We evaluated the prognostic and therapeutic significance of measurable residual disease (MRD) during remission induction in pediatric patients with acute lymphoblastic leukemia (ALL). In the Chinese Children Cancer Group ALL 2015 protocol, 7640 patients were categorized into low-, intermediate-, or high-risk groups based on clinical and genetic features. Final risk classification was determined by assessing MRD using flow cytometry on days 19 and 46 of remission induction with additional intensified chemotherapy for day 19 MRD ≥1%. Patients with B-ALL with negative MRD (<0.01%) on day 19 or day 46 had significantly better 5-year event-free survival (EFS) than those with MRD of between 0.01% and 0.99% who, in turn, had better EFS than patients with MRD of ≥1%. Provisional low-risk patients with day 19 MRD ≥1% but negative day 46 MRD who were reclassified as intermediate risk had a 5-year EFS that was comparable with that of low-risk patients with day 19 MRD of 0.3% to 0.99% and negative day 46 MRD (82.5% vs 83.0%) and better EFS than provisional low-risk patients with MRD on both days (83.0% vs 72.6%; P < .001). Similarly, patients with provisional intermediate-risk B-ALL with day 19 MRD ≥1% but negative day 46 MRD who received additional therapy had better 5-year EFS than those with day 19 MRD between 0.3% and 0.99% (70.7% vs 53.0%; P < .001). Among low-risk patients with negative day 46 MRD, those with negative day 19 MRD had superior EFS than those with positive day 19 MRD (91.7% vs 86.1%; P < .001). Optimal use of day 19 MRD could improve individualized treatment and outcomes. This trial was registered at www.chictr.org.cn as #ChiCTR-IPR-14005706.

Despite novel prophylactic regimens, chronic graft-versus-host disease (cGVHD) remains a challenging complication after allogeneic hematopoietic cell transplantation. cGVHD can affect multiple organs and reduces quality of life, and treatment can cause serious adverse effects. In the past 10 years, the drugs ibrutinib, ruxolitinib, belumosudil, and axatilimab were approved by the US Food and Drug Administration (FDA) for cGVHD. Here, we discuss which signaling pathways and cell types are targeted, the clinical studies that were the basis for FDA approval, and future directions for clinical research.

The term "unexplained cytopenia" is used to describe a condition characterized by peripheral blood cytopenia that cannot be attributed to identifiable causes using conventional tests or to any concomitant diseases. Unexplained cytopenia requires clinical attention and further investigation to identify individuals at risk of developing a hematologic neoplasm. The available evidence suggests that somatic mutation analysis may effectively complement the diagnostic workup and clinical management of unexplained cytopenia. Indeed, the presence or absence of somatic mutation(s) in myeloid genes shows high positive and negative predictive values for myeloid neoplasms (MNs). Mutation analysis is also crucial for identifying patients with clonal cytopenia of undetermined significance (CCUS), a condition at increased risk of developing a MN. Recently, clinical/molecular prognostic models have been developed, providing valuable tools for the personalization of clinical and molecular surveillance. Most patients with CCUS show mild cytopenia and do not require therapeutic intervention. Currently, there is no treatment approved for CCUS, and transfusion therapy is the sole therapeutic option for patients with severe symptomatic cytopenia. However, this field has been emerging as a domain of active clinical investigation. This article presents 4 case studies of patients with unexplained cytopenia, which hematologists may encounter in their clinical practice.

Significant progress in determining the molecular origins and resistance mechanisms of mantle cell lymphoma (MCL) has improved our understanding of the disease's clinical diversity. These factors greatly impact the prognosis of patients with MCL. Given the dynamic alterations in MCL clones and disease evolution, it is crucial to recognize high-risk prognostic factors at diagnosis and relapse. Clinical factors include a high MCL International Prognostic Index score with a high Ki-67 proliferation index, early disease progression within 24 months of first-line treatment, >3 previous lines of therapy at relapse, and an aggressive (blastoid or pleomorphic) histology. Molecular aberrations include dysregulated cyclin D1, an aberrant SOX11-CD70 axis, upregulated Musashi-2, MYC rearrangement, metabolic reprogramming, and epigenetic changes. Other factors that contribute to high-risk MCL include an immune-depleted microenvironment and clone adaptability with complex chromosomal anomalies and somatic mutations in TP53, NSD2, CCND1, CDKN2A, BIRC3, SP140, KMT2D, NFkBIE, SMARCA4, and NOTCH2. Ultra-high-risk MCL is indicated by the coexistence of multiple high-risk prognostic factors in the relapse setting and can portend very short progression-free survival. As MCL treatments advance toward cellular therapies, resistance to anti-CD19 chimeric antigen receptor T-cell therapy is also observed. These findings necessitate revisiting the prognostic impact of high-risk factors, current management strategies, new bi- and trispecific T-cell engagers, combination therapies, novel therapeutic targets, and next-generation clinical trials for patients with high-risk MCL. This article provides a comprehensive update on recognizing and managing high-risk MCL and encompass current practices and future directions.

