We carried out a single-cell (sc) multiomic analysis on a series of MYD88 mutated Waldenström macroglobulinemia (WM) cases and identified two distinct subtypes of disease, memory B-cell-like (MBC-like) and plasma cell-like (PC-like), based on their expression of key lineage defining genes. Biologically, the subtypes are characterized by their variable capacity to differentiate fully towards a plasma cell (PC) and exhibit unique transcriptomic, chromatin accessibility, and genomic profiles. The MBC-like subtype is unable to differentiate beyond the memory B-cell (MBC) stage, upregulates key MBC genes, and is characterized by upregulated BCR and AKT/mTOR signaling. In contrast, the PC-like subtype can partially differentiate towards a PC, upregulates key PC genes, has enhanced NF-kB signaling, and has an upregulated unfolded protein response. Pseudotime trajectory analysis of combined scRNA-sequencing and scATAC-sequencing supports the variable differentiation capacity of each subtype and implicate key transcription factors SPI1, SPIB, BCL11A, and XBP1 in these features. The existence and generalizability of the two disease subtypes were validated further using hierarchical clustering of bulk RNA-seq data from a secondary set of cases. The biological significance of the subtypes was further established using whole genome sequencing, where it was shown that CXCR4, NIK, and ARID1A mutations occur predominantly in the MBC-like subtype and 6q deletions in the PC-like subtype. We conclude that the variable differentiation blockade seen in WM manifests itself clinically as two disease subtypes with distinct epigenetic, mutational, transcriptional, and clinical features with potential implications for WM treatment strategies.

We sought to develop a survival model in chronic myelomonocytic leukemia (CMML) that is primarily based on clinical variables and examine additional impact from mutations and karyotype. A total of 457 molecularly annotated patients were considered. Multivariable analysis identified circulating blasts ≥2% (1 point), leukocytes ≥13 × 109/L (1 point), and severe (2 points) or moderate (1 point) anemia as preferred risk variables in developing a clinical risk stratification tool for overall survival (OS), acronymized to "BLAST": low risk (0 points; median, 63 months); intermediate risk (1 point; median, 28 months; hazard ratio [HR], 2.2; 95% confidence interval [CI], 1.6-3.0), and high risk (2-4 points; median, 13 months; HR, 5.4; 95% CI, 4.1-7.3); the corresponding 3/5-year OS rates were 68%/53%, 43%/18%, and 12%/1%. BLAST model performance (area under the receiver operating characteristic curve [AUC] 0.77/0.85 at 3/5 years) was shown to be comparable to that of the molecular CMML-specific prognostic scoring system (AUC 0.73/0.75) and the international prognostic scoring system-molecular (AUC 0.73/0.74). Multivariable analysis of mutations and karyotype identified PHF6MUT and TET2MUT as being "favorable" and DNMT3AMUT, U2AF1MUT, BCORMUT, SETBP1MUT, ASXL1MUT, NRASMUT, PTPN11MUT, RUNX1MUT, TP53MUT, and adverse karyotype, "unfavorable." Molecular information was subsequently encoded in a combined clinical-molecular risk model (BLAST-mol; AUC 0.80/0.86 at 3/5 years) that included the aforementioned BLAST clinical risk variables and a 3-tiered molecular risk score. BLAST and BLAST-mol were subsequently validated by 2 separate external cohorts. Independent risk factors for blast transformation included DNMT3AMUT, ASXL1MUT, PHF6WT, leukocytes ≥13 × 109/L, and ≥2% circulating or ≥10% bone marrow blasts. The current study proposes an easy-to-implement, globally applicable, and molecularly adaptive risk model for CMML.

