Intestinal Enterococcus domination has been associated with an increased risk of mortality from acute graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (allo-HCT), a curative-intent treatment for patients with hematologic malignancies. In this study, we investigated interactions between Enterococcus and the intestinal epithelium as a mechanism to aggravate GVHD. We observed that endogenous intestinal Enterococcus outgrowth was associated with increased GVHD mortality and major histocompatibility complex class II (MHC-II) expression by intestinal epithelial cells in the colon in an MHC-disparate mouse model of GVHD. Monocolonization of nontransplanted gnotobiotic mice with Enterococcus faecalis was sufficient to induce colonic MHC-II expression. Conversely, select species within the genus Enterococcus, as well as a consortium of 4 anaerobic commensal bacteria including Blautia producta, did not affect colonic MHC-II expression in gnotobiotic mice. In addition, E faecalis colonization induced inflammatory responses in CD4+ T cells and natural killer cells from the colonic lamina propria, the 2 main sources of interferon gamma production that drives MHC-II expression in nonprofessional antigen-presenting cells. We further explored the potential therapeutic benefit of establishing colonization resistance against E faecalis through administration of a lantibiotic-producing B producta strain after allo-HCT. Colonization of transplanted mice with a consortium of commensal bacteria containing the lantibiotic-producing B producta strain prevented intestinal Enterococcus domination after transplantation and improved GVHD survival. Our results demonstrate a potential mechanism by which Enterococcus aggravates GVHD through increased MHC-II expression in the intestinal epithelium. Targeting the Enterococcus-epithelium-MHC-II axis thus presents a therapeutic opportunity to prevent lethal GVHD.

NUTM1 rearrangement defines a significant subset of B-cell acute lymphoblastic leukemia (B-ALL), particularly in infants lacking KMT2A rearrangements, yet its underlying molecular characteristics remain poorly understood. Here, we establish that NUTM1-rearranged (NUTM1-r) leukemia is a discrete entity characterized by a unique transcriptional and epigenetic landscape, notably featuring global DNA hypomethylation, irrespective of the 5' fusion partner. Functional interrogation of NUTM1 fusions reveals a dual oncogenic role: they drive commitment toward the B-lymphoid lineage while concurrently conferring potent leukemic stem cell properties. Strikingly, expression of a representative fusion, BRD9-NUTM1, is sufficient to induce serially transplantable B-cell progenitor, prepro-B-like leukemia in vivo, faithfully recapitulating the key molecular and immunophenotypic features of human NUTM1-r B-ALL. Mechanistically, NUTM1 fusions establish an aberrant chromatin state, marked by global enhancement of H3K27 acetylation and the creation of distinctive open chromatin regions that co-opt both B-lineage and stemness-related transcriptional programs, including those involving NF-κB and posterior HoxA genes. In stark contrast to resistant KMT2A-rearranged leukemias, NUTM1-r leukemic cells exhibit a profound sensitivity to chemotherapy. This vulnerability is mechanistically linked to the leukemia's dependence on active transcription. Our findings delineate the unique molecular profile of NUTM1-r leukemias, revealing specific vulnerabilities that rationalize their favorable clinical outcomes and suggest opportunities for modified therapeutic strategies.

High levels of circulating tumor cells (CTC) are a powerful predictor of poor outcomes in newly diagnosed multiple myeloma, yet the mechanistic underpinnings of this correlation remain unknown. To investigate whether CTC-related pathobiology is driven by a specific CTC subset, paired bone marrow and blood samples from patients with newly diagnosed multiple myeloma were analyzed by single-cell transcriptomics and whole-genome sequencing. This revealed that down to the individual clone level, CTC and paired bone marrow cells are transcriptionally similar, without evidence for a distinct circulating population. In contrast, bone marrow myeloma cells from patients with high CTC levels had increased proliferation and unbalanced primary genetic events, including enrichment for MAF and CCND translocations. To investigate the impact of heterogenic genomic events on CTC levels, whole-exome and bulk RNA sequencing from the Multiple Myeloma Research Foundation CoMMpass data set were analyzed and validated in our in-house data sets. Bone marrow tumor cells from patients with high CTC levels were uniformly characterized by transcriptomic signatures of proliferation. Furthermore, CTC levels were uniquely dependent on primary genomic events and high-risk secondary genomic events, including amplification 1q, deletion 1p, deletion 13q, biallelic TP53 mutations, and increased apolipoprotein B editing complex-induced mutations even in patients without MAF translocations. Finally, we developed a model that predicts the impact of genetic alterations and tumor burden on CTC levels. In sum, we reveal that CTC are the net result of tumor burden, primary translocations, and secondary genomic events, making CTC a powerful biomarker for genomics-driven high-risk disease in patients with newly diagnosed myeloma.