Purpura fulminans (PF) is a rare but devastating complication of sepsis characterized by a highly thrombotic subtype of disseminated intravascular coagulation (DIC). A medical emergency, PF often requires the involvement of consultant hematologists to assist with diagnosis and management of patients who are in a highly dynamic and deteriorating clinical situation. Patients who survive past the first 24 to 72 hours often die from complications of unchecked thrombosis rather than shock, and survivors are usually left with severe scarring and tissue loss. Despite these challenging features, PF is a pathophysiologically distinct, homogeneous, and highly predictable form of sepsis-associated DIC for which poor outcomes are not a foregone conclusion. The fundamental pathologic lesion in PF is a failure of the anticoagulant protein C pathway, which leads to uncontrolled microvascular clotting and inadequate protein C-mediated cytoprotective effects, which are vital for survival in sepsis. Herein, we review the clinical features and diagnosis of PF. Drawing from existing clinical literature and recent advances in our understanding of the pathophysiology of PF, we describe rationally designed treatment approaches for this disorder, including repletion of natural circulating anticoagulants, use of therapeutic anticoagulation, and ways to optimize transfusion support, and we outline specific interventions that we would recommend avoiding.

Alloimmunization during pregnancy occurs when a mother produces antibodies against fetal antigens, leading to complications like hemolytic disease of the fetus and newborn (HDFN) and fetal and neonatal alloimmune thrombocytopenia (FNAIT). HDFN involves destruction of fetal red blood cells, potentially causing severe anemia, hydrops fetalis, and fetal death. FNAIT affects fetal platelets and possibly endothelial cells, resulting in risk of intracranial hemorrhage and brain damage. Traditional invasive methods for fetal antigen genotyping, like amniocentesis, carried miscarriage risks. The discovery of cell-free fetal DNA (cff-DNA) in maternal plasma enabled safe, noninvasive prenatal testing (NIPT). Initially used for Rhesus antigen D blood group typing, NIPT now covers various blood group antigens. Advances in technology have further enhanced the accuracy of NIPT. Despite challenges such as low cff-DNA fractions and complex genetic variations, NIPT has become essential in managing alloimmunized pregnancies. In NIPT it is important to prevent both false-positive results and false-negative results. Particularly in the coming decades, more possibilities for personalized antenatal treatment for HDFN and FNAIT cases will become apparent and accurate NIPT blood group antigen typing results are crucial for guiding clinical decisions. In this paper we describe this journey and provide practical tools for the clinic.

Patients with relapsed/refractory diffuse large B-cell lymphoma progressing after chimeric antigen receptor T-cell (CAR-T) therapy have dismal outcomes. The prespecified post-CAR-T expansion cohort of the ELM-1 study investigated the efficacy and safety of odronextamab, a CD20×CD3 bispecific antibody, in patients with disease progression after CAR-Ts. Sixty patients received IV odronextamab weekly for 4 cycles followed by maintenance until progression. The primary end point was objective response rate (ORR) by independent central review. The median number of prior lines of therapy was 3 (range, 2-9), 71.7% were refractory to CAR-Ts, and 48.3% relapsed within 90 days of CAR-T therapy. After a median follow-up of 16.2 months, ORR and complete response (CR) rate were 48.3% and 31.7%, respectively. Responses were similar across prior CAR-T products and time to relapse on CAR-T therapy. Median duration of response was 14.8 months and median duration of CR was not reached. Median progression-free survival and overall survival were 4.8 and 10.2 months, respectively. The most common treatment-emergent adverse event was cytokine release syndrome (48.3%; no grade ≥3 events). No cases of immune effector cell-associated neurotoxicity syndrome were reported. Grade ≥3 infections occurred in 12 patients (20.0%), 2 of which were COVID-19. Odronextamab monotherapy demonstrated encouraging efficacy and generally manageable safety, supporting its potential as an off-the-shelf option for patients after CAR-T therapy. This trial was registered at www.clinicaltrials.gov as #NCT02290951.