The prognosis for relapsed or refractory (R/R) nucleophosmin 1-mutated (NPM1m) acute myeloid leukemia (AML) is poor and represents an urgent unmet medical need. Revumenib, a potent, selective menin inhibitor, was recently approved for the treatment of R/R acute leukemia with a KMT2A translocation in patients aged ≥1 year based on results from the phase 1/2 AUGMENT-101 study. Here, we present results from patients with R/R NPM1m AML enrolled in the phase 2 portion of AUGMENT-101. Enrolled patients received revumenib with or without a strong CYP3A4 inhibitor every 12 hours in 28-day cycles. Primary end points were rate of complete remission (CR) or CR with partial hematologic recovery (CRh; CR + CRh), safety, and tolerability. Secondary end points included overall response rate (ORR) and duration of response. As of 18 September 2024, 84 patients received ≥1 dose of revumenib. Median age was 63 years; 1 patient was aged <18 years. The protocol-defined, efficacy-evaluable population for the primary analysis included 64 adult patients (≥3 previous lines of therapy, 35.9%; previous venetoclax, 75.0%). The CR + CRh rate was 23.4% (1-sided P = .0014); the ORR was 46.9%. Median duration of CR + CRh was 4.7 months. Of 30 responders, 5 (16.7%) proceeded to hematopoietic stem cell transplant (HSCT) and 3 resumed revumenib after HSCT. Treatment-related adverse events led to treatment discontinuation in 4 patients (4.8%). Revumenib demonstrated clinically meaningful responses in this heavily pretreated, older population with NPM1m AML, including remissions that enabled HSCT. The safety profile of revumenib was consistent with previously reported results. This trial was registered at www.clinicaltrials.gov as #NCT04065399.

Small molecules that inhibit LSD1 (lysine-specific demethylase 1, KDM1A) have been shown to induce abundant fetal hemoglobin (HbF) levels in red blood cells both in vitro and in vivo, therefore potentially serving as potent and cost-effective therapeutics to treat the β-globinopathies, sickle cell disease (SCD), and β-thalassemia major (TM). However, most LSD1 inhibitors (LSD1is) that induce HbF in vivo are covalent and irreversible, which leads to adverse effects. In this study, we utilized structure-aided drug design to develop potent new reversible LSD1is, leading to robust γ-globin expression in vitro. Moreover, in a mouse model of SCD, oral administration of these novel inhibitors leads to significant HbF elevation and alleviation of multiple features of disease pathology that are the usual consequences of SCD. In addition, we discovered that combined treatment of an LSD1i with a BRD4 degrader (BD-9136) represses the induction of RUNX1 and PU.1, thereby rescuing the erythroid to myeloid lineage conversion that accompanies LSD1is in hematopoiesis. The data indicate that this new generation of LSD1is can effectively induce HbF levels, reduce SCD pathologies, and are well tolerated by oral administration in SCD mice. We anticipate that the combination of these or related binary compounds offer exciting new therapeutic possibilities for treating SCD and TM.

The Jak2 V617F mutation stands as the main driver of myeloproliferative neoplasms (MPNs) by constitutively activating signaling through several type I cytokine receptors, namely the erythropoietin receptor, the thrombopoietin receptor (TpoR)/myeloproliferative leukemia (Mpl) protein, and the granulocyte colony-stimulating factor receptor. Among these, TpoR assumes a pivotal role in hematopoietic stem cell renewal and differentiation, being positioned as a key driver of MPNs alongside mutated Jak2. However, the impact of TpoR/Mpl absence in the context of Jak2 V617F in vivo has been explored only through a transgenic Jak2 V617F mouse model, in which regulation of Jak2 expression does not depend on its natural promoter. In this study, we use a novel mouse model expressing Jak2 V617F under its endogenous promoter at the heterozygous state within a Mpl knockout background. Our findings indicate that erythrocytosis, leukocytosis, and moderate splenomegaly with mild perivascular fibrosis of the spleen persist even in the absence of Mpl expression. Notably, the inherent growth-stimulating effect induced by Jak2 V617F remains consistent across diverse early hematopoietic progenitor populations in the absence of Mpl but is reduced at the stem cell level and does not allow clonal expansion in competitive transplantation. Our results delineate Mpl-dependent and -independent phenotypes induced by Jak2 V617F and confirm that inhibiting Mpl expression at the stem cell level negates the long-term advantage of the mutant clone. Consequently, although Mpl emerges as a major player in Jak2 V617F-positive MPNs, our study underscores that it is not the exclusive contributor, broadening the spectrum for therapeutic intervention.

We found that 8 of 10 patients with aplastic anemia experienced resolution of platelet transfusion refractoriness following daratumumab administration. Notably, 4 responders achieved hematopoietic recovery, including 3 participants who showed improvements in multilineage blood cell counts, even with daratumumab monotherapy. This trial was registered at www.clinicaltrials.gov as #NCT05832216.

