Pediatric acute myeloid leukemia (pAML) is a clonal disease with recurrent genetic alterations that affect epigenetic states. However, the implications of epigenetic dysregulation in disease progression remain unclear. Here, we interrogated single-cell and clonal level chromatin accessibility of bone marrow samples from 28 patients with pAML representing multiple subtypes using mitochondrial single-cell assay for transposase-accessible chromatin with sequencing, which revealed distinct differentiation hierarchies and abnormal chromatin accessibility in a subtype-specific manner. Innate immune signaling was commonly enhanced across subtypes and related to improved advantage of clonal competition and unfavorable prognosis, with further reinforcement in a relapse-associated leukemia stem cell-like population. We identified a panel of 31 innate immunity-related genes to improve the risk classification of patients with pAML. By comparing paired diagnosis and postchemotherapy relapse samples, we showed that primitive cells significantly reduced major histocompatibility complex class II signaling, suggesting an immune evasion mechanism to facilitate their expansion at relapse. Key regulators orchestrating cell cycle dysregulation were identified to contribute to pAML relapse in drug-resistant clones. Our work establishes the single-cell chromatin accessibility landscape at clonal resolution and reveals the critical involvement of epigenetic disruption, offering insights into classification and targeted therapies of patients with pAML.

The pathophysiology of sickle cell disease (SCD) is characterized by hemolytic anemia and vaso-occlusion, although its impact on the adaptive immune responses remains incompletely understood. To comprehensibly profile the humoral immune responses, we immunized SCD mice with T-cell-independent (TI) and T-cell-dependent (TD) antigens (Ags). Our study showed that SCD mice have significantly enhanced type 2 TI (TI-2) immune responses in a manner dependent on the level of type I interferons (IFN-I), while maintaining similar or decreased TD immune responses depending on the route of Ag administration. Consistent with the enhanced TI-2 immune responses in SCD mice, the frequencies of B-1b cells (B-1 cells in humans), a major cell type responding to TI-2 Ags, were significantly increased in both the peritoneal cavity and spleens of SCD mice and in the blood of patients with SCD. In support of expanded B-1 cells, elevated levels of anti-red blood cell (anti-RBC) autoantibodies were detected in both SCD mice and patients. Both the levels of TI-2 immune responses and anti-RBC autoantibodies were significantly reduced after IFN-I receptor (IFNAR) antibody blockades and in IFNAR1-deficient SCD mice. Moreover, the alterations of B-1 cell subsets were reversed in IFNAR1-deficient SCD mice, uncovering a critical role for IFN-I in the enhanced TI-2 immune responses and the increased production of anti-RBC autoantibodies by modulating the innate B-1 cell subsets in SCD. Overall, our study provides experimental evidence that the modulation of B-1 cells and IFN-I can regulate TI immune responses and the levels of anti-RBC autoantibodies in SCD.

X-linked sideroblastic anemia (XLSA) is a congenital anemia caused by mutations in ALAS2, a gene responsible for heme synthesis. Treatments are limited to pyridoxine supplements and blood transfusions, offering no definitive cure except for allogeneic hematopoietic stem cell transplantation, only accessible to a subset of patients. The absence of a suitable animal model has hindered the development of gene therapy research for this disease. We engineered a conditional Alas2-knockout (KO) mouse model using tamoxifen administration or treatment with lipid nanoparticles carrying Cre-mRNA and conjugated to an anti-CD117 antibody. Alas2-KOBM animals displayed a severe anemic phenotype characterized by ineffective erythropoiesis (IE), leading to low numbers of red blood cells, hemoglobin, and hematocrit. In particular, erythropoiesis in these animals showed expansion of polychromatic erythroid cells, characterized by reduced oxidative phosphorylation, mitochondria's function, and activity of key tricarboxylic acid cycle enzymes. In contrast, glycolysis was increased in the unsuccessful attempt to extend cell survival despite mitochondrial dysfunction. The IE was associated with marked splenomegaly and low hepcidin levels, leading to iron accumulation in the liver, spleen, and bone marrow and the formation of ring sideroblasts. To investigate the potential of a gene therapy approach for XLSA, we developed a lentiviral vector (X-ALAS2-LV) to direct ALAS2 expression in erythroid cells. Infusion of bone marrow (BM) cells with 0.6 to 1.4 copies of the X-ALAS2-LV in Alas2-KOBM mice improved complete blood cell levels, tissue iron accumulation, and survival rates. These findings suggest our vector could be curative in patients with XLSA.