The use of posttransplant cyclophosphamide was initially pioneered as a means of permitting haploidentical transplantation across HLA barriers. This approach has now become a standard of care for the prevention of significant acute and chronic graft-versus-host disease (GVHD) after related and unrelated HLA-matched allogeneic peripheral blood stem cell transplant across a full spectrum of conditioning intensities. This article discusses recent advances, the mechanisms of action, and important unresolved questions in the prevention of GVHD that will help inform new prospective clinical studies.

Sickle cell disease (SCD) and β-thalassemia are devastating genetic disorders resulting from defects in the β-globin subunit of adult hemoglobin. Both disorders are ameliorated by the induction of γ-globin, a component of fetal hemoglobin (HbF). Therefore, the development of safe, effective, and widely available inducers of HbF is needed. Here, we discovered that slow cycling erythroid cells exhibit increased γ-globin expression. To understand the molecular basis of this, we screened all cyclin-dependent kinase inhibitors (CDKIs) for their ability to induce HbF using CRISPR activation. We found that overexpression of CDKN1B, which encodes p27Kip1 (but not overexpression of other CDKIs), induces γ-globin expression at the transcriptional level. CDKN1B mutants expressing proteins unable to bind/inhibit CDKs and/or cyclins revealed that γ-globin induction by p27Kip1 depends largely on the domains involved in its cell cycle function. Pharmacological inhibition and genetic reduction of CDK4/6 also result in increased HbF. In genetic rescue experiments, we show that p27Kip1 induces HbF by inhibiting CDK4/6, through a mechanism that is likely BCL11A and ZBTB7A independent. Furthermore, palbociclib, an oral CDK4/6 inhibitor, significantly increases HbF in a murine SCD model at doses that are well tolerated. Moreover, we show that HbF induction by hydroxyurea, a drug currently in use to treat SCD, may be mediated in part by CDK4/6 inhibition. Overall, our findings establish a causal relationship between CDK4/6 activity and γ-globin production and suggest that single or dual CDK4/6 inhibitors might be therapeutically beneficial for SCD and β-thalassemia.

Venous thromboembolism (VTE) remains a leading contributor to maternal morbidity and mortality during pregnancy and the immediate postpartum period. Although pregnancy is recognized as a hypercoagulable state, the molecular mechanisms underlying this prothrombotic shift remain incompletely characterized. In this study, lactoferrin was identified as an enhancer of coagulation factor XIa (FXIa) activity. Elevated plasma concentrations of lactoferrin were observed in pregnant women and found to be estrogen dependent, mediated through estrogen response elements (EREs) within the lactoferrin gene promoter. In murine models, pregnancy-induced thrombotic pathology was ameliorated by either genetic knockout of lactoferrin or pharmacological blockade using HS9, a peptide that selectively inhibits lactoferrin-mediated potentiation of FXIa. Notably, HS9 (1 mg/kg) exhibited a substantially reduced hemorrhagic profile compared with low-molecular-weight heparin. These findings identify lactoferrin as a physiological modulator of gestational hypercoagulability and implicate it as a potential therapeutic target for pregnancy-associated VTE, with the capacity to reduce thrombotic risk while preserving hemostatic integrity.