We report on 8 patients with ankyrin repeat domain 26 (ANKRD26)-related thrombocytopenia 2 (ANKRD26-RT) with elevated bone marrow myeloblasts and dysmegakaryopoiesis, without somatic genetic abnormalities or progression to malignancy during long-term observation, findings which may constitute inherent ANKRD26-RT biology rather than progression to myeloid malignancy.

Graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic cell transplantation (HCT). Palifermin, a recombinant N-truncated keratinocyte growth factor (KGF), protects epithelial tissues, including the thymus and gut. Although high-dose KGF prevents GVHD in preclinical models, lower doses of palifermin were ineffective in humans. We conducted a phase 1/2 trial evaluating high-dose palifermin for preventing severe chronic GVHD (CGVHD) in matched unrelated donor T-cell replete peripheral blood HCT after reduced-intensity conditioning (RIC). Using a 3+3 design, we determined the recommended phase 2 dose (RP2D), followed by an expansion phase. Palifermin (180-720 μg/kg) was given on day -7 before HCT. All 31 patients received fludarabine/cyclophosphamide RIC with tacrolimus, methotrexate, and sirolimus for GVHD prophylaxis. Palifermin was well tolerated, with self-limiting rash and pancreatic enzyme elevations as notable grade 3/4 adverse events. The RP2D was 720 μg/kg. Remarkably, no patients at this dose developed grade 2 to 4 acute GVHD (AGVHD [0/19]), although severe CGVHD rates (primary end point) remained unchanged compared to historical controls. Posttransplant lymphocyte phenotyping suggests palifermin modulates regulatory and naïve CD4+ T-cell numbers. These findings indicate that high-dose palifermin with RIC is safe and may prevent AGVHD, although it did not affect CGVHD rates in this study. This trial was registered at www.ClinicalTrials.gov as #NCT02356159.

Coagulation factor Va (FVa) is the cofactor component of the prothrombinase complex required for rapid generation of thrombin from prothrombin in the penultimate step of the coagulation cascade. In addition, FVa is a target for proteolytic inactivation by activated protein C (APC). Like other protein-protein interactions in the coagulation cascade, the FVa-APC interaction has long posed a challenge to structural biology and its molecular underpinnings remain unknown. A recent cryogenic electron microscopy (cryo-EM) structure of FVa has revealed the arrangement of its A1-A2-A3-C1-C2 domains and the environment of the sites of APC cleavage at R306 and R506. Here, we report the cryo-EM structure of the FVa-APC complex at 3.15 Å resolution in which the protease domain of APC engages R506 in the A2 domain of FVa through electrostatic interactions between positively charged residues in the 30-loop and 70-loop of APC and an electronegative surface of FVa. The auxiliary γ-carboxyglutamic acid and epidermal growth factor domains of APC are highly dynamic and point to solvent, without making contacts with FVa. Binding of APC displaces a large portion of the A2 domain of FVa and projects the 654VKCIPDDDEDSYEIFEP670 segment as a "latch," or exosite ligand, over the 70-loop of the enzyme. The latch induces a large conformational change of the autolysis loop of APC, which in turn promotes docking of R506 into the primary specificity pocket. The cryo-EM structure of the FVa-APC complex validates the bulk of existing biochemical data and offers molecular context for a key regulatory interaction of the coagulation cascade.