Multiple myeloma (MM)-induced bone disease affects not only patients' quality of life but also their overall survival. Our previous work demonstrated that the gut microbiome plays a crucial role in MM progression and drug resistance. However, the role of altered gut microbiota in MM bone disease remains unclear. In this study, we show that intestinal Enterobacter cloacae is significantly enriched in patients with MM with osteolysis. Through fecal microbial transplantation and single bacterial colonization experiments in a 5TGM1 MM mouse model, we found that intestinal colonization of E cloacae promotes osteolysis by increasing circulating ammonium levels. Elevated ammonium promotes osteoclastogenesis by increasing Trap protein levels in osteoclast precursors and by acetylating and stabilizing chemokine ligand 3 protein in MM cells. Inhibition of ammonium synthesis, using E cloacae with a deleted dcd gene, along with probiotic supplementation, alleviated osteolysis in MM. Overall, our work suggests that E cloacae promotes osteolysis in MM by synthesizing ammonium. This establishes a novel mechanism and potential intervention strategy for managing MM with osteolysis.

B-cell acute lymphoblastic leukemia (B-ALL) is a rare malignancy in adults, with outcomes remaining poor, especially compared with children. Over the past 2 decades, extensive whole-genome studies have identified numerous genetic alterations driving leukemia, leading to the recognition of >20 distinct subtypes that are closely associated with treatment response and prognosis. In pediatric B-ALL, large correlation studies have made genetic classification a central component of risk-adapted treatment strategies. Notably, genetic subtypes are unevenly distributed according to age, and the spectrum of genetic alterations and their prognostic relevance in adult B-ALL have been less extensively studied, with treatment primarily based on the presence or absence of BCR::ABL1 fusion. This review provides an overview of genetic subtypes in adult B-ALL, including recent biological and clinical insights in well-established subtypes as well as data on newly recognized subtypes. Their relevance for risk classification, disease monitoring, and therapeutic management, including in the context of B-cell-directed therapies, is discussed. This review advocates for continuing efforts to further improve our understanding of the biology of adult B-ALL to establish the foundation of future precision medicine in B-ALL.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy with a poor prognosis and limited options for targeted therapies. Identifying new molecular targets to develop novel therapeutic strategies is the pressing immediate issue in T-ALL. Here, we observed high expression of WD repeat-containing protein 5 (WDR5) in T-ALL. With in vitro and in vivo models, we demonstrated the oncogenic role of WDR5 in T-ALL by activating cell cycle signaling through its new downstream effector, ATPase family AAA domain-containing 2 (ATAD2). Moreover, the function of a zinc finger transcription factor of the Kruppel family (IKAROS) is often impaired by genetic alteration and casein kinase II (CK2) which is overexpressed in T-ALL. We found that IKAROS directly regulates WDR5 transcription; CK2 inhibitor, CX-4945, strongly suppresses WDR5 expression by restoring IKAROS function. Last, combining CX-4945 with WDR5 inhibitor demonstrates synergistic efficacy in the patient-derived xenograft mouse models. In conclusion, our results demonstrated that WDR5/ATAD2 is a new oncogenic signaling pathway in T-ALL, and simultaneous targeting of WRD5 and CK2/IKAROS has synergistic antileukemic efficacy and represents a promising potential strategy for T-ALL therapy.

BMT CTN (Blood and Marrow Transplant Clinical Trials Network) 1506 ("MORPHO") was a randomized study of gilteritinib compared with placebo as maintenance therapy after hematopoietic cell transplantation (HCT) for patients with FLT3-ITD-mutated acute myeloid leukemia (AML). A key secondary end point was to determine the impact on survival of before and/or after HCT measurable residual disease (MRD), as determined using a highly sensitive assay for FLT3-ITD mutations. Generally, gilteritinib maintenance therapy was associated with improved relapse-free survival (RFS) for participants with detectable peri-HCT MRD, whereas no benefit was evident for those lacking detectable MRD. We conducted a post hoc analysis of the data and found that the level of MRD detected with this approach correlated remarkably with RFS and relapse risk, and that MRD detectable at any level negatively affected RFS. In the placebo arm, 42.2% of participants with detectable FLT3-ITD MRD relapsed compared with 13.4% of those without detectable MRD. We found that 14.8% of participants had multiple FLT3-ITD clones detected as MRD and had worse survival irrespective of treatment arm. Finally, we examined the kinetics of FLT3-ITD clonal relapse or eradication and found that participants on the placebo arm with detectable MRD relapsed rapidly after HCT, often within a few weeks. MRD-positive participants on the gilteritinib arm relapsed either with FLT3 wild-type clones (assessed by capillary electrophoresis), after cessation of gilteritinib with persistent MRD, or on progression of multiclonal disease. These data demonstrate the potential of FLT3-ITD MRD to guide therapy with gilteritinib for this subtype of AML. This trial was registered at www.clinicaltrials.gov as #NCT02997202.