Infections remain a challenge during treatment of patients with multiple myeloma (MM) with anti-B-cell maturation antigen (BCMA) and anti-G protein-coupled receptor class C group 5 member D (GPRC5D) bispecific antibodies (bsAbs). However, the mechanism underlying different rates and severity of infections induced by the 2 bsAbs remains poorly understood. Single-cell RNA sequencing of bone marrow (BM) aspirates of 11 patients with MM and 8 healthy donors revealed BCMA expression on mature B cells and, surprisingly, in small pre-B cells within B-cell precursors. GPRC5D expression was restricted to malignant and less to normal plasma cells (PCs). Next-generation flow cytometry immune profiling showed that anti-BCMA bsAbs severely depleted BM mature B cells, from 4.9% to 0% (P< .001), and normal PCs, from 0.17% to <0.0002% (P< .001), during treatment of 62 patients with relapsed MM. This was observed throughout therapy. Additional flow cytometry (n = 31) and single-cell RNA sequencing studies (n = 8) demonstrated that, in contrast to anti-GPRC5D, anti-BCMA bsAbs also depleted immature and small pre-B cells. The MIcγ1 mouse model was used as a negative control of BCMA expression in all stages of the B-cell lineage, confirming no depletion of any B-cell subset after anti-BCMA treatment. In conclusion, we show that although GPRC5D bsAbs selectively target PCs, anti-BCMA bsAbs target both PCs and B cells from the small pre-B stage onward. Our study provides mechanistic insight into the increased infection risk with anti-BCMA therapy and supports individualized bsAb strategies in MM. Moreover, dual targeting of B cells and PCs may have therapeutic potential in other B-cell malignancies or autoimmune diseases.

Antibody-drug conjugates (ADCs) have emerged as promising targeted therapies for acute myeloid leukemia (AML). However, most ADCs exhibit off-target binding to normal hematopoietic stem and myeloid progenitor cells, resulting in adverse hematotoxicity and narrow therapeutic windows, thereby limiting their clinical application to young and fit patients with AML who are eligible for intensive curative therapies. Proteoglycans with high levels of the glycosaminoglycan oncofetal chondroitin sulfate (ofCS) are abundantly expressed in solid cancers but are absent or expressed at low levels in normal adult tissues. Here, we report high ofCS levels on bone marrow (BM) cells from patients with AML and patient-derived xenografts (PDXs) from these patients, whereas BM cells from healthy individuals showed low or undetectable ofCS levels. Consistently, an anti-ofCS antibody demonstrated binding to and internalization into AML cells, and anti-ofCS ADCs effectively killed AML cells in vitro. Moreover, anti-ofCS ADC treatment significantly prolonged survival of AML PDXs compared with controls and was associated with low toxicity. Thus, anti-ofCS ADCs could represent an effective therapy with acceptable toxicity for patients with AML, including those who are ineligible for or unresponsive to current intensive curative therapies. In conclusion, this study demonstrates, to our knowledge for the first time, that a glycosaminoglycan-like ofCS is a druggable target for the development of effective antibody-based AML therapies.

Combination therapy incorporating programmed cell death protein 1 (PD-1) blockade results in unprecedented response rates in both frontline and relapsed/refractory (R/R) classical Hodgkin lymphoma (cHL). Previous retrospective studies have suggested benefit for PD-1 blockade before autologous stem cell transplant (ASCT) but included few patients receiving PD-1 blockade with cytotoxic chemotherapy. To explore the impact of anti-PD-1 based salvage on outcomes for patients with R/R cHL, we retrospectively reviewed 1280 patients with R/R cHL who underwent ASCT from 2010 to 2022 at 6 transplant centers, none of whom received PD-1 blockade as part of frontline therapy. Overall, 25% received a PD-1 inhibitor at any point before ASCT (10% in conjunction with chemotherapy), 28% received salvage brentuximab vedotin (BV) without PD-1 blockade, and the rest received salvage chemotherapy alone. Patients who received PD-1 inhibitors at any point before ASCT had a significantly higher 2-year progression-free survival than those who received BV without PD-1 inhibitors or patients receiving chemotherapy alone (88.2%, 70.2%, and 67.4%, respectively; P< .0001). When restricted to patients in complete response before ASCT, the benefit of PD-1 blockade remained significant. PD-1 blockade before ASCT is independently associated with superior post-ASCT outcomes and patients proceeding to ASCT should be treated with PD-1-based salvage.

