promotes Mk specification, whereas pan-RUNX inhibition favors E specification. Although total RUNX1 levels do not differ between Mk progenitors (MkPs) and E progenitors (ErPs), there are higher levels of serine-phosphorylated RUNX1 in MkPs than ErPs, and mutant RUNX1 with phosphorylated-serine/threonine mimetic mutations (RUNX1-4D) significantly enhances the functional efficacy of RUNX1. To model the effects of RUNX1 variants, we use human erythroleukemia (HEL) cell lines expressing wild-type (WT), phosphomimetic (RUNX1-4D), and nonphosphorylatable (RUNX1-4A) mutants showing that the 3 forms of RUNX1 differentially regulate expression of 2625 genes. Both WT and RUNX1-4D variants increase expression in 40%, and decrease expression in another 40%, with lesser effects of RUNX1-4A. We find a significant overlap between the upregulated genes in WT and RUNX1-4D-expressing HEL cells and those upregulated in primary human MkPs vs MEPs. Although inhibition of known RUNX1 serine/threonine kinases does not affect phosphoserine RUNX1 levels in primary MEPs, specific inhibition of cyclin dependent kinase 9 (CDK9) in MEPs leads to both decreased RUNX1 phosphorylation and increased E commitment. Collectively, our findings show that serine/threonine phosphorylation of RUNX1 promotes Mk fate specification and introduce a novel kinase for RUNX1 linking the fundamental transcriptional machinery with activation of a cell type-specific transcription factor.

Asciminib is a myristoyl site BCR::ABL1 inhibitor approved for patients with chronic-phase chronic myeloid leukemia (CP-CML) failing ≥2 prior lines of therapy. The Australasian Leukaemia and Lymphoma Group conducted the Asciminib Evaluation in Newly Diagnosed CML study to assess efficacy of asciminib for newly diagnosed CP-CML. Patients commenced asciminib 40 mg twice daily. Patients with treatment failure, defined as BCR::ABL1 of >10% at 3 or 6 months, or >1% at 12 or 18 months, received either imatinib, nilotinib, or dasatinib in addition to asciminib. In patients with suboptimal response, defined as levels of 1% to 10% at 6 months, >0.1% to 1% at 12 months, or >0.01% to 1% at 18 months, the asciminib dose was increased to 80 mg twice daily. With a median follow-up of 21 months (range, 0-36), 82 of 101 patients continue asciminib. Most common reasons for treatment discontinuation were adverse events (6%), loss of response (4%), and withdrawn consent (5%). There were no deaths; 1 patient developed lymphoid blast crisis. The coprimary end points were early molecular response (BCR::ABL1 of ≤10% at 3 months), achieved in 93% (96% confidence interval [CI], 86-97%), and major molecular response by 12 months achieved in 79%; (95% CI, 70-87%), respectively. Cumulative incidence of molecular response 4.5 was 53% by 24 months. One patient had 2 cerebrovascular events; no other arterial occlusive events were reported. Asciminib as frontline CP-CML therapy leads to high rates of molecular response with excellent tolerance and a low rate of discontinuation for toxicity. This trial was registered at https://www.anzctr.org.au/ as #ACTRN12620000851965.

HLA-DP permissive mismatches can be assigned a direction according to their immunopeptidome divergence across core and noncore subsets. Noncore permissive graft-versus-host mismatches show significantly reduced risks of relapse without increased nonrelapse mortality compared with allele-matched pairs.

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome characterized by aberrant immunological activity with a dismal prognosis. Epstein-Barr virus (EBV)-associated HLH (EBV-HLH) is the most common type among adults. Patients with EBV infection to B cells could benefit from rituximab, whereas lethal outcomes may occur in patients with EBV infection to T cells, nature killer cells, or multilineages. The necessity of allogeneic hematopoietic stem cell transplantation (HSCT) in adult patients with EBV-HLH remains controversial. A total of 356 adult patients with EBV-HLH entered this study. Eighty-eight received HSCT under medical recommendation. Four received salvage HSCT. The 5-year overall survival (OS) rate for patients who underwent HSCT was 48.7% (vs 16.2% in patients who did not undergo transplantation; P < .001). There was no difference in OS between patients who received transplantation at first complete response (CR1) and those at first partial response (PR1) nor between patients at CR1 and CR2. Patients who received transplantation at PR2 had inferior survival. The rate of reaching CR2 was significantly higher in patients with CR1 than PR1 (P = .014). Higher soluble CD25 levels, higher EBV-DNA loads in plasma after HSCT, poorer remission status, more advanced acute graft-versus-host disease (GVHD), and the absence of localized chronic GVHD were associated with inferior prognosis (P < .05). HSCT improved the survival of adult EBV-HLH significantly. For patients who achieved PR after initial treatment, HSCT was recommended. A wait-and-see strategy could be adopted for patients who achieved CR after initial treatment but with the risk of failing to achieve CR2.

