Modern intravenous (IV) iron formulations allow treatment of iron deficiency anemia (IDA) with one or two infusions. Ferric carboxymaltose (FCM) is a widely used IV iron, which causes hypophosphatemia in the majority of patients. Osteomalacia and fractures are increasingly recognized after repeated infusions of FCM. It is unknown why ferric derisomaltose (FDI) rarely causes hypophosphatemia. In this study, we compare the effects of FCM and FDI on fracture risk and investigate potential underlying mechanisms explaining different effects on bone- and mineral-metabolism. For this aim, fracture rate and osteomalacia were assessed in a cohort of 357 patients treated with either drug, which reported a significantly higher rate of incident osteomalacia or fracture after FCM. These findings were validated in over 20,000 patients from the TriNetX database, where FCM-treatment was independently associated with a higher fracture risk compared with FDI. The underlying mechanisms were investigated in a mouse model of IDA treated with FCM or FDI, an osteocyte model and biochemically. FCM caused lower expression of collagen and ossification genes, associated with significantly higher bone iron concentrations than FDI. Electron microscopy showed iron-loaded vesicles in osteoblasts and early osteocytes. FCM but not FDI inhibited binding of dentin matrix protein 1 to [alpha]V[beta]3-integrin on osteocytes. This is a potential mechanism for reduced bone formation and higher levels of intact fibroblast-growth factor-23 after FCM. Our data report that IDA and FCM treatment can directly impair bone formation and increase fracture risk.

The lysine acetyltransferase (KAT) activity of p300/CREBBP has traditionally been linked to transcriptional activation. This has been attributed largely to acetylation of histone residues such as H3K27ac, a defining hallmark of active regulatory elements. Here we show that, in acute myeloid leukemia (AML), inhibition of p300/CREBBP catalysis can paradoxically increase transcription. We combined time-resolved dynamics of nascent and total transcription with chromatin binding dynamics of p300/CREBBP and their associated TFs/co-regulators (inferred from chromatin pull-down proteomics, acetyl-proteomics and motif enrichment) to uncover mechanisms of transcriptional rewiring after p300/CREBBP catalytic inhibition. In parallel, we dissected the functional contribution of individual p300/CREBBP acetyl-interactome members to KAT inhibition using genome-wide CRISPR-Cas9 dropout and focused Perturb-seq screens. Together, these approaches revealed that KAT inhibition paradoxically retains p300/CREBBP and promotes cooperative TF assembly and increased H3K27 acetylation at a subset of regulatory elements. The effect was most pronounced at IRF motif-enriched loci, including interferon-stimulated genes (ISGs), where KAT inhibition triggered p300/CREBBP accumulation and enhanced combinatorial TF binding, enabling recruitment of the ISG activator STAT1. Consequently, ISG loci were converted into transcriptionally active states that induced cell-cycle arrest, differentiation and apoptosis. Therapeutically, combining KAT inhibition with interferon-alpha augmented ISG expression, synergistically drove AML cell death in vitro and significantly extended survival in both AML xenografts and murine models. These findings refine our understanding of p300/CREBBP KAT activity, demonstrating that cooperative TF assembly can reconfigure p300/CREBBP-containing complexes under catalytic inhibition to induce transcription, with translational implications for reprogramming interferon-driven programs through catalytic inhibition in AML and beyond.

The protein-protein interaction between menin and KMT2A (histone lysine methyltransferase 2A) plays a critical role in acute leukemia with KMT2A rearrangements, nucleophosmin 1 (NPM1) mutations and nucleoporin 98 rearrangements, and represents an emerging opportunity for therapeutic intervention. Here, we report development and comprehensive evaluation of the activity of ziftomenib as an orally bioavailable, highly potent and selective small molecule inhibitor of the menin-KMT2A interaction. In leukemia cells and primary patient samples with the menin-KMT2A dependency, ziftomenib profoundly inhibited proliferation, reduced clonogenic potential and induced differentiation, which was associated with strong downregulation of the menin-KMT2A target genes, including MEIS1, HOXA9 and HOXB2. In xenografts and patient-derived xenograft models of KMT2A-rearranged leukemia, ziftomenib induced leukemia regression or reduced leukemia burden, accompanied by a pronounced reduction of the menin-KMT2A target genes. We next assessed ziftomenib against four MEN1 (gene encoding menin) mutants (T349M, M327I, G331R, G331D) associated with clinical resistance to another menin inhibitor revumenib. Ziftomenib retained anti-leukemic activity against T349M mutant cells and demonstrated low-nanomolar potency (GI50≤25 nM) against G331R cells, despite several-fold reduced potency relative to MEN1 wild-type cells, whereas M327I and G331D mutants were resistant. The crystal structures of ziftomenib in complex with menin wild-type, T349M or G331R mutants revealed a similar binding mode of ziftomenib to these menin variants, rationalizing potent inhibitory activity towards these mutants. Ziftomenib has recently received FDA approval for adult patients with NPM1-mutated acute myeloid leukemia and continues to be evaluated clinically in leukemias with NPM1 or KMT2A alterations, both as monotherapy and in combinations.