BTK inhibitors improve outcomes for patients with chronic lymphocytic leukemia (CLL). Long-term data with continuous therapy are limited. With a median follow-up of 10.0 years, we report final results on 84 patients with TP53 aberrations (del(17p) or TP53 mutation) or ≥65 years of age treated with 420mg of single-agent ibrutinib daily until progression or unacceptable toxicity. 52 (61.9%) patients were previously untreated, 56 (66.7%) had unmutated IGHV, and 53 (63.1%) had TP53 aberrations, including 34 who were treatment-naive. As of July 31, 2024, 9 (10.7%) patients continued ibrutinib, 39 (46.4%) discontinued ibrutinib for progressive disease, 31 (36.9%) for adverse events, and 5 (5.9%) withdrew consent. The median progression-free survival (PFS) was 7.2 years; median overall survival (OS) was not reached. In patients with and without TP53 aberrations, median PFS was 5.6 years and not reached, and 10-year OS was 51.3% and 75.3%, respectively. The estimated 10-year PFS and OS for patients with TP53-aberrant CLL treated in first line was 38.6% and 65.7%, respectively. Minimal residual disease (MRD) was quantified by peripheral blood flow cytometry annually. Undetectable MRD (at 10-4) was achieved in 13 (15.5%) patients after a median of 5 years. Twelve patients maintained uMRD, the longest observation ongoing at 8.0 years. Seventeen (42.5%) patients with best response of high MRD (>10-2) remained progression-free for over 5 years. These results highlight durable benefits and deepening responses with ibrutinib, including in high-risk CLL. Whether patients maintaining uMRD for years can safely discontinue therapy should be assessed prospectively. Clinicaltrials.gov: NCT01500733.

Proinflammatory signaling is a hallmark of myeloproliferative neoplasms. Several studies have shown that monocytes are a major source of proinflammatory cytokines and that monocyte-derived fibrocytes play a pivotal role in the pathogenesis of myelofibrosis (MF). To further explore the role of monocytes in MF, we generated inducible NrasG12D/+Jak2V617F/+ (NJ) mice. Recipients transplanted with NJ bone marrow (BM) cells developed MF with an early onset of anemia and monocytosis. In vitro, NJ recipients' BM nucleated cells exhibited an increased quantity of CD45+CollagenI+ fibrocytes, which were mainly derived from the Ly6chigh monocytes. RNA sequencing identified a significant elevated expression of CD38 (a NAD+ hydrolase) in Ly6chigh monocytes from NJ mice, which results in a pronounced lower level of NAD+. In humans, CD14+ monocytes from patients with MF showed a significantly higher expression of CD38 than controls and monocytes from patients with polycythemia vera with grade 1 fibrosis had higher CD38 expression than those without fibrosis. Finally, boosting NAD+ via pharmacological CD38 targeting or NAD+ precursor supplementation inhibited the differentiation of fibrocytes in vitro and targeting CD38 can effectively prevent the onset of fibrosis in vivo. Collectively, our findings shed light on the role of CD38 in monocytes and suggest potential clinical applications such as the use of CD38 as a biomarker of fibrotic progression and the clinical utility of CD38 inhibition in patients with MF.

The evolutionary history of cancers is encoded in molecular patterns that provide critical insights into the mechanisms of tumor progression. However, reconstructing cancer lineages in patient tumors remains challenging, as conventional sequencing captures only static snapshots of an ongoing evolutionary process. DNA methylation at CpG sites is a heritable epigenetic mark that accumulates stochastic errors - termed epimutations - at rates far exceeding those of somatic DNA mutations. These epimutations serve as a 'molecular clock' and can be harnessed for retrospective lineage tracing. When applied at single-cell resolution, methylation-based lineage tracing enables the reconstruction of cancer phylogenies and provides a powerful framework for studying the dynamics of treatment resistance, cell-state heritability, and metastasis directly in human tumors. In this review, we outline the strengths and challenges of single-cell DNA methylation-based lineage tracing, highlight key insights gained from its application with an emphasis on hematological cancers where relevant, and discuss its future potential in advancing our understanding of cancer evolution.