Anemia of inflammation is a prevalent comorbidity in patients with chronic inflammatory disorders. Inflammation causes hypoferremia and iron-restricted erythropoiesis by limiting ferroportin (FPN)-mediated iron export from macrophages that recycle senescent erythrocytes. Macrophage cell surface expression of FPN is reduced by hepcidin-induced degradation and/or by repression of FPN (Slc40a1) transcription via cytokine and Toll-like receptor (TLR) stimulation. Although the mechanisms underlying hepcidin-mediated control of FPN have been extensively studied, those inhibiting Slc40a1 messenger RNA (mRNA) expression remain unknown. We applied targeted RNA interference and pharmacological screens in macrophages stimulated with the TLR2/6 ligand FSL1 and identified critical signaling regulators of Slc40a1 mRNA repression downstream of TLRs and NF-κB signaling. Interestingly, the NF-κB regulatory hub is equally relevant for Slc40a1 mRNA repression driven by the TLR4 ligand lipopolysaccharide, the cytokine tumor necrosis factor β/lymphotoxin-alpha (LTA), and heat-killed bacteria. Mechanistically, macrophage stimulation with heat-killed Staphylococcus aureus recruits the histone deacetylases (HDACs) HDAC1 and HDAC3 to the antioxidant response element (ARE) located in the Slc40a1 promoter. Accordingly, pretreatment with a pan-HDAC inhibitor abrogates Slc40a1 mRNA repression in response to inflammatory cues, suggesting that HDACs act downstream of NF-κB to repress Slc40a1 transcription. Consistently, recruitment of HDAC1 and HDAC3 to the Slc40a1 ARE after stimulation with heat-killed S aureus is dependent on NF-κB signaling. These results support a model in which the ARE integrates the transcriptional responses of Slc40a1 triggered by signals from redox, metabolic, and inflammatory pathways. This work identifies the long-sought mechanism of Slc40a1 transcriptional downregulation upon inflammation, paving the way for therapeutic interventions at this critical juncture.

We identified 347 pregnancies in patients with β-thalassemia minor. Hemoglobin was <9 g/dL in 31% during third trimester and 7.6% at delivery. Postpartum hemorrhage occurred in 8.9%. Forty-six percent of IV iron administration was to iron-replete patients.

Early intervention in smoldering multiple myeloma (SMM) may delay progression to MM. Here, we present the final analysis of the phase 2 CENTAURUS study. In total, 123 patients with intermediate/high-risk SMM were randomized to IV daratumumab 16 mg/kg after a long-intense (n = 41), intermediate (n = 41), or short-intense (n = 41) dosing schedule. At a combined median follow-up of 85.2 months, in the long-intense, intermediate, and short-intense arms complete response or better rates were 4.9%, 9.8%, and 0%; overall response rates were 58.5%, 53.7%, and 37.5%; progressive disease/death rates were 0.096, 0.102, and 0.109 (P < .0001 for all arms); and median progression-free survival was not reached, 84.4, and 74.1 months, respectively. Median overall survival was not reached in any arm. Thirty-six patients in the long-intense or intermediate arms continued daratumumab in an optional extension phase after completing 20 cycles of per-protocol treatment. The median duration of study treatment was 44.0 (range, 1.0-91.6), 35.2 (range, 1.9-90.6), and 1.6 (range, 0.1-1.9) months in the long-intense, intermediate, and short-intense arms, respectively. No new safety signals were observed. With extended follow-up (median, ∼7 years), these data highlight the tolerability of daratumumab and support ongoing trials investigating daratumumab as an early intervention for SMM. This trial was registered at www.ClinicalTrials.gov as #NCT02316106.