The optimal graft-versus-host disease (GvHD) prophylaxis strategy in haploidentical peripheral blood stem cell transplantation (haplo-PBSCT) remains controversial. In this open-label, phase Ⅲ study, patients aged 14-70 years with acute myeloid leukemia or myelodysplastic syndromes with excess blasts Ⅰ or Ⅱ were randomized (2:1:1) to receive low-dose ATG (5 mg/kg)/PTCy (50 mg/kg), standard-dose ATG (total dose 10 mg/kg), or a PTCy (total dose 100 mg/kg)-based regimen for GvHD prophylaxis. The co-primary endpoints were the cumulative incidence (CI) of grade Ⅱ-Ⅳ acute GvHD (aGvHD) by day 100 and GvHD/relapse-free survival (GRFS) at 1 year post-transplant. A total of 407 patients were randomized to receive ATG/PTCy (185 patients), ATG (113 patients), or PTCy (109 patients) regimen for GvHD prophylaxis. By day +100, the CI of grade Ⅱ-Ⅳ aGvHD did not differ significantly among the three groups (P=0.210). Although the overall incidence of chronic GvHD (cGvHD) was comparable across all groups (P=0.110), the 2-year CI of moderate-to-severe cGvHD was numerically lower in the ATG/PTCy (17.4%) and ATG (17.3%) groups compared to the PTCy group (28.3%), without reaching statistical significance (P=0.095). No significant differences were observed in survival outcomes among the three groups. Notably, the cumulative incidence of neutrophil and platelet recovery was significantly higher in the ATG/PTCy group compared to the other groups (P<0.001). This trial suggested that the three GvHD prophylaxis strategies presented similar efficacy in preventing grade II-IV aGvHD and yielded comparable survival. This trial was registered at www.clinicaltrials.gov as NCT03608059.

Immunodeficiency-associated primary CNS lymphoma (ID-PCNSL) represents a clinicopathologically distinct PCNSL subtype, for which large studies and prognostic models are lacking. To address this gap, the International PCNSL Collaborative Group conducted an international retrospective multi-center study, integrating clinical, radiological, and pathological data from 308 ID-PCNSL, diagnosed at 23 participating sites in 7 countries. Pre-existing immunodeficiency included administration of immunosuppressants for transplantation (41.2%) or autoimmunity (36.7%), and HIV infection (21.7%). All tumors were diffuse large B-cell lymphomas, with Epstein-Barr virus (EBV) detected in 79.2%. Immune reconstitution together with rituximab-methotrexate-(RM)-based chemotherapy was associated with highest response rates and prolonged progression-free survival, irrespective of immunodeficiency subtype and EBV status. Survival outcomes were highly variable with a 54-month median overall survival. Multivariable Cox regression identified age (per year increment HR: 1.05 (95%-CI:1.02-1.07); p < 0.001), Karnofsky Performance status (KPS) < 70 (HR: 3.10 (95%-CI:1.67-5.87); p < 0.001), EBV positivity (HR: 3.26 (95%-CI:1.47-7.33); p = 0.004) as prognostic factors for OS. A prognostic score was developed based on the sum of these adverse variables (age > 60 years, KPS < 70, EBV positivity). Stratification by this score yielded median survival times of 135, 29, and 3 months in patients with up to one, two and three unfavorable markers (p < 0.0001). It allowed improved prognostic stratification of ID-PCNSL as compared to the well-established MSKCC and IELSG models developed for immunocompetent PCNSL. Collectively, this large international cohort defines clinicobiologic features of ID-PCNSL and introduces an easily applicable prognostic system with potential to guide future management.