Many patients receiving frontline tyrosine kinase inhibitors (TKIs) for chronic-phase chronic myeloid leukemia (CML-CP) experience inadequate disease control and/or adverse events (AEs) that impair quality of life. Treatments offering optimal efficacy, safety, and tolerability will support long-term therapy. In the primary analysis from the ASC4FIRST trial, a phase 3 randomized trial comparing asciminib with investigator-selected TKIs (IS-TKIs) in newly diagnosed CML-CP, asciminib demonstrated superior efficacy vs all IS-TKIs and vs imatinib in the imatinib stratum, meeting both primary objectives. In the secondary analysis (2.2 years' median follow-up), major molecular response (MMR) rate at week 96 was 74.1% with asciminib vs 52.0% with IS-TKIs (treatment difference, 22.4% [95% confidence interval (CI), 13.6-31.3]; 1-sided P< .001) and 76.2% with asciminib vs 47.1% with imatinib in the imatinib stratum (treatment difference, 29.7% [95% CI, 17.6-41.8]; 1-sided P< .001), meeting both key secondary objectives. MMR rate was 72.0% with asciminib vs 56.9% with second-generation (2G) TKIs (treatment difference, 15.1% [95% CI, 2.3-28.0]; 1-sided P< .05), suggesting possible clinical benefit, although the study was not designed to formally confirm statistical significance for this secondary end point. Safety/tolerability remained favorable with asciminib vs IS-TKIs. Dose reductions and interruptions, respectively, occurred with asciminib (18.5%; 46.5%), imatinib (23.2%; 47.5%), and 2G TKIs (54.9%; 63.7%). The hazard ratio for time to discontinuation of treatment due to AEs for asciminib vs 2G TKIs was 0.46 (95% CI, 0.215-0.997). With longer follow-up, asciminib continued to demonstrate a favorable benefit-risk profile over IS-TKIs and imatinib, supporting its potential as a treatment option for newly diagnosed CML-CP. This trial was registered at www.clinicaltrials.gov as NCT04971226.

Efficient derivation of transplantable hematopoietic stem cells (HSCs) from human pluripotent stem cells (hPSCs) is constrained by epigenetic silencing. Through a clustered regularly interspaced short palindromic repeats/Cas9 screen with a BCL11A-enhanced green fluorescent protein reporter, we identified the epigenetic reader SP140 as a suppressor of hematopoiesis. Transient genetic or pharmacologic inhibition of SP140 in hPSC-derived teratoma and embryoid body cultures promoted robust multilineage hematopoiesis and accelerated production of HSCs with serial transplantability and durable reconstitution in immunodeficient mice. Mechanistically, SP140 blockade unlocked transcription at endothelial-to-hematopoietic transition (EHT) loci through topoisomerase 1-dependent chromatin remodeling, activating key hematopoietic and stem cell programs. Transcriptomic analysis showed activation of these regulators upon SP140 inhibition, which was prevented by topoisomerase 1 blockade. Cleavage under targets and tagmentation profiling identified SP140 binding at EHT and HSC-specification gene loci. SP140's function as an epigenetic gatekeeper was conserved in diverse hPSCs and murine embryo models, where its downregulation enhanced physiological HSC emergence. Importantly, selective SP140 inhibition in a chemically defined, scalable protocol enabled rapid in vitro generation of bona fide human HSCs suitable for transplantation. These findings identify transient SP140 inhibition as an effective strategy to overcome epigenetic barriers and unlock clinically relevant HSC specification from hPSCs, advancing regenerative hematopoiesis and cell therapy.