Outcomes are poor in patients with higher-risk myelodysplastic syndromes (HR MDS) and frontline treatment options are limited. This phase 1b study investigated safety and efficacy of venetoclax, a selective B-cell lymphoma 2 inhibitor, at the recommended phase 2 dose (RP2D; 400 mg for 14 days per 28-day cycle), in combination with azacitidine (75 mg/m2 for 7 days per 28-day cycle) for treatment-naive HR MDS. Safety was the primary outcome, and complete remission (CR) rate was the primary efficacy outcome. Secondary outcomes included rates of modified overall response (mOR), hematologic improvement (HI), overall survival (OS), and time to next treatment (TTNT). As of May 2023, 107 patients received venetoclax and azacitidine combination at the RP2D. Best response of CR or marrow CR was observed in 29.9% and 50.5% (mOR, 80.4%), respectively. Median OS was 26.0 months, with 1- and 2-year survival estimates of 71.2% and 51.3%, respectively. Among 59 patients with baseline red blood cell and/or platelet transfusion-dependence, 24 (40.7%) achieved transfusion independence on study, including 11 (18.6%) in CR. Fifty-one (49.0%) of 104 evaluable patients achieved HI. Median TTNT excluding transplantation was 13.4 months. Adverse events reflected known safety profiles for venetoclax and azacitidine, including constipation (53.3%), nausea (49.5%), neutropenia (48.6%), thrombocytopenia (44.9%), febrile neutropenia (42.1%), and diarrhea (41.1%). Overall, venetoclax plus azacitidine at the RP2D was well tolerated and had favorable outcomes. A phase 3 study (NCT04401748) is ongoing to confirm survival benefit of this combination. This trial was registered at www.clinicaltrials.gov as #NCT02942290.

Anti-CD19 chimeric antigen receptor (CAR)-engineered T and natural killer (NK) cell therapies have revolutionized the treatment of B-cell malignancies, but challenges including CD19 antigen loss greatly hinder their full therapeutic potential. Here, we revealed that cotreatment with anti-CD19 monoclonal antibody enhances antitumor activity of anti-CD19 CAR-T and -NK cells. Even though the treated antibody interferes with CD19 antigen binding of CAR, it significantly induces rapid detachment of anti-CD19 CAR effector cells from target cells, facilitating improved serial killing. This reduced interaction between CAR effector cells and target cells also leads to the alleviation of CAR-mediated trogocytosis. Interestingly, cotreatment with anti-CD19 antibody reveals time-dependent effects on the antitumor activity of anti-CD19 CAR-T cells, characterized by a reduction in early T cell activation followed by sustained high activity during prolonged exposure to target cells. This temporal modulation ultimately results in enhanced antitumor potency in vivo. These findings underscore the improved therapeutic efficacy achieved by combining anti-CD19 antibody with anti-CD19 CAR-T or -NK cells against B-cell malignancies.

The transcription factor GATA-binding protein 3 (GATA-3) and the transcriptional program it regulates have emerged as oncogenic drivers across diverse T-cell lymphomas (TCLs), many of which are resistant to conventional chemotherapeutic agents and characterized by recurrent losses of key tumor suppressor genes, including TP53 and PTEN, both of which are clients of the nuclear export protein XPO1. Here, we demonstrated that XPO1 is highly expressed by malignant T cells expressing GATA-3 and by lymphoma-associated macrophages (LAMs) within their tumor microenvironment (TME). Using complementary genetically engineered mouse models, we demonstrated that TP53- and/or phosphate and tensin homolog (PTEN)-deficient TCLs, and LAMs within their TME, are sensitive to the selective exportin-1 (XPO1) antagonist selinexor. In an effort to identify TP53- and PTEN-independent mechanisms, we used complementary and orthogonal approaches to investigate the role of eIF4E and XPO1-dependent messenger RNA nuclear export in these TCLs. We identified a novel role for eIF4E/XPO1 in exporting GATA-3 and GATA-3-dependent transcripts from the nucleus in TCLs, and in the export of therapeutically relevant transcripts, including colony-stimulating factor-1 receptor, from LAMs. Therefore, XPO1 antagonism, by impairing oncogenic transcriptional programs in TCLs and depleting LAMs from their TME, is a novel approach to target 2 independent dependencies in a group of therapeutically challenging TCLs.