Hereditary hemorrhagic telangiectasia (HHT), an autosomal dominant vasculopathy afflicting 1 in 5000 individuals, is the second-most-common inherited bleeding disorder worldwide. Despite this prevalence, comprehensive data on disease manifestations and complications remain limited. To address this gap, the U.S. Congress allocated funding leading to the Comprehensive HHT Outcomes Registry of the United States (CHORUS; NCT06259292), a prospective, 15-center longitudinal registry enrolling unselected patients with confirmed HHT. In this initial report, we describe findings from the first 600 participants, with a median (range) age of 53 (0-88) years and 60% female. Despite most participants developing typical HHT manifestations by age 13, the majority (63%) were not diagnosed until mid-to-late adulthood. Recurrent spontaneous epistaxis occurred in 95% of participants, chronic gastrointestinal bleeding in 30%, and heavy menstrual bleeding in 35% of post-menarche females, together resulting in moderate-to-severe mucosal bleeding in 76%. Iron deficiency and/or anemia were diagnosed in 68%, with 41% requiring intravenous iron and 25% requiring red cell transfusions. Serious complications of solid-organ arteriovenous malformations were frequent, including intracranial hemorrhage (3%), pulmonary hemorrhage (2%), venous thromboembolism (7%), arterial thromboembolism (11%), heart failure (7%), and pulmonary hypertension (7%). This data from CHORUS, the first national registry of its kind, provides reliable, real-world estimates of the incidence, prevalence and severity of numerous HHT manifestations and complications. HHT has a high burden of moderate-to-severe bleeding, anemia, thrombosis, and major neurologic and cardiopulmonary complications. There is a mean interval between first symptoms and diagnosis of over two decades, during which substantial serious, preventable HHT morbidity, including early intracranial hemorrhage, may occur.

Traumatic Brain Injury (TBI) is the leading cause of death in children and adults aged 18-44. Despite its high prevalence and devastating consequences, there are currently few effective therapies that target the acute, life-threatening complications of TBI - particularly cerebral edema and intracranial hemorrhage (ICH). The blood-brain barrier (BBB) and regulation of vascular stability following injury are emerging as critical therapeutic targets. In this study, we evaluate the therapeutic potential of a first-in-class, freeze-dried platelet-derived biologic (FDPlts) in a murine model of TBI. FDPlt transfusion significantly reduces post-TBI ICH and restores cerebral vascular perfusion. Additionally, FDPlts attenuate BBB permeability, suppress intravascular leukocytosis, and mitigate neuroinflammation evidenced by decreased microglial activation, astrocyte reactivity, and macrophage infiltration. Transcriptomic profiling of cortical and hippocampal tissues reveals that FDPlts downregulate gene networks associated with inflammation and fibrosis, suggesting a role for FDPlts in the modulation of post-injury repair. Mechanistically, FDPlts are enriched in Angiopoietin-1, a key bioactive protein that signals through the Tie2 receptor pathway, a central regulator of endothelial stability. Inhibition of Tie2 exacerbates BBB permeability after TBI, an effect attenuated by FDPlt administration; implicating Ang-1 as a key mediator of FDPlts mediated BBB protection in TBI. The BBB plays a vital role in maintaining cerebral homeostasis, and its breakdown after TBI initiates harmful cascades of edema, inflammation, and neuronal injury. Our findings demonstrate, for the first time, that a dried, platelet-derived biologic can promote vascular repair and neuroprotection in TBI.

Lenalidomide, a maintenance treatment in multiple myeloma first-line therapy, increases the risk of secondary malignancies, including B-cell precursor acute lymphoblastic leukemia (B‑ALL). We present a comprehensive molecular characterization of 57 patients with lenalidomide-associated B-ALL (LenB-ALL), revealing three mutational subgroups: (1) TP53mt (30%), (2) IDH2mt (p.R140Q) (23%) and (3) other, including NRAS/KRASmt. Remarkably, IDH2 R140Q mutations were highly enriched in LenB-ALL compared to primary B-ALL (p<0.001). Furthermore, IKZF1 intragenic deletions - often subclonal and likely RAG-mediated - were observed in 54% (7/13) of IDH2mt LenB-ALL cases. IDH2 mutations were not restricted to the leukemic clone: they persisted during MRD-negative remission and were identified in lymphoid as well as myeloid cell populations using fluorescence-activated cell sorting and single-cell RNA sequencing. This indicates a preleukemic origin of the IDH2 mutation within the context of clonal hematopoiesis. Transcriptomic and DNA methylation analyses revealed a distinct gene expression profile and a DNA hypermethylation phenotype in IDH2mt LenB-ALL, including IDH2mt-specific as well as lenalidomide-associated features. We propose that lenalidomide promotes expansion of IDH2-mutated clonal hematopoiesis and, via IKAROS downregulation, induces a maturation arrest at the B-cell precursor stage. Subsequent genetic or epigenetic alterations render leukemogenesis independent of ongoing lenalidomide exposure. Altogether, these data define IDH2mt B-ALL as a distinct molecular subtype that is markedly overrepresented after lenalidomide treatment and highlight clonal hematopoiesis as a key contributing factor in the development of LenB-ALL.