Cancer develops through the interactions between cancer stem cells and components of the tumor microenvironment (TME). To model in vivo cancer stem cell-TME interactions and elucidate their functional consequences, we focused on myelofibrosis (MF), a stem cell-driven myeloproliferative neoplasm. We cocultured MF hematopoietic stem and progenitor cells (HSPCs) with normal donor endothelial cells (ECs) and mesenchymal stromal cells (MSCs) to investigate the consequences of interactions between malignant MF HSPCs and nonmalignant microenvironmental cells. This tricultivation system proved to be a simple and reproducible platform, which promoted malignant clone dominance and the persistence of MF HSPCs that recapitulate the MF phenotype upon transplantation into immunodeficient mice, including splenomegaly and marrow fibrosis. Transcriptional profiling revealed extensive reprogramming of not only the cocultured MF HSPCs, but also MSCs and ECs. Although numerous disease-relevant pathways were upregulated, the proinflammatory response stood out as a key consequence of MF HSPC-TME interactions. We validated these findings through quantitation of proinflammatory transcript upregulation and cytokine production. This human multicellular model system has proven useful in demonstrating the multidirectional interactions of MF HSPCs with TME cells that are essential for sustaining fully functional MF stem cells.

Leukemic stem cells (LSCs) in acute myeloid leukemia (AML) depend on oxidative phosphorylation (OXPHOS) sustained by fatty acid oxidation (FAO) and mitochondrial fusion (mitofusion). In this study, we demonstrate that microRNA-126 (miR-126) maintains LSC function by promoting B-cell lymphoma 2 (BCL-2)-dependent FAO, OXPHOS, and mitofusion, whereas its inhibition disrupts mitochondrial metabolism, induces mitochondrial fission (mitofission), and triggers apoptosis. Mechanistically, miR-126 stabilizes BCL-2 through the SPRED1/extracellular signal-regulated kinase axis, which upregulates CPT1B (FAO) and NRF2 (antioxidant response) while regulating mitochondrial dynamics through DRP1 phosphorylation (inhibiting mitofission) and MFN1/2 phosphorylation (enhancing mitofusion). miRisten, a CpG-conjugated anti-miR-126 oligonucleotide now in clinical trials (NCT07025564), synergized with venetoclax (VEN) to suppress FAO/OXPHOS, promote mitofission, and impair LSC homeostasis. In vivo, miRisten potentiated the VEN/azacitidine regimen, an US Food and Drug Administration-approved therapy for older or unfit patients with AML, significantly prolonging survival in patient-derived xenograft models. VEN/miRisten combination also reduced LSC burden and restored VEN sensitivity, establishing miR-126 inhibition as a transformative therapeutic strategy for AML.

Measurable residual disease (MRD) monitoring has become a critical component in the management of acute myeloid leukemia (AML), to inform prognosis, guide therapy, and serve as a key end point in clinical trials. The 2025 update of the MRD guideline provides a comprehensive and refined framework for MRD assessment, aligned with the European LeukemiaNet (ELN) 2022 genetic risk classification. Developed by members of the ELN AML MRD Working Party, the guidelines incorporate expert consensus determined through a 2-stage Delphi round. They address the clinical implementation of MRD methodologies, technical considerations, integration into clinical trials, and future directions. Importantly, MRD recommendations are tailored to individual prognostic and genetic subgroups. A new qualitative MRD response category, designated as optimal, warning, or high risk of treatment failure, has been introduced to facilitate contextual interpretation of the MRD burden and its clinical relevance. Notably, ultrahigh-sensitivity next-generation sequencing-based MRD assessment is now recommended for FLT3 internal tandem duplication-mutated AML after intensive chemotherapy and before allogeneic hematopoietic cell transplantation. A total of 56 recommendations were formulated, with 53 achieving a high level of consensus (≥90%). These updated guidelines represent a major step forward toward harmonizing MRD assessments in AML and enhancing its clinical utility across diverse treatment settings.