The maintenance of cellular redox balance is crucial for cell survival and homeostasis and is disrupted with aging. Selenoproteins, comprising essential antioxidant enzymes, raise intriguing questions about their involvement in hematopoietic aging and potential reversibility. Motivated by our observation of messenger RNA downregulation of key antioxidant selenoproteins in aged human hematopoietic stem cells (HSCs) and previous findings of increased lipid peroxidation in aged hematopoiesis, we used selenocysteine transfer RNA (tRNASec) gene (Trsp) knockout (KO) mouse model to simulate disrupted selenoprotein synthesis. This revealed insights into the protective roles of selenoproteins in preserving HSC stemness and B-lineage maturation, despite negligible effects on myeloid cells. Notably, Trsp KO exhibited B lymphocytopenia and reduced HSCs' self-renewal capacity, recapitulating certain aspects of aged phenotypes, along with the upregulation of aging-related genes in both HSCs and pre-B cells. Although Trsp KO activated an antioxidant response transcription factor NRF2, we delineated a lineage-dependent phenotype driven by lipid peroxidation, which was exacerbated with aging yet ameliorated by ferroptosis inhibitors such as vitamin E. Interestingly, the myeloid genes were ectopically expressed in pre-B cells of Trsp KO mice, and KO pro-B/pre-B cells displayed differentiation potential toward functional CD11b+ fraction in the transplant model, suggesting that disrupted selenoprotein synthesis induces the potential of B-to-myeloid switch. Given the similarities between the KO model and aged wild-type mice, including ferroptosis vulnerability, impaired HSC self-renewal and B-lineage maturation, and characteristic lineage switch, our findings underscore the critical role of selenoprotein-mediated redox regulation in maintaining balanced hematopoiesis and suggest the preventive potential of selenoproteins against aging-related alterations.

Philadelphia chromosome-like B-cell acute lymphoblastic leukemia (Ph-like ALL) is driven by genetic alterations that induce constitutive kinase signaling and is associated with chemoresistance and high relapse risk in children and adults. Preclinical studies in the most common CRLF2-rearranged/JAK pathway-activated Ph-like ALL subtype have revealed variable responses to JAK inhibitor-based therapies, suggesting incomplete oncogene addiction and highlighting a need to elucidate alternative biologic dependencies and therapeutic vulnerabilities, whereas the ABL-class Ph-like ALL subtype seems preferentially sensitive to SRC/ABL- or PDGFRB-targeting inhibitors. Which patients may be responsive vs resistant to tyrosine kinase inhibitor (TKI)-based precision medicine approaches remains a critical knowledge gap. Using bulk and single-cell multiomics analyses, we profiled residual cells from CRLF2-rearranged or ABL1-rearranged Ph-like ALL patient-derived xenograft models treated in vivo with targeted inhibitors to identify TKI-resistant subpopulations and potential mechanisms of therapeutic escape. We detected a specific MYC dependency in Ph-like ALL cells and defined a new leukemia cell subpopulation with senescence-associated stem cell-like features regulated by AP-1 transcription factors. This dormant ALL subpopulation was effectively eradicated by dual pharmacologic inhibition of BCL-2 and JAK/STAT or SRC/ABL pathways, a clinically relevant therapeutic strategy. Single cell-derived molecular signatures of this senescence and stem/progenitor-like subpopulation further predicted poor clinical outcomes associated with other high-risk genetic subtypes of childhood B-ALL and thus may have broader prognostic applicability beyond Ph-like ALL.