Erythropoiesis, the process of red blood cell production, is highly dependent on iron uptake via transferrin and its receptor, transferrin receptor 1 (TfR1), but the mechanisms governing the proper recycling of TfR1 in relation to cellular iron demands remain elusive. Here, we identify human TMEM187, a Golgi transmembrane protein of unknown function, as a novel negative regulator of erythropoiesis. Lack of TMEM187 in a cell model initiates erythropoiesis without the normal induction protocol and accelerates iron uptake. Following the induction protocol, TMEM187 ablation leads to premature erythroid maturation, resulting in early phosphatidylserine ectopia and cell membrane fragility, hallmarks of cellular senescence that renders the cells susceptible to macrophage recognition and phagocytosis. In zebrafish embryos, tmem187 deletion leads to enhanced early erythropoiesis, although the phenotype is later compensated, whereas hematopoietic stem-cell expression of human TMEM187 in mice, which lack endogenously a homologous gene, resulted in compromised erythropoiesis and moderate anemia. Mechanistically, we demonstrate that TMEM187 interacts with RAB11 to restrain endosomal recycling, interfering with RAB11-GRAB association that activates RAB11. Consequently, TMEM187 modulates TfR1 recycling to the cell membrane to fine-tune iron uptake efficiency for erythropoiesis. Our findings reveal a novel modulatory pathway in which TMEM187 plays a crucial role in regulating erythroid differentiation, maturation, and senescence, providing a previously unexplored perspective of TMEM187's physiological function.

Mice lacking Tissue Factor Pathway Inhibitor (Tfpi-/-) succumb to embryonic lethality from excess thrombin production and associated cerebrovascular defects called glomeruloid bodies. A transgene producing hyperactivatable mouse protein C (hMPC) was bred into Tfpi+/- mice to determine if excess activated PC (aPC) would correct the cerebrovascular defects in Tfpi-/- embryos. Tfpi-/-/hMPC+ embryos survived to adulthood. Despite the rescue of embryonic lethality, hMPC reduced glomeruloid body numbers by only 36% and did not prevent fibrin deposition or disruption of the blood-brain barrier within glomeruloid bodies. However, there was decreased hypoxia and cellular death in Tfpi-/-/hMPC+ brains suggesting that cytoprotective effects of hMPC contributed to Tfpi-/- rescue. The glomeruloid bodies were completely resolved in Tfpi-/-/hMPC+ P10 pups revealing a distinct temporal effect of TFPI on embryonic cerebrovascular development. Bulk RNAseq of E15.5 brain tissue identified increased angiogenesis as the overwhelming biological process altered in Tfpi-/- brain. This included changes in genes encoding apelin, adrenomedulin, and UNC5b, which was consistent with abundant endothelial tip cells within glomeruloid bodies. The increased expression of these angiogenic genes was reversed by the hMPC transgene. These findings define TFPI as an essential inhibitor of thrombin generation during embryonic angiogenesis that acts temporally within or around developing cerebral vasculature in a manner that is not compensated for by other anticoagulant proteins. The findings emphasize the importance of blood coagulation proteases and regulation of their activity in diverse biological processes.

Radiotherapy is an established treatment for low-grade primary cutaneous B-cell lymphoma. Recommendations on its use differ internationally, which prompted our group to conduct the present analysis. Twenty-two institutions participated in this international study. Patient eligibility required a diagnosis of limited (T1/T2) primary cutaneous marginal zone or follicle center lymphoma treated with radiotherapy between 1995 and 2023. Data were collected retrospectively until February 2024 in the framework of the International Lymphoma Radiation Oncology Group. Overall, 535 patients were analyzed. Predominant locations were the head (40%) and trunk (36%). Radiotherapy had a median dose of 24 Gy in fractions of 2 Gy. Complete responses were seen in 91% at a median time of 3.6 months following radiotherapy. There was no statistically significant difference between treatments ≤4 Gy or >4 Gy for complete or overall response rates (p=0.077 and p=0.056). However, there was an inferior duration of local control with ≤4 Gy (5-year local control 73% ± 12% vs. 96% ± 2%; p<0.001). Radiation dose was the main prognostic factor in the univariate and multivariate Cox analysis; however, higher doses did not translate into an overall survival benefit. Toxicities rarely exceeded grade 2 but were more frequent in the >4 Gy group. Radiotherapy remains an effective treatment option for indolent skin lymphoma with low toxicities. High response rates are observed with low doses ≤4 Gy. In comparison to conventional doses, these treatments have a shorter duration of local control but a favorable toxicity profile.