To prevent graft-versus-host disease (GVHD) in patients undergoing myeloablative allogeneic hematopoietic stem cell transplantation (alloHSCT), a calcineurin inhibitor plus methotrexate is routinely used. Early phase studies suggested improved outcomes with Orca-T, an allogeneic T-cell immunotherapy that uses purified donor regulatory T cells to prevent GVHD with significantly less immunosuppression. This phase 3 trial randomized adult patients (N = 187) with acute leukemias or myelodysplastic syndrome undergoing myeloablative conditioning to receive either Orca-T with tacrolimus or a conventional allograft with tacrolimus and methotrexate (Tac/MTX), using granulocyte colony-stimulating factor-mobilized peripheral blood from HLA-matched donors. The primary end point was survival free from moderate-to-severe chronic GVHD (cGVHD; cGFS). Using a stratified log-rank test, cGFS was significantly higher in the Orca-T arm than in Tac/MTX (hazard ratio, 0.26; 95% confidence interval, 0.14-0.47; P< .001). One-year estimates were as follows: cGFS was 78.0% with Orca-T vs 38.4% with Tac/MTX; cumulative incidence of moderate-to-severe cGVHD was 12.6% with Orca-T and 44.0% with Tac/MTX (Gray test P< .001); overall survival was 93.9% with Orca-T vs 83.1% with Tac/MTX (P = .12); GVHD-free and relapse-free survival was 63.1% and 30.9% in the Orca-T and Tac/MTX arms (P< .001), respectively; nonrelapse mortality (NRM) was 3.4% with Orca-T vs 13.2% with Tac/MTX (P = .03). Orca-T met the primary end point of improved survival free from cGVHD compared with Tac/MTX prophylaxis and should be considered a new therapeutic option with low toxicity for GVHD prophylaxis. Moreover, significantly less toxicity was observed with Orca-T patients, including fewer serious infectious complications and less NRM. This trial was registered at www.clinicaltrials.gov as NCT05316701.

Hemophagocytic lymphohistiocytosis (HLH) is an interferon gamma-driven hyperinflammatory syndrome with high morbidity and mortality. Identifying reliable prognostic biomarkers is challenging due to various predisposing conditions and triggers. C-X-C-motif ligand 9 (CXCL9) is a clinically validated biomarker and surrogate marker of interferon gamma-mediated inflammation. We aimed to identify the role of CXCL9 in predicting severe disease and death in adults with HLH using a multicenter retrospective cohort of consecutively hospitalized patients who underwent a clinical evaluation for HLH that included CXCL9 testing. Patients were classified as HLH if they met HLH-2004 and/or HScore criteria. Conditional inference decision trees and Cox regression models were used to identify which clinical variables associated with acute mortality in patients with HLH. Overall, 171 patients were reviewed, and 126 patients met HLH criteria. The median age was 55 years (interquartile range, 40-66), with 62% male and 51% White. CXCL9 was markedly elevated in patients with HLH. Unbiased decision tree modeling, incorporating all clinical laboratory values, identified only CXCL9 of >16 100 pg/mL as the optimal predictor of inpatient mortality. Cox regression models demonstrated that CXCL9 of >16 100 pg/mL was significantly associated with 90-day mortality when controlling for important covariates. This shorter time to death in the elevated CXCL9 subgroup remained significant even after subdividing patients into those with malignancy (n = 53) and nonmalignancy HLH (n = 73). Continuous increases in CXCL9 within the cohort strongly associated with greater mortality. CXCL9 is a novel clinical marker that identifies high-risk HLH independent of underlying disease and could be used to select patients for early and aggressive targeted immunomodulatory therapy.

Recent studies have reached opposing conclusions about whether clonal hematopoiesis (CH) is increased or decreased in patients with sickle cell disease (SCD). Given that CH is typically age-related, its presence in children with SCD could offer unique insights into early-life mutagenesis and disease-related stressors. We tested the primary and secondary hypotheses that children with SCD would have a higher prevalence of CH than age-, sex-, and race-matched children without SCD and that children with hydroxyurea would have a higher CH prevalence than children not treated with hydroxyurea. To address this, we conducted a cross-sectional study in 2 independent cohorts of children aged 0 to 18 years with SCD (N = 1025 and N = 1293, respectively) and a 2957-person matched comparison group. Using a highly sensitive, error-corrected sequencing assay capable of detecting CH at a variant allele frequency of ≥0.5%, we found that children with SCD have a significantly higher prevalence of CH than the comparison group (odds ratio [OR], 4.2; P = 7.4 × 10-13). In addition, CH was not associated with exposure to hydroxyurea therapy (OR, 0.76; P = .44).