Sickle cell hemoglobin C (HbSC) disease results from compound heterozygosity of hemoglobin S (HbS) and hemoglobin C (HbC), comprising 30% of sickle cell disease (SCD). HbC induces red blood cell (RBC) dehydration/xerocytosis, which promotes sickling. HbSC-SCD causes significant morbidity despite being milder than homozygous HbSS-SCD. Current research/treatment strategies have focused on HbSS-SCD, whereas patients with HbSC are deprived of disease-modifying/transformative therapies because of lack of preclinical models. We generated HbSC mice, which resemble human HbSC-SCD: HbSC erythrocytes showed marked xerocytosis. Anemia, hemolysis, inflammation, and organ damage were milder than HbSS mice but hypoxia/reperfusion injury was similar. Retinopathy developed at higher frequency than HbSS mice (66.7% vs 16.7%; P < .05), as in patients with HbSC-SCD. Although HbSC RBCs sickled at lower oxygen tension than HbSS RBCs, they did not completely recover deformability after hypoxia/reoxygenation. Using the HbSC mice, we studied the mechanism by which hydroxyurea causes significant clinical benefit in patients with HbSC-SCD, despite minimal/modest increases in fetal Hb (HbF). We found hydroxyurea had distinct non-HbF and HbF effects. Hydroxyurea did not increase HbF in adult HbSC/HbSS mice but reduced RBC reactive oxygen species, ferryl Hb, and Heinz-body formation, thereby reducing membrane damage; however, RBC hydration was unaffected. When given to unborn pups before γ-globin expression was switched off, and continued postnatally, we could induce HbF in both HbSC and HbSS mice (higher HbF in HbSS vs HbSC mice). Minimal increases in HbF (∼1%) improved HbSC RBC hydration. Peak HbF levels of 7% in HbSC mice abrogated sickling. Overall, this HbSC model will help bridge the knowledge gap in mechanistic/therapeutic studies in this neglected disease.

Heavy menstrual bleeding (HMB) is a widespread occurrence among women of reproductive age and inflicts a substantial impact on their well-being and on health care expenses. To better characterize the genetic architecture of HMB, we conducted a meta-analysis of the summary statistics of genome-wide association studies (GWAS) from 5 biobanks that included up to 84 633 HMB cases and 598 195 controls from several ancestries. Of the 21 signals significantly associated with HMB in a discovery GWAS meta-analysis that combined 4 biobanks, 20 had a concordant direction of effect in the remaining cohort, including 10 that were significantly replicated. By combining the discovery and replication data sets, 15 additional signals were identified in subsequent meta-analyses. These genetic analyses identified 36 signals (33 novel) that were significantly associated with HMB, and gene prioritization techniques (eg, transcriptome-wide association studies, polygenic priority score) subsequently revealed likely causal genes. Notable discoveries included the strong protective effect of the F5-Leiden variant (rs6025-T; odds ratio, 0.75; P = 6.8 × 10-33); variants at the FSHB and LHB/CGB loci, both involved in hormone production regulation; and several signals near genes involved in the Wnt/β-catenin signaling pathway. We also observed strong and significant genetic correlations with disorders of the female genital tract, including uterine fibroids, endometriosis, or ovarian cysts. Overall, we identified 33 novel genetic loci associated with HMB, thereby significantly improving our understanding of the genetic etiology of this condition, which may provide new targets for the development of therapeutic strategies.

Chronic graft-versus-host disease (cGVHD) is characterized by dysregulation of the adaptive immune system, including an aberrant B-cell homeostasis after allogeneic hematopoietic stem cell transplantation (allo-SCT). It is uncertain, however, whether this B-cell dysregulation is a result of manifest cGVHD or develops as a sign of aberrant B lymphopoiesis after allo-SCT before cGVHD becomes apparent. To gain insight into the development of B-cell dysregulation before the onset of cGVHD, we analyzed B-cell subpopulations by multiparameter flow cytometry on days 90, 180, and 356 after allo-SCT in a prospective study design. After completion of follow-up, patients were assigned retrospectively to 3 groups according to onset of GVHD: (1) no GVHD (n = 17); (2) acute GVHD (aGVHD) without subsequent cGVHD (n = 32); and (3) cGVHD (n = 59). Although CD21lowCD11c+ B cells were increased in all groups, the frequency of CD20-CD38hi plasmablasts was significantly elevated already 90 days after allo-SCT in patients who subsequently developed cGVHD, compared to patients without GVHD or with aGVHD only (median of CD19+ cells, 5.9% vs 2.2% vs 2.2%; P = .0016 and .0304, respectively). Detailed molecular analysis of expanded plasmablasts revealed a dominance of the immunoglobulin A isotype, with molecular evidence for recent generation in mucosal sites and markers for intestinal homing. A large fraction of the clonally expanded plasmablasts produced antibodies that bound to subgroups of commensals known to produce short-chain fatty acids. In summary, our data suggest that dysregulated intestinal antibody responses against commensals contribute to the pathophysiology of cGVHD.