Air pollution exposure may induce procoagulant effects, and chronic exposure may be linked to greater risk of venous thromboembolism (VTE). We tested the hypothesis that air pollution is associated with increased VTE risk in the prospective Multi-Ethnic Study of Atherosclerosis, which has well-characterized air pollution measures and information on potential confounding factors. We included 6651 participants recruited in 2000 to 2002 (baseline age range, 45-84 years; 53% female). Air pollution was assessed with a validated spatiotemporal model that incorporates cohort-specific monitoring. Four indexes of air pollution updated each fortnight over follow-up were averaged to estimate participant-level chronic exposure: fine particulate matter ≤2.5 micrometers in aerodynamic diameter (PM2.5), oxides of nitrogen (NOx), nitrogen dioxide (NO2), and ozone (O3). Mean±SD PM2.5 was 13.5±3.0 μg/m3, NO2 17.9±8.2 parts per billion (ppb), NOx 36.1±19.6 ppb, and O3 22.2±3.7 ppb. Incident VTE was identified using hospitalization discharge codes through 2018. A total of 248 VTE events accrued over a median follow-up of 16.7 years. After adjustment for baseline demographics, health behaviors, and body mass index, the hazard ratio (95% confidence interval) for incident VTE associated per 3.6 μg/m3 higher PM2.5 was 1.39 (1.04-1.86); per 13.3 ppb higher NO2 concentration was 2.74 (1.57-4.77); and per 30 ppb higher NOx was 2.21 (1.42-3.44). O3 was not related. In this prospective community-based cohort with individual-level estimation of chronic air pollution exposure, higher average ambient concentrations of PM2.5, NO2, and NOX were associated with greater risk of developing VTE. Findings add to accumulating evidence of adverse health effects attributed to air pollution exposure.

Chimeric antigen receptor T-cell (CAR-T) therapy has emerged as a breakthrough treatment for relapsed and refractory multiple myeloma (RRMM). However, these products are complex to deliver, and alternative options are now available. Identifying biomarkers that can predict therapeutic outcomes is crucial for optimizing patient selection. There is a paucity of data evaluating the utility of both serum soluble B-cell maturation antigen (sBCMA) levels and metabolic tumor volume (MTV) at baseline in patients with RRMM undergoing CAR-T therapy. We identified a cohort of 183 patients with available serum to measure sBCMA and/or pretreatment MTV, derived from positron emission tomography-computed tomography scans obtained per standard of care. Expectedly, high pretreatment levels of sBCMA correlated with other established markers of tumor burden (eg, bone marrow plasma cells and β2 microglobulin) and inflammation and were highly prognostic for CAR-T-related toxicities and inferior progression-free survival (PFS). High MTV values were also associated with shorter PFS and inferior overall survival. The poor correlation observed between these 2 measures prompted evaluation of those with discordant results, identifying that those with low sBCMA and high MTV frequently had low/absent BCMA expression on plasma cells and suboptimal response. Our findings highlight the potential utility of sBCMA and MTV to facilitate more personalized treatment strategies in the management of RRMM eligible for BCMA-directed CAR-T.