B-cell acute lymphoblastic leukemia (B-ALL) is the most common pediatric cancer, with long-term overall survival rates of ∼85%. However, B-ALL harboring rearrangements of the MLL gene (also known as KMT2A), referred to as MLLr B-ALL, is common in infants and is associated with poor 5-year survival, relapses, and refractoriness to glucocorticoids (GCs). GCs are an essential part of the treatment backbone for B-ALL, and GC resistance is a major clinical predictor of poor outcome. Elucidating the mechanisms of GC resistance in MLLr B-ALL is, therefore, critical to guide therapeutic strategies that deepen the response after induction therapy. Neuron-glial antigen-2 (NG2) expression is a hallmark of MLLr B-ALL and is minimally expressed in healthy hematopoietic cells. We recently reported that NG2 expression is associated with poor prognosis in MLLr B-ALL. Despite its contribution to MLLr B-ALL pathogenesis, the role of NG2 in MLLr-mediated leukemogenesis/chemoresistance remains elusive. Here, we show that NG2 is an epigenetically regulated direct target gene of the leukemic MLL-ALF transcription elongation factor 4 (AF4) fusion protein. NG2 negatively regulates the expression of the GC receptor nuclear receptor subfamily 3 group C member 1 (NR3C1) and confers GC resistance to MLLr B-ALL cells. Mechanistically, NG2 interacts with FLT3 to render ligand-independent activation of FLT3 signaling (a hallmark of MLLr B-ALL) and downregulation of NR3C1 via activating protein-1 (AP-1)-mediated transrepression. Collectively, our study elucidates the role of NG2 in GC resistance in MLLr B-ALL through FLT3/AP-1-mediated downregulation of NR3C1, providing novel therapeutic avenues for MLLr B-ALL.

DNA methyltransferase inhibitor decitabine plus anti-programmed cell death 1 (DP) therapy was effective in relapsed/refractory classic Hodgkin lymphoma (cHL). However, a subset of patients experienced primary resistance or relapse/progression after DP therapy. In this study, we evaluated the efficacy and safety of a triplet regimen consisting of the histone deacetylase inhibitor chidamide, decitabine, and anti-PD-1 camrelizumab (CDP) in 52 patients who previously received DP therapy. CDP treatment was well tolerated and resulted in an objective response rate of 94% (95% confidence interval [CI], 84-99), with 50% (95% CI, 36-64) of patients achieving complete response (CR). Notably, all patients who were recalcitrant to previous DP treatment exhibited therapeutic responses after CDP therapy, although their CR rate was lower than patients responsive to prior DP. Overall, the median progression-free survival was 29.4 months. Through single-cell RNA sequencing of pretreatment and on-treatment cHL tumor biopsy samples, we observed the heterogeneity of rare malignant Hodgkin Reed/Sternberg (HRS)-like cells. The classical CD30+ HRS-like cells interacted with abundant immunosuppressive IL21+CD4+ T helper cells, forming a positive feedback loop that supported their survival. While the CD30- HRS-like cell population showed potential resistance to anti-PD-1 immunotherapy. CDP treatment promoted the activation of diverse tumor-reactive CD8+ T cells and suppressed the proliferation of IL21+CD4+ T cells by inhibiting STAT1/3 signaling, thereby alleviating their immunosuppressive effects. These findings provide insights into the cHL microenvironment that contributes to anti-PD-1 resistance and highlight the therapeutic effectiveness of dual epi-immunotherapy in overcoming immunotherapy resistance. This trial was registered at www.clinicaltrials.gov as #NCT04233294.

Patients with thrombocytopenia require platelet transfusion to prevent and stop hemorrhage. Cold storage of platelets results in complex molecular lesions, including changes in membrane microdomains that are recognized by host macrophages and hepatocyte counter-receptors, resulting in phagocytosis and clearance upon transfusion. For this reason, platelets are stored at room temperature, a method that confers increased risk of bacterial contamination. By applying signaling analysis and genetic and pharmacological approaches, we identified that cold-induced activation of RAS homolog family, member A (RHOA) GTPase causes the major hallmarks of platelet cold storage lesions. RHOA deficiency renders murine platelets insensitive to cold storage-induced damage, and pharmacological inhibition by a RHOA activation inhibitor, R-G04, can prevent the cold storage-induced lesions. RHOA inhibition prevents myosin activation and clathrin-independent formation and internalization of lipid rafts enriched in active glycosyltransferases as well as abnormal distribution of GPIbα. RHOA inhibition further prevents the metabolic reprogramming of cold storage-induced lesions and allows the maintenance of glycolytic flux and mitochondria-dependent respiration. Importantly, human platelets transfused in mice after cold storage, in the presence of R-G04 or its more potent enantiomer S-G04, can circulate in vivo at similar levels as room temperature-stored platelets while retaining their hemostatic activity in vivo, as assessed by bleeding time correction in aspirin-treated mice. Our studies provide a mechanism-based translational approach to prevent cold storage-induced damage, which is useful for human platelet transfusion in patients with thrombocytopenia.

Coagulation factor VIII (FVIII) is essential for hemostasis. After activation, it combines with activated FIX (FIXa) on anionic membranes to form the intrinsic Xase enzyme complex, responsible for activating FX in the rate-limiting step of sustained coagulation. Hemophilia A (HA) and hemophilia B are due to inherited deficiencies in the activity of FVIII and FIX, respectively. Treatment of HA over the last decade has benefited from an improved understanding of FVIII biology, including its secretion pathway, its interaction with von Willebrand factor in circulation, the biochemical nature of its FIXa cofactor activity, the regulation of activated FVIII by inactivation pathways, and its surprising immunogenicity. This has facilitated biotechnology innovations with first-in-class examples of several new therapeutic modalities recently receiving regulatory approval for HA, including FVIII-mimetic bispecific antibodies and recombinant adeno-associated viral (rAAV) vector-based gene therapy. Biological insights into FVIII also guide the development and use of gain-of-function FVIII variants aimed at addressing the limitations of first-generation rAAV vectors for HA. Several gain-of-function FVIII variants designed to have improved secretion are currently incorporated in second-generation rAAV vectors and have recently entered clinical trials. Continued mutually reinforcing advancements in the understanding of FVIII biology and treatments for HA are necessary to achieve the ultimate goal of hemophilia therapy: normalizing hemostasis and optimizing well-being with minimal treatment burden for all patients worldwide.