Monoclonal antibodies (mAbs) improve survival of patients with mature B-cell malignancies. Fcγ receptor-dependent effector mechanisms kill tumor cells but can promote antigen loss through trogocytosis, contributing to treatment failures. Cell-bound mAbs trigger the complement cascade to deposit C3 activation fragments and lyse cells. Within 24 hours after ofatumumab administration to patients with chronic lymphocytic leukemia (CLL), circulating tumor cells had lost CD20 and were opsonized with C3d, the terminal covalently bound form of complement protein C3. We hypothesized that C3d provides a target to eliminate residual CD20- tumor cells. To test this hypothesis, we generated C8xi, a mouse/human chimeric immunoglobulin G1 (IgG1) that reacts with human but not mouse C3d. C8xi was effective in a patient-derived xenograft model against CD20-, C3d opsonized CLL cells from patients treated with ofatumumab. We also generated rabbit mAbs, 2 of which were chosen because they bound mouse and human C3d with low nanomolar affinity but were minimally cross-reactive with full-length C3. Anti-C3d rabbit/human chimeric IgG1 in combination with ofatumumab or rituximab prolonged survival of xenografted mice that model 3 different types of non-Hodgkin lymphoma (NHL). For example, in a diffuse large B-cell lymphoma model (SU-DHL-6), median survival with single-agent CD20 mAb was 114 days but was not reached for mAb combination treatment (P = .008). In another NHL model (SU-DHL-4), single-agent and combination mAb therapy eradicated lymphoma in most mice. In long-term survivors from both cohorts, there was no evidence of adverse effects. We propose that C3d mAbs combined with complement-fixing CD20 mAbs can overcome antigen-loss escape and increase efficacy of mAb-based therapy.

One of the most remarkable achievements of the TKI era has been the capacity to induce deep molecular remissions that are sustainable off therapy in chronic myeloid leukemia (CML) patients - treatment-free remission (TFR). TFR was first described in a handful of patients within 3-4 years of imatinib approval. In 2004 TFR was tested in a small French pilot study, followed soon after by the French STIM and Australasian TWISTER studies. These early trials demonstrated that TFR was achievable, but also showed that rapid relapse was equally likely. Perhaps the most critical observation was that relapsing patients could be rapidly and safely returned to deep molecular remission after restarting therapy, minimising the risk associated with TFR attempts. Consensus criteria for TFR eligibility were established soon after those studies were reported. Over the past decade TFR criteria have been broadened, key predictive markers of success identified, and overall safety of TFR in the wider clinical community confirmed. Despite this progress, TFR is still only achieved in a fraction of CML patients globally. Over the next decade the focus will be making TFR the mainstream pathway for as many patients as possible as well as scaling back the duration of therapy required. More potent, better targeted TKIs, and immune modulation will likely have a significant impact. Predictive assays should enable most patients who attempt TFR to do so with a high probability of success. Ultimately TFR should be seen as the first step on an ambitious pathway towards cure for CML patients.

High-dose methotrexate (MTX) results in high rates of acute kidney injury (AKI), neutropenia, and hepatotoxicity. Glucarpidase is a recombinant enzyme that cleaves MTX, but clinical data supporting its use are scarce. We examined the association between glucarpidase administration and outcomes in adults with MTX-AKI from 28 cancer centers across the United States using a sequential target trial emulation framework. The primary end point was kidney recovery at hospital discharge, defined as survival to discharge with serum creatinine <1.5-fold baseline and without dialysis dependence. Key secondary end points were time to kidney recovery, neutropenia, and transaminitis on day 7, and time to death. Using multivariable logistic and Cox regression models, we compared outcomes in patients who received glucarpidase within 4 days following MTX initiation with those in patients who did not. Among 708 patients with MTX-AKI, 209 (29.5%) received glucarpidase. Overall, 183 (25.8%) had a primary end point event. Glucarpidase receipt was associated with a 2.70-fold higher adjusted odds of kidney recovery (95% confidence interval [CI], 1.69-4.31) compared with no glucarpidase receipt. Patients treated with glucarpidase also had faster time to kidney recovery (adjusted hazard ratio [aHR], 1.88; 95% CI, 1.18-3.33) and lower risks of grade ≥2 neutropenia (adjusted odds ratio [aOR], 0.50; 95% CI, 0.28-0.91) and grade ≥2 transaminitis (aOR, 0.50; 95% CI, 0.28-0.91) on day 7. There was no difference in time to death (aHR, 0.76; 95% CI, 0.49-1.18). These data suggest glucarpidase may improve both renal and extrarenal outcomes in patients with MTX-AKI.