Immunomodulatory drugs (IMiDs) are a major class of drugs for treating multiple myeloma (MM); however, acquired resistance to IMiDs remains a significant clinical challenge. Although alterations in cereblon and its pathway are known to contribute to IMiD resistance, they account for only 20% to 30% of cases, and the underlying mechanisms in the majority of the resistance cases remain unclear. Here, we identified adenosine deaminase acting on RNA1 (ADAR1) as a novel driver of lenalidomide resistance in MM. We showed that lenalidomide activates the MDA5-mediated double-stranded RNA (dsRNA)-sensing pathway in MM cells, leading to interferon (IFN)-mediated apoptosis, with ADAR1 as the key regulator. Mechanistically, ADAR1 loss increased lenalidomide sensitivity through endogenous dsRNA accumulation, which in turn triggered dsRNA-sensing pathways and enhanced IFN responses. Conversely, ADAR1 overexpression reduced lenalidomide sensitivity, attributed to increased RNA editing frequency, reduced dsRNA accumulation, and suppression of the dsRNA-sensing pathways. In summary, we report the involvement of ADAR1-regulated dsRNA sensing in modulating lenalidomide sensitivity in MM. These findings highlight a novel RNA-related mechanism underlying lenalidomide resistance and underscore the potential of targeting ADAR1 as a novel therapeutic strategy.

Initial clinical trials with drugs targeting epigenetic modulators, such as bromodomain and extraterminal protein (BET) inhibitors, demonstrate modest results in acute myeloid leukemia (AML). A major reason for this involves an increased transcriptional plasticity within AML, which allows the cells to escape therapeutic pressure. In this study, we investigated the immediate epigenetic and transcriptional responses after BET inhibition and demonstrated that BET inhibitor-mediated release of bromodomain-containing protein 4 from chromatin is accompanied by acute compensatory feedback that attenuates downregulation or even increases the expression of specific transcriptional modules. This adaptation is marked at key AML maintenance genes and is mediated by p300, suggesting a rational therapeutic opportunity to improve outcomes by combining BET and p300 inhibition. p300 activity is required during all steps of resistance adaptation; however, the specific transcriptional programs that p300 regulates to induce resistance to BET inhibition differ, in part, between AML subtypes. As a consequence, in some AMLs, the requirement for p300 is highest during the earlier stages of resistance to BET inhibition, when p300 regulates transitional transcriptional patterns that allow leukemia-homeostatic adjustments. In other AMLs, p300 shapes a linear resistance to BET inhibition and remains critical throughout all stages of the evolution of resistance. Altogether, our study elucidates the mechanisms that underlie an "acute" state of resistance to BET inhibition, achieved through p300 activity, and how these mechanisms remodel to mediate "chronic" resistance. Importantly, our data also suggest that sequential treatment with BET and p300 inhibition may prevent resistance development, thereby improving outcomes.

We have identified a new inherited bone marrow failure syndrome with severe congenital neutropenia (CN) caused by autosomal recessive mutations in the coatomer protein complex I (COPI) subunit zeta 1 (COPZ1) gene. A stop-codon COPZ1 mutation and a missense (MS) mutation were found in 3 patients from 2 unrelated families. Although 2 affected siblings with a stop-codon COPZ1 mutation suffered from CN that involves other hematologic lineages and nonhematologic tissues, the patient with a MS COPZ1 mutation had isolated neutropenia. Both COPZ1 mutations were localized to a highly evolutionarily conserved region. The resulting truncated (TR) COPZ1 protein was predicted to display diminished interaction with its COPI complex partner, COPG1. These findings were consistent with the observed block in retrograde protein transport from the Golgi apparatus to the endoplasmic reticulum (ER) in human fibroblasts carrying TR COPZ1. Human CD34+ cells with TR or MS COPZ1 had significantly impaired granulocytic differentiation, and in zebrafish embryos, TR Copz1 also resulted in defective myelopoiesis. Intracellularly, TR COPZ1 downregulated JAK/STAT/CEBPE/G-CSFR signaling and hypoxia-responsive pathways, while inducing STING, interferon-stimulated genes, stimulating oxidative phosphorylation activity, and increasing reactive oxygen species levels in hematopoietic cells. MS COPZ1 deregulated interferon and JAK/STAT signaling but less than the TR protein. Finally, treatment with the small molecule HIF1α stabilizer IOX2 or transduction of cells with COPZ2 restored defective granulopoiesis in COPZ1-mutated human CD34+ cells, offering potential therapeutic options.